Copyriglit]^" IfA k CQEiiRiGia' D£Posm Published under Supervision of A. Eugene Michel and Staff, Advertising Engineers, New York, and printed by Franklin Printing Co., Philadelphia STEAM HEATING ■A Manual of Practical Data Compiled by THE GENERAL ENGINEERING COMMITTEE OF WARREN ^YEBSTER & COMPANY Published by WARREN WERSTER & COMPANY CAMDEN, N. J. First Edition, Revised. May, 1922 Copyrighted 1922 by Warren Webster & Company Price $3.25 Net FOREWORD THE subject of Heating and Ventilation has been covered broadly in many handbooks that are available for reference, but there has been a demand also for a book of information confined exclusively to Steam Heating and covering that field in all necessary detail. Steam Heating is therefore the one topic of this volume and the editors have aimed to cover the subject with comprehensive data, arranged in such convenient and useful form as will best meet the needs of technical men in the engineering and contracting fields. The information given is authentic, being based upon actual practice and largely upon the experience of Warren Webster & Company, who, as pioneers, have specialized for more than thirty years in the effective use of steam for all heating purposes. Many of the designs and methods originated by this firm are now the recognized service standards. Special articles and helpful suggestions have been contributed by John A. Serrell, by the General Engineering Committee, and by John B. Dobson, Ralph T. Coe, William Roebuck, Russell G. Brown, Harry E. Gerrish, Howard H. Fielding, George A. Eagan, E. K. Lanning and other members of the Webster organization. "Steam Heating" offers the best thought of this organization, and as part of Webster Service, it is intended to be of real value throughout the pro- fession. The observance of good judgment and painstaking care in following its teachings will do much toward obtaining creditable and satisfactory results. If further explanations, additional information or helpful co-operation are desired, the Engineers and Service Men in the branch offices of Warren Webster & Company throughout the country are always available for consultation and assistance. CAMDEN, NEW JERSEY ^ WARREN WEBSTER & COMPANY JANUARY 1, 1922 General EiNgineering Committee OF Warren Webster & Company William M. Treadwell, Chairman John A. Serrell, Advisory Engineer WiUiam F. Bilyeu J. Logan Fitts Harry M. Miller Charles F. Eveleth Sidney E. Fenstermacher Rudolph G. Rosenbach 4 ©CI.A674256 nM 23 !922 CONTENTS PART L— STEAM HEATING PAGE Chapter I. — Elements of Steam Heating 9 Chapter H. — Data Required for Steam Heating- System Design 15 Topography 15 Location and character of soui'ce of heat 15 Exposiu'e and protective conditions 15 Outside temperatures 16 Floor plans, elevations and cross-sections 18 Inside temperature requirements 18 Contents and use of enclosure 19 Chai-acter and location of heating surface 19 Location of supply and retm'n lines 20 Chapter HI. — Heat Transmission 21 Chapter IV. — Air Infiltration 31 Chapter V. — Method of Calculating Heat Requirements 34 Chapter VI. — Method of Computing and Selecting Heating Surface. . . 42 Chapter VII. — Ventilation Problems as They Affect the Design of Heat- ing Systems 59 The fu-eplace 60 Dii-ect-indirect system of heating and ventilation 60 Indkect system of gravity ventilation 60 School buildings 61 Theatres and auditoriums; churches 63 Banquet halls, dining rooms, meeting halls, etc 64 Exhaust ventilation of industrial plants 65 Hot blast systems of heating for industrial plants 66 Factors entering design of complete heating and ventilating plant 67 Air quantities required for ventilation 67 Sizing of the ducts 68 Calculation of resistance or pressure 69 Selecting the apparatus ^. . 72 Size and arrangement of fans; heaters 72 Boiler horsepower requu-ed 73 Chapter VIII. — Proportioning of Chimneys 74 Chimneys for house-heating boilers 74 Chimneys and draft for power boilers 78 Draft 78 Draft formula 79 Draft losses and loss in stack 80 Height and diameter of stacks 81 Losses in flues 83 Loss in boilers and in the furnace 84 Draft required for different fuels 85 Bate of combustion 85 Solution of a problem 86 Correction in stack sizes for altitudes 87 5 Chapter IX.— Boilers 89 Chapter X. — Selection of the Proper Type of Steam Heating System . . 95 Size and type of building 97 Residences 97 Apartment buildings 97 Store and office buildings 97 Public buildings 98 Use of building, ._ 100 Location of building and topography of site 101 Construction and architectural features 103 Sources of steam supply 103 Operation and attention 107 Chapter XI. — Flow of Low-pressure Steam Through Piping 110 Flow of steam through pipes 110 Friction in run Ill Condensation loss 113 Effect of deflection, contraction and expansion 113 Pressure drop 114 Modulation systems 116 Vacuum systems 120 Sizing of piping 123 Vacuum system 123 Condensation allowances 124 Pressure drop for initial velocity 125 Modulation system 127 Chapter XII. — Critical Velocities in Radiator Run-Outs 132 Chapter XIII. — Vacuum Pumps and Auxiliary Equipment 137 Proportioning of steam end of reciprocating vacuum pump 143 Power-driven reciprocating vacuum pumps 143 Disposal of vacuum pump discharge 144 To waste 144 To air-separating tanks 144 To open vent tanks 145 To hydro-pneumatic tanks 147 To loop seal on tank outlet to heater or boiler 148 To receiver and boiler-feed or tank pump 148 Dry-vacuum pump receiver and water pump 150 Suction strainers 151 Vacuum governors 151 Chapter XIV. — Laboratory Tests of Return Traps 153 Tests for heating efficiency 154 PART II.— WEBSTER SYSTEM SPECIALTIES AND APPLICATIONS Chapter XV. — Webster Systems of Steam Heating 161 Webster Modulation Systems 161 Boilers operating up to 10-lb. pressure 162 Boiler pressure from 10-to 50-lb 163 Street system carrying any pressure 164 6 Chapter XV. — Continued Webster Vacuum Systems 165 With power boilers 165 Dripping supply mains and risers 167 Radiator cormections 169 Disposal of the products of condensation 170 The vacuum pump 170 Final disposal of the condensation 171 Ventilation problems 172 With medium-pressm'e boilers 172 With low-pressiu-e boilers 173 Steam furnished from street system 173 Special modifications 173 Webster Conserving System 173 Webster Hylo Vacuum System 176 Chapter XVI. — Applications of the Webster System to Lumber and Other Kiln-Drying Problems 179 Chapter XVII. — Apphcations of the Webster System to Slashers and to Cloth and Paper Drying Apparatus 188 Cloth and warp drying machines 190 Paper machines 192 Chapter XVIII. — Apphcations of the Webster System to Railroad Terminals and Steamship Piers 194 Chapter XIX. — Applications of the Webster System to Vacuum Pans and Similar Apparatus 196 Chapter XX. — Applications of the Webster System to Sterilizers, Cooking Kettles and Similar Apparatus 202 Hospital equipment 202 Cooking kettles, plate warmers, bain-maries, coffee m-ns and other kitchen equipment 204 Chapter XXI. — Applications of the Webster System to Greenhouses . . 205 Chapter XXII. — Installation Details 215 For Webster Vacuum System and Webster Modulation System 215 For Webster Vacuum System only 222 For Webster Modulation System only 228 Chapter XXIII. — Capacities and Ratings of Webster Valves and Traps 233 Modulation Supply Valves 234 Return Traps 237 Selection of Modulation Supply Valves and Return Traps 238 Heavy-duty Return Traps 239 Series 20 Modulation Vent Traps 239 Modulation Vent Valves 240 Chapter XXIV. — Appliances for Webster Systems of Steam Heating 241 Return traps 241 Sylphon Trap 242 No. 7 Trap 246 7 Chapter XXIV. — Continued Heavv-duty Trap, standard and high-differential types 247 Type W Modulation Valve 250 Double-service "\^alve 252 Oil Separators ' 254 Low-pressure Receiver Oil Separators 257 Grease and Oil Traps 257 Suction Strainer 258 Dirt. Strainers 259 Vacuum-pump Governor 260 Suction Strainer and Vapor Economizer 261 Lift Fittings, Series 20 .^ 263 Receiving Tanks 264 Water Accumulator 267 Gauges for Webster Systems 267 Modulation Vent Trap 268 Modulation Vent Valve 270 Damper Regulator 271 Hylo Vacuum-control Sets 272 Sylphon Conserving Valve 273 Low-pressure Roller Feeder, Series 16 274 High-pressure Sylphon Trap 275 Hydro-pneumatic Tanks 276 Expansion Joints 278 Steam Separators, Series 21 283 Chapter XXV. — Specifications for Webster Systems 286 A^acuum System 286 Modulation System 289 Chapter XXVI. — Webster Sylphon Trap Attachments 293 For Sylphonizing Webster Traps of eeu'lier types 293 No. 422 Webster Thermostatic Valves 294 Webster Motor Valves 294 No. 422 Webster Water-seal Motors 294 No. 522 Water-seal Traps 295 Multiple-unit Webster Valves of eai'lier types 296 For Sylphonizing radiator outlet valves of other makes 297 Chapter XXVII. — Fuel Saving by Preheating Boiler-feed Water ..... 301 Webster Feed-water Heaters 302 Standai'd Type 304 Preference Cut-out Heater 308 The Webster-Lea Heater Meter 313 PART III.— ADDENDA Chapter XXVIII. — Miscellaneous Useful Information 315 For lists of illustrations and tables, and detailed index, see back of book (Page 354). NOTE. — For convenient reference, each table, illustration and formula is given a compound number, the first part of which indicates the chapter and the second the sequence in that chapter. Example: Table 3-6 indi- cates the sixth table in Chapter 3. T Part I— Steam Heating CHAPTER I Elements of Steam Heating HE purpose of a heating system is to warm the interior of a structure to a desired degree of temperature and to maintain this condition against a lower exterior degree. It is usual to assume the exterior temperature to be the average minimum expected in the locality. To warm the interior and to maintain a given temperature, heat is required to replace thau which is absorbed by the contents and that trans- mitted tlu'ough the structure to the exterior. The unit measure of heat in English-speaking countries is the British thermal unit, which is the heat necessary to raise the temperature of one pound of water from 59 to 60 deg. fahr. This is commonly known as B.t.u., or heat unit. The quantity of heat required to raise the temperature of a given weight of a substance through one deg. fahr. as compared with the quantity of heat required to raise the same weight of water from 62 deg. to 63 deg. fahr. is called the specific heat of that substance. The heat content, or quantity of heat per degree of a given mass of a substance, is the product of its specific heat and its weight in pounds. The rate at which initial heat is required to raise the temperature of a cold structure and its contents to the desired degree in a given time may be much greater than that n,ecessary to maintain the required temperature after initial heating, or warming up, has been accomplished. The greater the length of time permitted for initial warming, the less difference there will be between the heat requirement per unit of time during initial heating and that required during subsequent maintenance. Heat losses by transmission tlirough various forms of building structure have been ascertained with more or less accuracy, and much information on this subject has been published from time to time. These data are being constantly improved as new forms of construction appear. The principal discrepancies between published data on transmission are probably due mainly to various allowances which have been included for infiltration. Infiltration, or air leakage, should be considered indei^endently of structural transmission. Local differences in workmanship and material of structure, as well as errors in obserA^ation, have further contributed to discrepancies, and in many instances the results of tests observed at one temperature difference have been reduced by direct proportion to a " per-degree-difference " basis. Until recently it has not been generally recognized that this last-men- tioned basis is in error, in that it is likely to give too high a rate of heat loss for smaller temperature difference and too low a rate for larger temperature difference than that existing during the test. 9 The heat transmission factors in Chapter 3 are based upon experience Avith various substances used in construction under average conditions at a difference of 70 deg. fahr. between interior and exterior temperatures. Factors for other temperature differences are stated as percentages of the 70 deg. normal. The effects of exposure and of varying wind velocities are separately considered as losses due to infiltration. In order to determine the amount of heat required it is necessary to know or establish : First: The lowest temperature to which the interior will fall, that is, the "initial" temperature; and the temperature which it is desired shall be maintained within the enclosure, or the "maintained" temperature; Second: The time period in which it is required that the structure and its contents must be raised from initial to maintained temperature; Third: The nature and the weight of the building and its contents (especially if large quantities of glass, metal or water are included) ; Fourth: The minimum exterior temperature; Fifth: The direction and anticipated velocities of prevailing cold winds; Sixth: The construction of the enclosure ; Seventh: The topography of the site, and other local peculiarities. The heat transmitted hourly through the structure at a temperature difference between maintained interior and minimum exterior temperatures, plus the heat required to warm the infiltrated air through the same difference of temperature, gives the hourly maximum heat requirement during main- tenance. In Chapters 3 and 4 these two causes for heat requirements are further discussed. During initial heating or "warming up," heat units in addition to those required for maintenance must be supplied to raise the temperature of the structure and its contents of air and stored materials from their initial temperature to the desired temperature. In practice the heat absorbed by the structure and its stored materials is usually neglected, as the error is small. However, if the interior walls or columns are massive, or if the contents of the building include large quan- tities of materials with high specific heats, such as iron, steel, water, glass, etc., the heat which is absorbed by these must be taken into account. In almost all cases the heat required to raise the air contents of the enclosure from the initial to the maintained temperature must be considered. After determining the amount of heat required to warm the various substances during initial heating, the lioiu"ly rate at which this additional heat must be supplied during initial heating is obtained by multiplying this heat quantity by the reciprocal of the warming-up period in hours. Applications of the problem of determining the heat requirements will be found in Chapter 5. Where the heating requirements for warming-up are large compared with those for maintenance, the radiation necessary for the warming-up requirements and consequently the heat emitted will be correspondingly excessive during maintenance. It is often advisable to increase the length of the warming-up period first allowed in order to reduce this excess radiation. 10 Overheating after the initial warming-up period, may be avoided by the manipulation of the hand-controlled inlet valves on the radiators or by a system of automatic temperature control. Having estimated the total hourly heat requirement, the next consider- ation is the proper proportioning and distribution of radiating surfaces throughout the enclosure, for obtaining the desired heating effect from the circulation of a fluid of higher temperature. In the following chapters the fluid considered for conveying heat is steam at pressures slightly above that of the atmosphere. The high thermal value, or B.t.u., per pound of steam and the convenience with which it can be utilized by means of commercial boilers, radiating surfaces, pipe and fit- tings and the special apparatus of the Webster Systems, have demonstrated the superiority of steam at low initial pressures for the great majority of installations. The radiating surfaces, or radiation, normally used in low-pressure steam heating to transmit heat from steam to the enclosure to be warmed, are of two general classes. Direct and Indirect, each of which has many specific sub-divisions. Direct radiation, properly classified, comprises only those arrangements of radiating surface which are located directly in the space to be heated. Radiation which is not wholly exposed in the space to be heated is termed indirect radiation. Units which are concealed under window boxes, or in housings having an air inlet near the floor line and a heated air outlet above the radiation, or which are enclosed in casings outside of the space to be heated and which have a cool-air inlet from any source and a warm- air connection to convey by heated air the necessary heat units to the space to be heated, are examples of this type of radiation. Originally the circulation of air for indirect heating by the method last mentioned was induced entirely by the difference in weight of the air columns before and after coming into contact with the enclosed radiating surface. Present usage designates such surfaces as gravity indirect, distinguishing them from surfaces used in the later development, where additional circu- lating velocity is imparted mechanically by a fan or blower. Where mechan- ical means are used these surfaces are now designated as mechanical indirect or blast surfaces. Certain forms of radiating surfaces exposed in a room and so arranged with dampers and ducts that air wholly from the room or partly from without may be used to convey heat from the surface of the radiator to the room, are called direct-indirect surfaces. The rate of heat transmission through radiating surfaces from a given interior to a given exterior temperature varies not only with all classes of radiation but w ith all sub-divisions of those classes. This is due mainly to variation in convection, that is, in the facility for absorption of heat from the outer surface into the surrounding medium, and, in a lesser degree, to the dispersion of radiant heat. So great is this variation that, under similar conditions of location and temperature difference, and even in the simplest form of direct radiation, a low, narrow radiator gives off 40 per cent more heat per square foot of radiation than one that is extremely high and w ide. I 11 The term "square feet of radiation," therefore, means nothing specific and should not he used indiscriminately for sizing boilers, mains or other apparatus in the heating system. The radiating surface for the local conditions, heat requirements and architecture, having been selected and located, the proper size of radiating units should be determined. For this purpose the information on heat emission of various types of radiation. Chapter 6, will be found useful. The pipes which convey the heating fluid from its soiu-ce to the radiating surfaces are termed suj^ply mains. Those conveying the products of con- densation from the radiating surfaces to the point of disposal are termed return mains. The vertical parts of these mains are usually called risers, to distinguish them from horizontal runs. Risers, in turn, are classified by their direction of flow, as up-feed or down-feed risers. The small branches to individual units of radiation are known as run-outs ; those supplying several units as branches, and those conveying all of the heating medium are usually termed trunk mains. The flow of the heat-carrying medium is always toward a lower pressure, and if the medium is steam confined in pipes or ducts sealed from the atmos- phere, the arbitrary dividing line conventionally drawn between pressure and vacuum does not enter. The problem involves only heat content, density, difference in pressure, condensation and friction. If the lowest terminal pressure in the system is that of the atmosphere as in an open-return line or modulation system, the initial pressure must be somewhat above that of the atmosphere. The amount of pressiu'e above atmospheric depends largely upon the friction which must be overcome in the piping and upon the pressure necessary to give the steam its initial velocity. If, however, a terminal pressure lower than that of the atmosphere is mechanically maintained, as in vacuum systems, the initial pressure may be above, at or below that of the atmosphere as best meets the local conditions. Vacuum system practice, with few exceptions, demands that a steam pressure at least equal to that of the atmosphere be maintained in the run- outs most distant from the source of steam suj^ply, in order to avoid the in- leakage of air that would otherwise probably occur through minute leaks. This terminal pressure requires an initial pressure higher in some degree than that of the atmosphere. Local conditions, such as source of supply, length and character of pipe run, and use and permanency of the plant, make the selection of pressure difference one of good engineering judgment rather than the application of any fixed rule. The proper basis for propor- tioning the supply system is dealt with in Chapter 11. The primary function of return mains is the removal and disposal of the products of condensation. These mains should provide gravity flow wherever possible. Pressure difference should be used to stimulate flow only where gravity alone is not practical. The products to be removed consist of water, air. vapor, gases from impurities and last, but not to be overlooked, dirt and foreign matter. The last consists of initial impurities such as core-sand, gravel, chips, mill scale, grease, etc., left in the heating system Avhen erected, together 12 with rust particles and scale from impure feed water. Were it not for the dirt which collects and the uncertainty as to its volume, return mains might be made much smaller. Formulae and tables of capacities of straight, smooth pipes laid on even grades for return of condensation, and tables of accepted capacities com- pensating for uncertainties of grade and dirt are given in Chapter 11. The hot distilled water should be returned to the boiler wherever pos- sible. The saving due to the heat content of this Avater and its freedom from scale-forming and other impurities, warrants considerable initial out- lay in retm-n apparatus. No specific type of return apparatus will best fit all conditions. The single low-pressure heating boiler may have its water line so located that the water of condensation will flow back into the boiler by gravity against the highest steam pressure carried. Between this simple case and a modern high-pressure central generating plant, where part of the exhaust steam is used as a by-product for heating purposes in an extended group of build- ings, there is a wide range of conditions. The selection of the best combi- nation of return apparatus for the individual plant is therefore dependent upon comprehensive practical experience. Some of the possible combinations of return apparatus are described and shown in typical diagrams in Chapter 13, and basic rules are given for estimating proper sized apparatus. However, it is manifest that discussion in this volume cannot cover all requirements, and in this, as in the selection of all apparatus for special conditions, it is recommended that specific engineering advice be obtained from the home office or a nearby branch of the manufacturer, before a selection is made. i;i 3 P. a i 14 CHAPTER II Basic Data Required for Design of a Steam Heating System INTELLIGENT design of any heating system in either new or existing buildings requires that certain basic data shall be available. For exist- ing buildings the present use of which will continue, it is usually possible to obtain quite definite data to work upon. If plans are the available in- formation, much of the necessary data must be based upon assumptions of probable conditions. In any event, good judgment, preferably founded upon ripe experience, must play its equal part with scientific knowledge in the final application of the data obtained. Topography: The design of an efficient heating system, especially where a group of buildings is being considered, requires that a careful study be made of the grade levels of the different buildings, each one to the other, so that, if possible, the condensation from the heating surfaces may flow by gravity to a central point from which it may be returned to the source of steam supply. In cases where the conditions are such that the condensate will not flow by gravity to a central point, special methods for lifting the con- densate to a higher level are necessary as described hereafter. Location and Character of Source of Heat: It follows from the above that wherever possible the source of steam supply should be located at a lower level than that of the buildings to be heated. In a plant consisting of a group of buildings there is usually a power generating plant, the by-product from which, in the form of exhaust steam, should be utilized to the fullest extent in the heating of the buildings. The economies incident to the use of this exhaust steam as a by-product frequently determine the adoption of an isolated power generating plant rather than the purchase of power from outside sources and the installation of a boiler plant for heating purposes only. Exposure and Protective Conditions: By exposure is meant the relation of the outside surfaces of the building or buildings to the prevailing cold winds of winter, which by their pressure cause infiltration of excess quantities of cold air and the rapid removal of heat from the outside surfaces of the structure. To ofl^set this, a larger amount of radiation must be provided on the sides having greatest exposure, than for sides more favorably located with the protection of surrounding buildings or hills. Consequently the designer should determine the direction of the pre- vailing winter winds and their probable velocities and duration as well as the topographic features which may afford protection. 15 r3i l~] r 131 16 21 26 31 5 10 15 20 25 30 5 10 15 20 25 30 4 9 14 19 24 29 3 r 1 T"" T" i I 1 13"! B 13 18 23 28 5 10 15 20 25 30 4 9 14 19 3i| I M I Fil I I I 1 T I I I Mill I 16 21 26 31 5 10 15 20 25 30 5 10 15 20 25 30 4 9 14 19 24 29 3 8 1 3 18 23 28 5 10 15 20 25 30 4 9 14 19 Fig. 2-2. Daily maximum and minimum temperatures in New York City during the heating seasons of 1916-1917 and 1917-1918, (on opposite page) 1918-1919 and 1919-1920. Based upon United States Weather Bureau Reports. Outside Temperatures: Although the records of the United States Weather Bureau (See Figure 2-1) may show an extreme minimum tempera- ture much lower than that usually experienced in a given locahty, it is not customary to estimate heating requirements with that extreme tempera- ture as a basis. Generally, the average minimum temperature, obtained from United States Weather Bureau records over a period of ten years or longer, is the fundamental consideration. To illustrate the necessity for considering a period of years, rather than to establish the basis on the result of two or three years, charts (Figure 2-2) have been prepared showing the minimum . . I I I i I T I I I l3lM I ^1| I I I 29| I I |3, . , 16 31 26 31 5 10 15 20 25 30 5 10 15 20 25 30 4 9 14 19 24 29 3 a 13 18 23 28 4 9 14 19 24 29 3 8 13 18 and maximum temperatures for each dav of the heating season for the winter months of 1916-1917 to 1919-1920 for New York City. These charts show the extreme variation of minimum temperature for different winters and indicate that a safe average cannot be obtained without having records of a long period of years for consideration. They are shown also as a suggested form for the preparation of similar data from Weather Bureau reports for any locality where it is desired to study the temperature conditions upon which the design of a heating system is to be based. It is possible to operate the most effective types of steam heating systems with a slight increase in steam pressure, which results in an increased rate of heat emission from the radiating surfaces. This flexi- bility is advantageous during short periods of very cold weather. 17 Floor Plans, Elevations and Cross-Sections : To properly design the heating system for one or more buildings, complete floor plans and suffi- cient elevations and cross-sections, showing details of construction, materials, etc., must be available for accurately calculating the heating requirements. In designing heating systems for existing buildings, accurate data may be obtained by survey, but with designs of new buildings certain assump- tions are necessary. These may or may not be justified when construction is complete. A frequent element of error lies in change from original plans without proper consideration for the effect upon the heating system. These possible discrepancies in construction and deviation in design from original j^lans make it quite necessary for the designer of the heating system to place himself on record as to the basic factors of his calculation. Inside Temperature Requirements: The temperature to be main- tained and the lowest permissible temperature, are usually governed by the use for which the enclosure is intended. Inside temperatures are usually determined at the breathing line and not closer than 5 ft. from the most exposed wall. The important considerations for decision lie in the following questions: Is the heat to be maintained continuously 24 hours per day or for stated portions of the total 2^i hours? If intermittent heating, how tong a time may be alloived to raise the room temperature to the required maintained temperature? Through how long a period will heat be shut off and how low may the room temperature become during this closed down period? The following table indicates the usual range in maintained tempera- tures desired for various classes of occupancy, but it should be kept in mind that temperature is largely a matter of individual preference so that such a table can be considered only as a guide in the final selection. Table 2-1. Temperature for Various Rooms in Deg. Fahr. Bath rooms 75 to 85 Churches 60 to 70 Entrance halls to public buildings 50 to 60 Factories 60 to 70 Foundries 50 to 60 Gymnasiums 60 to 65 Homes for aged 80 Hospitals 72 to 75 Lecture halls 60 to 70 Living rooms 68 to 72 Machine shops 60 to 70 Offices 68 to 72 Operating rooms 70 to 90 Paint shops 80 to 90 Prisons, day confinement 60 to 65 Prisons, night confinement 50 to 55 Public buildings 68 to 72 Schools 70 Shops (stores) 50 to 65 Swimming halls 70 to 75 Vestibules for stores and office buildings 70 to 80 18 The relative humidity of the atmosphere which is hkely to exist in any room or building has a bearing upon the desirable inside temperature. For a living apartment, a normal temperature of 70 deg. fahr. and rela- tive humidity of 50 per cent (about 4 grains of water vapor per cubic foot of content) is considered by most authorities to be a very satisfactory condition of the air. If the temperature is lower than 70 deg., the relative humidity should be higher than 50 per cent or if the temperature is higher, the relative humidity should be lower if the same effect of comfort to the occupant is to result. It is usual, however, that the relative humidity is found to be much less than 50 per cent in living apartments heated to 70 deg. fahr. and has been observed to be as low as 28 per cent. With very low relative humidity the effect upon the occupant is a feeling of chilliness even though the temperature may be increased to 78 or 80 deg. falu". This cooling effect is due to the rapid evaporation of moisture from the occupant's skin, which is brought about by the low vapor pressure of the atmosphere. Conversely, where extremely high relative humidity exists, a temperature of 70 deg. fahr. might feel oppressively hot to the occupant. Contents and Use of Enclosure : A very important consideration for the designer is that of the materials and machinery within the enclosure, and their capacities for absorbing heat. This has an important bearing upon the permissible time limit for warming up. Large quantities of material or machinery having a high heat content will prolong the time for warming and will have an opposite effect of re- tarding the loss of temperature when the heat supply is cut off. For consideration of this factor, the designer should have details of the weight and substance of each of the various items of machinery and materials. With this data and a table of specific heats of substances such as on pages 342-3, the total heat contents or heat-absorbing capacities which influence the warming-up period can be determined. Likewise, the designer should determine the total heat given off by the operation of the machinery, motors, lights, etc., although this is not of so much importance in buildings where the temperature requirements are those to be maintained during periods when machines, etc., are not in operation. In schools, theaters, auditoriums, churches, etc., where large numbers of persons may gather, it is necessary to allow for the heat given off by the human bodies if overheating is to be prevented. In such cases, ventilation is usually required to remove the bodily heat with its excessive humidity. In manufacturing plants, portions of buildings often require unusual quantities of heat to warm the large amounts of air which replace that drawn from the rooms through exliausting fans on grinders, dryers and similar apparatus. This condition requires a careful investigation of the factors involved in the unusual rate of air change. Character and Location of Heating Surfaces: The selection of the radiation from a choice of direct, indirect, direct-indirect or blast type depends largely upon the use for which the enclosure is intended, the ven- 19 tilation requirements, the local building laws, school and labor codes, and other general considerations. Whether pipe coils, cast-iron wall radiation or column cast-iron radi- ators are to be used for direct heating is usually a question of availability of materials, cost of installation and the esthetic effect required. The selection of the type and location of the different radiating units may best be determined by a study of the plans and elevations of the build- ing to be heated. Location of Supply and Return Lines : In installations of the type for hotels, hospitals, office buildings or other public buildings with finished or decorated walls it is customary to conceal the steam and return risers, and their run-outs to radiators, in the wall and floor construction. In factory instal- lations and other less expensive types of construction these lines are exposed and in many instances they are used as prime radiating surfaces. In cases where the outlets from the risers are taken below the level of entrance to the radiators it is essential that the run-outs shall be so graded that the condensation will flow back by gravity into the risers regardless of the maximum velocity of steam which may flow in the opposite direction. It is therefore of prime importance that the maximum velocity shall be kept well below that at which the condensation will be swept along with the steam. This important feature of design is discussed in further detail in Chapter 12. A down-feed system of supply is preferable wherever building conditions will permit, since the condensation will then flow in the same direction and will be assisted by the flow of steam as well as by gravity. This permits the use of smaller supply risers and run-outs due to the higher velocities of steam flow which are permissible. Return run-outs, risers and mains must grade in the direction of flow of condensation to some low point or points from which the condensation will be returned to the source of steam supply or other point of disposal. 20 CHAPTER III Heat Transmission THE same principle of transmission of heat from a higher to a lower temperature that makes steam heating effective, also functions in the transmission of heat through materials of construction to make such heating necessary. Heat seeks equilibrium, and consequently there is a transfer of heat from a higher to a lower temperature with greater or less rapidity, depending upon the difference in temperature and the character and thickness of the material through which it flows. For the purpose of estimating the heat losses from enclosures, numerous tests and deductions from practice have been made to determine the rate of heat transmission through the various types and materials of surfaces used for enclosing space. So many variables enter this problem that it is impossible to predict the heat transmission exactly unless all of the peculiari- ties of any case under consideration have been previously determined. Tables of heat transmission, therefore, attempt to provide for average conditions of construction of the enclosing substances. Due regard must be given to the facility with which heat is absorbed and removed from the surfaces of the enclosing substances, and to the heat which is transmitted through them, due to the difference between the temperatures existing at their surfaces, which may be termed "heat head." This heat head has been considered in many formulae as a constant increase per degree of temperature difference. As the result of tests with the same substance under various temperature differences this deduction has been proved to be incorrect. Higher temperature differences cause greater transmission per degree difference than lower temperature differences. The probable variation in heat transfer under various conditions of heat head is shown in Fig. 3-1. The rate of transfer for any difference between inside and outside temperatures other than 70 deg. is expressed as a percentage of that at 70 deg. difference. The discussion of Rates of Heat Transmission in this book recognizes the following fundamental conditions: (1) The maintained inside temperature is that normally existing at the breathing line (5 ft. above the floor) and about 5 ft. from the wall. The breathing line is more often mentioned hereafter as the datum line. (2) The basic rate of transmission for any substance is the number of B.t.u. which will be transmitted in an hour through each square foot of surface of that substance when the outside temperature is zero and the maintained inside temperature is 70 deg. fahr. (3) From the above it will be evident that the basic rate is that which is transmitted at the datum line. 21 (DiO'*cocM'-oo)a3r>*co S3dnXVy3dlAI31 3aiSNI aSNIVlNIVW QNV 3aiSinO N33M±3a 30N3a3Jdia 22 In many structures with a ceiling height of 20 to 30 ft., with no mechanical agitation and a low transmission rate through the roof, the aver- age increase in temperature recorded above the datum line to a point close under ceiling has been fully 1 deg. fahr. per ft. In other buildings of similar height with cold roof the average rise has been less than \'2 deg. per ft. The downward circulation set up by the absorption of heat from the air near cold enclosing surfaces tends to agitate the entire contents and reduce the stratification effect. The greater the difference between the exterior and the maintained interior temperature, the greater the agitation and the less the heat rise per unit of height above the datum line. In estimating heat flow, the average height above the datum line for each class of service should be considered. Due to the increase in tempera- ture above the datum line, the transmission rate for each surface will cor- respond to that of the temperature of the strata at the average height above datum of such surface rather than that at datum line. Where the space above the ceiling is heated, the temperature of the strata closest to ceiling will be the highest. In such case it is usual to con- sider the average temperature to be that midway between the datum line and the upper edge of the vertical enclosing surface and obtain from Figure Fig. 3-2. Illustrating heat stratification 23 3-1, the percentage to be applied to the basic transmission rate of the surface under consideration. In the case where the space above the roof or ceihng is cold, the tem- perature of the strata ceases to increase beyond a height somewhat below such roof or ceiling; the distance depending on the rate of transmission through the roof. In this case it is necessary to assume two limits when correcting the basic factor of the enclosing surface to allow for stratification. It is usual to consider the average temperature in this case as that midway between basic level and a level five feet vmder the cold roof. The temperature does not always continue to increase in equal amount per unit of elevation above the datum line and in very high rooms the level at Avhich it ceases to increase is likely to be more than 5 ft. below the cold ceiling. In rooms with a ceiling height over 10 ft. where air is mechanically agitated, there will, in most cases, be a higher average temperature than that at the datum line with a consequent increase in transmission rate; this, how- ever, will be materially less than in cases of similar height where there is no mechanical agitation. Heat losses through monitors must be specially considered. In such cases it is usual to install heating surfaces within the monitor construction, and for that reason the entire monitor construction should be considered as an individual unit of enclosure with an imaginary floor across the space between the lower edges of its vertical sides. However, the factors for stratification for figuring heat losses from monitors should disregard the 5-ft. datum line; that is, assuming that the temperature at this imaginary floor line is approximately 70 deg. In the cases where consideration must be given to the transmission of heat through surfaces at a level beneath the datum line it is advisable to disregard stratification and estimate the heat transmission at the difference between the temperature at the datum line and at the other side of exposed surface. Basic factors for average height above datum should be fixed on the basic temperature difference of zero outside and 70 deg. fahr. maintained inside. If the outside temperature for which any particular enclosure is figured is different from zero, or if the temperature to be maintained at the breathing line is more or less than 70 deg., or if both inside and outside temperatures are different from the basic tables, the rates of transmission should be ad- justed for the new difference in temperature by factors obtained from Figure 3-1, and applied to all transmission losses through the structure. It is hoped that in the next edition of "Steam Heating," the result of tests now under way will be sufficiently complete to indicate the probable maximum degree of stratification likely to be encountered in the erecting shops and other structures with high ceilings, which are with increasing frequency presenting their problems to the Heating Engineer. To obtain the maximum transmission rate due to the average height above the floor of various surfaces mentioned in tables on following pages, the formulae on next page should be employed and a probable maximum value given to S. the rate of heat increase due to stratification. 24 Windows, doors, walls, and other vertical surfaces T, =T + S('^ + D — 5) Formulae 3-1 Roofs, ceilings, or other liorizontal or sloping surfaces Where upper side is cold Where upper side is heated T, = T + S(H2- 10) Ti = T + S(H2-5) in which T = temperature at the datvun hne. Ti = average temperature due to stratification at mean height of the surface above datum S =rate of heat increase above datum, in degrees per foot, due to stratification. H = height, in feet, of upper level of vertical surface above lower edge. H2 = average height in feet above floor of nearly horizontal surface. D = height in feet aboA^e floor of lower level of vertical surface. Basic Factors: Assuming a value of S in Formulae .3-1, Ti may be found for any given condition and bj^ referring this Ti to Figure 3-1, the percentage to be applied to the basic rate maj^ be found. If the tempera- ture conditions are other than basic (zero deg. to maintained 70 deg.) the rates of transmission for heights other than basic should be adjusted to the new temperature difference. The heat transmission values in the following tables have been proven by experience to be approximately correct. These values may need revision when results are published, of tests contemplated by the Research Bureau of the American Society of Heating and Ventilating Engineers. Table 3-1. Walls, Clapboard Construction Basic factor, to 70 deg. Clapboard on studs, bare 50 Clapboard on studs, with lath and plaster 35 Clapboard and paper on studs, with lath and plaster 30 Clapboard on studs, with 1-in. sheathing, bare 40 Clapboard on studs, with 1-in. sheathing, papered 35 Clapboard, with 1-in. sheathing on studs, lath and plaster 25 Clapboard and paper, with 1-in. sheathing on studs, lath and plaster 20 Clapboard on studs, with brick fill, bare 28 Clapboard on studs, with brick fill, papered 25 Clapboard on studs, with brick fill, lath and plaster 22 Clapboard and paper on studs, with brick fill, lath and plaster 20 Clapboard and sheathing on studs, sawdust fill, lath and plaster 15 Clapboard, paper and sheating on studs, sawdust fill, lath and plaster 10 Table 3-2. Interior Walls Construction Basic factor, to 70 deg . Plaster, wood lath, studs, wood lath and plaster 24 Plaster, metal lath, studs, metal lath and plaster 28 Studs, wood lath and plaster 42 Studs, nielal lath and plaster 48 4-In. hollow tile plastered one side 40 4- In. hollow tile plastered both sides 35 2-In. gypsum block plastered one side •. 45 2-In. gypsum block plastered both sides 42 25 Table 3-3. Walls, Stucco on Studs Construction Basic factor to 70° Wood Plaster Stucco on lath, with wood lath and plaster on the inside 10 1^^ Studs Metal Stucco on metal lath, with Plaster nietal lath and plaster on the inside 15 ''^tuds Table 3-4. Walls, Corrugated Iron Construction Basic factor to 70° Cof.^Y -jjjlJs Plain loose construction on '™" G' «'f framework 125 im'n "-0 -leaks Tight construction on frame- ^"'" 6-' no Air work 90 Cot- Iron ,^ood On 1-in. tongue-and-groove sheathing 45 Table 3-5. Walls, Brick Thickness in incties T Basic factor to 70° Plain < T > 4 8 12 16 20 24 28 32 36 45 30 22 18 16 14 12 10 9 Plastered inside 4 8 12 16 20 24 28 32 36 40 28 20 15 14 12 11 10 Furred and plastered inside < T > i| 4 8 12 16 20 24 28 32 36 30 20 15 12 11 9 8 7 6 Table 3-6. Walls, Hollow Tile Faced with Brick Thickness in inches Basic factor to 70° ■^B-> a D n D Brick Tile Plain 4 25 8 20 12 14 16 10 ■^B >|< T > □ v Plastered inside 4 8 12 16 20 16 12 Furred and plastered inside 12 16 16 14 12 8 Table 3-7. Walls, Concrete Faced with Brick 4-in. Thick Tliickness in inches Basic factor to 70° ■ee-=> Brick Concrete Plain 4 4 35 4 8 28 4 12 22 4 16 18 "i-B^ *C* Plastered inside 4 4 32 4 8 25 4 12 19 4 16 16 Furred and plastered inside 4 8 12 16 25 20 16 12 26 Table 3-8. WaUs, Hollow Tile Thickness in inches T Basic factor to 70° Plain 4 6 8 10 12 45 40 28 24 18 Table 3-9. Walls, Concrete 4-in. Thick Faced with Stone Thickness in inches Basic factor to 70° ■tS* i Furred and plastered inside 4 4 4 4 4 8 12 16 Table 3-10. Walls, Sandstone or Limestone Thickness in inches T Basic factor to 70° Plain 1 6 8 10 12 16 20 24 75 65 55 50 45 38 33 27 Plastered inside 4 6 8 10 12 16 20 24 67 58 49 45 41 34 29 24 Stucco, furred and plastered inside 4 6 8 10 12 16 20 24 50 43 37 33 30 2i 22 18 Ta')le 3-11. Walls, Hard Stone or Concrete Thickness in inches T Basic factor to 70° Plain 4 6 8 10 12 16 20 24 70 60 50 45 40 35 27 20 Plastered inside 4 6 8 10 12 16 20 24 63 54 45 41 36 32 24 18 Stucco, furred and plastered 4 6 8 10 12 16 20 24 47 40 33 30 27 3 18 13 Glass- Glass- Glass- Solid Metal Glass-- Table 3-12. Windows Construction Glass -!^ Glass ^^ Wood sash, single glazed Wood sash, double glazed Solid metal sash, single glazed Hollow metal sash, single glazed Solid metal sash, double glazed Hollow metal sash, double glazed Basic factor to 70° 75 The factors in this table are for trans- mission rates at the datum line 5 ft. from floor and a temperature of 70 deg. fahr. The temperature Ti at the centre of a window of any height above the floor will be Ti = 70 -)-S 42 (^+D-5y H = D = Where S = rate of heat increase above datum in degrees per foot, due to stratification. = the number of feet of height of the upper edge of window opening above lower edge. = the number of feet of height of the lower edge of window opening above the floor. (See Figure 3-2) With Ti established, the factor for cor- recting the tabular values wiU be deter- mined from Fig. 3-1. Apply this corrected factor to the entire area of window opening. Monitors must be considered as separate problems, as if they are structures of themselves with theoretical floors at the level of the base of the monitor. Their transmission losses and the sizing and placing of radiating surfaces should be figured accordingly. The factor should disregard the usual 5-ft. datum line. That is, assume that the temperature at this imaginary floor line is 70 deg. fahr. Table 3-13. Doors and Wood Partitions 90 80 65 45 Construction Basic factor, to 70 ° ^-In. to 1-in. thick, tongued-and-grooved 45 1 -In. to 1,14 -in. thick, tongued-and-grooved 40 lJ4-In. to IJ/^-in. thick, tongued-and-grooved 35 1 J^2-In. to 2-in. thick, tongued-and-grooved 30 2 -In. to 2V2-in. thick, tongued-and-grooved 25 21-2-ln. to 3-in thick, tongued-and-grooved 20 Table 3-14. Roof Construction Construction Basic factor, to 70** Flat tile on strips 75 Flat tile on sheathing 45 Slate on strips ■ • 78 Slate on sheathing and paper 35 Corrugated iron on strips 125 Corrugated iron on sheathing 45 Tin on strips 110 Tin on sheathing 40 Tin on sheathing with paper 30 Shingles on strips 60 Shingles on sheathing 30 Shingles on strips over tar paper and sheathing 15 Reinforced concrete composition 2-in.. paper, tar and gravel 50 Reinforced concrete composition 3-in., paper, tar and gravel 45 Reinforced concrete composition 4-in.. paper, tar and gravel 40 Hollow tile 4-in.. paper, tar and gravel 20 HoUow tile 6-in., paper, tar and gravel 18 Metropolitan 3-in., paper, tar and gravel 20 MetropoUtan 4-in., paper, tar and gravel 15 1-In. wood with 5 to 8-ply paper, tar and gravel 20 1-In. wood with felt roofing 25 1 J^-ln. wood with 5 to 8-ply paper, tar and gravel 18 2-ln. wood with 5 to 8-ply paper, tar and gravel 15 23/^-In. wood with 5 to 8-ply paper, tar and gravel 12 2-ln. Federal cement tile, paper and tar and gravel 50 28 Table 3-15. Roof Glass and Skylights The surface to be considered is the total surface of glass and frame Construction Basic factor, to 70° Wood Glass- Wood Glass -^ Solid M elal Glass -^ Hollow Melal Glass'' Solid Metal Wood sash, single glazed. ^ Gl ass 1^ r'^ Wood sash, double glazed . -|^;-J'.',' \ Solid metal sash, single glazed . _ |r ( Hollow metal sash, single glazed . 'Glass — _^ Solid metal sash, double glazed . Glass--^ ^^i^Meial ^"^'p S— , Hollow metal sash, double glazed . Glass -^ 75 42 90 80 65 45 Table 3-16. Floors Above Cold Space The factors are for to 70 deg. difference in temperatures. For any other difference, the basic factor should be corrected in accordance with chart, Fig. 3-1 Above cold space Description Basic factor, to 70° ^ Lath jnd Plasier- Wood— ^ m U-"Hoisl Wood -^ JoisI iid ^ - Lath and Plaster "^ Wood -^ E [ihoisi Joistl^ '-Insulation ^-- Lath and Plaster Wood -A Wood-^ Concrete Wood ^, Concrete-"' Mill construction, .S-in. wood and paper plus Js-in. surface . 12 1-In. single wood floor on joists 25 2-In. double wood floor on joists 15 l-In. single wood floor on joists with lath and plaster 1-1 2-In. double wood floor on joists with lath and plaster 10 2-In. double wood floor on joists with insulation and lath and plaster 4 2-In. double wood floor on 4-in fireproof concrete 6 1-In. wood flooring on double wood and 4-in. fireproof con- crete . Reinforced Concrete^" ^^^!^ n ,:^^.^^ Reinforced Concrete' Reinforced Concrete-'' Reinforced Concrete-'^ 4-ln. concrete slab, metal reinforced 70 6-In. concrete slab, metal reinforced 60 8-In. concrete slab, metal reinforced 50 10-In. concrete slab, metal reinforced 40 29 Table 3-17. Floors Laid on Ground These factors are for to 70 deg. difference in temperature. It is usual, however, to assume the temperature of the ground beneath the floor as 50 deg. fahr. For this difference the above basic factor must be corrected by means of the chart in Fig. 3-1 Basic factor to 70° Construction ^Sleepers^ Ground' Wood-^, Walcrprooling , 1 Concrete-^ f^ 73" 2 'Wood blLLptr ^ Concrete Ground^ Conrrete- ^ VCinc Cinder till Ground'^ 1-In. single wood floor on wood sleep-irs 9 2-In. wood floor on 4-in. water-proofed concrete 7 3-In. double wood floor with paper between on sleepers in 4-in. concrete 4 4-In. concrete floor on ground 22 4-In. concrete floor on cinder fiU 20 I .^//////////////•'^ Concrete Ground' rf Crick^^ .1.1 II II I I. I J 11 .Z3I 'y777777P7i^7777777777. 1-In. tile floor on 4-in. concrete. 2}^-In. brick floor on 4-in. concrete . 20 Table 3-18. Ceilings The factors are for to 70 deg. difference in temperatures. For any other difference, the basic factor should be corrected in accordance with chart. Fig. 3-1 Construction Basic factor to 70° Plaster ' Wood-^ 'Wood Lath Plaster^ BE -Joists - 3sr Metal Ceiling Wood lath and plaster on joists 42 Metal lath and plaster on joists 46 1-In. single wood floor on joists with wood lath and plaster ... 18 2-In. double floor on joists with wood lath and plaster 14 1-In. single wood floor on joists with stamped metal ceiling . . 25 30 CHAPTER IV Air Infiltration WIND blowing against walls causes a leakage of air into the enclosure and an outward leakage from the enclosure through the opposite sides. Additional leakage is caused by temperature difference within and without regardless of wind velocity. These leakages are sometimes referred to as air change, but in this book are called air infiltration. As the air enters and leaves the enclosure at different temperatures, sufficient B.t.u. or heat units must be provided to heat this air between the two temperatures. Air infiltration therefore becomes one of the important factors in the determination of the heat requirements of a room or an en- closure. Some rules for heat requirements of an enclosure regard that portion due to ah" infiltration as an additional quantity to be based upon an arbi- trary hourly air change or upon a certain percentage of the best trans- mission factor. Examination of the air infiltration shows that most of the air leaks are around the doors, windows and other similar openings. The quantity that expresses the heat requirements due to this infiltration of cold air should therefore be based upon the sum of the openings through which this leakage occurs, rather than upon the area of the doors, windows and similar openings of the structure. Any determination of the quantity of air infiltrated must take into consideration the velocity and direction of the wind in relation to the openings of the enclosure. Where an enclosure has openings on more than one side, the infiltration for all openings must be determined and the radiation for this loss proportioned and located according to the maximum degree of infiltration that may occur on any side. This method will give an excess of radiation on the sides where leakage is outward, but there is no alter- nate without having some sides of the room feel cool at some wind direction. In small rooms having window exposures on more than one side, and which ordinarily can be heated with one radiator, it is only necessary to consider the infiltration for the side of maximum exposure and locate the radiation on that side. The leakage in narrow monitors and rooms where cold drafts will not be objectionable may be considered only on the side where maximum wind velocities occur. A portion of the heat to care for this infiltration can then be applied to the other side. Where the wind strikes the surface at an angle, the resultant velocity at right angles to the surface must be considered. This is equal to the actual velocity times the sine of the angle of incidence. Normally the same maximum wind velocity should be considered on the north and west sides, while on the south and east sides one-half of these velocities may be used except where special wind conditions exist. A suggested extreme condition for New York and vicinity would be 15 miles per hr. wind velocity with a temperature of zero. Generally low wind velocities prevail at extremely low temperatures. The many variables make reference to experiment more reliable than attempts to determine theoretically the perimeter air infiltration of windows, doors and similar openings. Little dependable experimental data is avail- able at present, but such as is now obtainable must be used as a basis until better is to be had. Experiments on air infiltration of windows have been made by using a fan to direct wind velocities against a test window set in the side of a tight enclosure and having an opening for pitot tube readings on the opposite side. Further details regarding some of these experiments by Whitten will be found in the 1908 Transactions of the American Society of Heating and Ventilating Engineers, and others by Voorhees and Meyer in the 1916 Transactions. Similar tests are being conducted by the Research Bureau of the American Society of Heating and Ventilating Engineers and the United States Bureau of Mines. In these tests natural air velocities are used and the infiltration determined by reduction in carbon-dioxide content of air in the room. A preliminary report of these tests describing the method in detail was given by Mr. O. W. Armspach in the Journal of American Society Heating and Ventilating Engineers, Januarj^ 1921. Figure 4-1 gives the approximate leakage in cubic feet per minute per lineal foot of sash perimeter for double-hung locked windows, with and without metal weather strips. The type and construction of the windows to be used shoidd be definitely bu / ■T/ ■ 1/ ■■■■,■ ii-'T 1 ;r ■-■■ 1 1 /' '^ / ^ n LkT / ' c / 1 ■ ■ 7 .' ,' ■ ^ ! ' ' *" _. -^T ^7. . Y--.. ■- .^j-. - .^i. -[- ^' ; ! ^ : 'it-' ^'k- - ""Ji:... ::"~" ::' "i „~"":-_ : " . ' ^ ^l r-l "^hi ^•/ \ i.y y^ \ M 1 ■ i ' 1 f ,/ /n / - j 1 > 1 ' Ml ,1 1 1 ill nWf] : , 1 i 1 N 1 1 1 1 1 1 1 1 1 ( 1 ! 1 1 1 I 2 ;i 4 5 C 7 8 AIR INFILTRATION IN CUBIC FEET PER MINUTE PER LINEAL FOOT OF APERTURE Fig. 4-1. Air infiltration for double-hung windows 32 10 known before the infiltration is estimated and this data recorded in a similar manner to data regarding the type of wall, roof or other construction of the enclosure. Due allowance should be made for special sash. The meeting rail must be considered in measuring the perimeter of double-hung sash. In windows with steel-section frames properly bedded, only the perim- eter of that portion which opens, or the ventilating sash, need be considered. In industrial plants where it is intended to install mechanical exhaust systems for removing dust or fume-laden air, special means must be provided to care for the corresponding increase in infiltration as described on page 65 of Chapter 7. For well-fitting doors the average window values can be used, but for sliding and similar poorly fitting doors, as used in industrial buildings, the values for a poor window should be used. The leakage values as read from Figure 4-1 when multiplied by 60 x 0.0864 (density of air at zero) x 0.2375 (sp. ht. of air), will give the heat units per hour required to warm the infiltrated air from 1 ft. of perimeter, 1 deg. fahr. Exavvple: Assume an average double-hung window 3 ft. wide by 6 ft. high with a perimeter of 21 ft., outside temperature zero, inside tempera- ture 70 deg. fahr. with wind velocity of 15 miles per hr. Referring to Figure 4-1, the leakage per foot of perimeter is found to be 1.60. Then 21x 1.60x60x0.0864x0.2375x70 = 2893 B.t.u. per hr. required to heat the air infiltration from this window. The following tables will be found useful in determining the heat units required to care for the infiltration. These values are for plain double- hung windows. If equipped with a good metal weather strip, use 20 per cent of the tabulated values. Table 4-1. B.t.u. per Hour Required per Lineal Foot of Perimeter for Windows Infiltration Cu. ft. per min. Wind vel. per ft. of Temperature difference inside and outside of enclosure Miles per hr. perimeter 50° 60° 65° 70° 80° 5. .36 ■->■-> 27 29 31 35 •"== 7.5 .54 32 39 42 45 52 s? 10. .72 44 53 58 62 71 O.G 15. 1.08 66 80 86 93 106 20. 1.42 87 105 114 122 140 5. .56 34 41 45 48 55 »S 7.5 .85 52 63 . 68 73 84 %i 10. 1.12 69 83 90 97 110 5-? 15. 1.68 103 124 134 145 165 20. o oo 137 164 178 191 219 5. 1.07 66 79 86 92 105 . -! 7.5 1.60 95 115 125 134 154 10. 2.12 131 157 170 183 209 15. 3.12 192 230 250 269 307 20. 4.07 251 301 326 351 401 83 CHAPTER V Method of Calculating Heat Requirements CHAPTERS 1 and 2 give the general data that must be known in calculating the heat requirements of any structure. Several rules and formulae have been devised to determine the amount of heat that must be supplied to maintain a room or enclosure at a predetermined temperature with a known surrounding temperature. Many of these formulae were derived when construction, size of window opening, etc., were similar and are not flexible enough to cover the problems of today. If the air within an enclosure is maintained at a temperature higher than that surrounding, there must be a natural transfer of heat through the enclosing structure to the air of lower temperatures. This transfer may be to the air outside, to any adjoining rooms and to air above and below, if these are at lower temperature than that in the room. To heat the enclosure to and maintain it at a predetermined temper- ature, an equal amount of heat must be supplied at the rate at which it is transferred. The most accurate method of determining the quantity transferred is to determine the hourly rate of heat transfer from the heated enclosure to the surrounding air. This quantity is usually calculated in British thermal units per hour; that is, on the B.t.u. basis. The total quantity transferred is made up of four principal heat requirements. The first is the heat required to warm to the desired inside temperature, the air that leaks in through the various openings around the window and door perimeters, etc., from the outside. To calculate the heat units for these requirements, the width and lineal feet of the openings, and the wind velocity against the side of the enclosure where the openings are located, must be found, and with these data the air infiltration determined. The product of the air infiltrated in cubic feet per hour, the density of the air, its specific heat and the difference between the inside and outside temperatures will give the heat required per hour for infiltration. This subject is further discussed in Chapter 4. The second is the heat transmitted through the various materials of which the enclosure is constructed. To calculate this recjuirement, the area, thickness and kind of the various materials through which this transfer occurs, and the temperature difference between the air on the two sides of the material must be known. The product of the area of any material in square feet, the transmission coefficient for that material in B.t.u. per hour, and the difference between the inside and outside temperatures will give the heat transmitted per hour through that material. The sum of quantities so found for all materials of the structure is the total loss of heat from the enclosure by transmission. A desired maintained interior temperature of 70 deg. fahr. and a mini- mum external temperature of zero have been adopted in this book as a 34 standard. All transmission coefficients, therefore, are given in B.t.u. per hour per square foot of surface for this temperature difference, with correc- tion factors for other differences. A table of these factors for various materials used in building con- struction will be found on pages 25 to 30. A third requirement enters into the calculation where the heating is not continuous. This may be referred to as a heating requirement, or the heat necessary, to raise the air of the enclosure from its initial temperature to the desired maintained temperature. It is evident that if only sufficient heat is supplied to compensate for the air infiltration and transmission requirements, the temperature of the enclosure would approach but not reach the predetermined temperature, unless additional heat units are supplied for heating an aniount of air equivalent to the cubic contents of the space to be heated. To calculate this requirement, cubic contents of the enclosure, initial and final temperatures of the internal air, and time desired to raise the air through this temperature range must be determined. The product of the quantity of air in cubic feet, the density of the air, its specific heat, and the temperature difference, is the quantity of heat required for initial heating of the air. If this quantity be then multiplied by the reciprocal of the heating-up period in hours, the product will be the quantity of heat that must be supplied per hour during the heating-up period, to supply the heat absorbed in heating the air. A fourth heat requirement should be included in calculations where the heating is not continuous, and where large quantities of materials such as metal, water, glass, etc., are stored in the enclosure and must be heated like the air contents, from initial to maintained inside temperature. The product of the weight of such material in pounds, its specific heat and the desired temperature range is the heat absorbed by the material. This quantity must also be multiplied by the reciprocal of the heating- up period in hours to obtain the hourly heat requirement during initial heating to compensate for this absorption of heat. The longer the heating- up period selected the less will be the difference in the hourly requirements during initial and maintained heating. Where large quantities of such stored materials are taken into and re- moved from the enclosure at intervals the heat absorbed by these materials must be considered. The sum of these four requirements gives the total hourly rate at which heat must be supplied to maintain the enclosure at a predetermined tem- perature, or to raise the temperature of the enclosure from its initial to predetermined temperature, as the case may be. Applying this method of calculating heat loss requirements. Figure 5-1 represents the main floor of a residence with warm basement and second floor. Under these conditions, no ceiling or floor loss need be considered. The quantities taken from the plan and the basic data are entered on the Heat-requirement Computation Sheet, Table 5-1. The requirements are figured for each exposed side as in Room 1. The requirement for the north side is 12230 B.t.u., for the east side 4830 B.t.u., for the west side 1635 B.t.u. and the B.t.u. required for initial heating 35 I WINDOW RADIATOR 17 SEC. I 20'= 85 SQ.FT. / J COL. T8 sec. '' 28'= 72 so. FT ENCLOSED BOTTOM CBlLLE 9" WlOE X ^ LENGTH OF RADIATOR FREE TOP GRILLE WIDTH X f- OF GRILLE +4 LENGTH OF RADIATOR P£R CENT fr~B REGISTER 312 SO. Ui ? RADIATORS EACH f 1 COL. G EEC, 3E=1B SQ.FT. ROOM No. 1 ir-JJ = ^. "*-« ROOM No. 2 ROOM No. 4 2 COL. 14 SEC. "-^^1 SQ.FT. HEATED ROOM Cz [U J RADIATORS EACH — — ^ 1 COL. 5 SEC. 32 =13i!; 5Q.FT;~ ROOM No. 3 3 RADIATORS EACH 2 COL. 30 SEC. 23' = 46 f SQ.FT. ROOM NO. 5 1 COL ■; EEC \^ 32"=12- SQ.FT. n sec. 30" VENJO ON 4" CENTERS !i._ 8i 5Q.FT. I I 3 SEC. 50 ' VENTO "DAMPEH't?J_j :,-' "-I /ON 1" CENTERS /f*"""^ ir"^., JC SQ.FT. T6S0lN^' Ir"--? 5 SEC 30 VEMTO ON 4" CENTERS j.--^40 SO FT. REGISTER |.;3 SO.IN. BUILDING A Fig. 5-1. Plan of residence floor used as basis for heat-requirement computation sheet, Table 5-1 of the air contents is. 632, ■ making a total maximum requirement of 19,327 B.t.u. per hour. The heat supply for this room should he placed under the north window. The requirements in B.t.u. per hour as taken from the computation and divided in a similar manner are marked on the plan for each room. Another illustration of the method of calculation is given in the Heat- requirement Computation Sheets, Table 5-2, for the factory building shown in Figure 5-2. The calculation has been separately made for the sections as marked in the figure, so that the losses may be proportioned to the exposures. It will be noted that the correction factors are used to change the 70-deg. temperature-difference coefficients to correct values for the given temperature differences which may vary due to stratification. In section C, the calculations for the north and south walls with their windows and doors from the floor to line a — b were made separately from the balance of the losses for this section. As the air infiltration from the upper sash would not be felt directly by the operators in the building, the infiltration has been calculated for only the west or side of maximum wind velocity. The infiltration factor for the doors has been taken as that of a poor window, and in calculating the window infiltration losses only the perimeter of the ventilating portion of the window has been considered. The requirements for the various walls and sections as taken from the calculations are marked on the drawing in their relative locations. 36 ill S II l\ r O LiJ CO CQ O CQ o o UJ CO CO z o I— o LlJ I c s II l; II I Fig. 5-2. Factory building used as basis for heat-requirement computation sheet. Table 5-2 37 ^"Sm 10 CO 1 -a M II C II c: II 1 > £ '-cS '^« II '■ r^E II '~ n "ic ., >- - 1? 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(M . . eg ■ c^ )TI10d s5Edni03 ZZ^Z^ ajcoMcocc ^^^SHKo ^^^^^^>'f§fag oj o-r ■5^ u o 4: m O t) M Q O'^ ^ 4, o O (y . , a, . . ff o £ rt"c5 C.'E o O CHAPTER VI Method of Computing and Selecting Heating Surface DETERMINATION of the heating surface depends first upon the total hourly heat requirements which are assumed to have been calculated as described in the preceding chapter. The heating surface must supply heat units to equal the requirements and should be of the form that best fits the conditions for the room or enclosure. The method of heat supply must first be determined — that is, whether the heating surface is to be direct, indirect or direct-indirect. The last two methods are used principally where ventilation must be considered in addition to the heating reciuirements. although the indirect method is considerably used where it is not desired to have the surface located in the room to be heated. Normally, the heat should be supplied at the locations where the greatest requirements occur, and this is generally at the windows, where, in addition to a high transmission requirement, there is the air infiltration requirement as well. Rooms or enclosures where more than one unit of radiation is to be installed should have the heating surface divided in proportion to the requirements of the spaces served. Heating surface placed under the windows should not project above the sills, should be as wide as the window openings, and should also be installed with a 2J^-inch space between the wall and the surface, as this distance gives maximum efficiency of heat emission. Direct heating surface, inasmuch as it is used in a large majority of installations, should be considered first. Residences, office, school, library, hospital and similar buildings usually have cast-iron column radiation y>i.Uii|-i'^f^iy; ^^ Fig. 6-1. Cast-iron wall radiation on side walls under windows, for heating a factory building 42 Fig. 6-2. Connections to a direct hot-water type radiator showing modulation supply valve and thermostatically actuated return trap together with some cast-iron wall radiation. Factory and manufacturing buildings are usually heated by means of wrought-iron or steel pipe coils or cast-iron wall radiation. Hot-water pattern radiation is preferable for those systems in which modulation supply valves are to be used. The supply valve should be placed at the upper inlet and the return trap at the lower opening diagonally opposite. Good practice in the use of groups of wall radiation suggests that no individual group exceed .30 ft. in length, as expansion and contraction become an important factor on longer groups. Where greater lengths of this type of radiation must be used, the supply connection should be made at top and bottom and expansion and contraction properly provided for. Pipe coil practice demands a spring or mitre piece in the coil to provide for expansion and contraction, and the desirable length is limited to 60 ft. not including the mitre piece. Coils should be securely anchored at the return header so as to throw the expansion toward the mitre end, the length of which should be not less than one-twelfth the coil length for 1-in. pipe and one-tenth for 13^-in. or 13>2-in. pipe. 43 Fig. 6-3. Arrangement of cast-iron wall radiation on side wall of a factory building + 50 g+40 '•& E UJ 1+30 \ \ \ \ e Variation + o \ \ S Percentag + \ ■^ -^ —in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Length of Radiator in Sections Fig. 6-4. Percentage of variation in heat emitted from cast-iron heating surface per square foot for various numbers of sections as compared with a standard 10-section radiator 44 The amount of heat emitted from any given type of direct heating surface is usually stated in B.t.u. per hour per square foot of heating surface. This heat is given off in two ways, by convection directly to the air which passes over the heated surface, and by radiation directly to surrounding materials independent of that carried off by the air. The heat given off by radiation does not heat the air through which it passes, but travels in straight lines and heats the objects upon which it impinges. After selecting the type of surface best suited for the particular case, the number of square feet of heating surface required should be deter- mined next. The total number of heat units that must be supplied per hour divided by the heat units emitted per hour per square foot of heating surface gives the required surface in square feet. Table 6-1 will be of assistance in determining the heat emitted by dif- ferent types of surface. Table 6-1. B.t.u. Emitted per Hour per Square Foot of Heating Surface* Radiators 10 Sections Long Steam Temperature, 215 deg. fahr. Room Temperature, 70 deg. fahr. Percent Number Height B.t.u. B.t.u. Total convected of of by by heat of columns radiator convection radiation B.t.u. total heat One 38 in. 150 106 256 58.6 " 32 in. 158 108 266 59.4 *' 26 in. 162 111 273 59.4 " 23 in. 160 119 279 57.4 ** 20 in. 166 117 283 58.7 Two 45 in. 148 86 234 63. '* 38 in. 148 92 240 62. '* 32 in. 154 94 248 62. *' 26 in. 149 106 255 58. <« 23 in. 151 109 260 58. ** 20 in. 153 112 265 58. Three 45 in. 142 76 218 65. " 38 in. 147 79 226 65. *' 32 in. 158 75 233 68. " 26 in. 166 75 241 69. *' 22 in. 166 82 248 67. *' 18 in. 162 92 254 64. Four 45 in. 149 56 205 73. " 38 in. 150 60 210 71.5 ** 32 in. 151 66 217 69.5 " 26 in. 155 70 225 69. '* 22 in. 156 76 232 67. ** 18 in. 151 87 238 63.5 Wall radiation 3 in. wide 14 in. 152 171 ' 323 47. (C it 22 in. 154 156 310 49.7 " 29 in. 138 157 295 48. Pipe coil 6-1 li in. pipes 8-14 in. " 10-14 in. " 12-14 in. " 360 343 330 319 * John R. AUen, A. S. H. &■ V. E. Journa/— January, 1920 From Table 6-1 it will be noted that low, narrow surface is most efficient and that the efficiency decreases as the height and width increase. 45 Some other factors and their effect upon the efficiency of the radiating surface are worthy of explanation. The preceding table is based upon a radiator 10 sections long. As the number of sections decreases, the efficiency increases, due to increase of the more efficient end-section surface in proportion to total heating surface; also a short radiator emits proportionally more radiant heat than a longer one. Figure 6-4 shows the effect of varying the number of sections, and that increasing the number of sections above 10 has not as much effect as decreasing the number below 10. It will also be noted that a 4-section radiator will give off about 10 per cent more heat per square foot of surface than one 10 sections long. 300 290 280 270 200 i 250 a 240 230 220 210 . 200 190 ISO 170 IGO / / / / / / / / / f / / / / / / / / / / / / / / / / / / / / / / - / / / / / / / / / / / / / f / / / / / y / / -40 -30 -20 -10 +10 +20 +30 +40 Percentage Variation in Heat Emission + 50 + 00 +80 Fig. 6-5. Percentage variation in heat emitted from heating surface due to varying the steam temperature from 215 deg. fahr., room temperature 70 deg. fahr. 46 Where 215 deg. fahr. is considered as the standard temperature of steam in the heating surface, the effect upon the heat emission of tlie surface due to varying this temperature is shown in Figure 6-5. The percentage variation can be read directly from the curve. Example: If steam at a temperature of 230 deg. fahr. is supplied to the radiator, the heat emission will be increased 12 per cent over one supplied with steam at 215 deg. fahr. T^u •s. "s v _ 's •i + 10 . E x ' N. ^ s. -i- ^ •n . "S = ^ V -— s CO " X m > S CD '■ ■«* ,^ TO ■N. C £f-10 ■v . ' S £ ^ X, \ N s ■■ ^on ' s 40 50 Fig. 6-6. 60 70 80 90 Room or Surrounding Temperature -Deg. Fahr. 100 110 Percentage variation in heat emitted from heating surface due to \ arying the room temperature from 70 deg. fahr. The surrounding or room temperature is taken at 70 deg. fahr. as a standard. The effect upon the heat emitted from heating surface, due to varying this temperature, is shown graphically in Figure 6-6. From the curve it will be observed that, for instance, a radiator in a room temperature of 60 deg. fahr. will emit 6 per cent more heat than the same radiator in a room temperature of 70 deg. fahr. The effect on heat emission due to variation in steam temperature is much greater than an equal temperature variation in the surrounding or room temperature. The following example will illustrate the use of the curves in Figures 6-4, 6-5 and 6-6 for determining the heat emission under given conditions; it is desired to know the B.t.u. emitted per hour per square foot of heating surface of a standard cast-iron radiator, two columns wide, 38 in. high, and six sections long when supplied with steam at 240 deg. fahr. and located in a room heated to 80 deg. fahr. Referring to Table 6-1, a similar radiator except that it is 10 sections long, gives off 240 B.t.u. per hr. per sq. ft., with steam at 215 deg. fahr. in room temperature 70 deg. fahr. A radiator six sections long is 4.5 per cent, more efficient (Figure 6-4), when supplied with steam at 240 deg. 47 < 1= I I I I i k— 0- 24 25. o: .M /A^'i 24 I Fig. 6-7 Fig. 6-8 m — 0— ^ I I I I l~M 2i < — -> ^i^ Fig. 6-9 ^ I I 15 U Fig. 6-10 I ^ ^ .V-- 2 < — ;> b -Metal Shield T 49 T I y////////////////////////// Fis. 6-11 i Y V K— 1— >l |< — — ■>! I -u '>0Z^zm^^mz^9yy7yy>m Fis. 6-12 ^ rlUill-lHllWh i J W W W Plan W V ] \J I l<— a_>| Length of all outlets = length of radiator Length of all inlets I = length of radiator Width of all outlets O = width of radiator or as given in table Screens or grilles have 44 per cent free area Fig. 6-13 Enclosures for radiators 48 fahr., the efficiency is increased 20 per cent (Figure 6-5), and if located in a room heated to 80 deg. fahr. there is a decrease in efficiency of 6 per cent (Figure 6-6). The heat emission of the radiator required would be 240 x 1.045 X 1.20 X 0.94 = 283 B.t.u. per hr. per sq. ft. of radiating surface. Painting a radiator influences only the heat emitted by radiation, the con- vection factor remaining practically unchanged. As paint affects the surface only, the number of coats makes little difference. It seems to depend on the last coat applied and when made of flake metal the result is more marked. Direct radiators are sometimes set behind grilles or screens, in window enclosures or wall recesses, all of which greatly decrease the efficiency of the radiation. Tests by Professor Brabbee, as reported by George Stumpf, Heating and Ventilating Magazine, May, 1914, show that a radiator in an enclosure is most efficient when located with 23/^ inches between the wall and radiator and between the inside of the enclosure and the radiator. Abstracts from these tests follow. The inlet and outlet openings of any form of enclosure should extend at least the entire length of the radiator. The width of the outlet is usually made that of the radiator. Tests show little gain in efficiency for wider outlets, but a decrease of about 5 per cent for each inch narrower than that of the radiator. The outlets and inlets in Tables 6-7 to 6-13 are the full length of the radiators. The width of outlet is the width of the radiator except in Table 6-4, where it is as given. The width of inlet I is as stated in the tables. Fig. 6-14. An enclosed radiator having grilles or screens on front and top of enclosure. The modulation supply valve control is shown on top of enclosure 49 Both openings are covered with screen of 44 per cent free area. The design of the screen or grille has no effect provided the free area is not changed. Figure 6-7 shows a form of enclosure frequently used. Table 6-2. Decrease in Radiator Efficiency with Form of Enclosure Shown in Fig. 6-7 Radiator width Radiator height Width of 1 Decrease in efficiency Two-column 42 in. and over 9 in. 15% Under 42 in. 9 in. 20% Under 42 in. 5 in. 25% Three-column 42 in. and over 9 in. 15% 32 in. to .38 in. 9 in. 15% 32 in. to 38 in. 7 in. 20% 26 in. and under 9 in. 20% " " 26 in. and under 5 in. 25% If the width of inlet is made equal to the free area and not screened, the efficiency reduction will remain as above. Another form of enclosure, Figure 6-8, gives the effect upon the radi- ation efficiency as shown in Table 6-3. Table 6-3. Decrease in Radiator Efficiency with Form of Enclosure Shown in Fig. 6-8 Radiator width Radiator height Width of O Width of I Decrease in efficiency Two-column 42 in. and over 8 in. 8 in. 20% 32 in. to 38 in. 9 in. 9 in. 20% 32 in. to 38 in. 7 in. 7 in. 25% '' " 26 in. and under .6 in. 6 in. 33% Three-column 26 in. and over 9 in. 9 in. 20% " " 26 in. and over 6 in. 6 in. 25% Enclosure of the form shown in Figure 6-9 is sometimes used and by test gives the following effect: Table 6-4. Decrease in Radiator Efficiency with Form of Enclosure Shown in Fig. 6-9 Perforated screen fuU front of enclosure only — decrease in efficiency 20% Same screen with deflector — " " " 15% If an outlet is provided in addition to front screen and made equal to width and length of the radiator, the efficiency decreases only 10 per cent. Sometimes it is desirable to set the radiators in wall recesses, as shown in Figures 6-iO and 6-13 which causes a decrease in efficiency as follows: Table 6-5. Decrease in Radiator Efficiency Due to Wall Recess Fig. 6-10 When = 13^ inches — decrease in efficiency 11% " = 3 :%) " " " 7.3% "0 = 4 "J " " " 6% The distance a has little or no effect, and therefore need only be sufficient for connections to the radiator. A shield in front of a radiator as shown in Figure 6-11 increases the radiator efficiency as follows: 50 Fig. 6-15. An enclosed radiator in a window seat, with grilles of rattan cane. The modulation supply valve control is placed on the window seat Table 6-6. Increase in Radiator Efficiency by Use of a Shield Fig. 6-11 Height of shield, H 52 in. Width of open slot, 1 6J4 in. Increase in efficiency 2. 2% Another form of enclosure, shown in Figure 6-12, by test gives the fol- lowing effect upon the radiator efficiency: 52 in. 52 in. 72 in 9 in. 12 in. 12 in 6.3% 12.5% 13% Table 6-7. Decrease in Radiator Efficiency with Form of Enclosure Shown in Fig. 6-12 Width I Decrease in efficiency . . Sin. .10% 6 in 15% 5 in. 20% 4 in. 3 in. 25% . 33% Table 6-8. Comparative B.t Based u. Transmission on 3-coluinn 30-in. and Cost of Cast-Ii radiation as 1.00 on Heating Surface Rad. Relative cost of r adiator per sq. ft. B.t.u. given off per s ,. ft. Relat ve cost based on heating efficiency height 1 2 3 4 1 2 3 4 1 2 3 4 Column Columns Columns Columns 1.43 Col. Col's Cors Col's Column Columns Columns Columns 18" 1.43 2,54 238 1.27 1.36 20" 1.49 1.43 283 265 1.19 1 0'7 22" 1.28 1.28 248 232 1.17 1 25 23" 1 38 1.31 279 260 1.10 1.14 26" 1.30 1.25 1.18 1.18 273 255 241 225 1.08 1.11 1.10 1.18 32" 1.18 1.13 1.08 1.08 266 248 233 217 1.01 1.03 1 . 04 1.12 38" 1.09 1.04 1.00 1.00 256 240 226 210 .96 .9^ 1.00 1.08 45" 1.04 1.00 1.00 234 218 20,3 1.01 1.04 1.11 These tables are based on investigations of 10-section radiators For Radiators under 6-section, the B.t.u. per sq. ft. increases rapidly and the tables cannot be used with accuracy. Above 6-section the error is small .51 Table 6-8 will be of interest as it compares the relative costs of cast- iron heating surface of different heights and number of columns where the efficiency of the surface is taken into consideration. As an example, compare the relative cost of 3-column 38-in. with single-column 23-in. surface. The 3-column surface cost is figured as 1.00 and it emits 226 B.t.u. per sq. ft. per hr. The single-column radiator cost is 1.36 but it emits 279 B.t.u. per sq. ft. per hr. Although the actual cost per square foot for the single-column radiator is 36 per cent more than for the 3-column, the 1-column radiator is 23 per cent more efficient in heat emission. If this increase in heating efficiency is considered, the cost of the single-column radiation is only 10 per cent more. Indirect heating surface generally refers to that located below and outside of the room to be heated. (See Figure 6-16<) The heat is delivered to the room by a system of ducts that convey^fWh'air from outside. The air passes over the surface, is heated and then discharged into the room through ^register faces located in the room floor or wall. This method of heating is Ceiling Line 1^" Air Line into Top of Dry Return. ?^"when Dry Return is over 10' 0" Distant Dry Return Supply Main Indirect Radiator Parts of Casing removed 12"x 12" Sliding Door at Bottom of Casing Full size Nipple to outside of Radiator , Casing, than a full size Ell and Nipple connecting to a reducing Ell Not less tfian 30" Union above Water Line of Boiler- Water Line of Boiler ^^ Connect into Wet Return Main- Fresh Air Quadrant Damper ' Clean Out Door ^^. „ Special Swing Cfieck Valve This Connection to be on tfie same Centre as Wet Return — — \ T Floor Line Z J=. /Wet Return near Floor 5 Fig. 6-16. Connections to an indirect radiator 52 called /res/t air indirect, as a constant supply of fresh heated air is dehvered into the room. The cold air duct is sometimes so arranged that outside air may be closed oflf and air taken from the basement in extreme cold weather. Where the air supply is taken from the room, passed over the heating surface and then discharged into the room again, the method is known as recirculatincj indirect. In either system no heating surface is located in the room to be heated. The indirect method of heating is most used in the principal rooms of residences, clubs, churches and similar types of buildings, and is much more expensive to install and to operate than is the direct system. All rooms heated by the fresh air indirect system must be provided with vents for the escape of the air replaced by that delivered by the "indirect stack," as this type of heating surface is often called. Many variable factors, each of prime importance, enter into an accurate calculation of the proper proportions of a system of this type. These vari- ables include velocity and direction of the wind, frictional resistance to the air flow in the ducts, and the loss of heat due to transmission through the walls of hot-air ducts. Each manufacturer of heating surface for this system has his own special design, which is usually sold by catalogue ratings in square feet of surface. Reliable data as to the free area between sections and the heating effect under the variable conditions of steam and air temperatures at various air velocities are unfortunately not available for each make of heating surface used in this method of heating. Proper values are very difficult to assign to the variable factors, and the several rules for determining the proper proportions of such a system are all based upon some standard conditions and assumptions. The general principle of an indirect system is the delivery of air to the room at a temperature higher than that of the room, and in such volume that in cooling to room temperature, sufficient heat units are given up to replace those required for transmission, infiltration and other requirements. The requirements for this method of heating are usually computed in the following way: First: Calculate the total heat requirements in B.t.u. per hour for the room to be heated as described in Chapter 5. Second: Determine the height of the column of heated air ; that is, the distance from center of indirect stack to center of the room register. Third: Assume the temperature of the air entering the room. This is usually taken about 120 deg. fahr. where air enters the radiator at zero and the radiator is supplied with steam at atmospheric pressure or slightly above. Fourth: Determine the velocity of air due to difference in densities between heated and outside air for columns of equal height. Fifth: Ascertain from the manufacturer of the selected type of heating- surface the velocity at which air must pass through the surface to produce the final required temperature , when the surface is supplied with steam at a predetermined temperature and air enters the heating stack at the minimum outside temperature. Ascertain also the temperature of the air on which this performance is based, the free area between the sections, and the 5.3 number of square feet of heating surface per section. The amount of heating surface may then be determined as follows: H = total B.t.u. losses per hour for the room. ti = temperature of air entering the room. ts = temperature of air in room (room temperature) . t, = temperature of air on which heating surface performance is based. d = density of air at temperature fc. V = performance velocity of air in feet per minute. a =free area per section of heating surface in square feet. none (f i \ £,0 ^ pounds of air required per minute = P where 0.2375 is the specific heat of the air. p T = cubic feet of air per minute at t=. p -T -^ av = number of sections of heating surface required from which the square feet of heating surface can be determined. The sizes of the ducts or flues for conveying the air to and from the heating surface are dependent upon the velocity of the air due to the unbalanced air column. This velocity may be determined theoretically from the formula : 4 on /h (t — to.) in which ^ = ^^^^m+T V = velocity in feet per minute. h = height of warm air column in feet or distance from center of heating surface to center of register, t = average temperature of air in column, to = average temperature of outside air. To allow for friction in ducts, through heating surface, register face and elsewhere, velocities of one-third of the theoretical may be assumed. The area of the hot-air duct may be determined as follows : X ■ 1 144 P ' Area m square mches = — ^ — d V in which P = pounds of air required per minute. d = density of air at average temperature in hot-air duct. V = velocity in feet per minute in duct. The register can have a free area equal to the area of the hot-air duct where velocity in hot-air duet is not in excess of 300 ft. per min. For higher velocities the register area should be increased. The area of the cold- air duct can be determined in a manner similar to the hot-air duct area, using density of the air at the cold inlet temperature. Direct-indirect heating surface, as the name implies, consists of radiators arranged so that a portion of each serves on the indirect principle and the remainder as a direct radiator; the entire surface, however, is located in the room to be heated. This combination is accomplished by providing a direct radiator and installing a metal box base under some of the sections. Cold fresh air is taken from the outside of the building directly through the wall and connected to this box base. The fresh air passes up through its portion of the surface into the room. The balance of the surface acts as plain dii'ect heating surface. This method of heating has come into quite general use in recent years in some localities where the state ventilation laws for public buildings specify either the quantity of air to be supplied per minute per person, or the number of square inches of fresh-air inlet duct per person. The latter requirement can be met with this type of heating surface. The size of the opening in the wall or the wall box determines the size of the box base, and the number of sections of the radiator enclosed by the box base are to be considered as available only for heating the incoming air. Sufficient additional direct heating surface must be provided, either by adding sections to the radiator, extending same outside of the box base on either end, or by installing separate units for supplying the heat necessary for requirements of the wall, glass and infiltration, as already mentioned. Vent flues must be extended from all rooms heated and ventilated by this method. In order to obtain desired air movement and prevent back draft in flues, they must have aspirating radiation or rotary type ventilators. The radiation best suited for direct-indirect surface is that with high and wide sections. One manufacturer of the most modern devices for this type of system states the size of the ventilating base, together with its capac- ity, fresh-air inlet area and amount of radiating surface to be enclosed, as given in Table 6-9. Table 6-9. Data for Direct-indirect Heating Surface Offered by One Manufacturer. Not Standard for Other Similar Equipment Capacity in Area of fresh Size of wall box cu. ft. per tnin. air openmg Heating surface 8 in. X 20 in. 180 120 sq. in. 50 sq. ft. 8 in. X 24 in. 240 144 50 8 in. X 30 in. 300 180 60 10}^ in. X 20 in. 270 160 50 lOK in. X 24 in. 330 192 60 lOM in. X 30 in. 420 240 60 As an example of selecting and computing heating surfaces, i-efer to the heat requirements as shown on Pages 38-39 for the various rooms in Figure 5-1, Page 36, and assume that steam will be used at 215 deg. fahr., or 1-lb. per sq. in. pressure. Room 3 requires a total of 22933 B.t.u. per hr. and is to be heated by means of direct radiation. The window sills are 24 in. high. There- fore, 23-in. high radiators should be installed. For a room of this size, it appears that 2 -column radiation should give sufficient surface. The B.t.u. emitted by 2-column, 23-in. high radiation is given in Table 6-1 55 Table 6-10. Surface in Square Feet of One to Twelve ll/4-inch Pipe Coil, 1 to 100 Feet Long (For other sizes of pipe, see note at bottom of next page.) Length Number of 1J4'' ' pipes of coil in feet 1 2 3 4 5 6 7 8 9 10 11 12 Square feet of heating surface 1 0.43 0.86 1.29 1. 72 2. 15 2. 58 3. 01 3. 44 3. 87 4. 30 4. 73 5.16 2 1 2 3 3 4 5 6 7 8 9 9 10 3 1 3 4 5 6 8 9 10 12 13 14 15 4 2 3 5 7 9 10 12 14 15 17 19 21 5 2 4 6 9 11 13 15 17 19 22 24 26 6 3 5 8 10 13 15 18 21 23 26 28 31 7 3 6 9 12 14 18 21 24 27 30 33 36 8 3 7 10 14 17 21 24 28 31 34 38 41 9 4 8 12 15 19 23 27 31 35 39 43 46 10 4 9 13 17 22 26 30 34 39 43 47 52 11 5 9 14 19 24 28 33 38 43 47 52 57 12 5 10 15 21 26 31 36 41 46 52 57 62 13 6 11 17 22 28 34 39 45 50 56 61 67 14 6 12 18 24 30 36 42 48 54 60 66 72 15 6 13 19 26 32 39 45 52 58 65 71 77 16 7 14 21 28 34 41 48 55 62 69 76 83 17 7 15 22 29 37 44 51 58 66 73 80 88 18 8 15 23 31 39 46 54 62 70 77 85 93 19 8 16 25 33 41 49 57 65 74 82 90 98 20 9 17 26 34 43 52 60 69 77 86 95 103 21 9 18 27 36 45 54 63 72 81 90 99 108 22 9 19 28 38 47 57 66 76 85 95 104 114 23 10 20 30 40 49 59 69 79 89 99 109 119 24 10 21 31 41 52 62 72 83 93 103 114 124 25 11 22 32 43 54 65 75 86 97 108 118 129 26 11 22 34 45 56 67 78 89 101 112 123 134 27 12 23 35 46 58 70 81 93 104 116 128 139 28 12 24 36 48 60 72 84 96 108 120 132 144 29 12 25 37 50 62 75 87 100 112 125 137 150 30 13 26 39 52 65 77 90 103 116 129 142 155 31 13 27 40 53 67 80 93 107 120 133 147 160 32 14 28 41 55 69 83 96 110 124 138 151 165 33 14 28 43 57 71 85 99 114 128 142 156 170 34 15 29 44 58 73 88 102 117 132 146 161 175 35 15 30 45 60 75 90 105 120 135 151 166 181 36 15 31 46 62 77 93 108 124 139 155 170 186 37 16 32 48 64 80 95 111 127 143 159 175 191 38 16 33 49 65 82 98 114 131 147 163 180 196 39 17 34 50 67 84 101 117 134 151 168 184 201 40 17 34 52 69 86 103 120 138 155 172 189 206 41 18 35 53 71 88 106 123 141 159 176 194 212 42 18 36 54 72 90 108 126 144 163 181 199 217 43 18 37 55 74 92 111 129 148 166 185 203 222 44 19 38 57 76 95 114 132 151 170 189 208 227 45 19 39 58 77 97 116 135 155 174 194 213 232 46 20 40 59 79 99 119 138 158 178 198 218 237 47 20 40 61 81 101 121 141 162 182 202 222 243 48 21 41 62 83 103 124 144 165 186 206 227 248 49 21 42 63 84 105 126 147 169 190 211 232 253 50 22 43 65 86 108 129 151 172 194 215 237 258 56 Table 6-10. Surface in Square Feet of One to Twelve 114-inch Pipe Coil, 1 to 100 Feet Long — Continued Number of IH" pipes Length of coil in feet 1 2 3 4 5 6 7 8 9 10 11 12 Square feet of heating surface 51 22 44 66 88 110 132 154 175 197 219 241 263 52 22 45 67 89 112 134 157 179 201 224 246 268 53 23 46 68 91 114 137 160 182 205 228 251 273 54 23 46 70 93 116 139 163 186 209 232 255 279 55 24 47 71 95 118 142 166 189 213 237 260 284 56 24 48 72 96 120 144 169 193 217 241 265 289 57 25 49 74 98 123 147 172 196 221 245 270 294 58 25 50 75 100 125 150 175 200 224 249 274 299 59 25 51 76 101 127 152 178 203 228 254 279 304 60 26 52 77 103 129 155 181 206 232 258 284 310 61 26 52 79 105 131 157 184 210 236 262 289 315 62 27 53 80 107 133 160 187 213 240 267 293 320 63 27 54 81 108 135 163 190 217 244 271 298 325 64 28 55 83 110 138 165 193 220 248 275 303 330 65 28 56 84 112 140 168 196 224 252 280 307 335 66 28 57 85 114 142 170 199 227 255 284 312 341 67 29 58 86 115 144 173 202 230 259 288 317 346 68 29 58 88 117 146 175 205 234 263 292 322 351 69 30 59 89 119 148 178 208 237 267 297 326 356 70 30 60 90 120 151 181 211 241 271 301 331 361 71 31 61 92 122 153 183 214 244 275 305 336 366 72 31 62 93 124 155 186 217 248 279 310 341 372 73 31 63 94 126 157 188 220 251 283 314 345 377 74 32 64 95 127 159 191 223 255 286 318 350 382 75 32 65 97 129 161 194 226 258 290 323 355 387 76 33 65 98 131 163 196 229 261 294 327 359 392 77 33 66 99 132 166 199 232 265 298 331 364 397 78 34 67 101 134 168 201 235 268 302 335 369 402 79 34 68 102 136 170 204 238 272 306 340 374 408 80 34 69 103 138 172 206 241 275 310 344 378 413 81 35 70 104 139 174 209 244 279 313 348 383 418 82 35 71 106 141 176 212 247 282 317 353 388 423 83 36 71 107 143 178 214 250 286 321 357 393 428 84 36 72 108 144 181 217 253 289 325 361 397 433 85 37 73 110 146 183 219 256 292 329 366 402 439 86 37 74 111 148 185 222 259 296 333 370 407 444 87 37 75 112 150 187 224 262 299 337 374 412 449 88 38 76 114 151 189 227 265 303 341 378 416 454 89 38 77 115 153 191 230 268 306 344 383 421 459 90 39 77 116 155 194 232 271 310 348 387 426 464 91 39 78 117 157 196 235 274 313 352 391 430 470 92 40 79 119 158 198 237 277 316 356 396 435 475 93 40 80 120 160 200 240 280 320 360 400 440 480 94 40 81 121 162 202 243 283 323 364 404 445 485 95 41 82 123 163 204 245 286 327 368 409 449 490 96 11 83 124 165 206 248 289 330 372 413 454 495 97 42 83 125 167 209 250 ncfo 334 375 417 459 501 98 42 84 126 . 169 211 253 295 337 379 421 464 506 99 43 85 128 170 213 255 298 341 383 426 468 511 100 43 86 129 172 215 258 301 344 387 430 473 516 Note : For all practical purposes, figure 1-3 sq. ft. of outside surface per lineal foot of 1-in. pipe ; and 1-2 sq. ft. for 1 1-2 in. pipe as 260 B.t.u. per hr. per sq. ft. of surface. As these radiators will be 20 sections long instead of the standard 10, on which the above efficiency was based, the efficiency, or B.t.u. emitted will be reduced by 3.5 per cent, making an actual efficiency of 251. This divided into the total heat require- ments gives 91 sq. ft. of heating surface required, which is supplied by two units of 46% sq. ft. each as marked on the plan. Data as above for determination of the other units are marked on the plan. Room 7, which is to be heated by indirect surface, is calculated as follows: The total requirements for the east side are 13058 B.t.u. per In*., and assuming that the air enters the room at 120 deg. fahr., the pounds of air required in accordance with formula on Page 54 would be 18.2 per minute. Vento radiation 30 inches long on 4-in. centers gives a temperature rise of air from zero to 120 deg. fahr. at 100 ft. per min. velocity, measured at 70 deg. fahr. volume. The free area per section is 0.225 sq. ft. The pounds of air as found above divided by the density at 70 deg. fahr., or 0.0749, gives 244 cu. ft. of air per minute. This volume divided by the velocity, then by the free area per section, gives eleven sections required. The distance from the center of the radiation to the floor above is 27 inches, which head with 120 deg. fahr. temperature difference gives a theo- retical velocity of 367 ft. per min., by the formulae on Page 54. For determining the size of the ducts, one-half of this value, or 184 ft. per min. velocity may be used. Using formula on Page 54 with a density for air at 120 deg. fahr., the area of the hot-air duct is 208 sq. in. The register if of 66^^ per cent free area should contain 312 sq. in. The cold-air duct by the above formula, using air density at zero, should have a sectional area of 165 sq. in. The indirect surface for the requirement of the west side of this room was calculated similarly. As another example, to determine the radiation necessary to supply the heat required for the factory building as calculated in the previous chapter and shown in Figure 5-2, Page 37. Assume that steam at 10-lb. per sq. in. pressure or at a temperature of 240 deg. fahr. is available for heating this building under maximum load conditions. The increase in B.t.u. emission of the heating surfaces for this increased temperature above the standard or basic temperature is 20 per cent, and there would be a further increase in efficiency of 3 per cent due to a 65-deg. fahr. instead of 70-deg. fahr. room temperature. This would make a total increase of 23.6 per cent in B.t.u. emitted per hour per sq. ft. of heating surface for this installation, over the basic value. The monitor portion of the building is provided with 1 J 4-in. pipe coils under the windows, with expansion springs at the ends, as shown. For the lower portion of the building cast-iron wall surface is to be installed as shown. The efficiency of the heating surface and method of determining the amount of surface are shown on the plan. S8 CHAPTER VII Ventilation Problems as They Affect the Design of Heating Systems VENTILATION in the past was based on more or less traditional and unscientific standards, but is now receiving more of the con- sideration warranted by its importance. The necessity of providing adequate ventilating facilities for public buildings and buildings for various classes of industrial operations has been recognized by the legislative bodies of numerous states and cities, which have passed laws and ordinances governing the quantity of air to be supplied per person, and in some instances also the locations from which the air supply is to be brought into the room and the vitiated air removed. Ventilation is classed, and rightly so, as a branch of applied science, and it is the duty of the ventilating engineer to apply the principles of this science to the problems with which he is dealing in such a manner that the results obtained will produce the most healthful and comfortable conditions in the ventilated rooms. A ventilating system may be very satisfactory in regard to the quantity and means of distribution of the air but still fail to produce healthful and comfortable conditions. A good ventilating system should produce im- mediate physical comfort. The human body is the best indicator as to whether or not these conditions are realized. Temperature and relative humidity are important factors in producing comfort; the human body is to a great extent influenced by the temperature of the surrounding air, and by the rate at which perspiration is evaporated from the body into the air, which again is influenced by the relative humidity of the air. It is generally considered that the dry-bulb temperature to produce a sense of comfort to a person at rest is 68 to 70 deg. fahr., provided a proper relation between the dry and wet-bulb temperatures is maintained. The human organism is very susceptible to abrupt changes such as might be experienced when passing from outdoors on a cold day into a heated room in which the relative humidity is below normal or vice versa. A ventilating system, to produce conditions of comfort and health, should therefore provide for maintaining a satisfactory relation between temperature and humidity. This relation, with a room temperature of 68 to 70 deg. fahr., generally assumes a relative humidity not below 40 per cent, nor over 60 per cent. Although this assumption is entirely traditional, a relation of humidity to temperature may be found between the limits of which true comfort will result. Investigations from time to time by various engineering organizations and civic bodies regarding ventilating methods employed in public buildings, and particularly in schools, have disclosed the fact that systems of complete hot-blast heating and ventilation have inherent defects. Many former 59 advocates of this type of equipment now favor the more modern types of "spht system." It has been proved improper from the standpoint of health and com- fort to employ a small quantity of highly heated air to replace the heat lost by transmission. The air supply should be large in volume and compara- tively low in temperature in order to obtain the best ventilating effect. The nearer the temperature of the incoming air corresponds to the room temper- ature to be maintained, the more nearly is the ideal condition obtained. To compensate for the heat losses tlirough waU and glass and other exposures, direct radiating surface should be installed. This direct radiat- ing surface, if placed under the windows, will also overcome the difficulties due to "outside wall and window chill" which, in the hot-blast system of heating, has been a source of considerable discomfort. The close relation of ventilation and heating makes necessary a discus- sion as to the effect of various methods of ventilation upon the design of the heating plant. To illustrate these effects, some of the commonest applica- tions of ventilation may be classified as follows : The fireplace. Direct-indirect system of heating and ventilation. Indirect system of gravity ventilation. Ventilating systems for school buildings. Ventilating systems of large theatres and auditoriums. Ventilation of churches. Ventilation of banquet halls, dining rooms, kitchens, etc. Exhaust ventilation of industrial plants. Hot-blast systems of heating for industrial plants. The Fireplace : The purpose of fireplaces is twofold, first, ornamental effect, and second, utility for warming at times when the heating plant is not in operation. Incidentally, also, the flue or chimney of the fireplace acts as a vent, the chimney effect or flue draft causing continuous outflow of air from the room into the atmosphere. This outflow of air from the room through the chimney of the fireplace has the tendency of lowering the air temperature and pressure in the room, causing a greater infiltration of air from outdoors than would take place without the fireplace. The additional air finding its way into the room tends to lower the temperature, unless compensation is provided in the form of sufficient additional radiating surface. Direct-indirect System of Heating and Ventilation : This method of heating and ventilation, as described in Chapter 6, has come into quite general use in certain sections of the country for ventilating school buildings, public libraries and courthouses. Indirect System of Gravity Ventilation: Heating by the indirect system, in which the heat is conveyed entirely by air to the space to be heated, also provides a fair means of ventilation, but is open to the objection of highly heated incoming air. The amount of air to be circulated is generally stipulated, which re- quires knowing the temperature to which the incoming air is to be heated 60 so that in cooling from incoming to maintained room temperature, enough heat units will be provided to offset the heat losses through windows, walls, and other exposures. In designing heating plants of the indirect type, the total air to be circulated must be known within a fair degree of accuracy in order to deter- mine the quantity of steam required. The indirect method of heating requires from three to four times the quantity of steam that would be needed with direct radiation for the same warming effect. This indicates the importance of carefully considering ventilating problems in connection with heating systems, in order to determine proper proportions for boilers, pipes, radiator supply valves, return traps, and any other heating system apparatus which would be affected by the in- creased steam requirement due to the ventilating equipment. With the indirect system it is also necessary to provide aspirating radiators in the vent flues. The method of computing indirect radiating surface for given heating effects and requirements is discussed in Chapter 6. Ventilating Systems for School Buildings: The direct-indirect and the indirect systems of heating previously mentioned are frequently used for ventilating school houses of the smaller type, but for buildings of larger proportions mechanical systems of ventilation are generally installed. The necessity for healthful and comfprtiible conditions in school build- ings has been the main stimulus for enacting ventilating laws by various states and cities. Great progress has been made in late years in the design of ventilating plants for school buildings. The antiquated hot-blast system of heating and ventilation without provision for humidification has been almost entirely abandoned and superseded by the modern split-system method of ventilating with tempered air, washed and humidified before being delivered into the rooms. Direct radiation is installed for taking care of the heat lost through direct exposures of walls, windows, doors, etc. Ajr is generally supplied to the class rooms through registers or dif- fusers placed at a level of seven to eight feet above the floor with the vent registers near the floor. The most satisfactory arrangement is generally obtained where the heat and vent flues are placed in the corridor walls and the air is blown towards the windows. The vitiated air is discharged from the vent flues into ventilators in the roof to the atmosphere. The cold air intake should preferably be at a point above the roof. The intake openings are dampered, and additional air intake openings are provided in the attic space, making the re-circulation of air from the building possible during the heating-up period in the morning. Delivering the air into the rooms at nearly the temperature to be maintained and with auto- matic temperature control or modulation supply valves on the direct radia- tors, gives ideal conditions as near as obtainable. In computing the requirements for direct heating in the ventilated spaces, it is only necessary to take into account the heat losses due to exposures. Exceptions, however, must be made of rooms which are to be in use after the ventilating system is shut down, such as libraries, reading rooms and offices. 61 Fig. 7-1. Arrangement of fresh air inlet with diffusers, vent outlet and direct radiators in a modern school room Ventilating systems of school buildings are usually shut down after the close of the afternoon session. Any rooms that may be in use after that period should have sufficient direct radiation to take care of the maxi- mum requirements without the assistance of the ventilating system. The steam required to temper the air needed for the ventilating system is generally greatly in excess of that required for the direct system of heating. Where air washers and humidity -control systems are installed, addi- tional steam is required to add to the heat in the air, compensating for the drop in temperature in passing through the air washer and to supply the humidity control apparatus. Masonry ducts under floors, if used for the main trunk supply system for air distribution, should be so constructed that they can be kept dry at all times. This can be accomplished by the use of a reliable system of waterproofing. The cooling effect of these masonry ducts must be considered in the design of heating and ventilating plants and during the heating-up period sufficient time should be allowed for heating the ducts thoroughly. The entire heating plant, including boilers, vacuum pumps, piping system and direct radiation, is affected by the method of ventilation. In the design of the plant all phases of the application and operation of the ventilating system must therefore be known and analyzed to make possible a well balanced system. 62 Ventilation of Theatres and Auditoriums: The ventilation of theatres and auditoriums presents an entirely different problem from that encountered in the ventilation of a building subdivided into a number of comparatively small rooms. The problem of proper air distribution in large spaces with seating capacities numbering into thousands requires special study to provide the required quota of fresh air for each occupant. Ventilating systems for theatres and auditoriums are usually operated only during the performances, so that portions of the structure which are in use at other times should be heated by direct radiation. The quantity of air supphed to theatre auditoriums, on the basis of 30 cu. ft. per min. per occupant, is usually so large that sufficient heat is supplied by delivering the air into the space at a temperature a few degrees higher than that to be maintained. The temperature regulating system should be flexibile enough to automatically reduce the incoming air temperature when a large percentage of the seats are occupied, and in this way prevent excessive temperature rise in the room. The modern theatre would not be complete without the installation of air washers, humidity-control system, and, for summer use, a refrigerating system for cooling the air. The design of heating and ventilating systems for large auditoriums presents an interesting problem in engineering. One is so closely affected by the other that both should be worked out together so that the results obtained will harmonize. Ventilation of Churches: Ventilation for churches is usually applied only to the main auditorium and Sunday-school room, the balance of the building being heated by direct radiation. Most churches are not continuously heated, and the warming-up period should on that account receive careful consideration by the designer. The ventilating system is generally operated during the Sunday services only. Whether to use the up-flow system of air distribution or to discharge the air into the room through registers in the wall will greatly depend on the size of the room to be ventilated. In large churches, a combination of both, blowing in the air partly through openings in the floors in the aisles, and partly through registers in the walls, will give good results. Vent openings are usually placed in the walls near the floor and in the ceihng. The ventilating system for a church should supply air for ventilation only and no attempt should be made to use the fan system for heating. For satisfactory results, sufficient direct radiation should be provided to com- pensate for all heat losses due to direct exposures and infiltration. Arrange- ment for re-circulating the air before the building is occupied will be found a convenience, both from the standpoint of shortening the warming-up period and also of effecting a considerable economy in the fuel consumption. It is considered good practice to have a separate boiler and piping system for that part of the heating and ventilating plant which will be in use Sundays only, having another boiler to heat the portions of the church in use during week days. 63 Ventilation of Banquet Halls, Dining Rooms, Meeting Rooms, Etc. : In no other class of ventilated rooms is the efficiency or inefficiency of the ventilating system so noticeable as in banquet halls, dining rooms and meeting rooms. Smoke-laden air indicates that the ventilating system is not functioning properly, while if the air is clear and fresh in spite of smoking by the guests, a satisfactory diffusion of air in the room is shown. As already pointed out in connection with other ventilating problems, the air should be brought in as nearly at room temperature as possible, and if heating of the room involves consideration of outside exposures, direct radiation should be used. The location and distribution of the exhaust open- ings is of prime importance and the exliaust should be accomplished by mechanical means. Vent openings should be placed near both floor and ceiling, and, if the structural conditions permit, additional vents should be provided in the ceihng toward the center of the room. Kitchens require a very large air change, which should be accomplished by means of exhaust fans. Ordinances of some cities specify a three-minute air change for hotel kitchens, requiring a separate steel vent stack to be extended through the roof for this purpose. An exliaust fan, with inlet connected to this vent shaft, is usually placed in the penthouse. Above the point where the fan inlet connection is made, a tight-fitting damper propped Anale Iron Frame bolted to Duct and anchored to Brickwork Steel Plate Fire Damper 7-2. Arrangement of fan, vent stack and safety damper of ventilating equipment for a kitchen 64 open with bar iron having a fusible hnk is placed in the vent shaft, and the fan discharge is reconnected to the vent shaft above this damper. In case the fusible link is melted, the damper in the fan intake drops by gravity, closing the fan inlet and the stack is opened to the atmosphere. This permits the stack to burn out without damaging the exhaust fan. Where kitchens adjoin the dining rooms, the latter can conveniently be exliausted through the kitchen. This greatly reduces the inflow of air from outdoors into the kitchen and at the same time prevents odors from the kitchen from flowing into the dining room. Where existing conditions do not permit induction of air from warmed spaces to replace that exhausted, the air must necessarily find its way into the kitchen from outdoors and provision must be made to prevent a drop below the desired temperature. This is best accomplished by installing direct or indirect radiation for heating to the temperature needed. Considerable heat is produced by the ranges and steam cooking utensils, so that the kitchen may be overloaded with radiation unless complete in- formation is available as to the kitchen equipment to be used. Exhaust Ventilation of Industrial Plants: Industries, which in their operations produce dust, acid fumes, or in any other way contaminate the air, require positive means for removing the dust or fume-laden air from _ the premises. Mechanical systems of exhaust ventilation are used to maintain a continuous air change by exhausting the dust-laden air. Various types of machines, such as grinders, buffers and wood-working machines, are provided with sheet-metal ducts running to the exhaust fans, which are usually centrally locat- ed, and discharge either into dust-collecting chambers or into the atmosphere, depending upon the nature of the dust or refuse to be handled. The continuous exhausting of air from any space will cause a corresponding inflow of out- door air which must be heated to avoid lowering the inside temperature. If the ventilated spaces have out- side exposures, the air is drawn directly from outdoors, and infiltration takes place uniformly ovev the entire exposed area. A sufficient amount of direct heat- ing surface to heat this air to the temper- ature to be maintained must be added to the heating surface required for heating the space without the exhaust system. Fig. 7-3. Indirect radiation con- nected for air supply through a wall. 65 The use of large indirect radiation connected for air supplj^ through window or other opening in outside wall, as shown in Fig. 7-3, has been found in practice to be an excellent method for Avarming the infiltrated air necessary to replace that remoA'ed by an exhaust fan system. In connection with temperature control of the warmed air this method has proved highly efficient. If, however, the ventilated space has no direct exposure and connects with other rooms so that the air will be drawn from these, the additional radiation must be placed in the rooms from which the air is drawn or indirect inlets must be provided. Chemical plants requiring the removal of acid fumes must usually exliaust large volumes of air from the rooms, and an equivalent quantity of air must be admitted directly from outdoors. This air is generally ad- mitted through special openings in the walls and is drawn through tempering coils, so that it enters the room at the temperature to be maintained. In such cases the heating-up requirement can be eliminated from the heat loss calculations, and the direct radiation should be sufficient only to compensate for the losses through direct exposures and infiltration. However, where the exhaust system is in use only at intervals, allowances for heating up the contents of the room should be made in figuring the warming-up period. Sufficient direct radiation should be added to su23ply the heat units required for this purpose. Hot-blast Systems of Heating for Industrial Plants: In indus- trial structures, such as large foundries, machine shops, erecting shops and round-houses, the hot-blast system of heating, instead of the direct method, is often selected, owing to its lower first cost. From the operating stand- point, however, the hot-blast system is considerably more expensive than the direct, because of the greater amount of steam required for heating by 1''ig. 7-4. Arrangement of hot-air ducts of hot-blast system in an industrial plant. The side walls are protected by direct radiation placed under windows any indirect method. This condition is particularly apparent in cases where all the air is taken directly from outdoors and after being circulated through the space is discharged into the atmosphere. Where air can be taken from the space to be heated and re-circulated, instead of taking it from outdoors, the steam requirements are considerably reduced. In either case, the air must be heated at the fan to such a tem- perature that in cooling from the air-outlet temperature to that maintained inside, all heat losses are offset under maximum conditions. Only a few general ventilating problems and their direct effect upon heating plant design have been mentioned in this chapter, but these show the importance of analyzing each problem thoroughly and making all necessary provisions for the ventilating system in heating system design. Factors Entering Design of Complete Heating and Ventilating Plant Air Quantities Required for Ventilation: Air quantities in many states and municipalities are fixed by legal restrictions which must be followed. However, some of the generally accepted standards are mentioned here. The type of building and the purpose for which it is to be used are the main factors entering into the design of any ventilating system, not only as to the type of ventilation Avhich is best adapted to each particular problem, but also as to the volume of air required. Tables 7-1, 7-2, and 7-3 list kinds of buildings, together with their air requirements and allowable air velocities. These quantities, with slight variation, have been universally adopted. Table 7-1. Air Requirements of Various Buildings Type of building Air supply. Cu. ft. per occupant per hr. School buildings 1800 Theatre and assembly halls 1500 Churches 1500 Prisons 2100 (Ordinary 2600 Hospitalsmounded 3500 [Contagion 6000 Residence 1600 to 2000 Factories 2000 to 3000 Table 7-2. Allowable Air Velocities. Public Building Work. Fan Systems Supply air Exhaust air Cold-air intake 700-1000 ft. per min. Register outlets 300-400 ft. per min. Cloth filters About 40 " " " Vertical flues (masonry) 400 " " " Air washers 500 " " " Vertical flues (sheet-metal) 500 " " Indirect heaters (Vento) 800-1200 " " " Horizontal ducts 600 " " Horizontal air ducts 1000-1200 " " " at far end up to 1000 at at fan, decreasing to 600 fan inlet. ft. at base of flues. Fan discharge outlet 700-1000 ft. per min. Verticalflues (masonry) 500 ft. per min. Vertical flues (sheet-metal) 600 " " Register outlets 200-300 " " For air outlets 15 ft. or more above floor velocity may be as high as 350 ft. per min. if not thrown directly down on persons below. 67 Table 7-3. Allowable Air Velocities in Various Buildings in Feet per Minute Horizontal ducts Vertical risers Outlets Factories 1500 to 2800 Schools 1000 to 1800 Hospitals 1000 to 1800 Theatres 1000 to 1800 Churches 1000 to 1800 900 to 1500 500 to 750 500 to 750 500 to 750 500 to 750 600 to 1200 300 to 500 300 to 600 300 to 600 300 to 600 Sizing of the Ducts : Two methods of estimating are in common use : First, the velocity method, in which the velocity is fixed in the various portions of the system, and decreases from the fan outlet to the various points of discharge. This method is applicable in single-duct systems and in public buildings layouts, where the law requires certain velocity standards. Referring to the duct design in Fig. 7-5, certain volumes and velocities are given. To determine the size of ducts at any particular point, the vol- ume in cubic feet of air passing that point is divided by the velocity in feet at that point, which gives the required area in square feet. Determination of the friction in any part of the duct is made by reference to the friction chart. Figure 7-7. In a single-duct system, the longest duct, or the duct requiring greatest pres- sure, should be designed for certain veloci- ties and the total pressure required at the 900'Vel.- ,5J Sq. Ft. Free Area 4f Sq. Ft. Free Area 1200 Cu. Ft. 1200 Cu. Ft. "^ ^ ~2tSq. Ft. Free Area 1200'Vel. lOOU'Vel. Fig. 7-5. Arrangement of ducts in a trunk-line system. Sized by the velocity method 900 Vel.- -900 Vel. -1-ISq. Ft. Free Area 3:=^ 1200 Cu. Ft. 1500 Cu. Ft. 1200 Cu. Ft. plenum chamber determined from the friction chart, Figure 7-7. All other ducts should then be designed for the same pressure. Second — The friction-loss method, in which the duct is proportioned for equal friction pressure loss in every foot of run. This method of duct sizing necessitates assumption of the velocity and volume at the outlets, and is adaptable to trunk-line duct systems such as are common in factories. Table 7-4 gives an easy and accurate method for sizing ducts by pres- sure loss method. An example of its application follows (See Figure 7-7) : Assuming a 1000 cu. ft. discharge from each outlet at 1000 ft. velocity per mill, the area of the outlet is 1 sq. ft. or say 14 in. in diameter. Referring to Table 7-4, a 14-in. pipe is equivalent to 737 1-in. pipes 68 29 — /' 1000 Cu. Fl. 1000 Cu. Ft. 1000 Cu. Ft. \^ (l / 1000 Cu. Ft. 1000 Co. Ft. 1000 Cu. Ft 39, T "^ Velocity at Outlets, 1000 Ft. per Min. Fig. 7-6. Arrangement of chicts in a trunk-line system. Sized by the pressure-drop method and two 14-in. pipes are equivalent to 1474 1-in. pipes. AJso, 1474 1-in. pipes are equivalent to approximately a 19-in. pipe, and so on. To deter- mine velocity at any point, the volume there is divided by the area in sq. ft. To determine friction in any portion of duct refer to Fig. 7-7. Calculation of Resistance or Pressure: It is not the intention to go into the many complex formulae entering into the loss of pressure in ducts but rather to arrange some easily workable method. Table 7-4. Comparison of the Air-carrying Capacity of Various Sizes of Pipes with That of a 1-in. Pipe of Same Length and Equal Friction Pressure Loss Example — With an equal pressure loss and equal length, a 4-in. diameter pipe wiU carry the same volume of air as thirty-two 1-in. pipes. Diam. 1" Pipes Biam. 1" Pipes Diam. 1" Pipes Diam. 1" Pipes Diam. 1" Pipes I 1 21 1985 41 10565 61 28850 81 .59122 9 5 99 2250 42 11300 62 30200 82 60831 3 16 23 2525 43 12030 63 31350 83 62540 4 32 24 2800 44 12621 64 32500 84 64249 5 56 25 3060 45 13400 65 33975 85 66396 6 88 26 3425 46 14100 66 35300 86 68542 7 129 27 3738 47 1.5000 67 36600 87 70687 8 180 28 4100 48 15850 68 38000 88 72833 9 244 29 4440 49 16610 69 39275 89 74979 10 317 30 4898 50 17600 70 40250 90 77125 11 402 31 5312 51 18275 71 41995 91 79271 . 12 501 32 5631 52 19335 72 43740 92 81416 13 613 33 6154 53 20000 73 45449 93 83562 14 737 34 6675 54 21500 74 47158 94 85708 15 876 35 7075 55 22300 75 48887 95 87854 16 1026 36 7735 56 23450 76 50576 96 89999 17 1197 37 8265 57 24500 77 52285 18 1375 38 8715 58 25600 78 53995 19 1580 39 9350 59 26700 79 55704 20 1775 40 10060 60 27700 80 57413 69 The friction chart, Figure 7-7, (based on accepted pressure loss formu- lae) provides quick, accurate determination of pressure loss. Example: Assume that 30000 cu. ft. of air per minute is passed through a duct 40 in. in diameter and 50 ft. long. From the 30000 cu. ft. division at the right of chart, trace horizontally to intersection with the line repre- senting 40 in. diameter pipe. PeriDendicularly down from this point the o o oooooo Friction in Inches Water Gauge per 100 Feet Fig. 7-7. Chart for determining pressure loss in ducts 70 Table 7-5. Resistance of 90-des. Elbows Radius of throat of elbow in diameters of pipe Number of diameters of straight pipe offering equivalent resistance Radius of throat of elbow in diameters of pipe Number of diameters of straight pipe offering equivalent resistance 1 . .67.0 .30.0 .16.0 .10.0 '. 6^1) . 5.0 . 4.3 -2V2 3 4.5 4.8 SW 5.0 4 5.2 4.1/^ 5.5 5 5.8 S'/Q 6.0 friction in inches of water per 100 ft. of pipe is given — in this case 0.54 inches. For 50 ft. the friction will be 50 per cent of 0.54 or 0.27 in. of water. Friction in inches of water multiplied by 0.58 gives friction in ounces. The resistance (Table 7-5) is expressed as that of the number of diameters of straight pipe of same diameter as the elbow, and is given for elbows hav- ing different radii of throat, also expressed in diameters of pipe. For instance, a 90-deg. elbow of 24-in. pipe, having a radius of throat equal to 1 diameter, that is 24 inches, offers the same resistance to the flow of air as 10 diameters of straight pipe or 20 ft. of straight pipe. n Ratio of Ion g sid of rectang ul r duct to diameter of Roun hpe fiaving lame resistance for same cu . ft. per mm. A ■^U — -i r r\ / B '■-^ U^ ^ / t <- -A ^ * ^ / / / :q J IV ale nt Duct :u ve / / / / / / 7 / / c / / 6 / / / c / / 5 / c / 5 , / c / A /(4-f+(if c r / D ~ '_ i y' / 1 "■'"' . > C 3 <' /" / ^ h ^ y 2 / ^ ^ ^ ^ 1 ^ ^ ^ _^ L. 0.; O.S 0.0 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 l.S 1.9 2.0 2.0 3.0 3.1 3.2 Fig. 7-8. Curve for determining the diameters of round pipes having the same friclion loss for same capacity as rectangular ducts of various dimensions 71 To the resistance of the duct system should be added the resistance through tempering and reheating coils, also air washers, plus a small factor of safety, thereby determining the total pressure against which the fan must deliver the specified volume of air. Where each branch duct leaves the trunk line, there should be a volume damper with trunnion, quadrant and locking device, for balancing the system. Figure 7-8 is a curve for determining diameter of round pipe having same friction for same capacity as rectangular ducts of varying dimensions. Selecting the Apparatus Sizes and Arrangement of Fans: For fan performances and capaci- ties, reference should be made to tables issued by the manufacturers. Table 7-6. Quantities of Air at Various Temperatures Which Will Be Raised 1 deg. fahr. by 1 B.t.u. At zero 1 cu. ft. of dry air weighs 0.0864 lb. and lib. .0864 Specific heat of air at constant pressure is 0.2375 = 11..574 cu. ft. ^^^ = 48.74 cu. ft. raised 1 deg. by 1 B.t.u Temp. Weight Cu. ft. 1 Temp. Weight Cu. ft. 1 Temp. Weight Cu. ft. 1 air deg. of 1 Cu. ft. B.t.u. will air deg. of 1 Cu. ft. B.t.u. will air deg. of 1 Cu. ft. B.t.u. will fahr. cu. ft. in 1 lb. raise 1 deg. fahr. fahr. cu. ft. in 1 lb. raise 1 deg. fahr. fahr. cu. ft. in 1 lb. raise 1 deg. fahr. . 0864 11.58 48.74 72 . 0747 13.39 56.40 152 . 0649 15.40 64.90 12 . 0842 11.87 .50.00 82 .0733 13.64 .57.40 162 .0638 15.65 66.00 90 , 0824 12.14 51.00 92 .0720 13.90 58.60 172 .0628 15.90 67.00 32 .0807 12.40 52.20 102 .0707 14.14 59.20 182 .0618 16.17 68.00 42 .0791 12.64 .53.10 112 . 0694 14.40 60.60 192 .0609 16.42 69.10 .52 .0776 12.88 54.10 122 . 0682 14.65 61.60 202 .0600 16.67 70.10 62 .0761 13.13 55.20 132 .0671 14.90 62.80 212 .0591 16.92 71.30 70 . 0750 13.34 .56.30 142 .0660 15.15 63 80 Heaters : To select a heater for any set of conditions it is necessary to know the volume of air to be handled, its initial temperature, and the temperature to which it must be raised. Two methods for detennining the above quantities are available where the building is heated as well as ventilated by the air. One applies where a definite air change is desired or where ventilation must be provided for a given number of people. Example: Assume a building requiring 18000 cu. ft. per min. measured at 70 deg. fahr. with a total of 860000 B. t. u. loss through exposed glass, walls, B.t.u. loss per hr. etc. Then Cu. ft. per min. X .2375 X 860,000 diffusion .075 X 60 45 deg. fahr 18000 X .2375 X .075 X 60 45 deg. diffusion + 10 deg. duct loss + 70 deg. desired room temperature = 125 deg. final temperature at coils. In this calculation 0.2375 is the specific heat of air and is constant and 0.075 is the weight of one cubic foot of air at the room temperature of 70 deg. (See Table 7-6.) The other method is to decide on the final temperature to be used with some fixed entering temperature. 72 Example: Suppose the hourly heat loss through exposed walls, glass, etc., is 1204500 B.t.u. Assume a final temperature at the heater of 135 deg. fahr. and a loss of 10 deg. in the ducts. The temperature at the duct outlets will then be 125 deg. fahr. The room temperature desired is 65 deg. and the outside temperature is deg. The difference in the temperature between the duct outlets and the room temperature is available for heating. (^ . . _ B.t.u. per hr. _ 1204500 u. . per mm. ^^ ^^ ^^ ^ ^^^^^ ^ ^^^ 60 X 60 X .2375 x .068 20720 cu. ft. per min. required, in which 0.2375 is specific heat of air and is constant and 0.068 is weight of one cu. ft. of air at 125 deg. (See Table 7-6.) Either of the above formulae can be used on split systems where a portion of the losses through walls, glass, etc., are taken care of by direct radia- tion, and the balance by the incoming air. In the split system where all heat loss through walls, glass, etc., is taken care of by direct radiation, the final temperature of the air is, of course, the same as the room temperature de- sired. However, in choosing the heater, allowance should be made for some temperature drop in the ducts (usually 10 to 20 degrees). After determining the volume and final temperature of the air the size of heater can readily be chosen from tables furnished by manufacturers. Table 7-7. B.t.u. Required for Heating Air* This table specifies the quantity of heat in B. t. u. required to raise 1 cu. ft. of air through any given temperature interval Temperature of air in room, deg. fahr. External Temp. 40° so° 60° 70° 80° 90° 100° 110° 120° 130° -40° 1.802 2.027 2.2.52 2.479 2.703 2.928 3.1.54 3.379 3.604 3.829 -30° 1.540 1.760 1.980 2.200 2.420 2.640 2.860 3.080 3.300 3.520 -20° 1.290 1.505 1.720 1 . 935 2.150 2.365 2.. 580 2.795 3.010 3.225 -10° 1.051 1.262 1.473 1.684 1.892 2.102 2.311 2.522 2.732 2.943 0° 0.822 1.028 1 . 234 1.439 1.645 1.851 2.0.56 2.262 2.467 2.673 10° 0.604 0.805 1.007 1.208 1.409 1.611 1.812 2.013 2.215 2.416 20° 0.393 0.590 0.787 0.984 1.181 1.378 1 . 575 1.771 1.968 2.165 30° 0.192 0.385 0.578 0.770 0.963 1.155 1.345 1.540 1.733 1 . 925 40° 0.000 0.188 0.376 0.564 0.752 0.940 1.128 1.316 1.504 1.692 50° 0.000 0.000 0.184 0.367 0.551 0.735 0.918 1.102 1.286 1.470 60° 0.000 0.000 0.000 0.179 0.359 0.538 0.718 0.897 1.077 1.256 70° 0.000 0.000 0.000 0.000 0.175 0.350 0.525 0.700 0.875 1 . 049 *F. BahMYnamns Manual of Heaiimj and Ventilation. Boiler Horsepoaver Required : To determine the boiler horsepower required for air heating, the following formula can be used: Cu. ft. per min. X 60 X A ^^ . i ~ ^ = lb. steam per hour. B in which A = B.t.u. required for heating 1 cu. ft. of air from initial to final temperature (See Table 7-7). B = latent heat of steam lb. steam per hr. i -i , qi~r^ ^ boiler horsepower From the manufacturers' tables the condensation rates per square foot of surface are given for various velocities and temperatures, and it is well to check up the above formula from these given factors. 73 CHAPTER VIII Proportioning of Chimneys "VTO problem in the heating of buildings presents greater elements of \ uncertainty than that of projDerly proportioning the chimney. In larger installations, such as isolated plants for the production of power, light and heat, the conditions may usually be very accurately determined in advance. By use of the formula given hereafter, proper results follow in almost every case. A. Chimneys for House-Heating Boilers In small plants and particularly residence heating, it is not practicable to make such accurate advance determinations of all the conditions. Usually the chimney is built into the wall, thereby requiring that its cross-section must be proportioned to the width of brick. Chimneys so built are usually either smoothly mortared on the inside or lined with thin tile of rectangular or circular cross-section. The latter gives such freedom from friction and eddy currents and lessened surface for loss of heat in the gases, that a round chimney lining will frequently give fully as good results as would be ob- tained in the square of brick-work in which it is enclosed. The inclination to cut down cross- sectional area to save cost and space in the portion of building through which the chimney passes should be discouraged as false economy. Once the chimney is built into the structure, increase of area is practically impossible, and a chimney that is too small Fig. 8-1. Cross-sections through typical house chimneys -169i- 678' Inside Area equals 80 sq.ins. 11!4 -13— Inside Area equals 188 sq.ins. ■/.■/^^//y^//y^y^^/^/V^/^^^/>M/y^^^^'/y'A Fig. 8-2. Seven bricks per course Fig. 8-3. Nine bricks per course 74 remains a source of discomfort and waste during the entire life of the struc- ture. Little is saved in building an 83/2-"i- by 13-in. flue as compared with a 13-in. by 18-in. flue, the latter having more than twice the area and more than twice the capacity, while the bricks per course are as 9 is to 7. (See Figures 8-2 and 8-3.) To get the greatest efli"ectiveness, a definite amount of draft must be available. The actual amount required varies widely for different types of commercial cast-iron boilers, and, unfortunately, it is not always possible to know in advance which make of these boilers will be selected or may later be installed. It is, therefore, preferable to provide for excessive draft which may be controlled by damper, rather than to risk insufficient draft, the remedying of which is almost hopeless. For ascertaining the probable interior cross-section of round or rectan- gular flue linings, also unlined brick chimneys necessary for average cast-iron heating boilers where height in feet from combustion chamber to top of chimney and maximum hourly rate of evaporation in pounds of water are known. Figures 8-7a and 8-7b will be found convenient. With the maximum rate and height of chimney determined, enter the table at right-hand column at the determined hourly evaporation rate ; fol- Table 8-1. Dimensions of Flue Linings Fig. 8-4 U Fig. 8-5 Fig. 8-6 As mauu 'actured by The Delaware Clay Products Co. W. S. Dickey Clay Mfg. Co. Robinson Clay Products Co. Pittsburgh, Penna. Kansas City, Mo. Akron, Ohio Rectangular and square Circular Rectangular and square Circular Rectangular and square Circular Sq. Sq. Sq. 1 Sq. Sq. Sq. m. m. m. m. m. in. free A B C D free E F free A B C D free E F free A B C D free E F area 3H 7K 4^ SK area 2S 6 714 area area area area 23 29 334 734 4V^ &V, 23 314 7 434 8H 28 6 714 36 ■m uy. 4J/, 13 3S 7 SH 61 VH ■/^ SM. S'/, 36 ■i^ 1134 434 13H 38 V ■6V, 47 2i/, IB^s 4U IX .^0 X 9U 46 ■AH 1214 4 I/O 13 60 ■i'/» lo'/o 41/, 17 50 S 9 39 6H. 6M 7M TA 64 9 10 li 92 7H VZVa 8i4 13 47 4^2 lOM 6 12 64 9 10^2 52 T^ 7A 8H SU 78 10 nv. 145 ISt^b 12A 13 13 33 534 534 7¥ ^Vi 78 10 12 SU B-hi 11 ,> XU 13 113 12 14 127 TV, I6V, XU 17'/, 125 12'^ UH 52.5 ■iv^ V'4 SH S'/o 113 12 14 IIU (i%( IBM X'/o IX 176 15 1714 202 12H 16 H 13 171/0 80 6''/, 113/a ■&V-, 13 176 15 17 V« 129 iiH IIH 13 13 254 18 20H 270 IBlV 16A 171/2 17^2 104 6i/2 16 8H IS 254 IS 20>^ 188 11 "4 1634 13 IS 314 20 2234 291 1914 21U 127 \\-Vi 11« 13 13 314 20 23 26ti i(> 16 IX IS 3SI) 22 25 M 169 1034 lb3/( 13 IS 346 21 452 24 27M 499 ^5iV 27^ 240 15H loM IS IS 380 452 572 707 855 lOlS 22 24 27 30 33 36 27 35 Note. All dimensions are in iaches and subject to slight variation 75 TYPES OF CHIMNEY CONSTRUCTION 1 /i/\A/ Rectangular Tile Circular Tile Ruueh Brick (T^ ^^ /' ' ^ / / / / 1 ^— ^^— ' 1 / / / / 1 — ^ / / / / f / / y / / / / / \^s • V / / / / / . j Jl / / 1 / / / ^-^^ \-^^\ ~ ;/ // 7 7 / Y~ SIZES OF CHIMNEYS / / 1 v// / / Inside dimensions in inches 7 / /, 'L / \/ / / / // > / /i/ / / ' / // 1/ ^ / / / / / f / //// / // 1 / // / ' y / // ' / 't / / / / / / / oq",. og" / 1 1 / // / / / / / '/, / /// / / 24'- / lU ' f ' / ^ / / / 11) X 3'2 - // 7//// / / / / / / W/J^/TAA / / y / / trJu/in / /' / / fn i/'/77/Y / / / / / / 20 'x 24- y / / / j/ / / / / ////////////. / / / V / y /////////// / / / / / y I,....,,- /////////// / ' / y / / 1 w/////// A / y y //////:/. // / 1/ / ^ A y SU X 20 — y/////7Z A / ^ A V y //////// / / ^ /^ ixry 20- / ' f/n / / / . V / ^y /A /// / / / . y y y . / ir.'x 24"- //j ' / / / / if / / A [y // '/ / / / / ^ / y y 1 / // r/ / / / / / / y y y lO'x 20- / /, /. / / / / / y y ^ 1«'- / / / / / / y y y y IC'/lSxlSHo- y V / / / / / y ^ ^ ic'x lo" _ / V / / ' / / y \y ^ y ,-,,," ,-. ," l^'x 1-t" > '/ / / / / / y y i6'x ie"_ / ^/ / / V / y ^ ^ y V, / ^ ^ / / / ^- ^ \y ^ ^. / V / / y ^ ^ ^ 15 - > y / / y y y^ ^ ^ i2M'Mie5^" - ^ i/ / / A ^ -^ -^ " 11?4"!:10X" _ ,,, . / / ^ y ^ ^ ^ ^ / /■ / i^ <- lllX"x-155(' _ / y ^ ^ -^ v^ \ ^ ^ 12-.;6='12Mg - / X ^ \^ ' — llJs V 113/' 12 — „ ,, '^^U,-;" = i2"xi2- y ^ \^ ^ -^ ■' "- S"x 20"- ^^ 1^ ^ -^ T^Viejs' - „ s"x ifi' ^ r^ ^ ' ^ ^ ^ ^^ __ 5^>lC- = "- s'^^i^-- •^ - — rT" 6%"xiiji; = s- — " __[__ 1 — ■ 7'.'|1' x'7i^' - -■•- . 8X8'- — r— f,x; X liK" - (i"- , . — 1 ~ 1 1 Fiff. 8-7a 30 40 50 GO 70 SO 00 100 FEET IN HEIGHT BETWEEN COMBUSTION CHAMBER AND TOP OF CHIMNEY IJOO UJO 1400 1350 1300 1250 1200 1150 1100 1050 1000 950 900 o= 850 o zr. 800^ (OO LU 700 fe CO 050^ CD GOO 550 500 150 400 350 300 250 200 150 100 50 76 TYPES OF CHIMNEY CONSTRUCTION / / / / CSUUU Rectangular Tile Circular Tile f^omh Brick 1 > 1 / / 2900 / / / / / ^^ [^— |.;_-^j '/ / / / 2S00 m ^-^ 1 / / / h4^ / / 1 1 1 / / / / 2700 liM\ h-^^ / 1 / / / / / ' / / / Iti^aJ / 2G00 1 / f / / / / ra) h-1' 1-/ 1/ A / 7 / A- 2500 SIZES OF CHIHflNEYS 1 ^ / J / / / / / Inside dimensions in inches 1 / / /, / / / / 2400 36"- ,.» .." 1 h > / / / / / / / 5s\- Jnl III ' / ' f '/ 'a / / / / 2300 / / / / / / / / 1 1 / 1 / / / / / / / 2200 1 } / / , > / f / / / 24"x 44"- 7 1,1 / / / / / / / / / 2100 2S X .36 - 1 // h ^ / / / / / / / HI /// // / / / / / / 2000^ 33 — //// /// / / / / / / / / 21 X 40 - 1 V////7/ '/ / / / / / / 1900 cE „ „ mTfm /, / / / / / imii/l / / / / / / / / 1800 s 3 24'x 36- , THT 1 / / / / / / / / 24X36'- ///// 'n O / / / / / / / / / 1700 '^ U- 1 hi // / / / / / / / / / 20"x 40|- 30- „„. „„» //////// / / / / / / / 3600^ ^ " 20"x 40" I'Nfj/ // ' / / / / / / / 24"x 32" ////// ^ / / / / / / 1500 o a l\/ 1 7 / / / / / / / 20 'x bb- //// ^/ / / / / / / 1400 24"x2S"- 20X36- //// // "^ / / V / / / V y 24'x 28- //// / /, Y / / / / ,/ / / y 1300 20'x 32^ - //// // / / / / /\ / ^ IX 20> S2l // /// / / / y / / / 1200 <^/ / / /, / V-, y / ^- ~" 1190 24''x 24- // /// / / // / / / / '^ ^ / X 1100 20lx_2a- , //I// A- V / / /• y 24 — // /V,' / / / /' / ^ y iOOO 16"x 32- "' " "" // A V / / / z' y y ^ 20"x 24- V 7 / / V- / y / ^ 900 k> / / / / u y ^ ■^ ■■"n'Sr "n" ifi''^* '^-s' ' ^ / / / / y y y ^ 300 '-i- - ...- ' 6 ^ / / y / ^ lO'x 24- ,1 ' ' , / / / /• y' ^ / ^ ,^ 700 2^- 16x24- / / V / / y^ --' / / y /' ^ 1^ ^ ^^ i—- 600 16"x 20l / y u^ ^ y y ^ y ^ ^ ^ -^ 500 30 40 50 GO 70 80 90 100 FEET iN HEIGHT BETWEEN COMBUSTION CHAMBER AND TOP OF CHIMNEY Fig. 8-7b — Probable capacities of chimneys of different forms, sizes and heights to produce proper draft for average cast-iron boiler of up-draft type using anthracite coal low horizontally to left to intersection of vertical line representing given height, then downward along the curve to its left end, then follow a hori- zontal line to left; the interior cross-sections of linings and rough brick above the horizontal should be ample under usual conditions. 77 When desiring to ascertain probable capacity of a chimney of known dimensions and construction, the chart is read in reverse order. Dotted hnes on Fig. 8-7b indicate that for 11800 lb. evaporation per hr. and 60-ft. chimney height, a 22-in. diameter, or 16 by 28-in. tile lining should be proper, or that 20 by 24-in. rough brick would be ample. It must, however, be borne in mind that the location of the building in relation to topography and surrounding structures may render a chimney absolutely inefficient, while another similar in every respect of height and cross-section, used for similar boiler and fuel, but favorably located, will be able to produce a superabundance of draft; also that the resistance due to thickness of coal bed, character and quality of fuel as well as resistance be- tween the combustion chamber and chimney, vary in difi^erent makes of boilers having similar ratings, and that these resistances form a large part of the total head for which chimneys are required. The chimney problem should be presented to the boiler manufacturer for his study and recommendation. B. Chimneys and Draft for Power Boilers* The height and diameter of a properly designed chimney depend upon the amount of fuel to be burned, the design of the flue, with its arrange- ment relative to the boiler or boilers, and the altitude of the plant above sea level. There are so many factors involved that as yet there iias been pro- duced no formula which is satisfactory in taking them all into consideration and the methods used for determining stack sizes are largely empirical. In this chapter a method sufficiently comprehensive and accurate to cover all practical cases will be developed and illustrated. Draft is the difference in pressure available for producing a flow of the gases. If the gases within a stack be heated, each cubic foot will expand, and the weight of the expanded gas per cubic foot will be less than that of a cubic foot of the cold air outside the chimney. Therefore, the unit pressure at the stack base due to the weight of the column of heated gas will be less than that due to a column of cold air. This diff'erence in pressure, like the difference in head of water, will cause a flow of the gases into the base of the stack. In its passage to the stack the cold air must pass through the furnace or furnaces of the boilers connected to it, and it in turn becomes heated. This newly heated gas also rises in the stack and the action is continuous. The intensity of the draft, or difference in pressure, is usually measured in inches of water. Assuming an atmospheric temperature of 62 deg. fahr. and the temperature of the gases in the chimney as 500 deg. fahr., and, neglecting for the moment the difference in density between the chim- ney gases and the air, the difference between the weights of the external air and the internal flue gases per cubic foot is 0.0347 lb., obtained as follows: Weight of a cubic foot of air at 62 deg. fahr. = 0.0761 lb. Weight of a cubic foot of air at 500 deg. fahr. = 0.0414 lb. Difference = 0.0347 lb. ■ Reprinted from Steam by permission of Babcock & Wilcox Co. 78 Therefore, a chimney 100 ft. high, assumed for the purpose of iUustration to be suspended in the air, would have a pressure exerted on each square foot of its cross-sectional area at its base of 0.0347 x 100 = 3.47 lb. As a cubic foot of water at 62 deg. fahr. weighs 62.32 lb., an inch of water would exert a pressure of 62.32^12 = 5.193 lb. per sq. ft. The 100-ft. stack would, therefore, under the above temperature conditions, show a draft of 3.47-^5.193 or approximately 0.67 in. of water. The method best suited for determining the proper proportion of stacks and flues is dependent upon the principle that if the cross-sectional area of the stack is sufficiently large for the volume of gases to be handled, the intensity of the draft will depend directly upon the height; therefore, the method of procedure is as follows : (1) Select a stack of height to produce the draft required by the partic- ular character of fuel and amount burned per sc^uare foot of grate surface (2) Determine the cross-sectional area necessary to handle the gases without undue frictional losses. The application of these rules follows : Draft Formula: The force or intensity of the draft, not allowing for difference in density of air and of the flue gases, is given by the formula : D = 0.52 HxP(i — i) {Formula 8-1) in which ^ ^ ^^' D = draft produced, measured in inches of water, H = height of top of stack above grate bars in feet, P = atmospheric pressure in pounds per square inch, T = absolute atmospheric temperature, Ti = absolute temperature of stack gases. In this formula no account is taken of the density of the flue gases, it being assumed that it is the same as that of air. Any error arising from this assumption is negligible in practice, as a factor of correction is applied in using the formula to cover the difference between the theoretical figures and those corresponding to actual operating conditions. The force of draft at sea level (which corresponds to an atmospheric pres- sure of 14.7 lb. per sq. in.) produced by a chimney 100 ft. high with the temperature of the air at 60 deg. fahr. and that of the flue gases at 500 deg. fahr. is, / 1 1 \ D = 0.52 X 100 X 14.7 (j4j-^-1^) = 0.67 Under the same temperature conditions this chimney at an atmospheric pressure of 10 lb. per sq. in. (which corresponds to an altitude of about 10000 ft. above sea level) would produce a draft of, D = 0.52 X 100 X 10 (gl^-^) = 0.45 For using this formula it is handy to tabulate values of the product, 0.52 X 14.7 (^^_^) 79 which we will call K, for various values of Ti. With these values calculated for assumed atmospheric temperature and pressure, Formula 8-1 becomes, D = K H. {Formula 8-S) For average conditions the atmospheric pressure may be considered 14.7 lb. per sq. in., and the temperature 60 deg. fahr. For these values and various stack temperatures K becomes: Temperature of slack gases Constant K 750 0084 700 0081 650 0078 600 0075 550 0071 500 0067 450 0063 400 0058 350 0053 Draft Losses : The intensity of the draft as determined by the above formula is theoretical and can never be observed with a draft gauge or any recording device. However, if the ashpit doors of the boiler are closed and there is no perceptible leakage of air through the boiler setting or flue, the draft measured at the stack base will be approximately the same as the theoretical draft. The difference existing at other times represents the pres- sure necessary to force the gases through the stack against their own inertia and the friction against the sides. This difference will increase with the velocity of the gases. With the ashpit doors closed the volume of gases passing to the stack is a minimum and the maximum force of draft will be shown by a gauge. As draft measurements are taken along the path of the gases, the read- ings grow less as the points at which they are taken are farther from the stack, until in the boiler ashpit, with the ashpit doors open for freely admit- ting the air, there is little or no perceptible rise in the water of the gauge. The breeching, the boiler damper, the baffles and the tubes, and the coal on the grates all retard the passage of the gases, and the draft from the chimney is required to overcome the resistance offered by the various factors. The draft at the rear of the boiler setting where connection is made to the stack or flue may be 0.5-in., while in the furnace directly over the fire it may not be over, say, 0.15-in., the difference being the draft required to over- come the resistance offered in forcing the gases through the tubes and around the baffling. One of the most important factors to be considered in designing a stack is the pressure required to force the air for combustion through the bed of fuel on the grates. This pressure will vary with the nature of the fuel used, and in many instances will be a large percentage of the total draft. In the case of natural draft, its measure is found directly by noting the draft in the furnace, for with properly designed ashpit doors it is evident that the pressure under the grates will not differ sensibly from atmospheric pressure. Loss IN Stack: The difference between the theoretical draft as de- termined by Formula 8-1 and the amount lost by friction in the stack proper, is the available draft, or that which the draft gauge indicates when 80 connected to the base of the stack. The sum of the losses of draft in the flue, boiler and furnace must be equivalent to the available draft, and as these quantities can be determined jProm record of experiments, the problem of designing a stack becomes one of proportioning it to produce a certain available draft. The loss in the stack due to friction of the gases can be calculated from the following formula : fW-rH AD = -l—r-, — {Formula 8-3) in which A D = draft loss in inches of water, W = weight of gas in pounds passing per second, C = perimeter of stack in feet, H = height of stack in feet, / = a constant with the following values at sea level: .0015 for steel stacks, temperature of gases 600 deg. falir. .0011 for steel stacks, temperature of gases 350 deg. fahr. .0020 for brick or brick-lined stacks, temperature of gases 600 deg. fahr. .0015 for brick or brick-lined stacks, temperature of gases 350 deg. fahr. A = area of stack in square feet. This formula can also be used for calculating the frictional losses for flues, in which case, C = the perimeter of the flue in feet, H = the length of the flue in feet, the other values being the same as for stacks. The available draft is equal to the difference between the theoretical draft from Formula 8-2 and the loss from Formula 8-3, hence: d' = available draft = KH - ^^^^ (Formula 8-J^) Table 8-2 gives the available draft in inches that a stack 100 ft. high will produce when serving different horsepowers of boilers with the methods of calculation for other heights. Height and Diameter of Stacks: From Formula 8-4, it becomes evident that a stack of certain diameter, if it be increased in height, will produce the same available draft as one of larger diameter, the additional height being required to overcome the added frictional loss. It follows that among the various stacks that would meet the requirements of a particular case there must be one which can be constructed more cheaply than the others. It has been determined from relation of stack costs to diameters and heights, in connection with the formula for available draft, that the minimum cost stack has a diameter dependent solely upon the horsepower of the boilers served, and a height proportional to available draft required. Assuming 120 lb. of flue gas per hr. for each boiler horsepower, which provides for ordinary overloads and use of poor coal, the method stated gives: For unlined steel stack — diameter in inches = 4.68 (hp.) *. (Formula 8-5.) For masonry lined stack — diameter in inches = 4.92 (hp.) *. (Formula 8-6.) In both of these formulae, hp. = the rated horsepower of the boiler. From this formula the curve. Figure 8-8, has been calculated and from it the stack diameter for any boiler horsepower can be selected. 81 Table 8-2. Available Draft Calculated for 100-ft. stack of different diameters, assuming stack temperature of 500 deg. fahr. and 100 lb. of gas per hp. For other heights of stack multiply draft by height -H 100 Horse- Diameter of stack in inches | Horse power Diameter of stack in inches power 36 42 48 54 60 66 72 78 84 90 96 102 108 114 120 90 96 102 108 114 120 132 144 100 200 300 .64 .55 .41 .62 .55 .61 2600 2700 2800 .47 .45 .44 .53 .52 .50 .56 .55 .55 ..59 .58 .58 .61 .60 .60 .62 .62 .61 .64 .64 .64 .65 .65 .65 400 500 600 .21 .46 .34 .19 .56 .50 .42 .61 .57 .53 .61 .59 2900 3000 3100 .42 .40 .38 .49 .48 .47 .54 ..53 .52 . 57 .56 .56 .59 .59 .58 .61 .61 .60 .63 .63 .63 .65 .64 .64 700 800 900 .34 .23 .48 .43 .36 .56 .52 .49 .60 .58 .56 .63 .61 .60 .63 .62 .64 3200 3300 3400 .45 .44 .42 .51 .50 .49 .55 .54 .53 .58 .57 .56 .60 .59 .59 .63 .62 .62 .64 .64 .64 1000 1100 1200 .29 .45 .40 .35 .53 .50 .47 .58 .56 .54 .61 .60 .58 .63 .62 .61 .64 .63 .63 .64 .64 .65 3500 3600 3700 .40 .48 .47 .45 .52 .52 .51 .56 .55 .55 .58 .58 .57 .62 .61 .61 .64 .63 .63 1300 1100 1500 .29 . 44 .40 .36 ..52 .49 .47 ..57 .55 .53 .60 .59 .58 .62 .61 .60 .63 .63 .62 .64 .64 .63 .65 .65 .64 .65 .65 .65 3800 3900 4000 .44 .43 .42 .50 .49 .48 .54 .53 .52 .57 .56 .56 .61 .60 .60 .63 .63 .62 1600 1700 1800 .31 .43 .41 .37 .52 .50 .47 .56 .55 .54 .59 .58 .57 .62 .61 .60 .63 .62 .62 .64 .64 .63 .65 .64 .64 .65 .65 .65 4100 4200 4300 .40 .39 . 47 .46 .45 ..52 .51 .50 ..55 .55 .54 .60 .59 .59 .62 .62 .62 1900 2000 2100 .34 .45 .43 .40 .52 .50 .49 .56 .55 .54 .59 .59 .58 .61 .61 .60 .63 .62 .62 .64 .63 .63 .64 .64 .64 4400 4500 4600 .44 .43 .42 .49 .49 .48 .53 .53 .52 .59 .58 .58 .62 .61 .61 2200 2300 2400 .38 .35 .32 .47 .45 .43 .53 .52 .50 .57 .56 .55 ..59 .59 .58 .61 .61 .60 .62 .62 .62 .64 .63 .63 4700 4800 4900 .41 .40 .47 .46 .45 .51 .51 .50 .57 .57 .57 .61 .60 .60 2500 . 41 . 49 .54 ..57 .60 .61 .63 5000 .44 .49 .56 .60 For other stack temperature add or deduct before multiplying by ^'^ as follows:* For 750 deg. fahr. add . 17 in. For 700 deg. fahr. add . 14 in. For 650 deg. fahr. add . 11 in. For 600 deg. fahr. add .08 in. For 550 deg. fahr. add . 04 in. For 450 deg. fahr. deduct . 04 in. For 400 deg. fahr. deduct . 09 in. For 350 deg. fahr. deduct . 14 in. ' Results secured by this method will be approximately correct For stoker practice where a large stack serves a number of boilers, the area is usually made about one-third more than the above rules call for, which allows for leakage of air through the setting of any idle boilers, ir- regularities in operating conditions, etc. Stacks with diameters determined as above will give an available draft which bears a constant ratio of the theoretical draft, and allowing for the cooling of the gases in their passage upward through the stack, this ratio is 0.8. Using this factor in Formula 8-2, and transposing, the height of the chimney becomes, H = -^ {Formula 8-7) .8K Where H = height of stack in feet above the level of the grates, d^ = available draft required, K = constant as in Formula 8-2. 82 120 --^ " 110 _^ , -'^ 100 ■^'"^ 90 J 80 ^^ ^ ^ ^ i 70 Si •S 60 ^ /^ / 1 50 ° 40 / / / 30 / / 20 10 / ( 200 100 600 800 1000 1200 1100 IGOO 1800 2000 2200 2400 2C00 2800 3000 3200 3400 3600 3800 4000 Horsepower of Boilers Fig. 8-8. Diameter of stacks and horsepower they will serve Computed from Formula (8-5). For brick or brick-lined stacks increase the diameter 6 per cent Losses in Flues : The loss of draft in straight flues due to friction and inertia can be calculated approximately from Formula 8-3, which was given for loss in stacks. It is to be borne in mind that C in this formula is the actual perimeter of the flue and is least, relative to the cross-sectional area, when the section is a circle, is greater for a square section, and greatest for a rectangular section. The retarding eflfect of a square flue is 12 per cent greater than that of a circular flue of the same area and that of a rectangular with sides as 1 and V/i, 15 per cent greater. The greater resistance of the more or less uneven brick or concrete flue is provided for in the value of the constants given for Formula 8-3. Both steel and brick flues should be short and should have as near a circular or square cross-section as possible. Abrupt turns are to be avoided, but as long easy sweeps require valuable space, it is often desirable to increase the height of the stack rather than to take up added space in the boiler room. Short right-angle turns reduce the draft by an amount which can be roughly approximated as equal to 0.05- in. for each turn. The turns which the gases make in leaving the damper box of a boiler, in entering a horizontal flue and in turning up into a stack should always be considered. The cross-sectional areas of the passages leading from the boilers to the stack should be of ample size to provide against undue frictional loss. It is poor economy to restrict the size of the flue and thus make additional stack height necessary to overcome the added friction. The general practice is to make flue areas the same or slightly larger than that of the stack ; these should be, preferably, at least 20 per cent greater, and a safe rule to follow in figuring flue areas is to allow 35 sq. ft. per 1000 83 horsepower. It is unnecessary to maintain the same size of flue the entire distance behind a row of boilers, and the areas at any point may be made proportional to the volume of gases that will pass that point. That is, the areas may be reduced as connections to various boilers are passed. With circular steel flues of approximately the same size as the stacks, or reduced proportionally to the volume of gases they will handle, a convenient rule is to allow 0.1-in. draft loss per 100 ft. of flue length and 0.05-in. for each right-angle turn. These figures are also good for square or rectangular steel flues with areas sufficient to provide against excessive frictional loss. For losses in brick or concrete flues, these figures should be doubled. Underground flues are less desirable than overhead or rear flues for the reason that in most instances the gases will have to make more turns where underground flues are used and because the cross-sectional area of such flues will oftentimes be decreased on account of an accumulation of dirt or water which it may be impossible to remove. In tall buildings, such as office buildings, it is frequently necessary in order to carry spent gases above the roofs to install a stack the height of which is out of all proportion to the requirements of the boilers. In such cases it is permissible to decrease the diameter of a stack, but care must be taken that this decrease is not sufficient to cause a frictional loss in the stack as great as the added draft intensity due to the increase in height, which local conditions make necessary. In such cases also the fact that the stack diameter is permissibly decreased is no reason why flue sizes connecting to the stack should be decreased. These should still be figured in proportion to the area of the stack that would be furnished under ordinary conditions or with an allowance of 35 sq. ft. per 1000 horsepower, even though the cross-sectional area appears out of proportion to the stack area. Loss IN Boilers: In calculating the available draft of a chimney, 120 lb. per hr. has been used as the weight of the gases per boiler horse- power. This covers an overload of the boiler to an extent of 50 per cent and provides for the use of poor coal. The loss in draft through a boiler proper will depend upon its type and baffling and will increase with the per cent of rating at which it is run. No figures can be given which will cover all conditions, but for approximate use in figuring the available draft necessary it may be assumed that the loss through a boiler will be 0.25-in. where the boiler is run at rating, 0.40-in. where it is run at 150 per cent of its rated capacity, and 0.70-in. where it is run at 200 per cent of its rated capacity. Loss IN Furnace: The draft loss in the furnace or through the fuel bed varies between wide limits. The air necessary for combustion must pass through the interstices of the coal on the grate. Where these are large, as in the case with broken coal, but little pressure is required to force the air tlirough the bed; but if they are small, as with bituminous slack or small sizes of anthracite, a much greater pressure is needed. If the draft is insufficient the coal will accumulate on the grates and a dead, smoky fire will result with the accompanying poor combustion ; if the draft is too great, the coal may be rapidly consumed on certain portions of the grate, leaving 84 1.4 1.3 £1.1 O CO V -S 1.0 £0.9 c o U.J CO c if 0.0 c V 3 0.5 a> .a f 0.4 ° 0.3 O "- 0.2 0.1 1 1 / ^y 1 1 y / // fl / tl fl ■* 7 f / / # V y V / 4 / ■ / / / / ..>o* ^ / / / f / / .#: / /> / / / / / / ■\»>* ^ y / / / / / ^>^ %-^ <»s>^ ^^ / / V ,^ / ^ / y ^ / 'y. y :^ ^ L--''^ J K ^ ==^ -— -^ n 10 40 45 15 20 25 30 35 Pounds of Coal Burned per Sq. Ft. of Grate Surface per Hour Fig. 8-9. Draft required at different combustion rates for various kinds of coal the fire thin in spots and a portion of the grates uncovered with the resulting losses due to an excessive amount of air. Draft Required for Different Fuels : For every kind of fuel and rate of combustion there is a certain draft with which the best general results are obtained. A comparatively light draft is best with the free-burning bituminous coals and the amount to use increases as the percentage of volatile matter diminishes and the fixed carbon increases, being highest for the small sizes of anthracites. Numerous other factors, such as the thick- ness of fires, the percentage of ash and the air spaces in the grates bear directly on this question of the draft best suited to a given combustion rate. The effect of these factors can only be found by experiment. It is almost im- possible to show by one set of curves the furnace draft required at various rates of combustion for all of the different conditions of fuel, etc., that may be met. The curves in Figure 8-9, however, give the furnace draft necessary to burn various kinds of coal at the combustion rates indicated by the abscis- sae, for a general set of conditions. These curves have been plotted from the records of numerous tests and allow a safe margin for economically burning coals of the kinds noted. Rate of Combustion: The amount of coal which can be burned per hour per square foot of grate surface is governed by the character of the coal and the draft available. Where the boiler and grate are properly propor- 85 tioned, the efficiency will be practically the same, within reasonable limits, for different rates of combustion. The area of the grate, and the ratio of this area to the boiler heating surface will depend upon the nature of the fuel to be burned, and the stack should be so designed as to give a draft sufficient to burn the maximum amount of fuel per square foot of grate surface cor- responding to the maximum evaporative requirements of the boiler. Solution of a Problem : The stack diameter can be determined from the curve. Figure 8-8. The height can be determined by adding the draft losses in the furnace, through the boiler and flues, and computing from Formula 8-7 the height necessary to give this draft. Example: Proportion a stack for boilers rated at 2000 horsepower, equipped with stokers, and burning bituminous coal that will evaporate 8 lb. of water from and at 212 deg. fahr. per lb. of fuel; the ratio of boiler heating surface to grate surface being 50: 1; the flues being 100 ft. long and containing two right-angle turns; the stack to be able to handle overloads of 50 per cent; and the rated horsepower of the boilers based on 10 sq. ft. of heating surface per horsepower. The atmospheric temperature may be assumed as 60 deg. fahr. and the flue temperatures at the maximum overload as 550 deg. fahr. The grate surface equals 400 sq. ft. The total coal burned at rating = = — ~ — - = 8624 lb. The coal per square foot of grate surface per hour at rating 400 "" "^• For 50 per cent overload the combustion rate will be approximately 60 per cent greater than this, or 1.60 x 22 = 35 lb. per sq. ft. of grate surface per hr. The furnace draft required for the combustion rate, from the curve. Figure 8-9, is 0.6-in. The loss in the boiler will be 0.4-in., in the flue 0.1 in., and in the turns 2 x 0.05 = 0.1-in. The available draft required at the base of the stack is, therefore, Inches Boiler 0.4 Furnace 0.6 Flues 0.1 Turns 0.1 Total T2 Since the available draft is 80 per cent of the theoretical draft, this draft due to the height required is 1.2 -^ 0.8 = 1.5 inches. The chimney constant for temperatures of 60 deg. fahr. and 550 deg. fahr. is 0.0071 and from Formula 8-7, H = ^=211ft. Its diameter from curve in Figure 8-7 is 96 in. if unhned, and 102 in. inside if lined with masonry. The cross-sectional area of the flue should be approximately 70 sq. ft. at the point where the total amount of gas is to be handled, tapering to the boiler farthest from the stack to a size which will depend upon the size of the boiler units used. 86 Correction in Stack Sizes for Altitudes: It has been assumed that a stack height for altitude will be increased inversely as the ratio of barometric pressure at the altitude to that at sea level, and that the stack diameter increases inversely as the two-fifths power of this ratio. This relation assumes a constant draft measured in inches of water at base of stack for a given rate of boiler operation, regardless of altitude. If the assumption be made that boilers, flues and furnaces remain the same, and further that the increased velocity of a given weight of air passing through the furnace at a higher altitude would have no effect on the com- bustion, the theory has been advanced* that a different law applies. Under the above assumptions, whenever a stack is working at its maxi- mum capacity at any altitude, the entire draft is utilized in overcoming the various resistances, each of which is proportional to the square of the velocity of the gases. Since boiler areas are fixed, all velocities may be related to a common velocity, say that within the stack, and all resistances may, there- fore, be expressed as proportional to the square of the chimney velocity. The total resistance to flow, in terms of velocity head, may be expressed in terms of weight of a column of external air, the numerical value of such head being independent of the barometric pressure. Likew ise the draft of a stack, expressed in height of column of external air, will be numerically independent of the barometric pressure. It is evident, therefore, that if a given boiler plant, with its stack operated with a fixed fuel, be transplanted from sea level to an altitude, assuming the temperatures remain constant, the total draft head measured in height of column of external air will be numerically constant. The velocity of chimney gases will, therefore, remain the same at altitude as at sea level and the weight of gases flowing per second with a fixed velocity will be proportional to the atmospheric density or inversely proportional to the normal barometric pressure. To develop a given horsepower requires a constant weight of chimney gas and air for combustion. Hence, as altitude is increased, the density is decreased and, for the assumptions given, the velocity through furnace, boiler passes, breeching and flues must be correspondingly greater at altitude than at sea level. The mean velocity, therefore, for given boiler horsepower and constant weight of gases will be inversely proportional to the barometric pressure and the velocity head measured in column of external air will be inversely proportional to the square of the barometric pressure. For stacks operating at altitude it is necessary not only to increase the height but also the diameter, as there is an added resistance within the stack due to the added friction from the additional height. This frictional loss can be compensated by a suitable increase in the diameter and when so com- pensated, the chimney height would have to be increased at a ratio inversely proportional to the square of the normal beirometric pressure. In designing a boiler for high altitudes, as already stated, the assumption is usually made that a given grade of fuel will require the same draft measured in inches of water at the boiler damper as at sea level, and this leads to mak- ing the stack height inversely as the barometric pressures, instead of inversely as the square of the barometric pressures. The correct height, no doubt, * Chimneys for Crude Oil, C. R. Weymouth, Trans. Am. Soc. M. E., Dec, 1912 87 falls somewhere between the two values as larger flues are usually used at the higher altitudes, whereas to obtain the ratio of the squares, the flues must be the same size in each case, and again the effect of an increased velocity of a given weight of air through the fire at a high altitude, on the combustion, must be neglected. In making capacity tests with coal fuel, no difference has been noted in the rates of combustion for a given draft suction measured by a water column at high and low altitudes, and this would make it appear that the correct height to use is more nearly that obtained by the inverse ratio of the barometric readings than by the inverse ratio of the squares of the barometric readings. If the assumption is made that the value falls midway between the tw o formulae, the error in using a stack figured in the ordinary way by making the height inversely proportional to the barometric readings, would differ about 10 per cent in capacity at an altitude of 10000 ft., which difference is well within the probable variation of the size determined by different methods. It would, therefore, appear that ample accuracy is obtained in all cases by simply making the height inversely proportional to the barometric readings and increasing the diameter so that the stacks used at high altitudes have the same frictional resistance as those used at low altitudes, although, if desired, the stack may be made somewhat higher at high altitudes than called for in order to be safe. The increase of stack diameter necessary to maintain the same friction loss is inversely as the two-fifths pow er of the barometric pressure. Table 8-3. Stack Capacities, Correction Factors for Altitudes Altitude, height in feet above sea level Normal barometer R, ratio barometer reading sea level to altitude R- R*^, ratio increase in etack diameter 30.00 1.000 1.000 1.000 1000 28.88 1.039 1.079 1.015 2000 27.80 1.079 1.164 1.030 3000 26.76 1.121 1.257 1.047 4000 25.76 1.165 1.356 1.063 5000 24.79 1.210 1.464 1.079 6000 23.87 1.257 1.580 1.096 7000 22.97 1.306 1.706 1.113 8000 22.11 1.357 1.841 1.130 9000 21.28 1.410 1.988 1.147 10000 20.49 1.464 2.144 1.165 Table 8-3 gives the ratio of barometric readings of various altitudes to sea level, values for the square of this ratio and values of the two-fifths power of this ratio. These figures show that the altitude affects the height to a much greater extent than the diameter, and that practically no increase in diameter is necessary for altitudes up to 3000 ft. For high altitudes the increase in stack height necessary is, in some cases, such as to make the proportion of height to diameter impracticable. The method to be recommended in overcoming, at least partially, the great increase in height necessary at high altitudes is an increase in the grate sur- face of the boilers which the stack serves, in this way reducing the combus- tion rate necessary to develop a given power and hence the draft required for such combustion rate. 88 CHAPTER IX Boilers THE boiler equipment is the production center of the heating system and the point Avhere the bulk of the operating expense is centered. For this reason, a heating plant can be successful and economical only if the boiler equipment is of correct type, good material and workmanship, well proportioned from the standpoint of its work and ample in capacity. Service from a heating system cannot properly be termed satisfactory unless the desired heating effect is secured without waste of fuel and without excess labor at the boilers, so it is the endeavor of this chapter to promote a better understanding of the boiler parts and what they should do. Due consideration should be given to the proper selection of a boiler, not only as to size and capacity, but also as to its adaptability to the existing local conditions which, if not properly considered, may affect the success of the entire plant. It is not intended in this discussion to cover any details of boiler con- struction, which properly come under the province of, and can best be solved by, the boiler makers themselves. Steam boilers haA^e been built in one form or another for nearly 200 years, yet today they are the least understood of all the important elements which make up a power or heating plant. If it were not necessary to consider the efiiciency of the performance of a steam boiler, such as the number of pounds of water evaporated by a pound of fuel, or the relation of grate surface to heating surface, etc., the problem would be simple. All the years of experience and the thousands of evaporating tests made have not produced any definite and reliable rule or formula for cal- culating either the amount of steam that will be generated per hour with a given fuel or the quantity of steam in pounds produced per pound of fuel burned in the furnace. Lucke* says: "There is no absolute measure of boiler performance as to capacity or efficiency as a basis of compeirison to measure the goodness of a boiler as a boiler; comparison must, therefore, be between one and another boiler, or one and another service condition ; one boiler may be said to be better than another, or one condition more favorable and another worse, for the result desired, but hardly more than this is possible." For commercial purposes, boiler capacities seem to be quite well stand- ardized, boilers used for heating work being rated in capacity of square feet of steam radiation, and boilers for power work in boiler horse-power. The boiler capacity rating in square feet is based on equivalent cast- iron direct radiation with condensation rate of 3^^ lb. steam per sq. ft. per hr. The American Society of Mechanical Engineers in 1885 adopted a double definition of the Boiler Horsepow er as follows : (a) The evaporation of 34.5 lb. w ater per hr. from and at 212 deg. fahr. * Engineering Thermodynamics 89 (b) The absorption by water, between fuel conditions and that of the steam leaving the boiler, of 33,305 B.t.u. per hr. A steam boiler consists of the following essential parts: A furnace in which the combustion of the fuel takes place; a vessel to contain water to be evaporated; a steam space where the steam is liberated and where the generated steam is contained; a heating surface to transmit the heat of the furnace to the water ; a smoke pipe to carry away the products of combustion, and various attachments, such as gauges, damper regulators, safety valves, etc. A proper relation of the first four parts to each other constitutes a suc- cessful heating boiler. It is of prime importance that the furnace is of proper design as regards grate area, size of combustion chamber, ash pit, etc., to give most efficient operation, permitting the consumption of the maximum effective quantity of fuel per square foot of grate area. Further references will be made to importance of selecting the proper kind of grates for the various grades of fuel available in various localities. The water space or the water-holding capacity of a boiler does not al- ways receive enough attention. It should be remembered that the boiler which holds the greatest quantity of water at or near the normal water line for given size or capacity is the safest one to use, because in such a boiler the water line is not so readily brought down to and below the danger point, as compared with another having only about half the water-holding capacity. An investigation of the various cast-iron boilers to which our remarks regarding the water-holding capacity particularly refer, will show that there is an astonishing difference in this particular feature. Selecting two boilers of the same capacity but of different makes, it will be found that the water- holding capacity at or near normal water line varies as much as 1 to 4. It stands to reason that the boiler from which 4 gal. of water can be with- drawn by lowering the water line J 2 in- will be safer than the boiler which shows Y2 in. lower water with loss of only 1 gallon. Boiler manufacturers recognize more and more that if a boiler is to be successful the steam space should be liberal. The velocity with which the steam bubbles are separated from the water in the liberating space is ex- tremely high. A boiler with limited steam-liberating surface will very likely lose its water under heavy load conditions because under the influence of this velocity, particles are carried over with the steam into the piping system. The heating surface of a boiler includes all parts of the boiler shell, flues, tubes, etc., covered by water and exposed to hot gases. Surface hav- ing steam on one side and hot gases on the other is superheating surface. The American Society of Mechanical Engineers recommends that in measuring heating surface, the side next to the gases be used. Thus when estimating the heating surface of water-tube boilers, the outside areas of the tubes are measured, and for return-tubular or fire-box boilers the inside areas are measured. The heat generated by the combustion of fuel permeates from the fur- nace through the heating surface to the water in the boiler. As the process of combustion proceeds, the heat liberated is immediately absorbed, partly by heat from the freshly added fuel, but mainly from the gaseous products of combustion. The absorption of heat by these substances causes a rise in their temperature and from these gases the heat is transmitted through the heating surfaces into the boiler water. This transmission of heat takes place in three distinct ways, each of which is governed by a definite law not applicable to the others. Before the heat reaches the body of the boiler water, it changes its mode of travel at least twice. It is first imparted to the heating surface: (a) by radiation from the hot fuel bed, the furnace walls and the luminous flames, and (b) by convection from the hot moving gaseous products of combustion. Upon reaching the heating surfaces the heat changes its mode of trans- mission and passes through the soot, metal and scale to the inner surface, which is in contact with the water, purely by conduction. From the wet side of the heating surface the heat is carried into the boiler water mainly by convection.* The water in the boiler can absorb only that heat called the "heat available for the boiler," which is above its own temperature. Heat below tliis temperature will not flow into the boiler and is, therefore, not available. A commercial boiler absorbs only part of the available heat, which expressed as a percentage, is the true boiler effciency. This efficiency de- pends chiefly on the arrangement of the heating surfaces. Therefore, from point of economy in operation, the heating surface available and its arrange- ment should be carefully considered by the designer when selecting boiler equipment for a heating plant. The boiler efficiency, which is the only true measure of the ability of the boiler to absorb heat, is expressed by the following equation : rr, 1 -, m • heat absorbed bv boiler 1 rue boiler eliiciency = -, — n— pj — tt^^— j — rr- "^ heat available tor boner The efficiencies ordinarily used in commercial boiler tests may not rep- resent the true performance of the boiler under actual working conditions. Boiler capacities as given in catalogues of manufacturers of heating boilers are based on the elficiencies obtained in the testing laboratories, and these may not be representative of true conditions. In selecting a boiler for a heating plant, due allowance should be made to take care of this dis- crepancy by adding a factor of safety to compensate for the difference in laboratory and actual working conditions. This allowance, which may be called the safety factor to be added to the theoretical capacity, varies widely for the various types of boilers. Before determining the safety factor to be added to the commercial rating, the designer should carefully consider the type of boiler, the kind of fuel to be used, and the kind of attention the plant will receive, as all these bear on the performance and efficiency. The necessity of providing an extra safety factor is recognized also by the heating trade and various trade associations that have established rules and regulations for guidance of members in determining boiler capacities. The difficulty in obtaining the more desirable grades of coal has re- sulted in an increasing tendency to use coals which are more readily obtain- able and lower in cost. The grates of the boilers should therefore be * Bulletin 18, United States Bureau of Mines 91 properly designed for the fuel which will most likely be used. Different authorities haA^e a wide range of opinion as to the width of the air space that should be used between grate bar openings for a given grade of fuel. Professor Gebhardt recommends an air space of ^ in. between the grate bars and bars ^4 in. wide for power boilers and for average bituminous coal. For No. 3 buckwheat coal an air space of 3/16 in. and for No. 1 buck- wheat 5/16 in. is recommended. Grate areas are usually determined in proportion to the heating surface of the boiler, that is, for a given fuel, the grate surface and heating surface have a fixed ratio. For normal operation, a ratio of grate surface to heat- ing surface of 1 to 35 to 45 develops the rated capacity of the boiler, while for fine coal or overload conditions, a ratio of 1 to 25 is desirable. For return-tubular boilers and water-tube boilers, the following table shows the usual ratios of grate surface to heating surface and also the grate bar openings applying with these ratios when using soft coal fuel. Table 9-1. Grate Surfaces for Soft Coals ^ . . ■ Ratio of erate surface to Coal ■ Grate bar openings heating surface. Mine run Slack Mine run Slack Va., W. Va., Md., Pa i^-in. %-m. 1:55 1:50 Ohio, Ky.. Tenn., Ala %-% ii 1:50 1:45 lU., Ind., Kan., Okla H - }4 H 1:45 1:40 Col. andWyo ?^ H 1:45 1:40 Determination of the amount of grate surface to be used under given conditions involves the available draft as well as the fuel to be used. The curves given in Figure 8-9, page 85, show hoAV much draft is necessary for burning different coals at various rates of combustion. The draft required to overcome resistances in the boiler is also given in Chapter 8, pages 83 and 84. These losses in the boiler and furnace must be deducted from the total available draft to determine the draft available for the fuel bed. The capacity of the boiler and the B.t.u. to be developed being known, the number of pounds of coal to be burned can be readily computed. The total grate area required is found by dividing the total number of pounds of coal to be burned by the rate of combustion taken from Figure 8-9, page 85. Hand-fired return tubular and water-tube boilers are readily operated at the rates of combustion in pounds of coal per square foot of grate area given in Table 9-2. Small boilers of the residence-heating type usually burn coal at rates ranging from 1 to 5 lb. per sq. ft. of grate surface per hr. and in larger heating Table 9-2. Rates of Combustion for Various Coals Anthracite 15 lb. per sq. ft. per hr. Semi-anthracite 16 " Semi-bituminous 18 " Eastern bituminous 20 " " Western bituminous 28 " 9-2 boilers the ratio ranges from 4 to 12 lb. per sq. ft. of grate surface per hr. These low rates of combustion are the result of demands for less fre- quent attention, in order that the man who fires the boiler may devote time to other work. In consequence, heating boilers are expected to do their work when fired once every hour or two or in residence heating, once in six to eight hom'S, whereas power boilers are fu-ed at regular intervals of five to ten minutes.* Another reason why heating boilers require different fu-ing methods to burn bituminous coals successfully is that the space in the fire-box above the fuel bed is usually very much smaller than is the corresponding space in power boilers.* This space, known as the combustion chamber, is where the smoky gases driven off from the coal must become mixed with air and burn. The more rapidly the combustible gases are driven off from the coal, the larger must be the space necessary for burning them completely. The relatively small combustion space in heating boilers makes it important that the firing be done in a way to prevent the gases from being driven off too rap idly, t The type of boiler to fit the given conditions most satisfactorily depends upon the physical conditions of the plant, as well as the type of heating system selected. The success of one depends upon the other. For this reason boiler selection is discussed also in Chapter 10, Selection of the Proper Type of Steam Heating System. On account of the great variation of governing conditions, no attempt will be made here to discuss in detail the method of installation of the boilers or their connections. Precautions should be taken in the design of the boiler plant to mini- mize bad effects from priming. Liberal bleeder or drip connections from the boiler header, connecting directly to the return header, eliminate a great percentage of this trouble. Priming in most cases is due to the presence of grease or oil in the boiler or to the presence in the water of certain alkalies which cause the water to foam or bubble, and be carried into the piping system by the steam. Before it can be expected to perform its functions uniformly, effectively and economi- cally, a boiler must be thoroughly cleansed of oil, scale, dirt and other im- purities. The priming of boilers is not confined to any particular type or make. The plant designer will safeguard the interest of the owner and him- self as well, if he makes sure that bleeder connections are made to protect the boiler in case of priming and that his instructions about proper cleaning of the boiler and the entire heating system are carried out in full by the heating contractor. For thoroughly cleaning a boiler, the safety valve should be removed and a sufficient quantity of soda ash should be placed within the boiler to cause saponification of oils and grease. A temporary overflow pipe should be run to waste from the safety valve outlet or highest point of the boiler. * Technical Paper 180, United States Bureau of Mines t For further reference to the importance and effect of combustion space see Technical Papers 63, 80 and 137 of the United States Bureau of Mines 93 With a moderate fire and the addition of feed water as required to prevent injury, the foaming of the boiler will cause the flow of oil and grease through the overflow pipe to waste. After thorough boiling, the fire should be drawn and when cool, the water should be withdrawn and then the boiler should be thoroughly washed with clean water to remove dirt and chemicals. This treatment for boilers should be repeated whenever neces- sary as indicated by abnormal fluctuations of the water line or by the appear- ance of foaming. Damper control is an important feature of boiler operation. There are two classes of damper regulators, (1) those that move the damper for slight changes in the steam pressure, with a proportional movement due to the change in pressure and (2) those that operate the dampers between extreme positions when the steam pressure changes. The first is preferable from the standpoint of economical combustion. As mentioned in Chapter 8, the fuel in a steam-boiler furnace is made to burn by passing through it a current of air, which supplies the necessary oxygen and carries away the products of combustion. A liberal supply of available air is therefore very important. Yet in many cases the space allotted to the boiler room is inside, small and without adequate air supply for combustion. Boiler rooms should be of ample size and depth to ac- commodate the boilers without crowding, and should have an abundant supply of air for both combustion and ventilation. The space in front of the boilers should be ample for convenience and comfort. A cramped boiler room is not only unsightly, but it also adds to the difficulty of taking care of the plant efficiently. The attendant, when firing, has to stand about 4)^2 or 5 ft. from the front of the furnace and usually about 12 to 18 in. to the left of a straight line running through the centre of the furnace door. He should have ample room to swing his scoop from the coal pile into any part of the furnace. Many a fireman is blamed for the poor economy shown by the plant he operates where the dissatisfaction should be charged at least partially to the plant designer. It is difficult to keep skillful firemen in a small, poorly- kept boiler room. The size and type of boiler to be specified and the evaporation the boiler will give are problems in which the advice of the boiler maker may well be considered. The boiler maker is usually quite willing to co-operate if provided with such data as the total radiation in square feet and pounds of condensation, total condensation of the steam and return lines in equivalent square feet of radiation and pounds, the quality and size of fuel available, the size and height of chimney and the firing period to be allowed. U4 CHAPTER X Selection of tlie Proper Type of Steam Heating System THE heat requirements of the building having been determined, the next step is the selection of the proper type of steam heating system to fit the particular needs. It is essential that the system of supply and return piping shall be such that the circulation of steam will be posi- tively and uniformly maintained and that the air and the products of condensation shall be disposed of continuously in order that the system shall be efficient as well as economical in operation. Two broad types of two-pipe steam heating systems have proved so successful during the past 20 years that their use has become the modern standard practice. Each type is flexible in its application and may be modified in detail to meet the variable conditions that arise. These two types are the Ofen Return-Line or Modulation System and the Vacuum System. In the Open Return-Line or Modulation System a pressure slightly above atmosphere is maintained in the supply piping and radiators, the products of condensation flowing by gravity to a point of disposal at which atmos- pheric or occasionally slightly lower pressure exists. Here the air is vented through suitable devices and the condensation is either returned to the boiler, if one is provided, or wasted to the sewer, if the source of supply is a so-called "street system." In its simplest form a modulation system consists of a low-pressure steam boiler and its appurtenances, supply piping, radiating surfaces, a modulation or graduated control valve at the inlet of each radiator and a thermostatic return trap at the outlet, a system of return piping with a device at the end to automatically remove the air and return the water of condensation to the boiler. Under favorable conditions the boiler operates, after initial heating, for long periods under vapor or partial vacuum, but due to the flexibility of the system, higher pressures are permitted in severe weather, when maximum heating requirements exist. It is very important that the steam pressure shall be closely controlled by means of an extremely sensitive damper regulator which will maintain the pressure always within a few ounces of that for which the regulator is set, thus making it possible to operate the boiler at or near atmospheric pressure during mild weather. The damper regulator also serves to quickly check the fire whenever there is a tendency for the pressure to rise, due either to a sudden closing off of a considerable amount of the radiating surface or carelessness on the part of the attendant, after firing up the boiler. For reasons of safety it is necessary that the device returning the con- densation to the boiler shall function properly when the steam pressure 95 rises above the normal operating point and e^'en when, for short period, it reaches the blowing-off pressure of the safety ^'alve, which is ordinarily not over 10 lb. in an open return-line system. In the Vacuum System, a pressure at or slightly above or below at- mospheric is maintained in the supply piping and radiators, and air and the water resulting from condensation of steam are continuously removed by mechanical apparatus which maintains, in the return piping, a pressure less than atmospheric. The partial vacuum required to remove the air and condensation is produced and maintained by mechanical displacement of the vapors of condensation. The two types of systems are similar, in that a positive circulation of steam is secured by the natural flow of the heating medium from a higher to a lower pressure. The distinguishing difference between the two types lies in the method of removing and disposing of the air and the products of condensation. In either modulation or vacuum svstems, modidation or graduated supply valves, when attached to the radiators permit control of the room temperature by simple hand operation, ensuring a distinct saving in fuel. The efficiency of either systeni is dependent to a large extent upon the ability of the return trap on the radiator to free it of all air and water of condensation without at the same time perniitting the escape of any steam. The open-ret vu-n or modulation system finds its widest application in a building covering a moderate area, in which the steam requirements are for heating only and where the radiation can be placed high enough above the water line so that the condensation will flow by gravity to the boiler. The system is noiseless in operation, simple in design, requiring no power-driven apparatus and except for periodical firing of coal and removal of ashes, the attention required is negligible. There are a number of modifications of the modulation system, de- pending upon varying conditions, and a system installed in a residence for instance, may be quite different from that in a hotel or school. The special advantages of the vacuum system can be realized to the fullest extent in projects such as the following: (a) A group of buildings scattered over a considerable area where savings in cost of installation can be effected by the use of smaller size supply and return piping. (b) One or more buildings so located with respect to the boiler plant that lifts are necessary in the return piping. (c) A plant utilizing the exhaust steam from the engines for heating purposes, wherein the elimination of the back pressure will save directly in fuel cost or permit the engine to do more work with the same expenditure of fuel. The foregoing examples do not by any means cover the entire field for use, for the vacuum system can be used in numerous other types of build- ings either as a regular vacuum system or in combination with the open return-line system. Indeed the adaptability of the two systems to widely different operating conditions makes possible the choice of one or the other for every type of building. In the following pages certain general rules 96 will be given which may influence the selection of a heating system for any particular case. Mention will also be made of modifications which may be desirable or necessary to suit individual conditions. In determining which of these types to employ, experience is the best guide, as the building conditions present so many variable factors that it is impossible to cover the subject exhaustively within the space of this chapter. When selecting a heating system, consideration should be given to the following points : (a) Size and type of building. (b) Use of building. (c) Location of building and topography of site. (d) Construction and architectural features of the building. (e) Source of steam supply. (f) Operation and attendance. Size and Type of Building: The first point to consider is the size of the building and its type. Residences: The prospective owner of a residence is particularly interested in the amount of attention necessary for operation and the economy of fuel. Whether he attends to the heating system himself or employs a caretaker, he desires a plant requiring minimum attendance. The modulation system is the most suitable in every respect either for a 30-room house or for a small bungalow. Except for periodical feeding of coal and removal of ashes, the attention required by such a system is negligible. The ability to vary the boiler pressure througla a range from the maximum permissible in very cold weather to a pressure at or slightly below atmosphere in mild weather, and to control the quantity of heat given off from each radiator by manipulating the graduated supply valve, result in a distinct economy. The heat emission and the coal consump- tion are regulated to correspond with the outside temperature and weather conditions. Apartment Buildings: Apartment buildings are erected by the owner for the revenvie which they will bring and a heating plant which can be operated with greatest fuel saving and the least janitor service is the best paying proposition. Unless the building spreads over too much ground or the overhead return piping cannot be properly graded without too much complication, the modulation sj^stem is particularly adaptable. The small amount of attention required by this system gives the janitor of the building more time for other duties. Control of the amount of steam admitted into each radiator gives the occupant of each room or apartment a convenient means of temperature regulation. Store and Ojfice Buildings: Where no mechanical system of heating and ventilation need be provided and where an open-return-line system can be applied, the same type of heating system can be used in the small store building as described for residences and apartments. This also applies with equal force to small and medium-sized buildings for offices and other commercial purposes. 07 Fig. 10-1. The entry of a modern apartment building showing heat outlets in the side walls Public Bnildings: In this classification may be inchided court houses, post offices, hbraries, and schools of small type where the ventilating systems are of the indirect or direct-indirect gravity ventilation type. Such buildings have, as a rule, no other mechanical equipment besides the heating and ventilating plant. For these structures a modulation system with open- line return is recommended. 9» We have considered so far the type of building wherein the area is moderate, the steam requirement is for heating purposes only, the basement radiation is well above the water line of the boiler and the overhead return piping can be properly graded, as required in the open-line system. In such cases the simplest form of system can be installed, requiring a minimum amount of attention. Frequently, however, conditions arise wherein the open-return piping cannot be run at a higher level than that of the water line of the boiler and discharge by gravity into the boiler, or where the radiation in the basement must be placed at or even below the boiler water line. The first mentioned situation occurs if the building covers considerable area or structural con- ditions cause the return piping to be kept well down from the ceiling. Where mechanical ventilation is installed having indirect radiation placed in the basement for warming the air, or where the character of the basement rooms is such that they will not be properly heated if the direct radiators are placed near the ceiling, it becomes necessary to locate them too low for successfully returning the water to the boilers by gravity. In such cases a vented receiver is installed and connected to either a motor-driven or steam-driven pump. The receiver contains a float at its water level, the rise and fall of which controls the operation of the electric motor or steam pump, and the water of condensation is automatically delivered to the boiler. The apparatus is placed at or below the floor on a suitable foundation and the water line of the heating system is thus governed by the level in the receiver, regardless of the water line of the boiler. Where no high-pressure steam is required for industrial or other purposes, the automatic return pump can be used in conjunction with low-pressure boilers, in which event the pump will have a motor drive. Where high-pressure steam is required for various purposes, one or more high-pressure boilers are installed. Steam for heating is reduced to suitable pressure by means of a pressure-reducing valve and is circulated through the modulation heating system by gravity, returning to the vented receiver. In such cases, a steam-driven return pump is installed, taking steam at boiler pressure and discharging the exhaust into the heating system through a suitable oil separator. The condensation from the various pieces of apparatus utilizing high-pressure steam is also delivered to the vented receiver and thence returned to the boiler. For buildings occupying considerable area and for groups of buildings to be heated from a common boiler plant, the vacuum system is to be preferred to the modulation system with vented receiver and return pump. Where lifts are necessary in the returns, the vacuum system is the best solution. In high buildings a vacuum system is usually selected, owing to the saving which can be effected by the reduced sizes of supply and return piping as well as radiator inlet valves and return traps. If high or medium- pressure steam is not required for any equipment or process, low-pressure boilers may be installed in connection with an electrically driven vacuum pump which will also return the condensation from the heating system to the boilers. From an operating standpoint a vacuum system with an electri- cally driven vacuum pump of the rotary type is quite as simple as the open- 99 return-line system or a modulation system, with a condensation pump. Where the steam requirements for the Ijuilding are such that high- pressure boilers are required, either motor-driven or steam-driven pumps may be used depending upon conditions which will be touched upon later. Use of Building: The use of the building, or the portion of time during which the building is in use and must be heated, is an exceedingly important factor in the selection of a sj^stem. Stores, office buildings, restaurants and the like are heated throughout during the daytime, while at night the requirement is only that of preventing the freezing of plumbing, water pipes, etc. In school buildings the ventilating system is usually put into operation about 8 o'clock in the morning and shut down at 4 o'clock in the afternoon. Rural schools often do not have electricity available for driving the ventil- ating fans and in such cases a steam engine is installed for the purpose. The boilers are usually operated at about SO-lb. pressure, steam for heating pur- poses is reduced to 1-lb. pressure and the condensation is delivered to the boil- ers by an automatic return-pump and receiver. The exhaust steam from the engine and pump are utilized in the heating system after extraction of the oil by passing the steam through an oil separator. Where electric current is available a combination modulation and vacuum system may be installed. In this case the boilers are operated at low pressure. While the mechanical ventilating system is in use, a motor- driven vacvuim pump is employed to remove the air and the water of con- densation from the heating system and discharge the water into the boilers. As soon as the ventilating system is shut down, the vacuum pump may be stopped and the direct heating system is then operated as an open-return line system, discharging the returns through a suitable trap, by gravity to the boiler. At night the heating plant recjuires almost no attention. The heating of a theatre may be accomplished in very much the same manner. In this instance however, the ventilating system is in use in the afternoons and evenings, during which the plant is operated as a vacuum system. After the close of the night performance the change is made to a modulation system. Heating systems in churches are usually operated intermittently. Where no mechanical ventilation is to be provided and where all radiation can be placed high enough above the water line for gravity return of the water of condensation to the boiler, a modulation system will give excellent results. It has the special advantage that by eliminating the use of wet returns, the danger of freezing of pipes, due to intermittent operation, can be avoided. Heating systems in churches as a rule do not receive the best of attention and therefore the simpler the installation, the more satisfactory the service. The operation of the modulation system in draining the condensation back to the boiler entirely by gravity also avoids the slight noise that usually accom- panies the action of mechanical devices, if the latter are employed for handling condensation. Where mechanical ventilation is installed in a church the combination of a modulation and vacuum system will be found to operate with the same reliability as described in connection with school buildings. 100 The use of the motor-driven vacuum pump will ensure a rapid as well as noiseless circulation of steam and quick remo^"al of the air during the warm- ing-up period. If it is not possible to eliminate the wet returns where the combination system is installed, care must be used to properly protect the pipes against freezing. Hotels, hospitals, institutions, asylums and the like have a 24-hour period during the entire heating season. It is absolutely essential that the service shall be continuous. Not only must the system be economical and noiseless in its operation, but it must also be very flexible to meet the varying demands of outside temperatures and weather. The comfort of each indi- vidual must be considered, and as is well known, the preferences vary. In all the above cases there are demands for high and reduced-pressure steam for various purposes and it is therefore probable that high-pressure boilers will be installed. With a single building covering a moderate area, an open-return-line system in conjunction with an automatic pump and return tank, together with modulation supply valves on the radiators, will meet all of the re- quirements outlined above. For a group of buildings or a single building covering considerable area, a vacuum system will be more flexible. In addition to all of the benefits of the modulation system, the vacuum pump will circulate steam very rapidly through the system, which is an important factor when quick heating up becomes necessary. A further advantage is the saving effected through the ability, in mild weather, when the demand for steam is light, to distribute a small volume of steam through- out the entire system as needed. AYith the modulation supply valve on each radiator properly adjusted, or with the radiators controlled auto- matically by thermostats, rooms on the cold side of the building will receive the proper amount of heat and those on the warni side will not be overheated and all this is brought about with a relatively small amount of steam. Location of Building and Topography of Site: Location of the building and the general topography of the site not only aft'ect the type of heating system used but may also influence the kind of boiler selected. For example, in rural districts electricity may not be available as a motive power or it may not be advisable on account of its unreliability. Where mechanical ventilation is required, as for example in a school or other similar building, a steam engine will be required for driving the fan. A type of boiler capable of generating steam at, say io to 30-lb. pressure must be selected. The steam for heating is reduced to 1-lb. pressure. A low-pressure steam pump will have to be installed to return the condensation to the boilers, operating in conjunction with a vented receiver and an auto- matic float control device. The receiver must be located a sufficient distance below the bottom of the indirect radiators so as to obtain the necessary fall required to secure a rapid flow of water by gravity. A modulation system of heating with open return line to receiver will give excellent results and if the direct radiators are provided with graduated supply valves, the quantity of heat given off by each may be easily controlled by hand. 101 JU" n n n n ; rr;-;-n-rm-n.^ '«■ Fig 10-2. Arrangement of cast-iron wall radiation in cove of ceiUng in a grill room. This can also be employed in barber shops and other basement rooms where a modulation system is installed' and it is necessary to keep the radiators well above the boiler water hne. Operation of the steam inlet valves of such radiators can, if necessary, be facilitated by the use of extension stems or chain attachments Fig. 10-3. Cast-iron wall radiation in garage. The radiation is placed at some distance from the floor level to avoid being damaged by cars and to prevent injury to tires from heat 102 The topography of the site may make the return of condensation difficult or impractical except by the use of vacuum or by direct pumping. Where lifts are necessary in the return the vacuum system is the only solution. A group of buildings spread out over considerable area, supplied with steam from a central boiler plant, may require the use of the vacuum system in order to balance the pressure differential between the supply and return at the several buildings, particularly if it is contemplated to add new build- ings to the group at some future time. A further distinct advantage of a vacuum system under these conditions lies in the ability to use smaller pipe sizes for both supply and return lines, with a consequent reduction in cost of installation. Construction and Architectural Features: The construction and architectural features of the building present a variety of problems. It is frequently necessary to heat finished basement rooms by placing the radiators under the windows or at other points near the floor. Under these circumstances the condensation from the low radiators will not return to the boilers by gravity, as they are located at or below the water line and it becomes necessary to install a vented receiver and an automatic return pump or a vacuum pump. The former will operate in conjunction with a modulation system, the latter with a vacuum system. Frequently the structural conditions of the building are such that the return piping has to be run near the ceiling of the basement or along the floor of the first story. The lifts resulting from this situation make the use of a vacuum system imperative. A very high building or one covering a very large area impose such conditions that the vacuum system is again the best solution of the problem. The greater pressure differential which results in this system, enables the use of smaller piping or with the same size piping reduces the back pressure which must be carried in the engines and pumps to secure complete circulation. Reference has been made to the use of modulation supply valves to control the quantity of steam delivered to the individual radiators. In department stores, loft buildings, warehouses, factories, etc., where there are large open spaces to be heated, usually containing a number of radiators, the modulation supply valves may be omitted and a fair degree of tempera- ture regulation may be obtained by completely shutting off one or more unit. Sources of Steam Supply : There are three main sources of steam supply : 1. Live steam from high-pressure or low-pressure boilers. 2. Exhaust steam from engines, turbines or auxiliaries. 3. High-pressmre or low-pressure steam from outside sources. If steam is required for heating purposes only, the selection of the boiler will be a part of the heating problem, based upon the building requirements. Where no mechanical apparatus is necessary, low-pressure boilers will be the natural choice. If electric current is not available and the system requires fan engines, return pumps or vacuum pumps or other power-driven apparatus, a type of boiler should be selected which is capable of operating 103 Fig. 10- 1. Cast-iron wall radiation arranged under the saw tooth of a factory roof Fig. 10-5. Arrangement of cast-iron wall radiation on side walls of a factory building 104 successfully with a working steam pressure of not less than 25 to 30 lb. The conditions under which the heating boiler must operate are to a large extent the governing factor in its selection. The kind of fuel, the intensity of draft which can be obtained, the length of time between firing periods, the character of attention which the boiler will receive, the abuse which it will stand without injury, are all important factors which should receive due consideration. The dimensions of the fire box, the proportion of direct and indirect heating surface in the boiler, the area and type of grate and the available draft are all influenced by the kind of fuel which is to be burned. This in turn depends upon the geographical location of the plant and the local fuel market. In many cities, boilers larger than a given size are required to comply with more or less drastic smoke prevention laws. It will thus be seen that the fuel plaj-s a very important part in the choice of a boiler. Sufficient attention is not always paid to selecting a boiler having flues and surfaces perfectly accessible for cleaning. It is also important in operating the boiler to see that there is a systematic removal of all soot and dirt at regular and frequent periods. In parts of the country where the water contains heavy scale-forming material, boilers having interior pockets should be avoided as scale will accumulate easily in these pockets and cannot be removed even by naore frequent blowing down. The shape of the boiler room may have some influence upon the type of boiler selected. A long, narrow room may lend itself better to the use of tubular or steel fire-box boilers, while a nearly square space may be best adapted to the cast-iron sectional pattern. Where tubular boilers are selected provision should be made for ample space to clean the tubes and to replace them, when renewals become necessary. The question of future extensions should be considered when the problem is in the preliminary stage. Unless provisions are made then, the owner maj^ find it very expensive to add to the boiler equipment at a later date. In buildings requiring 24-hr. heat, such as hospitals and like institutions, reserve units should be installed to provide for possible breakdown. In low-pressure installations, where a part or all of the water is returned by mechanical means, such as a motor-driven return pump, or a vacuum pump, it frequently happens that the water is delivered intermittently and in "slugs" instead of continuously; or it may fail completely on account of interruption of the current. The boiler must be of such a type or con- structed of such material that it will not be injured by the sudden lowering of the water line, even to the dangerous point. In other words, the design or construction should be chosen which will permit the greatest withdrawal of water per inch drop in water level. Priming of boilers arises from a number of causes, among which may be mentioned grease and dirt within the boiler, impurities in the water, lack of proper steam disengaging surface, insufficient steam space, and too high velocity of steam at the boiler outlets. If a type of boiler likely to produce priming must be selected for physical reasons, the arrangement of the connecting piping must be such as to eliminate any possibility of trouble from this source. 105 The Architect must not lose sight of the fact that a boiler used solely for heating purposes lies idle, without a fire under it, for a period of from four to five months of each year, depending somewhat upon the latitude and length of the heating season. Recognition must be taken of this fact in selecting the kind of material which is best adapted to withstand the cor- rosive action which is likely to occur in a damp basement room. If the material is subject to rust and deterioration when lying idle, it should have additional thickness to offset this action. It seems hardly necessary to call attention to the fact that boilers should conform to all requirements of local and State ordinances, and that compliance with the Boiler Code of the American Society of Mechanical Engineers will ensure first-class material and construction. The designer of the plant for a residence is in most cases confronted with two conditions which decide the type of boiler which he shall use: first, smallness of the boiler room, and second, the low head room in the base- ment. Both suggest the use of the cast-iron type of boiler because of its compactness and low water line. If there are other uses for steam, the type of boiler or the source of steam supply may be definitely fixed by other considerations than the re- quirements of the heating system. Most large modern hotels in cities are provided with high-pressure boiler plants, either for generating their own electric power or, in case electric current is purchased, for operating the pumping equipment and furnishing steam for kitchen and laundry purposes. The vacvuim system with steam-operated vacuum pumps is proper for heating such buildings. Great progress has been made in recent years by the country towns in providing more convenient hotel accommodations for the traveling public. The owner of the small-town hotel, while not in a position to equip with all the refinements of a metropolitan hotel, is anxious to have his guests provided with comfortable and properly heated rooms and therefore wishes to install an efficient and economical plant. The modulation system either with gravity return or with vented receiver and return pump is particularly advantageous, giving all that can be asked in heating effect, and enabling the janitor or engineer, who is also, in many cases, the porter, bell boy and general utility man, to take care of his many other duties. Y. M. C. A. buildings resemble the first mentioned type of hotels in many respects, as in addition to the recreational features, hotel accom- modations are provided for the members. Restaurant and cafeteria service are maintained, as well as swimming pools, Turkish baths, etc., in con- nection with which there is a demand for high-pressure steam in addition to the low-pressure steam needed for heating. For this reason all the con- densation cannot be returned directly to the boilers. The heating system should be of a type which permits regulation of the supply of steam to the bedrooms, according to whether they are occupied or empty. The graduated control system of steam supply to the radiators by means of modulation supply valves is a logical system to adopt. A steam-operated pump and receiver takes care of the returns from all the steam-using equipment and also from the heating system. 106 The modern hospital has a considerable amount of steam-using equip- ment such as sterilizers, blanket warmers, steam cookers, dishwashing machines, laundry machinery, etc.. requiring steam at pressures ranging from 30 to 90 lb. This makes a high-pressure boiler plant necessary. Many of the larger hospitals have their own electric power plants, and also use steam for operating refrigerating plants. In such cases the available exhaust steam should be utilized to the fullest extent and this is best accomplished by means of a vacuum system. High-pressure boilers are usually installed in manufacturing plants where high-pressure steam is needed for process work and cheap electric power is not available. In such cases the necessary electrical machinery for generating current is installed and the exhaust steam is used for heating. As with hospitals and office buildings, the vacuum system ensures quick circulation of steam and removal of air and reduces the back pressure to a minimum. Where the plant extends over considerable area, the use of smaller size supply and return mains, and the ability to lift the condensation where changes of grade occur, become important factors. In localities where street steam is available, with uninterrupted service guaranteed for the entire heating season, and where the rate does not exceed that at which steam can be generated in an individual plant, the installation of the modulation system with street steam supply provides very satis- factory heating for almost any type of building. The reduced first cost of the heating plant, due to the omission of the boiler and its appurtenances, and the fact that such a plant requires practi- cally no operating attention, make the arrangement very attractive from the owner's standpoint. The service company supplying steam to the building usually extends the service pipe through the fovmdation wall and to this the heating con- tractor makes his connection. The water of condensation is discharged to the sewer through a meter in the return line, except where a flat rate per square foot of radiation is charged, in which case no meters are used. This type of heating system can be installed in almost any type or size of building, except where too extensive area prevents satisfactory arrange- ment of the return line for gravity open-return circulation. In such cases, the motor-driven vacuum pump offers a simple means of insuring positive removal of the condensation and air. Operation and Attention: The initial cost is frequently the de- ciding factor in the selection of a heating system, and it is not until the end of the first heating season, when the purchaser finds out the cost of fuel and caretaker's services, that the question of operation and attention receives the consideration to which it is entitled. In this chapter, however, it is not possible to more than touch briefly upon this important subject. The most successful heating system is the one which will accomplish all of the results for which it is designed with the least amount of attention and the minimum expenditure for fuel. With the view of simplifying the system, the use of mechanical devices for handling the condensation should be limited to those cases where an open -line gravity return does not work 107 out satisfactorily. The conditions under which return pumps and vacuum pumps are necessary have been fully explained in previous paragraphs and it is not necessary to refer to the subject again. We cannot emphasize too strongly the important part which the radiator return trap plays in the economy of operation. It should be of a type that will permit the rapid removal of all air and all condensation but at the same time prevent the escape of any steam. This point is explained very thoroughly in Chapter 14. A system cannot be expected to give the best results unless all of the operating conditions are favorable. Three factors which have a great influence upon economical as well as successful operation are the location of the boiler room, its size and that of the chimney. In planning the basement of any building the architect should pay particular attention to both the boiler room and the coal and ash storage spaces. It is needless to say that the coal room should be so placed that the labor of stowing away the fuel, and afterwards feeding it to the boiler, is reduced to a minimum, and that suitable means is provided for the economical handling of ashes. Ample firing space must be provided in front of the boiler, ample room at the rear to give easy access to the return and blow-oft" piping and walking space at either side wide enough to enable the steamfitter to easily and quickly assemble the sections and later permit the application of the covering. If the boiler is the tubular type, there must be space for cleaning the tubes as well as for replacing them when repairs become necessary. Limiting the depth of the boiler room is a false economy and will only result in partial if not almost complete failure of the heating system to give satisfaction. There must be sufficient grade so that the overhead return piping can be given ample pitch toward the boilers, thus ensuring quick return of the condensation by gravity, and so that the lowest point of the return for an open-ret urn -line modulation system is at least 30 inches above the water line of the boiler. Lack of head room reduces the pitch of the return piping to a minimum and narrows the selection of boilers to perhaps a single type, having a low water line but otherwise not at all adapted to the work which it must perform. It may also compel the construction of a pit, which is not always desirable, or require an electric return pump which may unnecessarily complicate a system that would otherwise be very simple. Certain types of buildings require the simplest heating system possible. In residences the firing is infrequent and is done by the owner or a caretaker. The system must be rugged in design, with the least possible mechanical devices, but flexible enough to respond to varying changes of outside tempera- ture and weather. The janitors of school buildings have a multitude of duties to perform besides that of fireman. In the rural districts the school committees have limited appropriations for janitor service and apparatus has to be installed which is capable of giving satisfactory results with such unskilled attendance as is available. lOS As stated before, apartment houses are run on a business basis and the heating system must be economical of fuel and require little attention but must be flexible enough so that the occupants have a convenient and inde- pendent means of controlling the temperature of the various rooms. In the various types of buildings outlined above, the modulation system, with open return line to the boiler, will be found to meet the requirements of simplicity, flexibility and economy. Passing to the combination of the open return line with either the automatic retvu-n pump and vented receiver or the vacuum pump, or the straight vacuum system, we find the same economy and flexibihty with the addition of comparatively simple mechanical return apparatus. Summing up the advantages of the modulation and vacuum system we find them to be as follows: Modulation System.'^: 1. Simple in design. 2. Efficient in fuel. 3. No expert attendance required. 4. Quick response to demands for changes in rate of heating. Vacuum Sj/stems: 1. Circulation of steam is quick, positive and uniform. All surfaces are heated in a relatively short space of time after steam is turned into the system. 2. Saving in operating cost is accomplished practically by eliminating back pressure upon steam engines. This either saves directly in fuel cost or permits the engines to do more work at same expenditure of fuel. 3. Saving is effected through the ability during mild weather, when demands for heating are slight, to distribute a relatively small volume of steam throughout the system as needed, with a pressure at or even slightly below the atmosphere. In this country, mild weather constitutes about 75 per cent of each heating season, moderately cold weather about 'iO per cent and only 5 per cent can be classed as "severely" cold. 4. Saving of fviel results from utilizing the condensation and its con- tained heat as part of the boiler feed. Certain advantages are common to both systems, as follows : Modulation and Vacuum Systems: 1. Noiseless in operation. Water hammer is unheard of due to continuous relief of air and positive removal of condensation. 2. Radiators maintained at 100 per cent heating efficiency due to complete removal of air and water. Absence of air valves on radiators eliminates one of the most annoying features of many heating systems. 3. Independent temperature control of each room at the will of the occupant. 4. Efficient in fuel. To the foregoing advantages should be added comfort and convenience. More and better work is obtained from occupants of properly heated buildings. 109 CHAPTER XI Flow of Low- Pressure Steam Through Piping FLOW OF Steam Through Pipes: Flow of steam through piping is caused by difference in pressure, which diminishes continually from the source to the outlet, due to frictional resistance, deflection, con- traction and expansion. Likewise there is a continual drop in temperature due to the transmission of heat through the walls of the piping. Steam at initial pressure and density, but without material velocity, as in a boiler, requires a certain pressure drop, to impart initial velocity in the main. This drop varies with the velocity required, density of steam and shape of the orifice at entrance of the main. The pressure drop or head required for a given velocity, as of initial density at a point about three diameters beyond the entrance of a steam main, with sharp entrance edge, has been found from tests of the weight of low-pressure steam passing through a cylindrical sharp-edged orifice of length equal to three diameters. The pressure difference or head (hi) necessary to produce such velocity (vi) is fully 1.7 times that found by the well known velocity formula, v = V2 gh. It seems reasonable to assume that a like pressure drop is necessary to impart initial velocity within the heating main from a boiler or steam drum, as contrasted with the exhaust of an engine, reducing valve, etc. Table 11-1 gives 1.7 times the pressure drop or head (hi) in pounds and ounces per square inch, based on the above assumption. Table 11-1. Velocity of Steam in Feet per Minute Within Entrance of Main Initial Density) Produced by Pressure Drop (pi — P;)^h From various absolute initial pressures in pounds per sq. inch=pi (as of Pi-Pe Ounces per sq. inch Pi-P= Pounds per sq. inch Velocity in feet per minute Absolute initial pressure pi 17 18 19 .01 2260 2203 2138 2086 2036 1980 H .0156 2830 2758 2665 2610 2544 2475 .02 3200 3115 3020 2950 2880 2800 Vi .0312 3995 3885 3770 3680 3595 3495 .04 4530 4405 4270 4175 4070 3960 H .0468 4910 4775 4625 4520 4420 4280 .05 5060 4930 4780 4660 4540 4420 1 .0625 5660 5520 5340 5220 5090 4950 .07 6000 5840 5660 5520 5390 5240 Ik' .0781 6350 6180 5980 5840 5710 5540 .08 6420 6240 6050 5910 5770 5610 .09 6800 6615 6410 6260 6120 5940 Wi .0937 6940 6750 6540 6390 6250 6060 .1 7170 6980 6760 6610 6460 6260 .11 7520 7320 7090 6925 6770 6570 .12 7860 7650 7420 7240 7060 6870 •-> .125 8020 7810 7560 7390 7220 7010 .13 8180 7960 7710 7520 7350 7150 .14 8470 8250 7990 7800 7610 7410 .15 8790 8560 8290 8090 7910 7680 2M .1562 8970 8740 8460 8760 8080 7840 110 Friction in Run: Steam, having attained initial velocity at the entrance of the main by a pressure drop (p, — ps), will require a further drop (p2 — ps) to overcome friction. Various formulae have been published by which to determine the velocity or weight of steam of given quality which with a given pressure drop will flow in a given time through a given length of straight pipe of given uniform diameter. Analysis of the principal formulae, after reduction to common terms, indicates a substantial agreement among the majority of these formulae n the following fundamentals : that the velocity varies as the square root of the pressure drop. that the velocitv varies as -j r— density that the pressure drop varies as density that the pressure drop is proportional to length of run. that the pressure drop varies as the square of the weight flowing. The various fundamental equations for frictionless pipes may be reduced to the following form : w = (P2 - Ps) - d" V- and the allowance made for friction by multiplying the radical by a constant or numerical value, dependent on the diameter, in the following form: w = c (P2 - ps) - d' s V xL or (L + y) in which w = weight of steam flowing per minute. c = a constant or numerical value Pi = absolute pressure of initial steam when quiescent. P2 = absolute pressure within entrance of main. Ps = absolute pressure near end of main. d = diameter in inches. L = length of run in feet. X = a factor of L derived from some sub-formula. y = a formula or sum to be added to L in the basic equation. = mean weight of 1 cu. ft. of steam in pounds.. Regarding the value of c, the late Professor Kent made the following apt statement: "The coefficient of friction according to different authorities varies according to laws about which they do not agree." Investigation demonstrates that many of the laboratory experiments and tests of commercial pipe lines upon which the values of c, x and y have 111 been estimated were so made as to include the pressure drop necessary for initial velocity while in others this is not included. Other tests appear to have been made on but one or at best a very few different sizes of pipe and lengths of run. Some authorities assume that the factor c (which includes all friction) is constant for all sizes of pipe irrespective of relation of perimeter to in- cluded area of cross section; in this respect differing materially from all the conmionly accepted formulae for flow of water. These among themselves assign materially different constant values to c. Other authorities assign values varying with diameter, thereby recog- nizing the proportionate relation of perimeter to cross-section and the in- fluence of surface retardation on the flowing mass. The two principal investigators of the latter school do not dift'er materially in the values assigned to c although J. M. Spitzglass, in his analysis,* goes exhaustively into the frictional elements (skin friction due to rubbing of the fluid on the rough surface of pipe and internal friction due to relative motion of particles of fluid on each other) and deduces a formula which takes into consideration both the coefficient of friction and the relative capacity of pipes of various diameters together with experimental coefficients for the various fluids. Gebhart in his analysis of this subject makes the following very practical statement : "Notwithstanding the numerous investigations conducted on labora- tory apparatus and on pipe lines under actual power plant conditions, there is no trustworthy rule for accurately determining the flow of steam in commercial piping." Professor R. C. Carpenter in his investigations regarding flow of steam in pipes reaches the following conclusion: "For practical conditions, it is rather better to have aii allowance in pipes for an excess in friction than to have the reverse condition true." From an extended experience in steam heating practice and installation, it seems a fair conclusion that in none of the published formulae is sufficient consideration given to the excess friction liable to be encountered due to reduction in area and frictional resistance due to the very usual neglect of the workmen to ream pipes true after cutting. This excess friction is likely to increase as the proportion of perim- eter to area increases and be a serious source of inaccuracy in the deter- mination of flow in the smaller sizes of commercial piping, and pipes if inadequate, when once installed, will usually remain a source of trouble and discredit. This has led to the use of a table in which the value of c in the formula ' ^ has been increased for the smaller sizes bevond \ L that of any of the authorities above referred to. These values of c and the flow table based thereon are oft'ered as those * Flou' of Fluids and Frictional Resistance in Pipes, J. M. Spitzglass, Armour Engineer. March and May, 1917 112 found to be adequate in practice under any but the worst practical con- ditions to which it has been apphed. W = 60c V W = weight of steam in pounds per hour Diameter of pipe ,,/ ^i,, -.^,, .-,„ in inches * 2 - Value of c 31 11 41 49 Diameter of pipe o" q" in" in inches Value of c 61.2 64.8 65.4 This formula makes no allowance for drop due to initial velocity, condensation, or changes in direction or area of pipe. Table 11-2, Pages 114-5, has been computed from Formula 11-1 For example, ascertain the pressure necessary to overcome friction in a 400-ft. run of 4-in. straight pipe when conveying 600 lb. of steam per hr. and p2 is 16 lb. per sq. in. absolute. (~y = (0.821)' = 0.674 lb. pressure drop for 1000 ft. due to weight of steam other than tabulated; therefore, pressure drop for given length, or 400 feet is: (P2 - Ps) g-d' {Formula 11-1 L per hour. 21" 3" 3i" 4" 5" 6" 7" 52 55.6 57 59 61 62.5 63.4 12" 14" 16" 18" 20" 66 65 65 65 65 (400\ Yqqq) = 0.270 lb. per sq. inch. Condensation Loss: Tlirough the entire length of run, there is a further loss of pressure, due to radiation and condensation. This loss is least in well covered mains with still air, at high temperature. Condensation in long runs of small pipe frequently causes the greatest loss of weight and oc- casions large pressure drop. Figure 11-1, Page 116, gives averages of condensation loss in bare and covered pipes for various differences between temperature of steam in pipe and air surrounding the pipe or its covering. The following example is given to call attention to what is likely to happen if tabular steam values, for straight runs, be used to size mains sup- plying radiation through long runs of small pipe, even if the mauns are well insulated. From Table 11-2 it will be seen that a 13/2-in. pipe with a friction loss of 1/10 pound per 100 ft. and an initial pressure of 16 lb. absolute will convey steam at an hom-ly rate of 55.1 lb. or 53250 B.t.u. per hour. By inspection of Figure 11-1, we find that if the difference in tempera- ture between steam in the pipe and air surrounding it is 150 deg. fahr. and the pipe has good insulation, there is transmitted through that cover- ing about 25 B.t.u. per lin. ft. (J^ sq. ft.), or 25000 B.t.u. per hour for 1000 ft. run. Therefore, about 60 per cent of the entering steam will be con- densed. Effect of Deflection, Contraction and Expansion: Mains are seldom straight cylindrical pipe from end to end. Normally there are elbows, valves, branch outlets, reductions in size, separators, expansion joints, etc., 113 each adding to frictional resistance and causing pressure drop. Although not technically accurate, it has been found convenient in estimating, to express these resistances in units of the additional length of run of straight pipe that would produce an equal effect. Table 11-3, which is believed to be conservative and likely to produce results well within the tolerance necessary in so complicated a subject, is figured upon this basis. Fittings of different manufacturers vary in resistance in similar sizes and similar fittings vary in percentage of resistance. No Yery careful tests covering the entire range of flow of water, air and steam are available for data, but those that do exist have been studied in making up this table. Pressure Drop: The necessity for pressure drop to create flow in heating systems is further explained in following pages. Modulation and vacuum systems differ in degree of this pressure drop rather than in principle. Table 11-2. Weight of Steam Flowing Uniformly in One Hour Through Standard Straight Level Pipes 1000 ft. Long, with a Loss of 1 lb. per Sq. In., from Given Initial Pressure Within Inlet End P2 = absolute initial pressure within entrance of main. r = latent heat of steam at absolute initial pressure P2. 1000 B.t.u. = thousands of B.t.u. contained in the entering steam. V = velocity of steam in feet per min. at initial density 5 *> .s.s •35 3 . ■5,2 .Is I.S 3 . 1.315 S «.. 3 °-5 in as..s ^.9 'it 3 « Qj "= a) .ass 2.9 2.3 Sq. ft. of ext. surface per linear ft. 1 2 .S 11 Ss 34 41 4.4 49 52 55.6 57 59 P-> 15 16 17 18 19 20 s 26.27 24.79 23.38 22.16 21.07 20.08 1 Is 1 s .03806 .04042 .04277 .04512 .04746 .04980 K'S r 969.7 967.6 965.6 963.7 961.8 960 1" 1.019 167.5 .86 .345 1.13 Lb. 1000 B.t.u. Vel. ft.-min. 14.2 13.7 1044 33,9 32.8 1428 53.4 51.7 1650 111,2 107.9 2082 184.1 178 2432 14.63 14.15 1001 34.92 33.75 1385 15.08 14.5 983 35.92 34.7 1344 15.48 14.9 955 36.90 35.5 1310 58.2 56 1518 121 116.4 1906 201 . 5 194 2240 369.5 356 2660 545 524 2925 774 745 3235 1405 1350 3740 2280 2190 4195 3340 3210 4580 15,88 15,27 934 37.86 36.4 1276 59.65 57.3 1478 124.2 119.5 1865 205 197 2170 378 363 2595 558 537 2860 794 763 3155 16.23 15.6 908 H" 1.38 1.66 96.1 1.5 . 431 2,235 Lb. 1000 B.t.u. v 38.80 37.3 1248 IJ" 1.61 1.9 70.6 2.04 2.01 1.61 1.33 1.09 .955 .849 .686 .577 .501 .497 3.28 Lb. 1000 B.t.u. V Lb. 1000 B.t.u. V Lb. 1000 B.t.u. v 55.1 53.25 1607 114.5 110.8 2022 189.2 182.9 2353 349 337.5 2808 515 498 3095 56.6 54.6 1554 117.7 113.5 1960 195.2 188.3 2295 3.59 347 2725 530 512 3010 752 725 3315 1368 1322 3835 2218 2140 4300 3250 3140 4710 61,1 58.7 1444 2" 2.067 2.375 42.9 30.15 3.36 .621 6.13 127 122 1820 9i" -2 2.469 2.875 4.78 .751 .991 9.58 16.47 211 202.5 2130 3" 3.068 3.5 19.5 7.39 Lb. 1000 B.t.u. v 339 328.5 2890 500 485 3190 387 372 2530 31" 3.548 4 14.58 li.3 9.89 1.046 23.7 Lb. 1000 B.t.u. v Lb. 1000 B.t.u. v Lb. 1000 B.t.u. v Lb. 1000 B.t.u. V Lb. 1000 B.t.u. v 572 549 2790 4" 4.026 4.5 12.73 1.177 32.53 710 688 3520 731 706 3415 812 779 3075 5" 5.047 5.563 7. 22 19.99 1.457 57.17 90.6 61 62,5 63.4 1290 1250 4070 2092 2025 4565 3065 2970 5000 1328 1284 3950 2158 2085 4440 3155 3050 4845 1440 1385 3640 1475 1420 3550 6" 6.065 6.625 4.99 28.89 38.74 1.733 2340 2250 4100 2392 2295 3980 7" 7.023 7.625 3.72 2, 130.7 3425 3290 4475 3506 3365 4360 114 Table 11-2 — Continued 1" 'is ti 'O VI M.S 4) a •S.5 Is S S *0 3 ■ *.: "^ ■So,!-; .443 .397 . 355 .299 .255 .239 .212 .191 Sq. ft. of ex. surface per linear ft- o 3 .S 11 ds 64.2 64.8 65.4 P- IS 16 17 18 19 20 s 26.27 24.79 23 38 22.16 21.07 20 08 "3 1 s 03806 .04042 .04277 .04512 .04746 .04980 &;■« r 969.7 967 6 965.6 963.7 961.8 960 8" 7.981 8.625 2.88 50.02 2.257 180 Lb. 1000 B.t.u. V Lb. 1000 B.t.u. V Lb. 1000 B.t.u. V Lb. 1000 B.t.u. V Lb. 1000 B.t.u. V Lb. 1000 B.t.u. V Lb. 1000 B.t.u. V 4275 4140 5380 5735 5560 5760 7680 7440 6150 12170 11750 6800 18420 17850 7290 22750 22050 7630 30850 29940 8100 40300 39200 8.550 4400 4260 5240 4530 4375 5080 4652 4480 4950 6210 6005 5290 8360 8040 5640 13270 127.50 6230 20080 19300 6700 24800 23900 7020 4775 4580 4830 6400 6150 5175 8600 8270 5530 13620 13100 6100 20580 19780 6.540 4485 4690 4720 9" 8.911 9.625 2. 29 62.72 2.58 239 5900 5710 5600 7930 7660 5880 12.530 12120 6600 18970 18340 7060 23410 22620 7410 317.50 30700 7850 41600 40200 8310 6075 5860 5440 6560 6310 5050 10" 10.02 10.75 1.83 78.82 2.82 317.7 8145 7870 5790 12900 12460 6410 19520 18820 6800 24100 23250 7190 32700 31650 7650 42800 41300 8050 8800 8450 5380 12" 12 12,75 15 1.27 113.1 3.3 198. 8 66 65 13940 13360 5940 14" 14.25 .901 159.5 3.90 766.5 21100 20250 6400 16" 15.5 16 .765 188.3 4 16 945.9 65 25150 21150 6810 31150 33150 7270 45200 43400 7660 26100 25100 6660 18" 17.5 18 .601 240 4.71 1281 65 65 33550 32300 7425 44000 42300 7850 352.50 33850 7060 20" 19.5 20 .483 298 5.23 1679 Lb. 1000 B.t.u. V 46250 44400 7475 The pressure drop for lengths other than 1000 ft. will be 1000 X the tabular pressure drop, /lOOO where Li is the new length in feet, and the weight of steam discharged will be / lOOO X the discharge given above. \ Li The pressure drop varies as -j r- — The pressure drop varies as the (weight) 2. The weight of steam flowing varies as v pressure drop. Table 11-3. Resistance of Fittings in Feet of Straight Pipe to be Added to Actual Length of Run Long sweep Medium Standard Size of pipe ell sweep ell ell Angle Short Side outlet Globe in inches standard tee run of tee reduced tee valve bend tee valve Length in feet to be added in run 2 *-> 3 4 5 9 11 17 19 2J^ 3 4 5 7 12 15 21 26 3 3 5 6 10 16 19 27 33 SV2 4 6 8 12 19 22 32 39 . 4 5 7 9 14 22 24 36 45 5 7 9 11 18 27 30 44 58 6 9 11 14 22 32 36 51 70 7 10 13 17 26 37 41 56 82 8 12 15 20 31 42 47 63 94 9 13 17 22 35 47 52 68 104 10 15 20 24 39 52 57 76 117 12 18 24 30 47 62 68 91 140 14 20 26 33 53 71 79 105 160 115 :300 • 280 <260 = 240 !220 bo .5 200 -a :180 1160 1140 ■120 iioo 80 60 ^. 40 20 10 bJ3 Q / / \ / 1 / / / / / / / / / / / / / / 1 / / / / / / / v^ 1 / ri/ / .^ / / < 4/ . / / !■/ ■^ 7 7 ,^ V / 2 f t f 1 ,1 1 y { ' 1 / } / / / \ 1 1 / / ^ 1 A ^ ^ A ^ / t \^- ^ ■-^ A ,^^ vv^ / ^"0-, -• * / ^ ^ ^ c<^^ A t 'i '''l / / ^ / / -^ / / ^ ^ / / / // / ^ ^ ^ 240 260 280 300 10 20 30 40 50 60 70 80 90100 120 140 160 ISO 200 220 B.t.u. Radiation per Hour per Sq. Ft. of Pipe Fig. 11-1. Heat transmission in B.t.u. per hour per square feet of bare and covered pipe Pressure Drop in Modulation Systems: The typical modulation system, as illustrated in Figure 11-2, when operating at normal rate, requires suffi- cient pressure against the valve piece of the vent valve pi to cause it to open against the atmospheric pressure. Representing atmospheric pressure as p and this excess pressure as pi the expressions p + pi = pressure at en- trance of vent valve. 116 ^aFTT^. SleamMain, Vent Valves 1^:^ y ^^/^ ^CU Return Header__ Boiler ^^ -Steam Riser Jeturn Riser BETURN TRAP :> 7 ■?i^\ Supp'y Vjlve Dry Return Waler Line ot Boiler jas Cold Water Connection Wet Return., H2 j£ -/ M -Tn Drain ■Cliecl< Valve Fig. 11-2. Diagram of modulation system layout to illustrate pressure drop To cause the air to flow from the vent trap through the vent valve orifice requires a pressure difi'erence, which may be represented by ps, vary- ing with velocity of flow. Therefore, pressure in the vent trap becomes = p + pi + P2. To cause the air to flow from outlet of the radiator trap through return main to the vent trap, there must be another pressure difference, represented by ps, dependent on velocity of flow; also another pressure difference through orifice of radiator trap p4. Therefore, pressure ps in the radiator at the time of air displacement by steam from the boiler must equal the sum ofp4 + p3 + p2 + pi + p. Of these last expressions p is relatively constant with gauge at zero lb. The flow through the vent valve pi is nearly constant, being mainly that pressure difference necessary to overcome the gravity of the valve piece, and adhesion of wet surfaces of the seat. The variable due to the volume of air passing is so slight, owing to low velocity, that it may usually be neglected. The pressure pi of vent valve suitable for a modulation system is lb. per sq. in. The pressure drop through vent valve orifice p2 is a variable, greatest during initial heating-up period when a large volume of cool air is expelled from the heating system, and least during normal heating when velocity is that slight amount due to entrained air in condensation passing from the radiation. Air-vent traps are rated on basis of flow of initial air in 40 min- utes in a system with ^V ^- P^r sq. in. differential pressure through the vent-trap valve. For less than rated capacity, either the time or pressure factor or both may be less; for instance, with p, constant, one-half the amount of radiation would require one-half the time period. 117 1 The pressure drop in the return main pa is also a variable, greatest during initial heating and dependent on length of run and maximum velocity. In a well-proportioned system, ps should never exceed 1/20 lb. per sq. in. differential between the farthest radiator trap and the vent trap, and during normal heating it is so slight as to be almost negligible. The pressure drop through a radiator trap p4 is also a variable, least and almost negligible during initial expulsion of air from radiation, at which time the trap-valve orifice is wide open. As the radiator warms up and con- densation flows through the trap orifice with the last of the contained air, P4 gradually becomes greater. It becomes maximum when condensation at or near steam temperature is flowing at the full rating of the return trap for a given pi of }/$ lb. per sq. in., which pressure has been selected from tabular ratings of return traps (page 238). It is good practice not to have P4 exceed }/s lb. per sq. in. where it is advisable to carry less than 3^ lb. pressure on the boiler and }^ lb. where a pressure of 1 or 2 lb. can be ceirried. Representing the pressure difference necessary for flow, initially of air and subsequently of steam, from the radiator branch through the inlet or modulation valve to the radiator, requires another variable pe, H lb- P^r sq. in. at full rating, least (in a properly designed modulation valve full open), during initial expulsion of air, and greatest when the valve is partly closed for modulation effect, at the selected rating of this valve, for a given pressure difference pe. p? is usually assumed for a system of mains, risers, branches and run- outs, designed from data on flow of steam in mains given in Table 11-8 to carry the maximuni normal quantity of steam in a given time from the main heat pipe near the boiler to the inlet valve of farthest radiator, with this pressure drop p?. The quantity of steam, referred to in the preceding paragraph, flowing tlirough the selected size main supply pipe will have velocity at the boiler which depends upon the pipe area and the volume of steam flowing in unit of time. To impart this velocity to the steam from a state of quies- cence in the steam space of the boiler and to offset the resistance of the orifice requires another pressure drop ps- Knowing the maximum normal quantity of steam and the size of the main, the pressure drop to give the resulting velocity can be obtained from Table 11-1. It follows from consideration of the above that the pressure in the boiler Pb at time of maximum normal heating effect must be the sum of p + Pi + P2 etc., including ps as follows: p, constant at atmospheric pressure. pi, at least intermittent at that time. • P2, negligible at that time. Ps, negligible at that time if return has proper grade. P4, tabulair if fuU rated value in radiation is on farthest unit. Po, pressure drop in radiator, negligible at that time. pe, tabular if fuU rated value in radiation is on farthest unit. Pt, from assumption in design from flow of steam in main. (Table 11-8). Ps, that required for velocity head under above assumption. (Table 11-1). U8 The heating-up period will vary in accordance with initial pressure in the source of steam supply. Usually some time is required to raise steam to the normal pressure Pb- During that time air will be expelled and steam flow into the radiation at different rates due to the varying pressure caused by the increasing resistance of pi + ps- If steam is constantly supplied during the heating-up period at pressure Pb, as when a central plant is the steam source, the condensation rate in the radiation due to absorption of heat by the metal will be as far in excess of normal as the sum of maximum Pi + P2 + Ps + an intermediate p4, deducted from Pb — p, will produce a pressure difference (pd) to cause initial velocity. It will flow through mains at a rate substantially in the same proportion as pd is to py, provided initial velocity equal to ps has been previously imparted to the steam within the entrance of the main. The intermediate p4 referred to in the above paragraph is caused by the partial extension of the thermostatically moved valve piece in the return trap. This factor varies from full open and minimum resistance, when steam is first admitted and chilled condensation commences to pass, to nearly closed position and full resistance, when the radiator is completely filled up to the return trap with steam at a temperature corresponding with its pressure. Modulation systems when operated at less than normal condensation may circulate continuously at pressure materially lower than the normal Pb, or may be intermittently operated at a pressure less than p, provided the air has first been expelled by a higher operating pressure. Under such conditions, however, the system will gradually become air-bound and cease to circulate. In designing modulation systems, all. gravity drip points should be pro- vided with a hydraulic head (Hi) of at least 23^^ feet for each pound per square inch of p? + ps + frictional resistance in run of gravity drip and re- sistance of check valve between gravity drip and boiler, when the boiler is generating steam at its full capacity to supply cold radiation. If the gravity drip be taken from radiation located below the dry re- turn, with thermostatic air vent up to the dry return, then the resistance of any additional branch main, radiator, valve and check valve on gravity drip, must be added to p? + pe, etc., given above, to determine whether H2 is sufficient. The hydraulic head in inches of water on the check valves will vary with the make, weight and angle of the clapper and the size of pipe tapping. This head is seldom less than 3 in. with the clapper at an angle of 10 deg. from vertical and may run up to 18 in. and higher with vertical-lift valve pieces. In installing radiation with gravity drip for condensation as above, it is important that the branch connections and valve to such radiation have sufficient free area when in use, to cause little or no reduction in pressure in the radiator, from that in the main. A partially closed inlet valve might cause such a reduction in pressure, when added to the other resistances, that there would not remain sufficient total pressure in the radiator, when added to the available H2, to overcome the pressure Pb plus the check valve resist- 119 ance in gravity drip. In consequence of this, condensation would build up in the column H2, seal the radiator outlet and finally cause the radiator to become water-logged, possibly draining at a partial condensation rate, through the air vent into the dry return line. The closing level of the air-vent trap should be located at such a height above the water line of the boiler that a hydraulic column is produced fully equal to the resistance of its check valve and drain pipe plus normal Pf This, however, is not as important as to have Hi and Ho ample. An air pressure wdll accumulate in this vent trap due to closing of the vent out- let, when column H is not sufficient to overcome resistance of drip line and the pressure Pb in the boiler. This air pressure will continue to build up with vent closed, until the built-up pressure with the assistance of column H overcomes the resistance of the boiler pressure. Then column H will fall, the air vent will open and allow escape of some air, thereby relieving part of pressure in the vent trap. Column H will again rise, closing the air vent, and this cycle will be repeated. When intermittent venting is repeated for a sufficient length of time under excess pressure without admitting raw feed water containing gases, all the air will be expelled from the radiation. Such a system will continue indefinitely to circulate, due to a pressure difference which will be fully equal to that of its normal H ; that is, the pres- sure in the vent trap will be less than the pressure in the boiler, by an amount equal to an hydraulic column of height H less the resistance of the check valve on the drip of this column. In modulation systems designed for a stated pressure Pb and open vent at head H, the only difficulty occurs where a pressure exceeding Pb is built up rapidlj^ before the initial air has been fully expelled. Under such con- ditions complete circulation wall not be obtained as rapidly as if steam had been generated at a slower rate. To overcome the difficulty in expelling air and returning condensation to the boilers, where excessive pressure is rapidly generated, as in the use of certain grades of bituminous coal, wood, etc., a special high-duty vent trap should be employed. In this trap, due to the rise in column H, the air vent is automatically closed and an equalizing pipe between the boiler and the vent trap is opened, the water under equalized pressure flowing by gravity to the boiler, after, which the equalizing pipe is closed and the air vent again opened. The two operations taking place alternately, serve to vent the system completely of air and also return the condensation to the boiler, regardless of the boiler pressure. As follows in the discussion of pressure drop in vacuum systems, the return mains should be proportioned relatively to the steam mains selected for equal duty. This principle applies also to modulation systems. The basic proportional sizes of returns to supply mains recommended are given in Table 11-4. Pressure Drop in Vacuum Systems: The reason for employing a vacuum system rather than a modulation system lies in the greater total drop obtainable from a given initial pressure P above, to terminal pressure p below atmospheric, thereby obtaining circulation through greater resistance due to long pipe runs and lack of grade for gravity flow of condensation. 120 Table 11-4. Relative Proportions of Steam Supply and Return Mains in Modulation Systems Supply main Dry return main Return riser Wet return 1 11^ and 2 2J4 54 1 1)4 1 1 IK2 3 and 3V2 '1 A]4 and 5 6 " \y2 3 1)^ 2K 13/2 1,4 lJ/2 2 7 and 8 9 and 10 12 3 and 3}^ 4 and W2 5 3 4 2 9 2H Lowering the terminal pressure p by mechanical exhaustion in return mains (the vacuum system) allows greater pressure drops through each of the series of resistance. In good vacuum system practice, the total drop between source of sup- ply through the inlet valve of the farthest radiator on the system should be that between available initial and atmospheric pressure, so that normally the pressure in the radiator will be at or very slightly below that of the at- mosphere. The pressure drop p4 of the return trap may usually be two to three times that permissible in a well designed modulation system. The drop ps in the vacuum return lines, if graded in direction of flow, may equal that in the supply mains of the system under consideration, and if it be neces- sary to elevate the condensation at one or more vertical lifts in order to ob- tain horizontal grade toward the vacuum pump, this (within limits of tem- perature of condensation) may be obtained by increasing the displacement of air and vapor by the pump. In systems where the high vacuum neces- sary to lift the condensation at one or more points, would occasion a need- lessly high vacuum in that portion of return system which has a gravity flow, the degree of vacuum may be reduced by means of special vacuum controlling apparatus which provides for continuous discharge of condensa- tion and also for a reduction of degree of vacuum between the inlet and outlet of the apparatus. (See Chapter 15, page 176, for description of such apparatus.) In general, owing to greater pressure drop, a vacuum system will not require as large mains, branches to, and inlet valves of radiation as needed for a modulation system. Likewise, the radiator traps and return mains may be smaller for similar sized units of radiation provided radiator traps of high efficiency are properly installed to prevent leakage of steam to return lines. Return traps on radiators should be proportioned for a pressure dif- ference of between 3^ and l^lb. depending upon the condition of the partic- ular problem. Return mains should be proportioned relatively to the steam mains selected for equal duty by the table of comparative sizes (Table 11-5), allowing additional areas, however, where there is probability of high tem- perature in the outlet end of returns, due to steam leakage of return traps 121 or lack of vapor condensation occasioned by thoroughly insulated mains retaining the heat in the water passing through the radiator traps. Where high vacuum for lifts increases the volume of vapors and gases to be removed, at least one size larger return mains should be used. Such degree of partial vacuum should be carried by properly propor- tioned pump displacement as to cause a partial vacuum equal to the selected pressure difference (P4) through the most remote return traps on the system. In proportioning pump displacement for vacuum systems, the most complex problem is that of proper allowance for the amount of vapor and air. Pres- sure below atmosphere in any part of the system is liable to induce invisible air leaks. For full efficiency of radiation, the temperature of condensation passing through return traps must be close to that due to the steam pressure in the radiator. Part of the hot water, when flowing into lower pressure in the return line, flashes into vapor of high specific volume. The amount may be deter- mined by inspection of the re-evaporation chart shown on page 157. Some of this vapor will be condensed on the way to the vacuum pump, the vohmae dependmg upon whether or not the returns are insulated and also upon the amount of radiation, due to the length of the return pipe. It must be borne in mind that the vacuum or degree of partial pressure in the return line cannot exceed that corresponding to the temperature of the water of condensation. Inleakage of air through even minute imperfections in piping causes an increase of volume to be handled proportionately as the absolute tempera- ture of the air at inleak is to the absolute temperature in the return system, plus expansion from that volume at atmospheric pressure to that of vacuum pressure. As explained in Chapter 13 on Vacuum Pumps, it is frequently possible to take advantage of some condensing medium such as cool air for ventila- tion, or water which must be warmed for cooking and washing, boiler feed, etc., and use this medivuai for cooling and condensing the air and vapor to decrease its volume on the way to the pump. Table 11-5. Normal Relation of Return Mains and Risers to Supply Mains Caring for Equal Amounts of Steam in Vacuum Systems Horizontal Horizontal Vertical Gravity drip vertical Outlet at heel of risers 2 J^-in. and under, less supply mam return return ^^^^ ^.^ ^^^^.j^^ j^j^j^ 3^^ j^^ q^^^, ^2 stories or Over 2I^-in. riser 1-in. Iy4-in. and less •x4-in. /4-ii'- vertical outlet increasing in horizontal run to l^-in. 1/^ and 2-in. 1 % Horizontal gravity drips Number of i?4' or I-in. outlets which Q ITqi/ • 1/ 1/ graded at least J^|-in. in may be carried on one horizontal A ^1/ j'" • / ^^^^ ^^'^ usually capa- run when graded '4-in. in 10 feet, i, i /2 ana 5-m . _ 1/^ ble of caring for the num- provided radiation on steam riser o and ^-in. _ o - ber of ?'4 or 1-in. outlets does not drain as in one -pipe 8and9-m. 3 2I2 as follows: system 10-m. 3I/9 3 12-in. 4 3J4 Size 14 and 1.5-in. 4}4 i horizontal 16 and 17-in. .5 1}4 1^-in. 18 and 20 in. 6 5 IJ^ 122 No. of 34-in. No. of 1-in. outlets outlets 12 6 18 12 30 18 60 36 100 .50 5H' 3000" 5000' 2V2 100 '8" 3'/2 NO 4^ Trr-r- 6000' Sizing of Piping: The use of the tables in sizing piping may best be explained by the following examples. Vacuum System: Assume a central steam generating plant for a group of buildings, Figure 11-3. In the problem here presented ^ are a boiler house and three de- tached buildings A, B and C, connected by a system of well- covered mains in a tunnel. Through these mains it is desired to con- vey 6000 lb. of steam to building A, 5000 lb. to building B, and 3000 lb. to building C, per hour, with a pressure drop from 16-lb. absolute in the boilers to or near atmospheric pressure just beyond the main valve in each building. Good covering, still air at about 70 deg. and proper drainage are assumed. The total steam requirement per hour of buildings A, B and C is 14,000 lb. The longest run of main is from the boiler house to building C and without allowance for fittings is 880 ft. In estimating the sizes of pipes by the use of Table 11-2 it is necessary to first find the drop of pressure per 1000 ft. and then to find the corresponding quan- tity of steam flowing through the pipe for a drop in pressure of 1 lb. for this dis- tance of 1000 ft. The pressure drop varies directly as the length of a pipe, and the weight of steam discharged through a pipe varies directly as the square root of the pressure drop. We therefore multiply a given weight of steam by 4'/2 20 , 50 Fig. 11-3. Illustrat- ing the problem of siz- ing steam and return lines for group of build- ings as described in the text Boiler V- 1 lb. X (the tabular pressure drop per 1000 ft.) The given pressure drop per 1000 ft. to find the equivalent weight of steam at 1-lb. drop per 1000 ft. The assumed drop in pressure is 16 — 14.7 = 1.3 lb. per sq. in. For a given total drop of 1.3 lb., the drop per 1000 ft. is ^Q X 1000 = 1.48 lb. The first section of pipe to A conveys 14,000 lb. per hr. and the cor- responding weight of steam at 1-lb. drop per 1000 ft. is y 1.48 X 14,000 = 11500 lb. 123 Keferring to Table 11-2 we find that to convey 11500 lb. per hr. at a pressure drop of 1 lb. per 1000 ft. requires a 12-in. pipe. The second section of main from A to B conveys 8000 lb. per hr. at a pressure drop of 1.48 lb. per 1000 ft. Using the same reasoning we find that the corresponding weight of steam at 1-lb. drop per 1000 ft. is V ^ X 8000 = 6600 lb. 1.48 From Table 11-2 the pipe size is found to be 10-in. Similarlv the branch from B to building C convevs 3000 lb. per hour at 1.48 lb. drop per 1000 ft. The corresponding weight at 1 lb. drop per 1000 ft. is V X 3000 = 2460 lb. 1.48 And from Table 11-2 the pipe size is 7-in. The total steam to be carried will, however, be in excess of 14000 lb. by the amount condensed in the mains. The pressure drop for pipe friction will be less than 1.3 lb. by the amount necessary for initial velocity. The length of run equivalent to the lineal run plus the added allowances for fittings as shown in Table 11-3 will be materially in excess of 880 ft. It is therefore evident from an inspection of the plan that the above trial sizes may be too small and that it will be advisable to assume an increase of one size of pipe above those previously assumed, in all cases where there is a considerable number of fittings etc. This is true, in this problem, in the first section of the main. The trial sizes will then be, 14-in. for the run to branch A; 10-in. to branch B and 7-in. to C. Condensation AUoumnces: For 425 ft. of 14-in. main from the boiler to branch A. From Table 11-2 we find the square feet of surface per lineal foot of pipe to be 3.9 sq. ft., this equals 1657.5 sq. ft. for the 425 ft. of 14-in. main. To this should be added 5 per cent for radiation from fittings making approxi- mately 1740 sq. ft., radiating 50 B.t.u. per sq. ft. per hr., when the tempera- ture drop is 216 deg. — 70 deg. = 146 deg. Multiplying 50 (B.t.u.) by 1740 (sq. ft.) and dividing by 968 gives the total condensation for the 14-in. main, which equals approximately 90 lb. The 10-in. main condenses 2.82 (sq. ft. of surface per lineal ft.) X 200 (ft.) X 50 ^ 968 or 29.2 lb. + 5 per cent for fittings = 31 lb. The 7-in. main condenses 2 X 255 X 50 ^ 968 or 26.4 lb. + 5 per cent for fittings = 28 lb. It is evident that the condensation of the branches will be a small portion of the total quantity of steam carried by the main or branches. Estimating by comparison with branch to C, it is obvious that branches to A and B will condense hardly more than 40 lb. per hour each. This gives us the total quantitv of steam to be carried by the 14-in. main; 14000 + 90 + 31 + 28 + 40'+ 40 = 14229 lb. per hr. 124 The 10-in. main carries 8000 + 31 + 28 + 40 = 8099 lb. per hr. The 7-in. branch to C carries 3000 + 28 = 3028 lb. per hr. Pressure Drop for Initial Velocity: In a 14-in. main conveying 18970 lb. per hour the velocity is 7060 ft. per min., from Table 11-2. At 14229 lb. 14229 per hour the velocity will be " x 7060 = 5300 ft. per min. From Table 11-1 we find that 0.0625 lb. is recjuired to accelerate the steam from rest in the boiler to a velocity of 5520 ft. per min. in the main. For 5300 ft. per min. the drop is therefore [^^Vx 0.0625 lb. = 0.06 lb. drop velocity head. The residual pressure available for overcoming friction in the mains and branches is 1.3 — 0.06 = 1.24 lb. per sq. in. Referring to Table 11-3 we find the equivalent resistance in feet of straight pipe to be added to the run for friction in fittings, etc. The various quantities are tabulated on page 126 and the summation of the quantities gives the eciuivalent length of pipe for each section and for the total. We find that the revised ecjuivalent run is now 1559 ft. and with a given drop of 1.24 lb. in the total run, the drop per 1000 ft. is 0.796 lb. In the last column s found the revised actual pressure drop for each section. The pressure drop through a pipe varies as the sciuare of the weight flowing through it. If we know the weight of steam discharged through a pipe w th 1-lb. drop per 1000 ft. (as from Table 11-2) and wish to find the drop of some other weight (as the weights in column cj on next page) we can obtain it by applying this law. The square of the ciuotient of the given weight divided by the tabular weight, times the tabular drop equals the drop for the given quantity (column s). The total drop of l.l6 lb. shown in the table is as close to the desired drop as can be expected with commercial sizes of pipe. If the deviation had been greater, one or more of the trial sizes would have to be altered to bring the total drop nearer that desired. Inspection of column s will show in which portion or portions of the main the drop per 1000 ft. is farther- est from the average of 0.796 lb. It is this section or sections that should be refigured. The pressure available for friction in the branches is the difference between the total available drop of 1.24 lb. and the amount already utilized in the main up to the junction with the branch in question. The procedure for determining branch sizes is exactly the same as for the mains; assuming one size larger than the calculated trial size, adding condensation and allowance for fittings and checking to see that the actual drop to the building is close to the permissible drop. The drop in the branch to A is 1.24 lb. - 0.518 lb. = 0.722 lb. Di- viding this by 255 ft. (actual length of run to A) X 1000 gives 2.83 lb. drop per 1000 ft. in this run. The corresponding weight at 1-lb. drop per 1000 ft. is: ^ ^ly X 6000 (lb.) =3560 lb.; requiring (from Table 11-2) 8-in. pipe. 2.8D(ib.) The drop in the branch to B is 1.24 lb. - 0.768 lb. = 0.472 lb. Dividing 125 V. Table 11-6 Section Trial size pipe ra Actual length n Equivalent length for fittings Total equivalent length (n+o) p Weight of steam From Table 11-2 Weight passed by trial size at 1-lb. drop per 1000 ft. r Actual Actual pressure drop in drop per section 1000 ft. of main 1 — 1 xlflb.) xs \ "■ / 1000 s t Boiler house to branch A 14-in. 42.5 1 Gl. V. 160 ft. 6 ells 318 ft. 903 ft. lb. 14229 per hr. 18970 lb. per hr. . 564 lb. .518 lb. 478 ft. Branch A to branch B 10-in. 200 run of reducing tee 24 ft. 224 ft. 8099 lb. per hr. 7680 lb. per hr. 1.12 1b. .25 1b Tot. 21 ft. Branch B to bldg. C 7-in. 25.'5 1 Gl. V. 82ft, 3 ells 78 ft. run of reducing tee 17 ft. 432 ft. 3028 lb. per hr. 3155 lb. per hr. .921 lb. .398 lb. Tot. 177 ft. Total equiv. main 1.559 ft. Total drop 1.166 1b. this by 155 times 1000 gives 3.04-lb. drop per 1000 ft. in this run. The corresponding weight is i ^ x 5000 (lb.) = 2880 lb. requiring a 7-in. pipe. \3.04 Assume for the first trial, one size larger than figured above, to take care of the comparativelj^ large number of fittings, etc. The branch to A will be 9-in. and to B, 8-in. The estimated quantities of condensation are close enough for use in sizing these branches. The total quantitv carried bv branch to A is there- fore 6000 + 40 = 6040 lb. and by branch to B, 3000 + 40 =3040 lb. Table 11-7 Section Trial size pipe Fittings Total equivalent length Weight of steam Weight passed by trial size with 1-lb. drop per 1000 ft. y Actual pressure drop per 1000 ft. (-) Actual drop X 1 (lb.) in branch wXz Drop in main to branch Total drop boiler house to bldgs. Branch A 9-in. br. tee 68 ft. 2 ells 497 ft. 6040 1b. 5900 1b. 1.04 1b. 70 ft. Gl. v. 104 ft. .52 lb. .518 lb 1.038 lb. Total 242 ft. Branch B br. tee 63 ft. 2 ells- 374 ft. 62 ft. Gl. v. 94 ft. 5040 1b. 4400 1b. 1.311b. .49 1b. .768,1b. 1.2581b. Total 219 ft. 12b Since the total drop from the boilerhouse to the building in each case is not far from 1.24 lb., or is at least as close as commercial sizes of pipe will allow, the trial sizes of 9-in. to A and 8-in. to B are correct. The sizes of return mains should be based upon the sizes of the corre- sponding steam mains in the foregoing example. By referring to Table 11-5 we find as follows: branch returns from buildings B and C are respectively 3-in. and 2J2-iii- to the junction, where they increase to 3J/2-in-, continuing this size to the point where the 3-in. return from building A joins the above. Increase the return here to A}/2,-y(\. and continue this size to the vacuum pump in the boiler house. Long computations such as the above are required only in connection with extensive distributing systems, where the cost of one size larger pipe becomes important. For general use in sizing mains, branches and risers for both modulation and vacuum systems. Tables 11-8 A. B, C and D will be found sufficiently accurate if used with discretion. They are based upon 75 per cent of the values of Table 11-2 and will cover an ordinary amount of valves, fittings, etc., if globe valves are excluded. In the use of Tables 11-8 A, B, C and D the permissible pressure drop between the inlet of the supply main and the farthest radiator determines the alphabetical sub-division of the table which is to be used. Table 23-7 in Chapter 23 gives a list of pressure differentials, which will be found reason- ably accurate for various types of modulation and vacuum systems under ordinary conditions. The following rules should be employed to determine which column of length of run should be used for horizontal or vertical pipes in the alpha- betical sub-division selected- 1. For horizontal supply pipes, find the total run in feet along the pipe from the source to the farthest radiator and use the corresponding column in the table. 2. For sizing up-feed risers, add -yis of the length of the vertical pipes to the total run found by Rule 1, and use corresponding column in table. 3. For sizing down-feed risers deduct yV of the length of the vertical pipes from the total run found by Rule 1, and use the corresponding column in the table. 4. The sizing of supply run-outs, especially those in which the con- densation must flow by gravity in the opposite direction to the steam current, calls for special consideration and will be discussed in Chapter 12 on Critical Velocities in Radiator Run-outs. 5. The sizes of return mains and run-outs should be based on the sizes of supply mains, which will take care of a similar quantity, and are found by reference to Table 11-5. For convenience, the correct sizes of return mains and risers, for a given number of pounds of condensation, length of run and pressure differential, are also contained in Table 11-8 A, B, C and D. Modulation System: lu sizing piping for modulation systems, long com- putations such as described under vacuum systems are not necessary. The Tables 11-8 A to 8 D are sufficiently accurate for ordinary conditions. 127 Table 11-8. Ratings of Supply and Return Mains in Pounds of Steam per Hour, for Various Pressure Drops from Initial Pressure of 16 lb. Absolute, when in Horizontal Runs of from 300 to 1,000 ft. These tables are found by taking 75 per cent of the values of straight pipe given in Table 11-2, to cover an ordinary number of valves and fittings, entrance velocity and other resistances to the flow of steam A.— l/g-lb. Drop in Pressure Pipe sizes for modulation systems Length of run in feet Return (from table 11- 4) Steam supply 300 400 SOO , 750 1,000' Return- riser Dry return main Rating in pounds of steam per hour Va" H" 1" 7.08 6.12 5.48 4.48 3.88 %" 1" Ik" 16.9 14.6 13.1 10.7 9.25 1" IM" VA" 26.6 23. 20.6 16.85 14.6 1" Ik" 2" 55.4 47.8 42.9 35. 30.35 Ik"' Wz" 2y2" 91.5 79. 71. 57.8 .50.2 iH" I'A" 3" 169. 146. 131. 107. 92.5 iy2" VA" 3K" 249.5 215.5 193,4 157.7 136.5 IVo" 2" 4" 353.5 305. 274. 223.5 193.6 9" 2J/2" 5" 642.5 .554. 198. 406. 3.52. 2W 3" 6" 1043. 900. 808. 660. 572. 3" 3" J 1.525. 1318. 1185. 965. 836. 3" 3K" 8" 2130. 1840. 1650. 1347. 1168. 33^" 4" 9" 2855. 2465. 2215. 1806. 1564. 3^" 4M" 10" 3835 . 3315. 2975. 2425 , 2110. 4" 5" 12" 6060. 5230. 4700. 3835. 3320. 5" 6" 14" 9175. 7920. 7120. 5800. 5030. 5" 6" 16" 11320. 9780. 8780. 7160. 6210. 9" 7" 18" 1.5350. 13280. 11900. 9720. 8410. 7" 8" 20" 20100. 17400. 15600. 12720. 110.30. B — %-lb. Drop in Pressure Pipe sizes for modulation systems Length of run in feet Return (from table 1 1-4) Steam supply 300' 400' 500' 750' 1,000' Return riser Dry return riser Rating in pounds of steam per hour k" k" 1" 1" k" 1" VA" VA" 1" Ik" VA" 2" 10.03 23.9 37.7 78.4 8.67 7.75 20.7 18.5 32.6 29.2 67.8 60.7 6.34 15.1 23.8 49.6 5.48 13.1 20.6 42.9 Ik" VA" VA" VA" VA" VA" VA" 2" 2A" 3" 3^" 4" 129.5 239. 353. 510. 112. 100.3 207. 185. 305.5 273. 433. 387. 81.8 151.2 223 316 ! 71. 131. 193.4 274. 2" 2 A" 3" 3" 2%" 3" 3" 3A" 5" 6" 7" 8" 910. 1478. 2160. 3015. 786. 704. 1280. 1142. 1870. 1670. 2610. 2335. 574. 933. 1365. 1905. 498. 808. 1185. 1650. 3J^" 3A" 4," 5" 4" iA" 5" 6" 9" 10" 12" 14" 4040. 5430. 8580. 13000. 3495. 3125. 4700. 4200. 7420. 6640. 11250. 10060. 25.50. 3430. 5430. 8220. 2215. 2975. 4700. 7120. 5" 6" 7" 6" 7" 8" 16" 18" 20" 160,50. 21750. 28500. 13890. 12400. 18820. 16820. 24650. 220.50. 10130. 13750. 18000. 8780. 11900. 15600. 128 Table 11-8 — Continued C — 54-lb. drop in pressure Pipe sizes for modulati on systems Steam supply Length of run in feet Pipe sizes Steam supply for vacuum systems Return (from table 11-4) 300' 400' SOO' 750' 1000' Return (from table 11-5) Return riser Dry ret. main Ratings in pounds of steam per hour Horiz. Vert. H" 1" 1" H" 1" IM" IH" 1" IK" lA" 2" 14.18 33.8 53.3 110.8 12.28 10.98 8.95 7.75 29.25 26.2 21.35 18.5 46.2 41.3 33.7 29.2 96. 85.8 70.3 60.7 1" IH" n" K" Vi" 1" 1" H" H" H" H" VA" VA" VA" I'A" I'A" 2" 2J^" 3" W2" 4" 183. 338. 498. 707. 158.6 142. 115.8 100.3 292.5 262. 213.5 185. 432. 386.5 315. 273. 612. 548. 447. 387. 2A" 3" 3A" 4" lA" lA" 2" 1" IM" IM" lA" 2" 2M" 3" 3" 2y2" 3" 3" 3^" 5" 6" 7" 8" 1285. 2085. 3050. 4260. 1113. 997. 813. 704. 1808. 1620. 1320. 1142. 2645. 2365. 1930. 1670. 3690. 3300. 2695. 2335. 5" 6" 7" 8" 0" ~2A" 2W 3" lA" 2" 9" ~2A" 33^" sy2" 4" 5" 4" iA" 5" 6" 9" 10" 12" 14" 5720. 7675. 12130. 18360. 4945. 4430. 3610. 3125. 6650. 5950. 4850. 4200. 10500. 9400. 7660. 6640. 15900. 14220. 11600. 10060. 9" 10" 12" 14" 3" 3A" 4" 43-^" 2A" 3" 3J4" 4" 5" 6" 7" 6" 7" 8" 16" 18" 20" 22620. 30750. 40250. 19610. 17560. 14310. 12400. 26600. 23800. 19420. 16820. 348.50. 31200. 25420. 22050. 16" 18" 20" 5" 6" 6" iA" 5" 5" D— 1-lb. drop in pressure Pipe sizes for modulation systems Return (from table 11-4) Return Dry ret. riser mam H" H" %" 1" I" Ik"' I" IM" IM" ^A" lA" I A" lA" lA" lA" 2" 9" 2A" 2A" 3" 3" 3" 3" W2" 5A" 4" W2" ^A" 4" 5" 5" 6" 5" 6" 6" 7" 7" 8" steam supply 1" IH" lA" 2" 2A" 3" 3H" 4" 5" 6" 7" 8" 9" 10" 12', 14" 16" 18" 20" Length of run in feet 400' 500' 750' Ratings in pounds of steam per hour 20.2 17.4 47.8 41.4 75.4 65.4 157. 136. 259. 225. 478, 414. 706. 612. 1000. 867. 1820. 1575. 2955. 2565. 4320. 3750. 6030. 5230. 8080. 7020. 10870. 9425. 17160. 14900. 26000. 225.50. 32050. 27810. 43500. 37720. 57000. 49400. 15.5 37. .58.3 121.5 202. 370 546. 774. 1410. 2282. 3340. 4660. 62.50. 8400. 13300. 20130. 24800. 33620. 44100. 12.65 10.98 30.2 26.2 47.6 41.3 99. 85.8 163.6 142. 302. 262. 446. 386.5 632. 548. 1150. 997. 1867. 1620. 2730. 2365. 3810. 3300. 5110. 4430. 6860. 5950. 10850. 9400. 16400. 14220. 20250. 17560. 27450. 23800. 36000. 31200. Pipe sizes for vacuum systems Steam supply 1" Ik" \A" 2A" 3" ■iA" 4" 5" 6" 7" 8" 9" 10" 12" 14" 16" 18" 20" Return (from tadle 11-5) Horiz. 1" 1" Ik" lA" lA" 2" 9" 2A" 2A" 3" 3" 4" 434" 5" 6" 6" Vert. ?4 k" k" k" 1" Ik" Ik" lA" 2" 2" 2A" 2A" 3" 3A" 4" i.A" 5" 5" 129 The total quantity of steam to be supplied per hour at the time of maxi- mum normal heating effect being a known factor and the total maximum pressure drop in the heating system being determined for this period, the pressure drop in the supply main must be so chosen that the pressure to be carried on the boiler will exceed by a safe margin the sum total of resistances between the boiler and the outlet of the vent valve. For an illustration, assume a typical modulation system which requires 500 lb. of steam per hour for maximum normal heating effect. The length of run is assumed to be 300 ft. and the boiler pressure is not to exceed i^-lb. gauge. To find the proper size of supply main to meet these conditions, the pressure drops from p to pe as described in the discussion of pressure drop in modulation systems. Page 116, must be determined, before the permis- sible pressure drop p^ in the supply main can be ascertained. During maximum normal heating effect we find the pressure drop from p to p 6 to be as follows: p = constant at atmospheric pressure = 0.000-lb. gauge pi = pressure drop through vent check valve (intermittent at that period) = 1/20 lb. = 0.050 " Pa = pressure drop through vent valve orifice (negligible at that time) = 0.000 " ps = pressure drop in return main. Negligible if return has proper grade = 0.000 " p4 = pressure drop through orifice of radiator trap, which for the given condition will be the maximum tabular value of Vs lb.= 0.125 " " p5 = pressure drop through radiator. Negligible at that time = .0.000 " " pe = pressure drop through radiator valve will be the maxi- mum tabular value for the given period, 3^ lb. =0.125 Total drop p to pe = 0.300 '' || The pressure to be carried on the boiler = )^ lb 0.500 Pressure drop p to pe = 0.300 Difference of pressure available 0.200 Bearing in mind that in addition to the pressure drop p? in the supply main, we must consider also the pressure drop ps to impart initial velocity, we readily see that a pressure drop of 34 lb- in the supply main would be unsafe and we, therefore, select the 3^-lb. drop in the supply main p? as the basis for determining the size of pipe required. We find by referring to Table 11-8 A that a 5-in. main is necessary to sup- ply 500 lb. of steam with 3^-lb. drop in pressure in a run of 300 ft. We now have to determine the head or pressure drop ps necessary to impart initial velocity to the steam. From Table 11-2, we find S, the cubic ft. per pound of steam at 15.3 lb. absolute (assumed boiler pressure) is very nearly 26.27. Converting the total steam required in pounds per hour into cubic feet per minute 130 500X26.27 13135 _,„„ ^.„ „ y^ = ^„ = 218.9, or, say, 219 cu. ft. By referring to Table 11-2, column 3, we find the linear feet per cubic foot volume, which for a 5-in. pipe is 7.22. Multiplying 219 by 7.22 we obtain the velocity in feet per minute of the steam to be 1582 ft. We now determine the pressure drop ps necessary to impart initial velocity and by referring to Table 11-1 we find for a 2500-ft. velocity, a pres- sure drop of 0.01 lb., which for a 1582-ft. velocity would be approximately 0.009 lb. per sq. inch. The total pressure drop between the boiler and the outlet of the vent valve then becomes: Pressure drop p - pe as stated before = 0.300-lb. gauge Pressure drop p? in main J/g lb. = 0.125 " " Pressure drop p^ to impart initial velocity = 0.009 Total pressure drop = 0.434-lb. gauge We find an effective differential in pressure between the boiler pressure and the pressure losses in the sytem of 0.500 —0.434 = 0.0661b. gauge, for maintaining circulation in the system during the period of maximum heating effect. This proves that for the above condition, the 3^-lb. drop in pressure in Pt is the proper basis for selecting the table to be used, and this being de- termined, the intermediate sizes of the main and branches are taken from same. The sizing of run-outs requires special consideration as described in detail in Chapter 12, Critical Velocities in Radiator Run-outs. The sizing of returns involves the same procedure with modulation systems as outlined before in the discussion of sizing of piping for vacuum systems. The size of the return depends on the size of supply for an equal duty. TBy referring to Table 11-4, we find that the size of return correspond- ing to a 5-in. supply main is 23^2 in., which is the size we select. Taking care of the condensation in the steam main at the far point is often found necessary in modulation systems in which case the pipe sizes must be increased toward the end of the run, beyond the tabular values, to take care of the reduction in effective Eirea of the pipe due to the condensa- tion being carried along with the steam. A further reason for increasing the sizes of the pipes toward the end of the run is to compensate for the air carried along with the steam in the pipes, which, if not properly relieved, will retard the circulation of steam to a great extent. Air relief connections must be provided at the ends of the runs, through thermostatically actuated return traps into the nearest dry return, in all cases where gravity drips are made into a wet drip line. 131 CHAPTER XII Critical Velocities in Radiator Run-outs THE velocity in a nearly horizontal pipe in which the condensation is to be drained by gravity in the opposite direction to the flow of steam above it, becomes critical, when it reaches such rate that any velocity increase will cause the condensation to be swept upgrade against gravity. The need has been apparent to heating engineers of definite information regarding this critical velocity of steam in branch run-outs to radiation in which condensation must be drained in a direction opposite to steam flow. Individual opinion based on experience regarding velocity permissible at given slope without danger of noise due to surging, varies fully 300 per cent. Many modern buildings have very limited space in which to run pipes between the finished floor and the main beams and fireproof construction. There are many valid objections to exposing the run-outs above the finished floors, and the question frequently arises as to the proper size and grade for such pipes in the available space beneath the finished floor. Fundamentally the size of pipe for a given radiator run-out is de- pendent on the maximum number of heat units to be conveyed in a given time. The latent heat content per cubic foot of steam at the range of pressures usual in modern "low-pressure" heating is least at the lower pressures. Denser steam at higher pressures undoubtedly sets up greater wave-forming friction of steam over surface of the condensation and will sweep the water up the slope at a slightly lower steam velocity than that at which the condensation will flow against the current of less dense steam. These facts in a measure offset each other and the small error in the final result will have less effect on the problem than the inaccuracies of grade liable to exist despite any reason- able care in erection. In an endeavor to fix the critical velocity, a carefully conducted series of tests has been made. The first of this series was with glass tubes, to determine visually just what took place when steam at various velocities passed over its condensation in pipes graded against the steam flow. The result of this series was very instructive in determining the effect of velocity and what to look out for in subsequent tests. The second tests were with commercial pipe of 1 in., 1)^ in., IJ/2 ii^- ^^id 2 in. sizes, each 18 ft. long; each pipe being tested at uniform grades of 34 in., I/9 in., 1 in. and 13^ in. in 10 ft. It was found that the difference in critical velocity in the various sizes of pipe under test differed less at the same slope than the errors incidental to careful observation. In consequence of the fact that the size of pipe had no direct relation to critical velocity, only one size was tested at a grade of 3 in. in 10 ft. to complete the curve of velocity at slope. The result of these tests upset some preconceived theories and estab- lished some facts that appear to be fundamental. These established facts are : 1. That the size of the pipe has no visible relation to the critical ve- locity, which was practically the same in all sizes tested. 132 2. That the normal vokime of condensation in a covered pipe as compared with an uncovered pipe, had no effect on the critical velocity. In fact, increase in condensation up to the point where the volume of water limited the free area for steam and made a material difference in velocity, the condensation continued to flow as with normal condensation. 3. That greater or less length of run if at uniform slope makes no ma- terial difference. The controlhng velocity is that in the first foot or two of pipe, and if the velocity existing there is above critical, it will sweep the condensation to the high end. In fact, increase in condensation up to the point where the volume of water limited the free area for steam and made a material difi'erence in velocity, caused no change in flow of condensation. 4. That the direction of flow in the vertical supply riser to which the run-out is connected, will have a slight effect on the critical velocity in the run-out. The critical velocity is lower in a down-feed than in an up-feed riser. This is due to the change in direction of the highest velocity steam striking the run-out on the lower side and acting on the condensation which is endeavoring to flow in the opposite direction. The most surprising fact demonstrated during these tests was the rap- idly diminishing efi"ect of a slope greater than 1 in 120 on critical velocity, and the indication from the curves plotted for the entire series, that the critical velocity was little, if any, greater at slopes of more than 1 in 40 than at that slope. It follows from the above that a velocity of steam which will sweep up the condensation in a pipe having a grade of 1 in, say, 33 Avill sweep the condensation upward in a pipe having more grade. The practical application of this series of tests must take local conditions into consideration. The thermal capacity of the mass of iron in a cold radiator, will call for a large volume of steam during the heating-up period, and at the same time the difference in pressure at the two ends of the run-out will be greatest. Consequently the velocity of steam through the run-out will be far greater Fig. 12-1. lOustrating greater capacity of largest possible run-out pipe at a minimum grade compared with that of smaller pipe at much greater grade. The capacity of 2-in. pipe at grade of ^ § in. in 10 ft. is greater than that of a 1-in. pipe at li?^-in. grade in 10 ft. in the ratio of 7.20 to 4..35. Note application in limited space where run-out must cross structural frame beam 133 4 3^ 3 ■>' S "^2 O i 2 J / s a . 1 I2 / / / / 3 ^ 4 / 1 / / 2 ^ 1 4 . -- r' n ■— — 500 600 700 800 900 1000 1100 1200 1300 1400 Velocity in Feet per Minute Fig. 12-2. Critical velocities in feet per minute, of low-pressure steam in radiator run-outs at various grades, where condensation flows down-grade against steam. Specific volume of steam, about 26. .5 cu. ft. per lb . during initial heating-up than during normal maintenance. It is during the initial heating-up that the gurgling and hammering of condensation in run-outs causes most complaint. It is then that the flow of steam is most liable to exceed the critical velocity and sweep the con- densation up into the vertical riser pipe to the inlet valve. It would be possible to use a run-out of half the area of cross-section if the radiator is to be constantly hot during the heating season as compared with area of run-out at same grade for a radiator in which there are frequent alternations of heating and cooling. Again, there are many installations m which a httle noise during the heating-up period would not be considered objectionable, while in others the same amount and kind of noise would condemn the entire heating system. No fixed rule based on square feet of radiation may therefore be made for sizing run-outs in which the condensa- tion is normally drained against the flow of steam. A few things are evident from these tests and a number must be left to the good judgment of the designer of the system under consideration. Among the evident things are: 1. That a uniform grade approximating 1 in. in 10 ft. is about the maxi- mum useful limit. That a pipe if uniformly graded when cold is liable to 134 1 — \ — 1 — \ — 1 — 1 — 1 — n — ' — 1 — ^ — 1 — 1 — r~i — ' — 1 — 1 — n — i — i — i — i — i — i — \ — n — i 3' Jj 3 1 -' i? s: . = c t 1 " t 1 1 -. r ' I 1 r ~ 1 ' - ,' -i 4 -I ' :t M i t t T t i^' A- 4^1- y - I t J^ t / t 1^ 42 7 -> J ^ ^ 7 _/ / ^^^_ J 7 21 ^ z ^7 ;^ ^" ^ * y ^^_^-- — L- — " ^.^^=-^^ — v-^" 9 10 11 B. t. u. per Second 12 13 20 Fig. 12-3. B.t.u. per second conveyed in low-pressure steam through radiator run-outs at grades which are critical where condensation flows against the current of steam. Critical velocities established by test and as shown in Figure 12-2. buckle upward in the middle when hot and destroy the uniformity of grade. 2. That the most constant annoyance will occur when the flow of steam, at normal maintenance rate exceeds the critical velocity for the grade at which the run-out is laid. 3. That where noise is permissible during the heating-up period, the run-out should be sized and graded so as not to exceed the critical velocity during any normal heat maintenance. If so sized there will be little if any noise dm-ing the initial period when condensation is being swept on into the radiator by a velocity materially in excess of about 1350 ft. per min. There will, however, be a considerable noise as the heat capacity of the metal in the radiator becomes satisfied and this will continue during the time the steam flow is at a velocity of about 1350 ft. per min. until the steam flow falls below the critical velocity at the grade of the run-out. From the above tests certain practical conclusions may be inferred. The practice in sizing run-outs has been based on some relation to pressm-e drop or the friction of the steam in the pipe. This more properly apphes to mains and risers. The pressure drop due to friction in any normal run-out, when velocity is low enough to permit the current of condensation to flow against the steam, is less than .001 lb. per ft., therefore so slight that it is negligible. 135 It would be much more consistent to size run-outs on basis of critical flow rather than on pressure drop. Tables 1 and 2, based on the following assumptions, may prove of interest : 1. That a sKght noise due to condensation flowing into the radiator with the steam during the heating-up period will not be objectionable. 2. That at maintained rate, the condensation in the vertical rise pipe must also flow back against the steam. This is not necessary where bottom of the inlet to the radiator is at a higher level than that of the outlet. 3. That the radiation during maintenance does not condense at a rate in excess of 250 B.t.u. per sq. ft. per hour. 4. That there will be a uniform grade of not less than ^ in. in 10 ft. in two-pipe connection and 1 in. in 10 ft. in one-pipe connection. Table 12-1. Run-outs for Two-pipe Work Having Grade of Not Less Than ^-^ in. in 10 ft. Radiator Transmits Not More Than 250 R.t.u. per Sq. Ft. per Hour at Maintained Rate. Size of pipe 1" 1}4" 1)4" 2" Maximum radiation on pipe in sq. ft. Horizontal run-out grade 'ig in. in 10 ft 43 72 101 173 Vertical branch and valve .58 108 144 260 Fig. 12-2. Run-outs for One-pipe Work Having Grade of Not Less Than 1 in. in 10 ft. Radiator Transmits Not More Than 250 R.t.u. per Sq. Ft. per Hour at Maintained Rate. Size of pipe 1" \H" Wi" 2" Maximum radiation on pipe in sq- ft. Horizontal run-out grade 1 in. in 10 ft 25 .50 68 115 Vertical branch and valve 35 75 100 170 1.30 CHAPTER XIII Vacuum Pumps and Auxiliary Equipment VACUUM PUMPS are used: 1. To remove air and other products of condensation from the return main where these products cannot be expelled to atmosphere by gravity or internal steam pressure alone. 2. To induce circulation by reducing the pressure in the return main, thereby increasing the pressure differential. 3. To assist in the complete disposal of the products of condensation. Experience indicates two successful types of pump for this service^ namely, reciprocating steam-driven, and rotating electric-driven. The steam-driven pump has efficiency and economy in its favor where steam at 30-lb. or greater, absolute pressure, is continuously available and the pump exliaust and its contained heat may be fully utilized in the system. The electric-driven pump is generally most efficient where exhaust steam from the engines and other sources is continuously available in greater quantity than is necessary to supply the heating system; in other words, where the exhaust from the vacuum pump to waste would be a loss. The electric-driven pump is also preferable where the available live steam supply has a pressure too low to operate a steam-driven pump. Many rotating pumps in which both air and water were handled in one chamber have deteriorated very rapidly in service, largely because of the grit always present in the condensation. Rotating pumps with one pump chamber handling air and vapor and another containing a centrifugal impeller for handling the water have proved practical. Many variables enter the problem of ascertaining the proper size of pump for a given heating system. In the final analysis, good judgment based on wide experience in applying a table of probable pump displace- ment is of far greater value than any theoretical formula. Even for a close approximation, it is necessary to know enough about the heating plan in addition to "the square feet of equivalent radiation" to be able to estimate the probable maximum volumes in unit of time of both water and elastic fluids of condensation, necessary degree of vacuum at the pump and discharge head against which condensation must be delivered. The volume of water-condensation varies in different installations fully 40 per cent per square foot of equivalent direct radiation. The volume of elastic fluids — air, water, vapor, steam and gases from impurities — also varies with the initial and terminal pressures, with the efficiency of the radiator traps, with the degree of prevention of inward leakage of air, with the probable cooling effect in the return, and with the character of the im- purities in the boiler-feed. Lifts (see Figure 13-1) in the return call for greater terminal vacuum with consequent greater expansion in volume of the elastic fluids, thus calling for greater pump displacement. They should, therefore, be avoided if possible. Discharge head on reciprocating pumps handling water and air has the 137 a '3 .a V E-t -a a « o I- > *' (J bj « fl rt o »** i-> oS O ui in^ C ^ i: « 5 «, £ 3 « « « « o "■§ — 4t. fl rt o a m ^ ujifc- fc, o G O a> o a> o ^iOXOXOXOXO a 00000 -I I'- I CD I . a fc- o o o cd ^ ■3 o CO ♦^ a . P £ o O CO >- ° ^ c S = o O- as ^ ■ft s '3 00° o o S CO a o fc- fa J be O t/l " ilj3a31 jajaniBici CO"OCO OD OCl CO O 0(M\0(N ^ C^-^VO CO CO -^ -T- -^ -^ T? O O ^^\0(M (N CO CD CO i—i i-H ca M (N (N C^ CO CO CO CO CO TT" Tt< rr "Tt" ■TT' .sSg. q;3n3q uoijBJEdas JIB joj jyuBj in p3jini)3i EaJB JajBdi 'jj -bg d CO CO in d d q d t- « ci CO ^ q q 10 cd 1— H r-H CO CI CO ^ 00 o_ d to r-' io\o t-- 90.0 105.0 121.0 33iBqosip JO azis tnnuimiM d pH rH ^C^ C) C^l CO CO T? 5^ ^ LO 0^0 t~- r- CO J9UIBJ1S BOTJOns JO pOB UlEOI lUTuaj ;o azis ummraiM d i—t 1— 1 CI (MC^eocococo^^'^'^iOLOO^Dt— t^ - :: :: ^ d d ci ci t^COeOCOpHrHr.Hf-1 1-H i-H r— ( ajnssaJd raBajs -qi-ooi oj Si JOJ JotuaAo3 tnnnaBA puB jCiddns uiBais jo azig \N \N jnoq jad •n'ra JO spuBsnoqx noi;Bsnapno3 jnoq jad spnnO(j nopBsoapno3 'I* 10 UO CO CO (M OS I— I I— O rj -T" -f o r- CO I— ( t- ■-H !— I CI -r LO ,_j ^ LO ir: ,_! f— 1 \0\D rH CO LO r- CO r~^C■i\0 CO C^l "rr ^ r- m f>i C7^ 0\ r-H \0 CI LO I— CO CO 10 (MOO i-H t~- CO 0\cO cn CO T? O CO 1— I TP rHC-l CJ o t- o 00 rH 'T? CO 0\ LO 10 O CO CO C-I CO CO O 00 — r- r- CI o 000 o 000 O lO CO CO LO CO -^ CI -r LO t-- c^ 000 000 CO CO CO CI LO ^^ rH ro O 000 000 \D O O ONrH ^ CO C-] 10 rH CJ C-I saqoni in jajainBicx 138 effect of increasing clearance and slip and thereby decreasing the effective displacement. A discharge head of more than one added atmosphere on reciprocating pumps is best handled by separating the water and gases and removing them independently tlirough two separate pumps. For slip in reciprocating wet-vacuum pumps it is seldom safe to allow less than 3/6 of the displacement, although a newly packed pump may , show much less. j_^;3tz ^ i^ 3 CI 1-^ ^ :3 CL Fig. 13-1. Method of making step-ups using Webster Series 20 Lift Fittings. Pipes between lifts must grade down- ward in direction of arrows ^ Systems in which the pressiu-e throughout the supply lines and radiation as well as in the re- turns is normally less than that of the atmos- phere are subject to invisible inleakage of air around the valves and fittings. Such systems require increased displacement also, because of the greater volume of elastic fluids due to low terminal pressme necessary for circulation. Cooling and consequent reduction in volume of the elastic fluids in the return present an element of considerable magnitude and uncertainty. Well-insulated return pipes, also large volumes of condensation entering the main return close to the vacuum pump, require greater displacement than would the same radiation with returns in which a considerable portion of the vapors could condense between the radiation and the pump. Clearance reduces effective displacement in all pumps. The clearance for a given cylinder diameter in reciprocating pumps of some makes is ap- proximately the same in short-stroke as in long-stroke pumps. Commercial sizes of reciprocating vacuum pumps vary in ratio of bore to stroke between 1 to ^ and 1 to 2 ; it follows that a pump of the latter proportion has greater efficiency per displacement than the short-stroke pump because of smaller percentage of clearance. Experience with reciprocating steam-driven vacuum pumps indicates that for most favorable conditions the use of water cyhnders of less dis- placement than eight times the normal volume of water of condensation is seldom safe. With radiation divided into small units, a ratio of at least 10 to 1 will be required. Ratings for the rotating combination units should be based substan- tially on a 10 to 1 ratio of the combined displacement of water and air cylin- ders, the ratio of these cyhnders to each other being about 2 of water dis- placement to 8 of air. In these pumps the displacement of water must be high on account of the constant speed, while a lower proportion of air dis- placement may be taken because of the high efficiency of the air chamber as compared with reciprocating pump cyhnders which have greater clearance. The speed and displacement in rotating pumps Eire normally constant, unless expensive variable speed motors are used, whereas in reciprocating 139 steam-driven pumps piston speed may be varied through wide range. The temptation to gain displacement by excessive piston speed without regard to the consequent racking of the pump because of too frequent starting and stopping of pistons and valves, should be avoided by adhering to a definite relation between piston speed and length of stroke. This relation as used for the calculation of basic ratings expressed in column 2, Table 13-1 is that the permissible piston speed in feet per minute equals 20 times the square root of the stroke in inches. These ratings are calcu- lated for pumps having equal stroke and bore but they may be assigned to other pumps as will be explained later. The relation between the volume of the cylinder and that of the water discharged per stroke is figured as ten to one. Slip is assumed to be one-sixth of the total stroke. The following example will fully explain the method of calculations for column 2. Selecting from column 1, a pump having 4-in. stroke and 4-in. bore, the area of its cylinder is 4 x 4 x 0.7854 = 12.568 sq. in., or 0.0873 sq. ft. The piston speed is 20 x V 4 = 40 ft. per min., or 2400 ft. per hr. The gross displacement is therefore 0.0873 x 2400 = 209.52 cu. ft. per hr.,ofwhichthegrosswaterdisplacement is one-tenth, or 20.95 cu. ft. per hr. Since the condensation will weigh 60 lb. per cu. ft. at about 200 deg. fahr., the gross water displacement may be expressed as 20.95 x 60 = 1257 lb. per hr. This must be reduced one-sixth because of slip, or to 1047 lb. of condensation per hr. as a basic rating for this pump. Taking the average B.t.u. per pound of condensation as 970, the basic rating for the same pump may also be expressed as 1,015,600 B.t.u. per hr. Ratings for vacuum pumps are properly expressed only in terms of pounds of water condensed by the heating system in a given period of time, or the equivalent latent heat in B.t.u. given up by the steam while con- densing. Ratings in terms of "square feet of direct radiation" are not strictly correct and may be misleading since there is not recognition of steam pressures, temperature difference, and other factors entering the problem. However, for convenient use, factors are shown at the lower left of Table 13-1 for reduction of square feet of various types of radiation to pounds of condensation per hour which will give approximate results. Since many vacuum pumps may have unequal stroke and bore, the capacity factors in column 12 are provided to show the relative effective- ness of such pumps as compared with "square" pumps having same bore and equal stroke. Column 11 shows relative proportions of "unequal" pumps in terms of stroke divided by bore. The corresponding factor for a pump of any selected relation of stroke to bore is found directly across in column 12. These factors provide means for selection of stock size pumps where the rate of condensation to be handled is intermediate between basic rates for "square" pumps stated in column 2. For instance, assume a condensation rate of 15,000 lb. per hr. To find the proper size of pump, select the diameter of bore in column 1 correspond- ing to the basic rate in column 2 nearest equal to the required rate. This 140 basic rate is 16,300 lb. per hr. and the bore is 12-in. Then find the factor in column 12 equal to the quotient of required rate divided by the basic rate for the 12-in. pump. This quotient is 0.92 and the nearest equivalent factor in column 12 is 0.91. The corresponding figure in column 11 is 0.80 which is the decimal relation of stroke divided by bore. Multiply the bore (12-in.) by the factor (0.80) and it is found that the stroke should be 9.6-in. The nearest equivalent stock size of pump has 10-in. stroke and therefore a 12-in. x 10-in. pump is selected. Where the result of such a calculation does not fit obtainable stock sizes, select a stock pump of some other diameter and stroke which, when factored by use of column 12, will give a rating at least equal to that required. Another problem is that of finding the basic rating for any given pump of unequal stroke and bore; for instance, one having 4-in. bore and 6-in. stroke. The relation of stroke to bore is 6 divided by 4 or 1.5. Finding the number 1.5 in column 11 it is noted that the corresponding factor in column 12 is 1.19. Multiplying 1.19 by 1047, which is the basic rating for a 4-in. X 4-in. pump from column 2, the product gives 1246 lb. of condensation per hr. as the basic rating for this 4-in. x 6-in. pump. It is to be specially noted that the basic ratings shown in column 2 are calculated and shown for the standard conditions of operation stated in the upper right of the table. Other actual or expected conditions of opera- tion can be transformed to terms of standard. Where the B.t.u. to be emitted are individually calculated for each group of like class and size of radiation, these quantities may be multiplied by the factors in column 13 or divided by those in column 14. The sum of these factored quantities will be the basic rating (column 2) from which the size of water cylinder is selected. Under conditions requiring lift points in the return; or where there is inleakage around inlet valves or elsewhere; or where large volumes of high temperature returns enter near the pump ; or if the run of piping from source of steam supply to farthest radiator is long ; or where the radiator traps leak steam; additional factors must be applied to insure the proper size of pump. These factors cannot be summarized since their selection is entirely a matter of judgment and of experience with similar conditions. Column 4 shows the minimum size for return main entering pump. These sizes are based upon a grade in the piping of 1 ft. in 300 toward the pump and upon a condition where the return pipe is half-full of water and will then discharge condensation by gravity at rates not less than the basic rates in column 2. For these calculations, the Chezy formula Q = a c V r s is used, in which Q is the quantity discharged, a is the cross-sectional area of the pipe, r is the hydraulic radius, s is the hydraulic slope of the pipe and c is a coefficient. The size of returns inlet from column 4 will also determine the size of suction strainer which is to be used in this main at the pump. Column 5 is calculated from the same formula to determine the mini- mum size of pump discharge and delivery pipe from pump to air-separating tank. In this case the pipe is considered to be half-full of water and its grade is 1 in. in 20 ft. 141 For purposes of determining the proper size of air separating tank to apply for a given rate of condensation discharge from pump, the assumption is made from field experiences that 1 sq. ft. of liberating surface should be provided under average conditions for each 2100 lb. of water discharged per hoiu*. Column 6 of Table 1 shows the number of square feet of liberat- ing surface required for the basic discharge ratings in column 2. Where the tank is used only for air-separating purposes such as plain tanks and hydro-pneumatic tanks, the sizes of tanks may be designed directly from the figures in column 6. Dimensions of tanks following this design are shown in columns 7 and 8. In cases where the tank is used for storage of retiu-ns, the tank should be larger than that required for piu-poses of air-separation only. Columns 9 and 10 show dimensions of such tanks based upon storing the quantities of water which will be discharged during five minutes at the basic hourly rates shown in column 2. As an example of the complete calculations for sizing the water end of a vacuum pump and for selecting size of auxihary equipment, assume a group of three buildings, A, B and C, from which condensation flows at rates of 7500, 5000 and 3000 lb. per hr. respectively. Also assume that the 7500 lb. per hr. of condensation in building A is from blast coils and a closed heater; that the 5000 lb. per hr. from building B is from pipe coils, each containing 130 sq. ft.; that the 3500 lb. per hr. from building C is from direct radiators in 50 sq. ft. units; that return mains are exposed ; and that it is proposed to use a plain type of air sepa- rating tank. These condensation rates must be transformed to those which would be reahzed under the standard conditions upon which this table is based, by means of the factors in column 13, using 0.66 for blower stacks and closed heater, 0.70 for coils larger than 120 sq. ft. and 0.84 for radiator units of 50 sq. ft. By applying these factors the equivalent condensation rates are found to be 4950, 3500 and 2940 lb. per hr. for building A, B and C re- spectively or 11,390 lb. per hr. for the transformed equivalent total rate. From column 2, the nearest basic rate is 10,350 lb. per hr. and from column 1, the corresponding diameter of bore for this pump is 10-in. By dividing the required rate 11,390 by the basic rate 10,350, the capacity factor is found to be 1.10. Going into the table it is found that 1.10 in column 12 corresponds with a relation of stroke to bore of 1.25 (column 11). Multiplying 1.25 by 10 in. (the bore) gives 12.5 in. as the required stroke. The nearest stock size is 12-in. stroke so that a pump having 10-in. bore by 12-in. stroke is selected. From columns 4 and 5, the minimum requirements for size of retm-ns inlet and discharge for this pump are found to be 4 in. and 2^/2 in. respec- tively. If the return main is long, it is better to select 5-in. as the minimm size of return inlet, since 43 2-in. is not a regular stock size for pipe and fittings. The suction strainer will be the same size as the return main entering the pump. Selecting from columns 7 and 8, the size of plain air-separating tank is 18-in. diameter by 48-in. length. 142 Proportioning of Steam Ends of Reciprocating Vacuum Pumps: In proportioning the steam cylinder, the following is a safe rule to use. The area of the steam cylinder in square inches times one-third the boiler pres- sure should equal the water piston area in square inches, multiplied by the combined pressure on the water end {vacuum plus discharge pressure) expressed in pounds per square inch. This is given by the following equation : A3 X I" = A„ X G-^O From which we have A. X (X+P,)x3 -'^s = — {Formula 13-1) in which As = area of steam piston in square inches. A^ = area of water piston in square inches. Pb = boiler pressure in pounds per square inch. Pd = discharge pressure in pounds per square inch. V = vacuum at pump expressed in inches of mercury. V -7)-= approximate vacuum in pounds per square inch (2 in. mercury = approximately 1 lb. per sq. in.) Note: All pressures are by gauge. In the above formula, the working pressure is taken as one-third of the boiler pressure, in order to allow for the low mechanical efficiency of the pump, as well as for the inevitable drop in steam pressure between the boiler and the inlet of the pump. Carelessness in setting up the packing in the water-and-air piston is prevalent and to be expected. It is also necessary for the pump to keep going even when the boiler pressure may be considerably lower than the normal working pressure. While in some cases this formula may give dimensions which appear to be larger than necessary, it is seldom safe to make the area of the steam cylinder less than twice the area of the water-and-air cylinder. Column 3 of Table 13-1 shows sizes of steam supply and of vacuum governor, for boiler pressure of 75 to 125 lb. per sq. in. Power-driven Reciprocating Vacuum Pumps: Lack of available steam pressure to operate the piston in reciprocating vacuum pumps requires that some other source of power must occasionally be utilized. Where this is the case, a reciprocating pump is in many cases unsuitable because of the difficulty in handling the varying load during each stroke and because no satisfactory means for controlling the displacement to maintain the desired degree of vacuum has yet been devised for this type of pump. To move the reciprocating piston in the water cylinder by means of a connecting rod and crank, the latter necessarily rotating at low speed, entails gearing or an extremely large pulley and countershafting. Inasmuch as the torque varies from almost nothing at the ends of the stroke to a high maximum at about three-fourths stroke, back-lash, noise and wear of gears 143 or slapping and slip of belts are to be expected unless a heavy fly-wheel is used, and in any instance the power consumption is excessive. Variable-speed motors are sometimes utilized for driving, but are expensive, and give only two or three steps of displacement, which must be selected either manually or by complicated delicate electrical controllers. There is nothing to commend in intermittent control. Constant speed and displacement with a vacuum breaker to admit air when the load is below normal is probably nearest to a satisfactory arrangement where power-driven reciprocating vacuum pumps are used. Disposal of Vacuum Pump Discharge : Conditions vary to such an extent that good judgment is the only safe guide in determining the best method for the disposal of the vacuum pump discharge. In no case should the head against the discharge of reciprocating pumps exceed 15 lb. unless the pump stroke materially exceeds the bore and thus reduces the bad effect of clearance. Usually one of these seven methods will best apply : 1. Discharge to Waste: Disposal by discharge to waste involves loss of all the valuable heat and water, but in rare cases this is permissible. 2. Discharge through Air-separating Tanks: Where first thought seems to suggest disposal to waste, it will in many cases be found possible to deliver the water and air into a separating tank, or stand pipe sufficiently elevated for the water, after separation, to flow by gravity to some point of iT^,^ Steam to Vacuum Pump Globe Valve WEBSTER LIFT FITTING Fig. 13-2. Method of connecting vacuum pump to a plain receiving tank 144 valuable use, such as boiler or feed-water heater, etc., or for hot water supply. Where, due to structural conditions, a suitable elevated location cannot be found, the effect of head may be obtained by use of a hydro-pneumatic tank as described under heading No. 4. 3. Discharge to Open Vent Tanks: Open vent tanks, otherwise called plain separating tanks, normally serve the purpose of releasing the entrained air from the discharge of the vacuum pump. (See Figure 13-2.) This air removal requires the generous water surface area of either a tank of large horizontal cross-section, rather than one of large vertical sectional area, or a tank with a large vertical head and enough sectional area to permit of low-velocity downward water flow while entrained air is floating to the surface against the water current, as in a stand pipe. For removal of air, one square foot of horizontal cross-section has usually been found sufficient for each 2100 lb. of water per hour. A stand pipe, with diameter equal to that of the pump cylinder, is usually sufficient, although a more logical rule is to make the cross-sectional area of the stand pipe Water Control Valve. Cold Water Connection. Overflow to Waste Discharge from Vacuum Pump Multiply maximum back pressure carrieU in heater by 3 to determine least dimension in feet Fig. 13-3. Typical application of Webster Water-control Receiving Tank in connection with an open feed- water heater. The heater should be set on a foundation of sufficient height (a vertical rise of not less than three feet) between the pump outlet of the heater and the suction valves of the boiler-feed pump 145 bear some direct relation to the amount of condensation from which the air is to be separated, and to the height of column of water through which the air bubbles must rise against the flow of liquid. The fact that the discharge of reciprocating wet-vacuum pumps is a mixture of water and air favors the use of a freely vented separating tank wherever a suitable location may be obtained. This is such height that the pressure produced by the water column will be sufficient to overcome that in the low-pressure boiler, feed-water heater (see Figure 13-3), or other point of disposition. The effective column or head between the pump-discharge valve and the inlet of the separating tank will be less than that of solid water by the volume of air contained in the mixture. The contents in separating tank and discharge pipe therefrom will be water only. It is, therefore, possible with pump discharge properly proportioned and provided with lift fittings, vertical rise pipe to tank, etc., to obtain a gravity head in the tank discharge above the level of the pump valve deck, considerably greater than the pres- Vent lo Atmosphere Automatic Air Vent Valve Automatic Water Reliei Valve and Overflow To Drain unobstructetS. Funnel--'' Return to Boiler- Gate Valve V Check Valve ^ Valve- Dy-Pass to Sewer-- Connection from Low Pressure Steam Main to Steam Gauge JHGIobe Valve WEBSTER COMBINATION GAUGES WEBSTER TRAP WEBSTER SUCTION STRAINER SYLPHON V -Vacuum Pump Discharge Motor WEBSTER LIFT FITTINGS Fig. 13-4. Method of connecting geared-type vacuum pump and Webster Single-control Hydro-pneumatic Tank 146 sure in the pump cylinder necessary to lift the valves and discharge the con- densation to the elevated return tank. 4. Discharge to Hydro-pneumatic Tanks: As the name indicates, hydro- pneumatic tanks bring the elastic pressure of the liberated air to act on and supplement the head, in the discharge of the water of condensation. A float-controlled valve is placed on the air outlet of the separating tank, and so arranged that when the water of condensation has not sufficient head to flow by gravity to the point of use, the air will be confined in upper part of tank. As the pump continues to deliver water and air to the tank (see Figure 13-4) the pressure inside the tank increases until sufficient to discharge the water, thus lowering the water line and eventually permitting escape of the surplus air through the float-controUed air valve. The discharge of condensation to low-pressure boilers, in which the pres- sure may at times be less than that of the atmosphere, requires another float in the hydro-pneumatic tank (see Figure 13-5) to control the valve on the tank water discharge and keep this pipe closed at such times as there might be danger of air flowing from the tank to the boiler. The hydro-pneumatic type of tank is used only where an open tank cannot be located at a height sufficient to provide gravity head to discharge the tank contents against the maximum pressure in the heater or boiler, or Vent to Atmosphere Automatic Air Vent Valve l- Automatic Water Relief Valve and Overflow To Drain unobstructed" Equalizing Line connect to Boiler at Point having no Steam Flow ■ WEBSTER BOILER FEEDER High Water Line of Boiler . | 2" Center Line of , Boiler Feeder' To Boiler ^To other Boiler Floor LinCx ^Connection from Low Pressure Steam Main to Steam Gaug "Pump Discharge WEBSTER ^HYDRO-PNEUMATIC TANK Motor Check Valve-p^gjj^^jjgg^g^ "-WEBSTER SUCTION STRAINER Fig. 13-5. Typical connections to vacuum pump, double-control hydro-pneumatic tank and boiler feeder 147 where there are large variations between the maximum and minimum pres- sures to be overcome. Where the hydro-pneumatic tank is used merely as a substitute for an open separating tank, little advantage may be taken of the light density of the pump discharge. The confined air pressure in the hydro-pneumatic tank plus the gravity head in the tank discharge pipe must be sufficient to cause flow to the place of disposition. This confined air pressure plus the column of mixed air and water in the pump discharge to the tank is the total head against which the pump must act. Where pressure on the heater, boiler, etc., varies materially from time to time, but in general is near the minimum, a substantial saving in energy may be obtained by using a hydro-pneumatic tank instead of a plain tank set at higher elevation to overcome the peak pressure in the boiler or heater. The use of a plain tank under these conditions keeps the pump operating constantly against the maximum head, where a hydro-pneumatic tank set lower operates as a plain tank whenever the gravity head in the tank is sufficient to cause flow at the low elevation, and employs the combination of air pressure and gravity head (with air vent closed) only at times of peak load. Only then is the air pressure load added to the pump discharge. 5. Discharge to Loop Seal on Tank Outlet to Heater or Boiler: The dis- posal of water of condensation from a return tank to a feed heater (see Figure 13-3), boiler or other receptacle, in which there may be greater pres- sure than that of the atmosphere, requires guarding against back flow of steam, air or whatever other elastic fluid may be present at the outlet. A loop seal has been found most suitable for this purpose, provided the seal is made long and contains ample volume in the vertical leg on the pressure side. A variable pressure when increasing tends to force the level of water down in the leg on the pressure side and up in the leg toward the tank. If there is not sufficient water in the loop, the water will become displaced, and the seal broken before enough of a water column has been built up in the leg from the tank. The column will then blow into the return tank and the steam or other elastic fluid will continue to blow while its pressure is above that at the tank outlet. The fact that water in the tank is ready to seal the loop below will not avail as long as there is a difference in pressure between the tank and boiler sufficient to blow a comparatively short slug of water back into tank. The only way to restore the seal is first to equalize the pressure on both legs. A good practice is to proportion the leg on the pressure side to hold twice the contents of the pipe from the tank to the bottom of the seal. 6. Discharge to Receiver and Boiler-feed or Tank Pump: Where the head on the delivery side of steam-driven vacuum pumps exceeds 15 lb., it is good practice to deliver the condensation to a vented receiver (see Figure 13-6) located close to the level of the vacuum-pump outlet. This receiver should be connected to a separate steam or power-driven water pump which is capable of delivering against the maximum head. (See Figure 13-7.) If this pump is steam-driven, its displacement should be controfled by a throttle valve, actuated by the water line in the receiving tank; if power-driven, the effective displacement may best be controlled by bypass valve between 148 ^.^Discharge from Vacuum Pump Boiler Feed Pump and Receiver Drain to Sewer Check Valve V»EBSTER LIFT FITTING I'ig. 13-6. Method of connecting vacuum pump and Hutomatic boiler-feed pump and receiver Vent to Atmosptiere Run to Air above Roof WEBSTER LIFT FITTING^ To Sewer WEBSTER SUCTION STRAINER Fig. 13-7. Method of connecting vacuum pump, boiler-feed pump,a^d Webster Steam-control Receiving Tank 149 pump suction and delivery, and actuated by water-line float in the receiver. 7. Dry-vacuum Pump Receiver and Water Pump: This combination proves very effective under conditions of high delivery head where the main Globe Valve Globe Valve Lubricator Fig. 13-8. Method of making connections to steam-operated vacuum pump return can be arranged to flow by gravity to a closed receiver, which in turn is sufficiently elevated above the location of water pump to provide a head of 2 to 3 lb. on the pump inlet valves. The dry-vacuum pump being free from dirt and abrasive material, may have close clearance and fairly high efficiency. It may be located above and take its suction from the top of the receiver, and frequently some form of condenser may be arranged in the suction line to absorb and utilize other- wise wasted heat from the air and water vapor and at same time materially reduce the volume of vapor to be handled. The receiver, if properly designed, forms a receptacle for the grit and impurities which would otherwise injure the water pump; and it also affords space for a float governor for controlUng the water pump by the varying volume of return water. Excessive vacuum in the receiver will cause trouble in the water pump. For this reason, a vacuum governor should always be used to control the dry-vacuum pump and to hold the vacuum within pre-determined limits. ISO Suction Strainers : The worst of the grit and |^,,^ j,^^^ ,^^^ dirt from condensation should be retarded and re- ^"'^^ moved before entering the pump where it would score the water cylinder. Strainers (see Figure 13-8) with readily removed baskets for use on the main vacuum return line were first designed and recommended by Warren Webster & Company 24 years ago. The original Webster design with little modification has been almost universally adopted. In some instances, conditions arise where large quantities of returns, at unusually high tempera- tures, are discharged into the line near the vacuum pump. These may come from special apparatus such as cooking or hospital webster '~^W~ ' fixtures, dry kilns, or other devices vicuum governor-^ using high pressure steam. A combi- . .' n ,- , • 1 1 V* Vacuum Line 10 Vacuum nation oi suction strainer and a cook- Gauge and suction strainer ing device, shown on page 262, wiU be £=sai=^Ji[HlP=l Globe Valve Union Plug f found to be of advantage, particularly where it is desired to carry a high vacuum at the pump. Cold water, passing through copper coils, is used to condense the vapor in the main re- turn. Vacuum Governors: In steam- driven pumps, control of displacement by the degree of vacuum maintained in the return line may be effectually ac- complished by tlirottling the steam supply. (See Figure 13-9.) Simple forms of diaphragm-actuated throttle Fig. 13-9. valves will control the degree of vacuum in the main return within sufficiently narrow limits for all practical purposes. Connections for a Webster Vacuum- pump Governor 151 152 CHAPTER XIV Laboratory Tests of Return Traps THE object of laboratory tests of appliances is to determine the efficiency of the apparatus tested, as a guide to judgment in selecting materials or in the case of technical schools, as a part of the instruction of the students in methods of scientific research. All of the operating conditions possible or probable in an actual heating system cannot be artificially produced in the laboratory, nor is it practical to carry out tests long enough or upon sufficient numbers of samples to learn all facts which become evident in practice. Furthermore, as the whole heating system, including design and installation, has its effect upon the efficiency of the devices entering into it as parts, any laboratory tests for efficiency can indicate only the results which are probable when the devices are properly used in practice. Too much stress should not be laid, therefore, upon the comparative performances of any two makes of traps during laboratory tests. Knowl- edge of performances in actual installations of many heating systems, maker's ability and care in manufacturing, shop tests, inspection and proper engineering application of the traps are of great importance to the investi- gator who wishes to make commercial use of his study of such devices. However, as laboratory tests have their useful place in commercial investigation, the various types of traps and the results of tests which may be expected are outlined in this chapter. Mention is made of many com- mon forms of tests which give erroneous results so that these errors may be avoided. Methods and apparatus for reliable tests are mentioned and illustrated. Usually the object of a laboratory test of a return trap is to determine one or all of the following characteristics: 1. Effect of the trap upon radiator efficiency. 2. Efficiency of the trap for the removal of air and water of condensation and for conservation of steam and vapor. 3. Behavior of the trap without special adjustment to meet the varying conditions of pressure and vacuum in normal practice. 4. Durabihty of the trap through a long period of use. 5. Construction features of the trap, particularly the amount of valve movement, which indicates the ability to get rid of dirt and pipe scale. The results of tests by many investigators, of radiator and trap effi- ciency, have varied widely and have often been misleading, largely because the methods of testing have been faulty and partly because the devices themselves have not always been manufactured to operate uniformly. Most tests of which the results have been published have been faulty through failure to cover a wide enough variety of test conditions, tlirough limitation of the time period for each test to a few minutes instead of hours, and through considering and testing only one or two samples of any one 153 device, instead of six or more selected by the investigator from the manu- facturer's stock bins or purchased in the open market. Tests for Heating Efficiency: The heating efficiency of a radiator depends upon physical conditions within the radiator which are affected by the action of the return trap. The radiator, among a number of common size and type, which maintains the highest average temperature when tested under the same conditions, is the most efficient. The greatest possible steam economy is obtained where this efficiency is liighest; that is, where steam is being condensed to the greatest extent possible within the radiator and the trap passes the least amount of steam or vapor into the return pipe. The highest radiator efficiency can be obtained only where the dis- charge is sufficiently and properly restricted to prevent steam from blowing into the return. Also the air released from the steam in the radiator must be allowed to settle to the lower parts, from which it can enter the trap and be discharged. A return trap, in addition to restricting the discharge, must effectively accomplish the following: 1. The discharge of aU water of condensation as formed. Otherwise water accumulates in the radiator, prevents free discharge of air and thus reduces the amount of surface effective for emitting heat from the steam. 2. The discharge of all air and other gases from the radiator im- mediately upon their reaching the discharge outlet. 3. Thorough prevention of the discharge of steam to the return. To accomplish these requirements the valve of a return trap must open or close within a very narrow range of temperature, above or below that of steam at pressure, irrespective of variations in steam pressure, and must adapt itself to such changes of pressure and corresponding steam temperature as may be met in practice. A brief review of the various types of return traps will facilitate a better understanding of tests and the results which are desired. AU return traps commonly used in low-pressure or vacuum steam heat- ing practice may be classed as float, differential, and thermostatic traps. Float traps may have sealed floats, Figure 14-2, or inverted open buckets as the means of operation. In either case, the float is raised by incoming condensation to uncover the valve seat through wliich water is discharged. Air escapes into the return pipe through an air port, which must be located above the highest water level in the trap. The air port is con- trolled in some makes by thermostatic devices to prevent leakage of steam to the return. Tests upon a float trap may generally be expected to show considerable leakage of steam to the return unless the air port is thermo- statically controlled. If the air port is so 154 t Fig. 1^2 Float trap with sealed float controlled, the small port and its mechanism may be vulnerable to the effects of dirt and rust. Such traps, however, will be found to have large water discharge capacities and some of the various makes can be used to advan- tage where widely varying volumes of water must be discharged without respect to temperature. A differential trap depends for operation upon the difference in pres- sure at the inlet and at the outlet. In its simplest form, it is a check valve which is closed when the difference in the pressures ahead and back of the clapper is insufficient to overcome the weight of the clapper, Inasmuch as no special means are provided for discharge of air, such a valve may be ex- pected to leak steam to the return under any conditions of higher differential pressure, and to stay closed with consequent air binding and water logging of the radia- tion when the pressure differential falls below the predetermined limit for which the valve is adjusted. Another form of differential trap is shown in Figure 14-3. Water entering the valve body raises the float, thus closing the air port by means of the valve piece attached to it. A liigher pressure in the lower part of the trap B than that existing in the chamber A results in the operation of the piston which raises the valve from its seat by means of the connecting valve stem. As the condensation is discharged, the water level lowers and causes the float to faU, thus uncovering the air port, and equalizing the pressures on opposite sides of the piston. The weight of the operating parts and the force of the spring then closes the valve. Tliis trap may be expected to show fairly good results in laboratory tests but it is not satisfactory under the usual operating conditions in which dirt and scale are always present. A thermostatic trap depends for its operation upon the difference be- tween the temperature of steam at the pressure in radiator, and the tempera- ture of the condensate or air to which the thermostatic member is exposed. Many devices have been made which depend upon the expansion and contraction of metals or composition, or which make use of a bourdon tube. As a class these have failed because there is not enough difference in area between the inside and outside of the spring to produce the required force at normal difference in temperature between steam and air vapor at a given exterior pressure. This and other faults, such as the necessity for adjustment for varying pressure conditions and slowness in operation, have Jed to the abandonment of these types by most manufacturers. Of all types of return traps, the ones in general use today are those which depend for movement of the valve piece upon the change of vapor pressure of fluids confined within a flexible chamber when subjected to dif- ferent exterior pressures and temperatures. The volatile fluids contained in the flexible chamber vaporize to a greater or less pressure depending upon the l.-)5 Fig. 14-3. Differential trap with float and piston high con- temperature of the steam, vapor, water or air wliich surround the chamber. The expansion or contraction of the chamber moves the valve piece which is attaclied to the free end of the chamber. These traps are, generally speaking, of either the "inboard" type where the thermostatic mernber is exposed to the temperature and pressure of the steam, water and air as it exists at the radiator outlet, or of the "outboard" type which depends for operation upon the conditions existing between the valve piece and the entrance to the return piping beyond the trap. To be effective for the inboard type, the thermostatic member must expand and contract through a distance sufficient to open and close the valve under the influence of the extremely small differences of temperature which exist during normal operation. Most traps of the inboard type are inefficient because of the very short "stroke" which can be realized with the inelastic disc construction generally utilized for the flexible chamber, this defect resulting in inability of the trap to rid itself of dirt and scale. Traps of the outboard type are affected by the pressure and temperature of the return. They are in proper adjustment only at one definite pressure and temperature and out of adjustment at all other normal combinations of pressure and temperature. They cannot be adjusted even for these normal variations in radiator pressures and vacuum in the retur^i, and as a result usually water-log and air-bind the radiator by staying closed when temperature and pressure exist, or stay open and blow steam under ditions of low temperature and pressure. The trap shown in Figure 14-4 is a ther- mostatic trap of the inboard type and as such is affected in operation only by the temperature and pressures existing within the radiator. The multifold design of the thermostatic member gives it great elasticity and consequent ample move- ment in response to change of temperature and pressure in the medium surrounding it. This member contains liquid which makes the trap self-compensating for difference in operating pressures of steam within the radiator. Its con- struction, with conical valve piece seating on sharp-edged seat, assures positive self-cleaning. Dirt and scale cannot lodge between valve and seat and permit steam to leak into the return. It has been stated that a trap must not leak steam to the return, but in this connection there should be no confusion between steam discharged through a trap and vapor rising from hot condensate. Though their ap- pearance during certain forms of visual tests are much alike, they are two entirely different things, and if confused with each other, as is sometimes done, wrong conclusions will result. Many times, highly efficient radiator traps are condemned for leaking steam, due to the observed vapor of re-evaporation noted at their discharge outlet, and less efficient traps have been commended because of absence of such vapors. 156 •'S 14-1. The Webster Sylphon Trap 100 Fig. 14-5. Re-evaporation chart for determining the percentage of water re-evaporated from any tem- perature between 300 and 170 deg. fahr. into water vapor of a lower temperature and corresponding pressure 157 The absence of vapor at the discharge is in reality an indication that the trap is holding back condensation and entrained air until the temperature of the discharge is materially less than that of steam at the pressure of the outlet. The consequence of such holding back is a partially air-bound and water-logged radiator, with less than full radiating efficiency. Visibihty is deceptive. A great amount of moisture in the atmosphere and favorable light conditions both add to the visibility. The air dis- charged from an efficient trap is saturated with water at discharge tempera- ture and this water mixing with air at room temperature looks like steam, while the discharge of a trap utterly deficient in air removal shows only the vapor of re-evaporation. The water of condensation contains total heat in excess of that in water of condensation at lower pressure. This excess heat boils off some of the condensation into steam. The amount so boiled off is entirely dependent on excess of total heat in outflowing condensate above total heat of water at lower pressure. If steam passes out with condensate, a steam of greater total heat is dissipated. A fuUy efficient trap releases the condensation at or near steam temperature and radiator pressure, into a return of lower pressure. All heat above that consistent with lower pressure then generates vapor. This vapor passes to the vapor receiver in a test. A certain amount of vapor per pound of condensation is normal and any excess of vapor above the normal is steam leakage. The condensate from a higher pressure into a lower pressure wiU never be at a higher temperature than that due to steam at the lower pressure. The excess of the heat in the outflowing condensate will flash part of the water into steam. These points are emphasized to show the falhbility of visibility test to show the efficiency of return traps. Very rough tests are often made by connecting a trap to the end of a pipe or to outlets in a header to which steam is admitted at the pressure usually used, the trap discharging into the atmosphere. A test of this kind merely shows whether the trap shuts off. Comparative values are sometimes placed upon traps by considering the quantity of water discharged during equal periods of time. The traps are successively attached to the same test radiator, the condensate is care- fully weighed and the conclusion drawn that the trap passing the largest quantity in a given time is the best. It is evident that such a test shows merely the condensing rate of the radiator under the room temperature conditions. Nothing is demonstrated regarding the performance of the trap, for it is only when condensation is held back in the radiator that the capacity of the trap is exceeded. This test is only a determination of the condensate- discharging capacity of the trap. The vacuum which can be maintained at the discharge end of a trap is occasionally regarded as a criterion of the comparative worth of traps. For such tests, the apparatus consists of a radiator, a return trap, a return connection to a vacuum pump, and devices for maintaining constant pressure of steam supply to the radiator and for operating the pump at a constant 1S8 speed. The trap maintaining the highest vacuum during the test is consid- ered to be the best. With httle or no attempt to determine the extent to which the radiator is air and water bound, such data has frequently led to a wrong choice of traps and the results when in actual operation on a heating system have proved correspondingly unsatisfactory. Another test is to connect a trap to a radiator with discharge to atmos- phere, and noting the operation. Particularly erroneous conclusions will be reached unless careful distinction is made between the vapor which is steam and the vapor which is due to re-evaporation. Much can be learned as to trap behavior from such a test, yet the conditions are often not the same as in actual service operation. The return piping connection and the pressur^-'tkereiTr-hwve' consideralyle effect upon their operation so that rough tests of this nature should not be accepted as conclusive, but as indicative of trap operation. These few devices and methods are the ones commonly used for de- termining comparative worth of return traps where only the most easily procurable testing apparatus is available. Like other scientific investiga- tions more careful methods will lead to more reliable results and with proper apparatus and thoughtful procedure it is entirely practicable to obtain test data which can be relied upon as accurately forecasting the success which may be expected from the use of any return trap in an actual heating system. The first thought for any reliable test should be to create laboratory conditions as nearly as possilDle like those met in actual practice. Coinci- dently, the apparatus should be designed to provide exactly like and simultaneous test conditions where traps are tested for comparison, and of course, appliances for measuring the results must be carefully placed and adjusted. Then, by following a proper test, planned to exhaust the various possibihties of different operating conditions, results are secured which can be accepted as conclusive. Enough has been said to show that valuable data regarding the probable performance of return traps can be obtained in the laboratory where suitable apparatus is available and where suitable test methods are carefully applied. However, the long-time test of devices in actual heating systems is the best guide for determining the relative value of return traps, and further, the efficiency of a good return trap can be fully reahzed only when the heating system itself is properly planned and operated. 159 Part II. Webster System Specialties and Applications* CHAPTER XV Webster Systems of Steam Heating THE title "Webster Systems of Steam Heating" is used to designate not only the Webster Specialties which are used in the several types of heating systems, but also the methods and arrangements, most of them original with the manufacturer, which assure economical and efficient operation of the heating plant as a whole. In addition this designation embraces a far-reaching policy of co-opera- tion — Webster Service — which is rendered through branch offices and service centres of the manufacturer in the principal cities. This three-fold system of specialties, methods and service is the result of continuous development since 1888. Many of the methods of application have been reduced to the form of Standard Service Details, as shown in Chapter 22 and elsewhere in this book. The selection and adoption of a Webster System carries with it the assurance to the architect, to the designing engineer, to the heating con- tractor and to the owner, that the responsibility is not divided between manufacturers of various appliances. In a Webster System all of the appliances are co-ordinated in their application and function, and the great risk of patchwork selection and responsibility is avoided. Webster Specialties have been proved by the test of use over many years to be the highest quality attainable in design, workmanship and material. Webster Service and the standard and special details of recommended application are the result of long experience and pioneering in solving the practical problems that have arisen. Webster Systems are flexible. There is a type or a modification that will fit each building. Following the classification in Chapter 10, Webster Systems of Steam Heating are divided into two general types: Webster Modulation Systems and Webster Vacuum Systems. Webster Modulation Systems As stated in Chapter 10, the vacuum and modulation types of steam heating systems are sufiiciently alike to be classed as one broad type of system, in which the circulation of steam is produced by a flow of the heating *Drawings showing applications, and dimensions of apparatus are subject to change without notice. Certified drawings of apparatus will be furnished upon request. 161 medium from a higher to a lower pressure. They are dissimilar in the method of disposing of the products of condensation. The Modulation System may be sub-divided according to source of steam supply, or more particularly type of boiler, into three general classes: 1. Low-pressure heating boilers operating up to 10-lb. pressure. 2. Boilers operating at from 10 to 50-lb. pressure. 3. Street systems, carrying any pressure. 1. Boilers Operating up to 10-lb. Pressure: A typical arrange- ment of the Webster Modulation System as installed in connection with a low-pressure heating boiler is shown in Figure 15-1. The initial pressure is closely controlled by means of an extremely sensitive Webster Damper Regulator. The steam is admitted to each radiator through a Webster Modulation Valve which permits modulation of room temperature by simple hand manipulation. Condensation is discharged and air is vented from each radiator through a Webster Return Trap which maintains full heating efficiency of the radiator and eliminates the annoyance, difficulties and noises common to ordinary gravity steam heating systems. Condensation and air from each radiator flow by gravity through a system of return risers and mains into the Webster Modulation Vent Trap, where the air is automatically vented, permitting the system under favor- able boiler conditions to operate for long periods under partial vacuum or "vapor," but also due to the flexibility of the system permitting higher pressures to be carried in severe weather when a maximum amount of heat is required. Fig. 24-61, Page 268, shows the detail connections of the Modu- lation Vent Trap. The system of supply and return mains and risers should be sized and run as recommended for Modulation Systems in Chapter 11. As a general rule, supply mains and risers are not dripped through traps, but directly into a wet -return line, the air being vented into the dry-return line which is run back above the boiler water line to the Modulation Vent Trap. Where building conditions make the running of a wet-return line im- possible, the mains and supply risers are dripped and vented through Webster Return Traps into the dry -return line. It has however been found preferable from practical experience to run a wet-return line wherever it is physically possible to do so. In view of the general adoption of Webster Modulation Valves and the hot -water types of radiators, the top feed supply connections are more generally used. When placed in this position, the valves are in a very accessible location and it will be found easier to control the temperature of the room by operating the valve than by following the customary method of opening and closing the window. Figure 22-43 on page 228 illustrates the method of di'ipping and venting the supply main into the wet return. Figures 22-45 and 22-49 on pages 229 and 232 show how the basement radiators are connected up to the system. Several methods of dripping the risers and mains through Return Traps into the dry return are shown in Chapter 22 on pages 215, 216 and 217. The Webster Modulation Vent Trap is essentially a part of the Webster Modulation System, to be used on installations where the sizes of pipes, 162 valves and return traps have been computed in accordance with the methods explained in Chapter 11 and also on the basis of pressure differential outlined in Chapter 23, and summarized in Table 23-7. Where the pressure difference between that in the boiler and that in the main return line is likely to exceed the available gravity head between the return main and the boiler, the Webster High-duty Vent Trap may be required. The principal conditions under which the High-duty Vent Trap may be employed are as follows: 1. Where it is of advantage to design the system for a continuous operating steam pressure ranging from 2 to 3 lb. to occasionally 10 lb. 2. In an existing installation, where the pipe sizes are already fixed, as for example an old building in which complete steam circulation cannot be obtained under 2 or 3 lb. 3. In a proposed installation where the basis upon which the pipe sizes, valves and return traps are figured is either uncertain or unknown. 4. Under certain operating conditions such as continually changing janitor service, operating the boiler without the use of a sensitive low-pressure damper regulator or with the damper regulator entirely detached. 5. In cases where special grades of bituminous coal are burned in certain types of boilers, and it is impossible to maintain low steam pressure even with careful attention and correct damper regulation. 2. Boiler Pressure from 10 to 50 Lb.: With this type of system the heating medium is generally live steam taken directly from the boiler and is reduced to the desired pressure, varying from atmospheric up to 1 or 2 lb., by means of a pressure-reducing valve. This initial pressure in the heating main will vary according to the pressure drop for which the supply piping has been sized, and to a certain extent with respect to the outside temperature and weather conditions. The only exhaust steam available is that from boiler-feed pumps and other auxiliaries if steam-driven. The exhaust is utilized after it has been made suitable for use by passing through a Webster Oil Separator, drained by a Webster Grease Trap. The system of supply and return mains and risers should be sized and run as recommended for Case 1. In small and moderate size buildings the supply mains are usually run on the basement ceiling and connected through laterals to up -feed risers supplying the radiators. In tall buildings and in buildings of certain types it is desirable to avoid running the large supply mains on the basement ceilings. Where a building is spread over a large area, if the supply main is located on the basement ceiling, the pitch required by the main and by the dry return may cause the latter to be too low when approaching the point of discharge. In both of these cases, what is known as the "overhead" or down-feed system is em- ployed, the steam being fed through a main up-feed riser to a distributing main located at the ceiling of the top story or preferably in the attic, steam being delivered to the various radiators through a series of down-feed risers. The drop risers are connected into a wet return or gravity drip fine. 16.1 The return risers are joined into an overhead dry-return main, which is carried back to the point of discharge. The main supply riser is dripped either into the wet return or through a Webster Heavy-duty Trap or suitable size return trap into the dry-return main. In buildings of only one story, the steam supply line is run along the ceiling to feed each radiator through a short down -feed riser which must be dripped through a return trap into a dry return. The use of the Webster Double-service Valve attached to the radiator as shown in Fig. 24-23, page 253, performs the two-fold service of supply valve for the radiator and a trap for draining the riser. For factories, stores, loft buildings, etc., when there are a number of radiators heating one large room, Webster Modulation Valves are sometimes omitted and ordinary radiator supply valves used instead. Such systems are designated as Webster Semi-Modulation Systems to distinguish them from the usual type of modulation system. In general, for the type of building for which the Webster Modulation System is proper, the advantage of using Webster Modulation Valves is so evident that they are considered a necessary part of the equipment. Radiators may be exposed, concealed under window seats or behind grilles, or placed overhead to take care of skylights and unusual roof ex- posures, as with vacuum systems. The radiators are drained through Webster Return Traps, into a system of return risers, and in the same manner. Air-valves are unnecessary on the radiators, as the air is relieved through the return traps. It should be noted, however, that as the actual difference in pressure through the supply valve and return trap of a modulation system is less than Avith a vacuum system, these valves and traps must not be rated as high for modulation as for vacuum system practice. It will therefore be observed, from a study of Chapter 11, that it is necessary to deduct the pressure drop for which the system is designed from the initial pressure in the heating main. With atmospheric pressure in the return piping, this difference will represent the differential pressure on which the capacity rating of the valves and traps should be based. The products of condensation flow by gravity through the system of return risers into the basement return main, thence to a hot-well or to the receiver of a pump and receiver. If the former, a condensation pump is used to discharge the water into the boiler. In the latter case, the pump and receiver take care of the liberation of entrained air and return of condensation to the boiler. The condensation pump, or pump and receiver, will usually be electric- ally driven, but if the boiler pressure is 25 or 30-lb. or above, the steam- driven type may be used. 3. Street System Carrying any Pressure: "WTiere street steam service is maintained, the modulation system is similar in most respects to either Case 1 or 2 described above, except that no provision is made for returning the condensation to the boiler by a modulation vent trap, as in the case of a low-pressure heating boiler, or by some form of return pump where 164 higher pressures are carried on the boiler. The water of condensation is usually discharged to the sewer through a meter in the return line, except where a flat rate per square foot of radiation is charged in which case no meters are used. Where exhaust steam at 1 or 2-lb. pressure is supplied by the street service, a connection is made directly from the main to the supply piping in the building. If steam at higher pressures is furnished, a pressure- reducing valve is placed between the service connections and the main heating pipe, to regulate the steam to any desired initial pressure on the system. By this means the pressure may be controlled to best suit outside temperature and weather conditions. Webster Vacuum Systems Webster Vacuum Systems may be sub-divided into four classes, accord- ing to the source of steam supply: 1. High-pressure or power boilers, with exhaust steam available from engines and auxiliaries. 2. Medium-pressure boilers, 15 to 50-lb. pressure. 3. Low-pressure boilers up to 15 -lb. pressure. 4. Street systems. 1. Webster Vacuum System with Power Boilers: With this type of vacuum system the source of steam supply may be (A) Exhaust steam from the engine; or (B) Exhaust steam from engines or auxiliaries, supplemented by live steam at reduced pressure. In the Case A when the power load exceeds the heating load, the supply of exhaust steam will be ample for the requirements of the heating system and in addition may also be used in a Webster Feed-water Heater to preheat the water supplied to the boilers. Under such conditions the heating plant is exceedingly economical since it utilizes a by-product, exhaust steam, which otherwise might be wasted. It is under such conditions that the Webster Vacuum System is most advantageous since it ensures a rapid circulation of steam through the entire heating system with a minimum back pressure on the engine. The reduction in back pressure saves in the steam consumption of the engines. In the Case B where the quantity of available exhaust steam is not suffi- cient, live steam at reduced pressure is automatically admitted into the heating main to make up the deficiency. In this design of heating plant, care should be exercised to see that all of the exhaust steam is utilized, including that from the various pumps and auxiliaries. Fig. 15-2 illustrates a conventional layout in elevation, of a Webster Vacuum System, using both exhaust and live steam in combination with a Webster Feed-water Heater. Referring to the illustration, the exhaust steam is made suitable for efficient heating and for subsequent use, when condensed, by passing through a Webster Oil Separator, which must be properly dripped. It is very important that the oil separator shall be properly dripped. 165 ^UEj 36EJ01S 166 For ordinary cases, where the pressure in the exhaust main is maintained above that of the atmosphere, the Webster Grease Trap, also shown in the iUustration, is highly efficient. A daily inspection of the grease trap should be made while the plant is in use, to be sure that it is operating properly. In systems which lie idle for a portion of the year, a careful examination should be naade on starting up, to see that the grease trap and the pipe connections thereto have not become clogged on account of the solidification of the grease during the period of such idleness. Failure of the trap to function properly will cause the separated oil to be carried over into the heating system and eventually to reach the boilers, where it is very likely to produce bagging or blistering of the shell plates and tubes. If the partial vacuum created by the vacuum pump extends into the heating mains, at times when the supply of exhaust steam is insufficient, and it is not supplemented by live steam, it will be necessary to drain the oil separator in a special manner. Figs. 24-27 and 24-28 in Chapter 24 show both methods of draining the oil separator. The necessary live steam is admitted through a pressure-reducing valve of a suitable size and type. A Webster Water Accumulator is used, as shown in the illustration, lo ensure proper functioning of the valve.. The addition of a pop safety valve in the low-pressure main, set to blow at a few pounds above the normal working pressure, will give warning of any tendency of the reducing valve to build up pressure during periods when the demand for steam is very light. Dripping Supply Mains and Risers: Supply and return mains and risers should be sized and run as recommended for vacuum system practice in Chapter 11. The method of dripping mains and risers into the vacuum return line varies with the local conditions of each building. In the typical illustration the base or "heel" of the main supply riser is shown dripped through a Webster Heavy-duty Trap, protected from scale and sediment by a Webster Dirt Strainer. A few general suggestions regarding the dripping of supply mains and risers will be helpful and will assist in determining which of the several methods of application will be followed. As stated in the description of modulation systems, the overhead or down-feed system of supply piping is employed in tall buildings and in buildings of certain types where it is desirable to avoid the running of large supply mains in the basement. Steam is conveyed through a main up-feed riser to a distributing main located either on the ceiling of the top story or in the attic space above. The space should have sufficient head room to give easy access to the valves which are generally placed in the run-outs from the main to the riser, and also to permit future repairs. It is needless to say that either the attic floor should be made strong enough to carry the weight of a man or a narrow platform should be provided. Either can be made of two 2-in. thick, hard pine planks of 24-in. total width and sus- pended by iron hangers fastened to the roof framing and spaced at regular intervals. The platform should run parallel to pipe lines and close enough to allow a man suitable space for working. The main riser is dripped through a Webster Heavy-duty Trap and 167 Webster Dirt Strainer, as shown in Figure 22-2. The drop risers are in- dividually dripped through Webster Return Traps, with proper provision for cooling surface between the point of drainage and the trap, the sur- face being arranged either horizontally or vertically, as space conditions may determine. As dirt and scale are more apt to accumulate at such drip points than elsewhere in the piping system, it is essential also that the traps be protected by means of dirt pockets made up of pipe and fittings, as shown in Figs. 22-7 and 22-8, or by means of W^ebster Dirt Strainers, shown in Fig. 22-10. The latter are simple, self-contained fittings, easy to install, and convenient and readily accessible. The cleaning of these points where dirt accumulates is essential to the success of the heating system. Another method of dripping the drop risers of down-feed systems, which is very satisfactory where building conditions permit its use, is to connect all of these risers into a wet-return or gravity drip line. This necessitates the running of a separate wet-return line in the basement along the floor. In such case, return traps are not needed for dripping the risers, but each riser must connect to the gravity drip line through a hori- zontal line in which an efficient check valve is placed. Various methods of •accomplishing this are shown in Figs. 22-28, 22-29 and 22-30 in Chapter 22. Where building conditions justify the running of a basement supply main, with a series of up-feed risers, each riser is dripped through a Webster Return Trap, protected by a dirt pocket or Webster Dirt Strainer, into the vacuum return line. The main itself is dripped at various points where it rises or where its size is reduced, so as to relieve the condensation and air which would otherwise accumulate and interfere with the proper circulation of steam. These points are also dripped through Webster Return Traps, properly protected from dirt and sediment. Provision for cooling surfaces in the pipe connection to the return trap is of prime impor- tance with this method of dripping. (See Figs. 22-31, 22-32 and 22-33.) Very tall buildings sometimes require a combination of the up-feed and down-feed system of supply, with a combination of the various methods of dripping. The drip at the base of a main up-feed riser is commonly referred to as a "main riser drip" or "drip at heel of main riser." Drips at the bottom of up-feed or down-feed risers where traps are used are called "supply riser drips." Drips at various points on the basement main are called "main drips." Wet -return lines are called "gravity drips." Supply lines to fan heater coils, hot-water generators, etc., usually require separate drips, using either Webster Heavy-duty Traps or Webster Return Traps, depending upon the volume of condensation to be handled. Where such drips are to be taken into the vacuum return line comparatively close to the vacuum pump, special provision must be made on account of the relatively high temperature of the condensation. Supply lines to apparatus requiring steam at pressure above 15-lb., known as medium or high-pressure lines according to the pressure carried, should not be dripped directly into the vacuum return line. Special methods of taking care of such drip points must be followed. Figure 20-2, Page 203 shows one method. 168 Radiator Connections: Regardless of the arrangement of the supply mains and risers, and the methods of dripping them, the supply connections to the individual radiators will be similar, as shown in Figures 22-14, 22-15 and 22-19. Horizontal connections, known as "laterals," are taken from the supply riser to the radiator. In the case of radiators with top-feed connection, a vertical supply line will be taken from the lateral to the radiator supply valve. This applies particularly to radiators of the hot-water type, in which the radiator sections are connected together at the top by means of close nipples. Sometimes steam radiators may be similarly fed, using the first section to convey the steam in a downward direction, particularly where a fractional-control or modulation valve is used with this type of radiator. In Chapter 12 special attention is called to the necessity for proper sizing and grading of these laterals. In Figure 15-2 the cast-iron column radiation is shown supplied through a Webster Modulation Valve, while the heating coil is supplied through an ordinary gate valve. The advantage of the Webster Modulation Valve is that it provides a convenient, positive means of throttling the steam supply to each radiator so that the occupant of each compartment may maintain the temperature which he desires, without regard for the temperature in any other compart- ment. This results not only in increased comfort to the occupant, but in decrease of the amount of steam used, as the room temperature is varied by manipulation of a single valve on each radiator, and not by opening and closing windows. This latter method is the customary and inefficient way of varying room temperature where ordinary supply valves are used, owing to the inconvenience and uncertainty of such valves in throttling the sup- ply of steam. The Webster Modulation Valve, described and illustrated in detail in another chapter, is especially designed to give perfect modulation of room temperature with less than a full turn of the indicator, the position of the indicator on the dial showing the degree of opening. Further, during the period of initial warming-up of a cold room, it acts as a quick-opening valve and where the proper sizes are selected for the operating conditions, the radiator ivill be heated all over in 20 minutes, after which, if the weather conditions are such that a smaller volume of steam is required to viaintain the room temperature, the indicator is turned back, and steam is conserved. Radiators may be placed in exposed locations beneath windows or between columns, as shown in Figure 15-2, or may be wholly or partially concealed under window seats or behind grilles (Figs. 6-14 and 6-15) ; or may be located overhead as with skylight coils (Fig. 5-2). Each of these conditions requires special arrangement of supply con- nections and fixtures. Some helpful suggestions to meet particular connec- tions may be found by studying Webster Service Details in Chapter 22. Whether to employ Webster Modulation Valves or ordinary radiator supply valves is optional with the architect or designing engineer who selects the equipment. The modulation type is recommended wherever efficiency and economy of operation are desired, as the additional first cost of installation is very little, and repairs and upkeep are negligible. 169 They are especially to be recommended in hotels, apartment houses and other buildings with transient occupants who have no incentive to economize in the use of steam where ordinary valves are used. Also greater economy may thus be secured in dormitories, schools, institutions, etc., where the manipulation of the radiator valves is under control of a regular attendant rather than the occupant of the room. For such cases, a lock- shield type of Webster Modulation Valve with key is frequently used. The Webster Vacuum System is admirably adapted for use where special systems of automatic temperature control are used, as in large office buildings, hotels, etc., to control individual room temperatures. Disposal of the Products of Condensation: The air, gases and water comprising the products of condensation of steam within the radiators, are drained from each radiator by a Webster Return Trap connected at the return end. Lateral "run-outs" conduct this condensation to a series of return risers which convey it to a system of basement return mains, in which a partial degree of vacuum is maintained by a steam or electrically driven vacuum pump, according to conditions. The Webster Return Trap serves the triple function of relieving the air and gases as well as the water of condensation and also preventing the escape or loss of steam into the return line. Air valves are unnecessary. Their annoyances and discomforts are entirely eliminated. The several types of Webster Return Traps and the various methods of application for different conditions are explained in other chapters. As with laterals from supply risers, return run-outs to risers must be properly sized and graded. This is a detail which often requires personal inspection during the progress of the installation, particularly where the laterals and run-outs are run in pipe or sheet-metal sleeves which in turn are embedded in concrete or other solid floors. The Vacuum Pump: The vacuum pump and its auxiliary equipment may be referred to as the heart and lungs of a vacuum system. It is all- important that they be properly selected and sized, and that the function of all parts of this equipment be thoroughly understood so that the piping connections will be properly made. (See Chapter 13.) Various types and arrangements of equipment are necessary to meet different conditions. In the type of vacuum system which is now being described, the vacuum pump will usually be of the steam-driven reciprocating type, steam being furnished directly from boilers at relatively high pressure. The supply of steam to the pump is automatically controlled by a Webster Vacuum-pump Governor actuated by the degree of vacuum existing in the vacuum return line and adjusted to stop or slow down the operation of the pump as the vacuum approaches the point for which the governor is set, and starting or speeding up the pump as the vacuum drops below this point. The pump, where of the reciprocating type, is lubricated by the admission of cylinder oil into the steam supply line through a sight -feed lubricator, or if preferred, through a mechanical force-feed oiler, the latter being attached 170 to the pump preferably before shipment and actuated by the operation of the pump itself. The suction valves of the pump are protected from dirt and foreign material by a Webster Suction Strainer. The products of condensation will be conveyed by gravity through the system of return risers and main vacuum-return line to a point either above or below the suction inlet of the pump, depending upon building conditions. If this point is below, the vacuum pump will raise the condensation with its entrained air. The arrangement of "lifts" depends upon the ver- tical distance and degree of vacuum created and maintained by the pump. Webster Lift Fittings used in pairs will materially assist the vacuum pump where lifts are necessary. Various methods of applying vacuum-governors, lubricators, suction strainers and lift fittings in connection with vacuum pumps are shown in the Webster Service Details in Chapter 13 in which the practical problems of installation are worked out. Final Disposal of the Condensation: The vacuum pump discharges the products of condensation to a point of disposal, where the entrained air is liberated and the condensation returned to the boiler as feedwater. In Figure 15-2 the pump discharges into a Webster Receiving Tank which is vented to the atmosphere. The condensation flows by gravity from the tank to the Webster Feed-water Heater against the working pressure carried. In the typical case, the receiving and air-separating tank is of the water-control type, and the Webster Feed-water Heater also has an auto- matically controlled valve in its water-supply line. As the water level in the Feed-water Heater lowers, the automatic valve opens, and the condensation flows from the tank to the heater through the sealed connection. This arrangement of tank and heater may be used only where the tank can be located at sufficient height above the heater so that the static head will overcome the working pressure within the heater. Additional fresh water required to make up any losses that occur is admitted automatically into the tank by the lowering of the water level, which in turn actuates the automatic water-regulating valve. Surplus condensation overfiows from the tank to the sewer or drain. The waste of condensation at higher temperature from the overflow of the feed-water heater is thus eliminated. An alternate arrangement which is often desirable is the use of a Webster Receiving Tank of the plain type with a Webster Feed-water Heater of the Steam-control Type, as is shown in Fig. 27-7, Page 304. In this case the condensation flows continuously from the tank to the heater. As the water level in the heater rises, the automatic valve, placed in the steam line to the boiler-feed pump and actuated by the water level in the heater, causes the pump to withdraw the water from the heater. Another arrangement is the use of a Webster Tank of the plain type dis- charging into a special return inlet on the heater, fresh water as needed being automatically admitted into the heater. (See Fig. 27-6, Page 303.) Still another arrangement which is necessary where the tank cannot be 171 located at sufficient height above the heater to overcome the pressure therein, is the use of a Webster Hydro-pneumatic Tank, described in Chapter 13. Where an open feed-water heater is not used, the tank discharges to the boiler-feed pump, either the water-control or steam-control type of pump being used, according to conditions. The specific functions of each of these types of Webster Receiving Tanks are more particularly described in Chapter 24. Ventilation Problems: In Figure 15-2 a typical installation of a motor- driven ventilating fan, with its re-heater and tempering coils, is also shown. The fan heater supply line is dripped through a Webster Return Trap and Dirt Strainer, and the individual heater sections through Webster Return Traps. The method of dripping fan heater sections will vary with the size, arrangement and number of sections. Special study should be made of the various Webster Service Details shown in Chapter 22. It is exceedingly important not only to choose the right type of trap for use with indirect radiators but also to have the pipe connections properly made. The trap must be of the highest efficiency, with sufficient capacity to pass rapidly the maximum quantities of water and air which are present when first warming up, and afterwards open for the condensate and entrained air but absolutely prevent the escape of steam. This must be done even where core sand and greases are present and settle in the valve bodies. Where groups of radiators are made up of large numbers of sections nippled to- gether, there is a likelihood of air-binding sometimes extending over con- siderable areas. This trouble can be avoided if the traps and piping are right. Webster Return Traps and Webster Heavy-duty Traps meet every condition if installed in accordance with proper Service Details. Further reference should also be made to other chapters for description and method of application of various types of Webster Feed-water Heaters where power boilers are used for generating steam for prime movers ; Webster Steam Separators placed in the high-pressure steam lines to provide dry steam for engines; and Webster Expansion Joints, of both the single and double-slip pattern, for low and high-pressure steam lines, to take care of the expansion and contraction which occur in such lines. 2. Webster Vacuum System With Medium-Pressure Boilers, 15 TO 50-LB.: The foregoing description will serve as a general description of this type of vacuum system, except that the feed-water heater will not be used, the exhaust steam will be limited to that from pumps and auxiliaries, if steam-driven, and the vacuum pump will be either of the low-pressure steam-driven type or electrically driven. Under some conditions, particularly for pressures up to 20-lb., electrically driven pumps may be more suitable, and in these cases the lubricator and vacuum-pump governor will not be used. For boiler pressures up to 15-lb., either electrically operated re- ciprocating vacuum pumps or steam-driven pumps can often be used in conjunction with Webster Hydro-pneumatic Tanks to return the water to the boiler without the use of a separate boiler-feed pump. Webster Service Details in Chapter 13 show the proper arrangement for such cases. 172 3. Webster Vacuum System With Low-Pressure Boilers, up to 15-LB.: The description of this type of vacuum system is the same as that immediately preceding, except that the rotary type of electrically driven vacuum pump, handling air and water separately, is particularly suitable. These pumps also act as boiler-feed pumps if the conditions of the plant are within the range of the discharge head or pressure at which the manu- facturers guarantee these pumps to operate. 4. Webster Vacuum System. Steam Furnished from Street System: As steam at a pressure suitable for operating a steam-driven vacuum pump is usually not available, this type of vacuum system will require either rotary or reciprocating electrically driven vacuum pump. The condensation in such cases is discharged to the sewer or point of disposal through a condensation meter of a type for vacuum service. Webster Vacuum Systems, Special Modifications: There are two special types of modifications of Webster Vacuum Systems which will require special description: The Webster Conserving System and the Webster Hylo Vacuum System. Webster Conserving System: This is a special modification of the Webster Vacuum System which meets two general conditions: 1. Where necessary to operate steam-driven pumps from low-pressure boilers at very low pressure — from 5 to 20-lb. 2. Where necessary to provide steam for some special service con- tinuously at a pressure higher than that needed for heating. Referring to Figure 15-3, this system is in general respects similar to WEBSTER CONSERVING VALVE This Connection to be made 15'-0'' from Pressure Reducing Valve WEBSTER 1 WATER ACCUMUUTOR , Gale Valve WEBSTER HORIZONTAL OIL SEPARATOR /This Valve to be open when Pump is started and closed when Pump is in operation .Globe Valve Checit Valve Bypass to Sewer^ I 'WEBSTER SUCTION STRAINER WEBSTER LIFT FITTINGS Fig. 15-3. Typical layout of a Webster Conserving System 173 ^WEBSTER GREASE AND OIL TRAP the vacuum system described for working pressures from 15 to 50-lb. pressure. A low-pressure steam-driven vacuum pump is used, discharging to a Webster Hydro-pneumatic Tank, and thence to the boiler against pressure. The distinguishing feature of this special system is the Webster Con- Fig. 15-4. Typical installation and close-up of the Webster Conserving Valve 174 serving Valve, which is placed in the supply main near the boiler, and conserves or retains the steam on the inlet side of the valve until sufficient pressure has been built up to (1) operate the pump, or (2) meet the pressure requirements of the special service. Connections to the vacuum pump or for the special service are taken from the high-pressure side of the conserving valve. When the predeter- mined pressure has been built up, the excess pressure is released into the heating main by means of the conserving valve. In consequence, the vacuum pump begins to function before the steam enters the heating main and continues to operate even when the pressure drops on the high-pressure side to such point that the conserving valve closes against further admission of steam into the heating main. The heating system is therefore kept continuously drained of water at all times, insuring return of condensation to the boiler and preventing accidents or damage which would occur from lowering the boiler water level to a dangerous point. One other special feature of this system is the use of a Webster Damper Regulator to control the boiler pressure, operating from the low-pressure side of the conserving valve. The damper regulator must be connected in the special manner recommended. In a similar manner to the above, any special apparatus like kitchen equipment requiring steam continuously at higher pressure is always assured of constant supply regardless of operation of the heating system. Another adaptation of the Webster Conserving System is in large plants in which the engines are run condensing. A study of steam engine performance, where the engine exhausts into the atmosphere or into the heating system aga nst a back pressure slightly above that of the atmosphere, shows that engines working under such conditions actually convert only 5 to 10 per cent of the heat supplied to them into mechanical energy. The remaining 90 per cent of the heat origi- nally supplied to the steam entering the engine is retained in the exhaust. In some plants, power and heating loads are nicely ba anced so that all the exhaust steam available from power units can be utilized for process work or heating purposes, in which event the 90 per cent of heat energy remaining in the exhaust steam is put to useful work. In such cases the engine may be considered as a pressure-reducing valve which reduces the pressure from that carried on the boilers to that required for heating and process purposes. There are numerous industrial plants where the power load is greatly in excess of the heating load, so that the quantity of exhaust steam available is greatly in excess of that actually required. The surplus exhaust steam with its heat units must then be wasted. Where these conditions exist, the engines are often operated condensing instead of non-condensing, so that exhaust steam from the auxiliary ma- chinery only is available. In most instances the quantity is not sufficient to supply the heating load, and the deficiency is made up by live steam supplied from the boiler through a pressure-reducing valve. The work done by the pressure-reducing valve in reducing the steam from boiler pressure to that required in the heating system is converted into superheat on the low-pressure side of the valve. This work represents 175 about 10 per cent of the total heat energy supplied to the steam. If this 10 per cent of heat energj^ can be utilized by conversion into mechanical energy, nearly ideal conditions will be approached. Various attempts have been made in the past to improve the economy of power and heating plants by endeavoring to utilize the exhaust steam from the receivers of compound engines. This exhaust is bled into the heat- ing system and the deficiency made up by admitting live steam into the receiver through a pressure-reducing valve. In determining the advisability of this form of application, the effect of the relations between heating and power load and the relative proportion of the cylinders so vitally affects the economy that in each instance special consideration has to be given to all elements entering. The Webster Conserving System can be applied to this problem. In the same manner that the conserving valve is applied to conserve the pressure on the boiler by preventing the escape of its steam until a certain predetermined pressure is obtained, it can be applied to the receiver of a compound engine, opening and admitting steam at receiver pressure into the heating system, when the pressure on the receiver exceeds that which is necessary for the proper operation of the low-pressure cylinder, and closing when the receiver pressure drops below the point for which the con- serving valve is set. The quantity of steam taken from the receiver is made up by changing the cut-off on the high-pressure cylinder so that the high-pressure side acts as a pressure-reducing valve for the steam required for heating purposes. In expanding from boiler pressure to the receiver pressure, the heat energy given up in the expansion is converted into useful mechanical energy. By means of the Webster Conserving System many existing power and heating plants may be brought to efficiency where they are otherwise wasteful of steam. Webster Hylo Vacuum System: Where a number of buildings must be heated from a detached central plant, or where a building covers considerable ground, the source of steam supply and of vacuum cannot always be located to make a well-balanced system. The largest building in the group may, for various reasons, be farthest from the source of supply, and may also be the lowest point in the system of return piping, thus making it doubly difficult to secure perfect heating and easy return of condensation. Nearby points may be favored with unnecessary pressure difference. Attempts have been made to solve this problem by running the supply and return mains in reverse direction, so that the point of highest pressure is the point of lowest vacuum and inversely, thus maintaining, in some degree, the same differential between supply and return pressures. Where the largest building is at a low point away from the source of supply, it is obviously impracticable to solve the problem in this way. Furthermore, such a plan does not allow for extensions to or expansion of the plant, unless the new buildings can be located to suit the piping scheme, irrespective of the manufacturing need. This problem has been solved with unquahfied success by Webster Gate Valve Floor Line--- Fig. 15-5. Connections around Webster Hylo System equip- ment where the low-vacuum return main drops from over- head and discharges through a Webster Hylo Trap to the high-vacuum return main Fig. 15-6. Typical installation of Webster Hylo Trap, Con- troller and Gauges where high and low-vacuum returns are on the same level Gauge Cock iauge Cock -Gale Valve Line- Gauge Cock Connect to High Vacuum Returns / J^ WEBSTER ushing Gate Valve -^ Bushing^^^^Gaugg Cock V^EBSTER HYLO VACUUM CONTROLLER Union By-Pass on Side' Fig. 15-7. Arrangement of the Webster Hylo Controller, Trap and Gauges where the low- vacuum return is lifted to the high-vacuum return 177 Hylo Vacuum Controlling Sets, which are installed at certain points in the return line to restrict the vacuum to just the amount necessary for proper circulation and drainage at nearby points where high vacuum is not needed. The high vacuum is carried to extreme or low points where high vacuum is required. The result is a well-balanced system with perfect circulation in all parts. The operation of the vacuum pump is also improved to a marked extent as the degree of initial vacuum is reduced, making it unnecessary to use or waste cold water to condense the vapors arising from the hot water returned under high vacuum. Sometimes smaller pumps may be used, or the pumps may be operated at slower speed with less wear and tear. The Webster Hylo Sets consist of a Webster Hylo Trap, a Webster Hylo Vacuvuii Controller, Webster Hylo Vacuum Gauges, and when needed, Webster Lift Fittings. Figures 15-5, 15-6 and 15-7 show various methods of connecting Webster Hylo Sets to meet different building conditions. 178 CHAPTER XVI Application of the Webster System to Lumber and Other Kiln Drying Problems PROPER seasoning and drying of raw lumber is a first essential to well- finished products in any wood-working industry. This basic condition makes the dry kiln or room a most important feature, for as proved by experience in many instances, lumber that was found defective when worked would have been satisfactory if proper methods had been applied for drying. Very careful attention should therefore be given to the design of the drying room, the character of apparatus used and the heating medium employed. The method to be employed in drying will depend entirely upon the condition of the product when put in the kiln. Green lumber, or lumber having a high percentage of moistxire, will require a different method of procedure, and a longer time to dry than lumber which has been air dried. Hard woods such as oak or hard maple usually require a longer time than soft woods. Saw mills should determine the percentage of free moisture by test and so mark each pile of lumber when first piled in the yard. Later, when it is sold, the lumber should be tested again and the two records given to the factory or other purchaser. Factories should test and mark the lumber when first received, and if it is piled in the yard to be kiln dried later, it should be tested before going to the kiln and again before removal, these records being placed on file. The process required for the drying of lumber in kilns is properly divided into four parts, as follows: First: The primary treatment, during which all dampers are closed, 100 per cent humidity is maintained and the stock is warmed through without drying. Second : The initial drying period, during which the conditions of tem- perature and humidity within the kiln are advanced sufficiently to reduce the moisture content to 25 per cent. Third: The intermediate drying period, during which drying condi- tions are still more advanced to reduce the moisture content to 10 per cent. Fourth: A final drying period, during which extreme conditions are used to further reduce the moisture content to the percentage desired. Improper drying methods will usually result in one or more of the fol- lowing conditions: (1) Percentage of moisture not correct for working, (2) case hardening, (3) hollow-horning or honey-combing, (4) molding. The operator should make careful test readings to determine the mois- ture content both before and during the drying of the lumber. Records from such tests will give data on which to base his treatment of the stock. Tests should be made at stated intervals of 48 to 72 hours 179 during the drying period. For this purpose test boards from which samples may be taken should be inserted in the kiln. A good solid heavy piece as a sample, or better still, two or more sections out of as many different boards taken out of the pile one-third the distance from the bottom, will yield an average or representative test for moisture content. With two or more tests for moisture showing varying results, it is safer to use readings showing the highest moisture content rather than the average of the pieces. At the same time, tests should be made for case hardening. If the lumber becomes case hardened, it practically stops the drying process, or at least slows it to a great extent. Frequently this results in hollow-horning, cupping, internal strains and many other evils which affect the stock through- out the manufacturing process. Almost all '"working" which occurs in furniture, or other wood articles, is due to stresses which developed in the wood during the seasoning period. These stresses may be determined by two simple tests and eliminated before the stock leaves the kiln. The manufacturers of the different makes of dry kilns furnish detailed instructions for the various tests on which the successful operation of their kilns depend. The final condition of the lumber required in different factories varies with the purpose for which the lumber is used. For instance, in wagon work, many manufacturers do not use lumber containing less than 10 to 12 per cent of moisture; in auto body work, for open bodies, 6 to 8 per cent is considered proper; for closed bodies, 5 to 6 per cent. Furniture manufac- turers generally dry down to 4 to 6 per cent, while wheel manufacturers dry the spokes as nearly bone dry as possible, but do not dry the felloes below 8 per cent, the theory being that when the wheel is made the spokes may absorb moisture and make a snug fit. A modern kiln is usually constructed with brick side walls and a roof of tile or cement covered with roofing felt, tar and gravel. The doors are of special design to allow for easy loading and unloading, and to prevent, as much as possible, air leakage and loss of heat. Ventilating flues are provided in the side walls for supplying air and removing same as desired. The heating medium usually employed is steam at varying pressures, depending upon the kiln temperature desired. The temperature within the kiln is controlled by means of a thermostat operating a valve in the pipe supplying steam to the coils. A system of steam spray pipes is provided under the material to be dried for increasing the humidity as desired and to assist in warming the stock. The percentage of humidity in the kiln may be automatically controlled by means of a humidistat operating a valve controlling the supply of steam to the spray pipes. Where steam, whether exhaust from engines and auxiliaries, or taken direct from the boilers, is used as a heating medium, the success of the drying equipment depends upon the manner of carrying this steam to the heating units, the proper drainage of the supply mains, the circulation of the steam through the heating units and the removal of air and water of condensation. 180 All manufacturers of drying equipment utilizing steam as a heating medium recognize the importance of these features. One of the largest manufacturers of drying equipment in the United States says in its book of instructions : '"Where troubles have been experienced, investigations have shown that they are generally due to one or more of the following conditions : "Poor steam service. "Pressure not constant. "Wet steam due to improper condensation drainage. " Insufficient steam pressure. "Poor drainage from traps. "Improper design of supply and drainage piping. "Traps allowing steam to blow through into the main drainage line, holding back kiln drainage. "Traps on heating units not functioning properly. "Traps stopped with scale or dirt. "Trouble is often caused by faulty design in making steam connections to kilns. "All steam lines must pitch in the direction of steam flow. Automatic drain traps must be provided at all low points on these lines in order that there may be absolutely no condensation lying in the lines at these places, and that steam may enter the kiln dry and at a high temperature. Failure to provide proper methods of drainage will result in reduced volume and temperature of steam and correspondingly low temperatures and poor serv- ice in dry kilns." The important features in connection with the steam supply and drain- age system can be enumerated as follows. (1) Adequate and continuous supply of steam. Pressure of steam con- stant and sufficient to produce the required temperature within the kilns. (2) Manner of conveying steam to coils. (3) Method of draining main steam supply. (4) Character of design of heating vmits. (5) Method of complete and rapid air removal from heating units and from entire return system. (6) Method of removal of condensation from heating units. (7) System of drainage piping. (8) Ultimate disposal of water of condensation and of air. (9) Adequate and continuous pitch of pipes throughout the entire length of the coil. Items one, seven and eight will be governed materially by the condi- tions existing at the plant where kilns aie to be used, and as these conditions vary with the character of the plant, this discussion will be limited to the requirements of the kiln only. The pressure of steam supply, so far as the operation of the kiln is con- cerned, will depend upon the temperature required within the kiln. If a maximum kiln temperature of not more than 150 deg. fahr. is required, satis- factory results can be obtained by the use of exhaust steam from engines and auxiliaries at a pressure not to exceed 1 J^-lb. gauge. The same results 181 Vacuum Return A Typical Elevation A Typical Plan Fig. 16-1. Sections through a typical dry kiln with coils of the continuous-header type using Webster Heavy-duty Traps for drainage and Webster Return Traps for removal of air from return headers 182 will be obtained, of course, by using steam direct from the boiler, reduced to a corresponding pressure by means of reducing valves. It is very impor- tant to place a relief valve on the low pressure side of the reducing valve to prevent rise of steam pressure to a point where there is a liability of injur- ing the thermostatic return traps. The details are shown in Fig. 22-3, Page 216. Where temperatures greater than 160 deg. fahr. eu"e required it will be necessary to increase the pressure of the steam accordingly. In good practice the temperature of the steam must not be less than 60 degrees higher than the temperatiu-e desired in the kiln. The size of the steema supply mains will depend upon the volume of steam to be delivered, and the drop in pressure allowable. This may be determined with the help of the tables in Chapter 11 in this book after a decision has been reached as to the total heat requirements of the kiln and the distance of the kiln from the soxirce of steam supply. The same prin- ciples apply for the installation of steam mains to the kilns as would apply for the installation of steam mains for any other purpose. Extreme care should be given to the drainage of the steam main at the point of entrance to the kiln. It is advisable that water of condensation from the main shall be relieved from the bottom into the return and that steam for kilns shall be taken from the top of the main rather than to allow the condensation to drain through the coils. The supply main may enter the kiln from a point above the coils used for heating, or from below them. Manufacturers of drying equipment have devised numerous types of heating units but practically all have standardized on those constructed of pipe. The coils are placed either vertically along the side walls of kiln, or horizontally in a space provided underneath the material to be dried. In the latter instance they are usually installed in a horizontal position, although some manufacturers prefer coils placed vertically. The advantage of more equal heat distribution is claimed for the large unit laid horizontally, but this is not fully realized unless the removal of air and condensation is complete. With coils having short vertical headers, say 10 pipes high, it is very important to secure an equal distribution of steam to all of the pipes. The internal diameter of the supply header should be ample; 23^-in. is none too great. It is very important not to locate the inlet in such a position that steam will enter those pipes directly in front of it and passing tlxrough to the return header, tend to pocket the air in the other pipes. The re- moval of air will be very sluggish and meanwhile the efficiency of the whole coil will be low. A deflector placed within the header in front of the inlet wiU improve the steam distribution. A much better method is to have more than one inlet. These additional supply connections will also reduce materially the velocity of the entering steam. Figs. 22-21 and 22-22, on Page 220, show methods of splitting up the return header into two parts, for coils of more than 10 pipes, when there is a liabihty of air binding. With horizontal headers, particularly where of some length, the in- ternal diameter should be large and the niunber and location not only of supply openings but also of return and air vent outlets should be selected 183 with great care, so as to ensure uniform distribution of steam and complete removal of air and water. Practical experience has demonstrated that incomplete removal of air and condensation has caused unequal heat distribution throughout the kiln as well as a drop in temperature of from 20 to 50 per cent. The air must not only be removed from the coils but also must be rapidly and completely eliminated from the return system and discharged outboard. The selection of the proper type of trap to be used in any given case depends upon the steam pressure which it is necessary to carry on the coils to secure the requisite heating effect, the quantity of water which the trap must handle, the temperature of the room in which the trap is installed, the pressure in the discharge hne and the disposition to be made of the products of condensation. A continuous and uniform steam pressure of not over 3 to 5 lb., a moderate and uniform quantity of condensation to be handled, and a tem- perature of not over 80 deg. in the space where the traps are located, are the most favorable conditions for the successful operation of low pressure thermostatic traps. They should not he employed where the temperature requirements of the kiln necessitate carrying a continuous steam pressure which approaches closely the allowable maximum pressure of the trap. Traps on high Plan Fig. 16-2. Typical section through a dry kiln using coils of the sectional-header type 184 Dampers 1 i ■.'-:',,'..;; ~? ^''^/''yyy^'/^/ Vacuum Return Line from Colls' Supply to Coils ^, Drip from Spray \ \ Pipe Supply ^ Supply to Spray Pipe ^r ;;*■ Pipe Tunnel , Elevation Fig. 16-3. Sectional drawings of a typical small dry kiln using individual return traps for drainage of coils 185 pressure steam drips must never be permitted to discharge directly into the return pipe near the thermostatic traps on account of the liability of back pressure or water hanwier. The connection should be made at a point be- yond the traps, placing a check valve in the thermostatic trap return to prevent back pressure therein and in addition means should be employed for disposing of the high temperature vapor as shown in Fig. 20-2, Page 203. The types of heating units which are universally used and the manner of applying the Webster specialties for proper air removal and drainage of condensation are shown in Figs. 16-1 to 16-4 inclusive. Attention is called to the importance of providing a dirt strainer for the drain connection to each trap. Both the traps and strainers should be readily accessible. Where thermostatic traps are used they should be located where they will not be affected by the high temperatures of the kiln. This is usually accomplished by extending drain connections to the extreme front or rear of the kiln and placing the traps near the floor. On small units as shown in Figure 16-3, where thermostatic traps are used, additional provision for the removal of air is unnecessary, but where a large volume of condensation accumulates, additional provision for air removal is essential and heavy-duty traps should be used. Where the heating unit is of the continuous header type as shown in Figure 16-1 the air removal can be accomplished by the use of heavy-duty traps equipped with a ther- mostatically actuated air bypass within the trap and by means of additional thermostatically actuated air traps connected into the top of the main return header, as shown in Figures 16-1, 16-2 and 16-4. The number and location of these air traps is governed by the length and design of the main return header. The outlets of these air return traps should be connected into the main vacuum return line beyond the discharge connection of the heavy-duty trap. Where heavy-duty traps are used there should be a drop leg of from 8 to 10 inches between the outlet on the return header and the trap inlet. Where it is desired to drain the condensation from two or more coils to one heavy-duty trap, or where the return header of the coils is of special construction divided into two or more sections and the condensation from all sections is drained by one trap, it is essential for the proper removal of air to equip each return header, or each section of the return header, with a ther- mostatically actuated return trap. The outlets of these traps should be connected into the main vacuum return line in the same manner as de- scribed above. Pipe coils and return pipe connections to traps must have a sharp downward pitch their entire length in the direction of the flow of conden- sation. The coil supports must be of a permanent character and so arranged that any subsequent settlement of the kiln structure will not affect the pitch of the pipes. The dischEQ-ge from all heavy-duty traps and thermostatically actuated return traps used in connection with kilns may be connected into a com- mon return line, but it is preferable that this return line from kilns shall be extended independently from the kilns to the vacuum pump, rather than to connect it into returns from the heating system of the manufacturing 186 plant or other equipment. The condensation rate from the kilns will fluctuate, depending upon the temperature within the kiln, the nature and con- dition of the product being dried and the outside temperature. Consequently, at times when the air removal and condensation rate from the kilns is high, trouble may be experienced with the operation of other equipment if connected to the same return line. Also, if the same efficient equipment is not used in connection with the heating system or other equipment, as is used in connection with the kilns, the poor operation of the heating system or other equipment will natur- ally reflect in unsatisfactory operation of the kilns. The amount and location of radiation in- stalled within the kiln will depend upon the loca- tion of the kiln, the temperature desired within the kiln, the steam pressure, and nature of pro- duct to be dried. This constitutes a special branch of engineering and engineers thoroughly familiar with this class of work should be con- sulted. The method for figuring the total radiation required by a given dry kiln Avill not vary from the descriptions given in detail in Chapter 5, except that during the warming-up period an additional heat factor is required to care for the moisture content of the lumber or other material being dried. Much of the general information on lumber drying was furnished for this Chapter by the National Dry Kiln Co., of Indianapolis, Ind. Fig. 16-4. Showing the connec- tions where two or more coils are drained through one Webster Heavy-duty Trap 187 CHAPTER XVII Application of the Webster System to Slashers and to Cloth and Paper- drying Apparatus SLASHERS are used in the textile industry for sizing and drying warps I or yarns before they are placed in looms to be woven into cloth. In these machines, steam is supplied usually to two cylinders, of 5 and 7 ft. diameter, over which the yarn passes to be dried after sizing. Ordinarily the steam supply and the drainage connections are on op- posite heads of the cylinders, the connections passing through the cored shafts upon which the cylinders revolve. Steam is carried tlirough the mains to the slasher at about 80-lb. pressure and before it enters the cylinders is reduced to between 5 and 12-lb. per sq. in. by a pressure-reducing valve. The steam pressure in the cylinders of course always must be above that of the atmosphere as the rapid drying of the materials demands that the surface temperature of the cylinders shall be above the atmospheric boiling point. Owing to the light weight of the metal used in the construction of slashers, vacuum breakers, usually three in number, are provided in the head of the discharge side of each cylinder. These open when a partial vacuum occurs in the cylinder and prevent collapse of same. The condensation is raised to its point of removal from the slasher by means of troughs or buckets, usually three in number, attached to the in- side cylindrical surface. A pipe attached to each bucket carries the conden- sation to the hollow cylinder shaft and thence through the bearing to the outside. From there the condensation goes through the Webster Traps, etc., to the point of disposal. The Webster System for draining slashers provides the most efficient drying effect with least attention to the drainage equipment. It has suc- ceeded in overcoming entirely the frequent delays and slowing down of the manufacturing processes previously experienced with other devices. As will be seen in Figure 17-1, each cylinder is equipped with a Webster Return Trap, a Webster Dirt Strainer and a bull's-eye sight glass. The Webster Return Trap permits the free passage of air and water and closes against the discharge of steam. The Webster Dirt Strainer protects the trap from dirt and the sight glass enables the operator to see whether or not the drainage system is functioning. A bypass is provided around the drainage apparatus. When starting up, the bypass may be opened for a few minutes to permit the quick dis- charge of air. After starting, the slasher is drained automatically through the Webster equipment. A pressure sufficiently above that of the atmosphere must be carried in the cylinder to dry the goods and this is sufficient to discharge the con- densation and air through the Webster Trap, if free vent to atmosphere is maintained. There is no advantage in connecting the discharge of the traps 188 to a vacuum pump if sufficient vertical distance is available to allow a proper fall for the condensate to flow by gravity to an open receptacle. The condensation rate with this type of slasher will vary from 400 to 600 lb. per hr. One of the best-known American manufacturers of slashers states in his catalog: "We strongly recommend the use of Warren Webster & Co.'s appara- tus for slasher drainage. "Steam traps can be furnished if desired but we recommend the use of the Webster System in preference, as higher economy will certainly maintain Long Sweep Tee !] 1 Gate Valve To Drain'' WEBSTER SIGHT GLASS Fig. 17-1. Typicail application of Webster Apparatus to a slasher 189 a higher rate of production and its simpUcity lessens the HabiUty of stoppage to which a system of steam traps is apt to be subject after a few years of use. " The Webster System as compared with a steam-trap system insures steady, instead of intermittent, drainage and practically an entire absence of condensation in the cylinder with all consequent advantages." Cloth and Warp Drying Machines: Except in details, the process of draining drying machines of both vertical and horizontal types is the same as for slashers. Each cylinder is provided with troughs or buckets which, as the cylinder revolves, empty tlirough a pipe to a hollow shaft and through the journal to the return duct. Air Vent open to Atmosphere ^ Conned to Hot Well, or Drain independently Fig. 17-2. Application of the Webster Apparatus to a vertical drying machine A. Solid copper gasket inserted between bracket and housing. A copper gasket having hole equal in area to that in the bracket must also be placed between the bracket and housing on the inlet side to keep cylinder alignment true. B. Gate valve. C. Webster Dirt Strainer. D. Webster Return Trap. E. Webster Bull's-eye Sight Glass 190 Fig. 17-3. Application of Webster Apparatus to paper machines where there are separate drips for each cylinder The housings of the machine and the brackets supporting the cyhnders are cored to provide ducts for conveying steam to the cyhnders and con- densation away from them. The frame on one side acts as a supply pipe while that on the other side acts as a return. Steam at a pressure of 15 lb. per sq. in. or less is admitted to the housing and passes through the WEBSTER RETURN TRAP-, Union " \ WEBSTER DIRT STRAINER WEBSTER HEAVY OUTV TRAP Fig. 17-4. Application of the Webster System to a paper machine where there is a common return line for all cylinders with air removed separately from each cylinder 191 brackets and the journals to the cyhnders. To prevent collapse, vacuum breakers are installed in the cylinder heads, usually on the discharge end. Frequently it is advisable to make two or three separate steam supply connections to each housing, as the area of the cored opening in housing is too small to convey the required amount of steam without too great a pres- sure drop. The duct in the housing tlu-ough which the products of condensation pass can best be drained by the use of one or more Webster Heavy-duty Traps provided with thermostatically controlled air by-pass. Paper Machines: Two types of machines of particular interest are used in the manufacture of paper, cyhnder machines and Fourdrinier machines. Both require the evaporation of large quantities of water from the paper after the pvdp has been pressed and the web has formed. After passing through the presses the paper usually contains about 45 per cent of water. This moisture is reduced to about 5 per cent, depending upon the thickness of sheet and the finish desired, by passing the paper over a series of drying cylinders, the inside surfaces of which are heated by either exhaust or live steam at low pressure or a combination of the two. Usually the steam-supply header runs parallel with the machine, close to the floor, a hole being bored in the header and connected by a pipe to the cored journal on the cylinder. The return header runs either above or below the steam header and has the same kind of connections as the supply. The drying cylinders vary in size and length. For the purpose of re- moving the water, one type of cylinder is equipped with buckets and another with what is termed a siphon pipe. Cylinders equipped with buckets dis- charge the condensation only when in motion, while those equipped with Fig. 17-5. Method of draining cylinder of a paper machine using Webster Return Trap and Webster Dirt Strainer. These connections are suitable for operation with either vacuum or gravity discharge siphon pipes discharge whenever water accumulates, provided there is suf- ficient pressure in the cylinder or vacuum in the return line to give the neces- sary difi'erential. The condensation per square foot of exposed drying surface of the cylinders depends upon the speed of operation and the thickness and width of the paper on the cylinders. The stock from which the paper is made, together with the amount of water extracted by the press rolls, also has a direct bearing upon steam consumption. The condensation will average about 13^2 lb- per sq. ft. of total roll surface and naturally is greatest at the wet end of the machine. The drainage from the cylinders may be removed either by gravity or by means of a vacuum pump, whichever is desirable. Usually with the Webster System of drainage, a Webster Return Trap 192 Fig. 17-6. Method of draining cylinder of a paper machine using Webster Heavy-duty Trap and Web- ster Dirt Strainer Fig. 17-7. Method of draining cylinder of paper machine for gravity discharge where a water line is to be maintained, using Webster Heavy-duty Trap with balanced steam connection, Webster Dirt Strainer and a Webster Return Trap for vent discharging into dry returns with its Webster Dirt Strainer and bypass is provided for each cyhnder as shown in Figures 17-3 and 17-5. All traps discharge into a main return which leads to the point of disposal, which is a feed-water heater or hotwell, open to the atmosphere for the removal of air. Webster , Heavy-duty Traps are sometimes used instead of Webster Return Traps (Figure 17-6) especially where the presence of a water line is desirable in the return (See Figure 17-7). The reader is referred to Page 184 for a complete discussion of the selection of the proper type of trap and the precaution which should be observed where thermostatic traps are used. 193 CHAPTER XVIII Application of the Webster System to Railroad Terminals and Steamship Piers THERE are many uses for thermostatically actuated return traps where the pressures carried are greater than in heating-system work. In- stances involving operation under steam gauge pressures of from 15 to 100 lb. are described in this and following chapters. The requirement, in all cases, is that the return trap shall discharge the water and air of condensation without waste of steam and that the fix- ture being heated shall be maintained at maximum efficiency. In these special installations, certain fundamentals must be observed to secure successful operation. The first requires that the thermostatically actuated traps must discharge directly to the atmosphere or to a return line in which atmospheric pressure is maintained. This latter condition may be obtained by venting the return line free to the atmosphere. In some cases the same result is seciu-ed by discharging the returns into a flash tank, the vent of which is connected to the low-pres- sure heating main, while the condensation is cared for through the usual type of retiu-n traps to the vacuum return. Railroad Terminals — One of the greatest causes of delay in the daily movement of hundreds of trains into and out of terminals where there is freezing weather is the difficulty in keeping switches clear of snow and ice. Many terminals have therefore adopted the method (Figure 18-1) of placing steam-heating coils between the ties, under the switches. Due to the unusual exposure, these coils and their supply lines are operated under 60 to 80-lb. gauge pressure in order to prevent freezing. The dripping of Main Steam Line Gate Valve t^^r^-fi ^Nrf? WEBSTER HIGH PRESSURE SYLPHON TRAP Sheet Steel lastened' to Top and End of Ties Fig. 18-1. Ste9m coil arrangement for prevention of freezing of railroad switches 194 High Pressure Steam Line — Gale Valve - WEBSTER HIGH PRESSURE4> SYLPHON TRAP -Covering Stand Pipe Fig. 18-2. Method for prevention of freezing of fire protection lines. The water and steam pipes are encased in the same insula- tion and the steam pipe is drained by a thermostatic return trap these lines and coils pre- sents a double problem: First, water and air of con- densation must be freely discharged onto the road- bed, and Second, condensa- tion must not form steam clouds that might obscure nearby switch signals. A type of thermostat- ically actuated return trap which answers these re- quirements has been devel- oped by Warren Webster & Company after many tests and experiments. This re- turn trap is fitted with Monel-metal seats and valve pieces to withstand the wire- drawing effects of steam at high pressure differential. The thermostatic member is placed on the outboard or atmospheric side of the trap, and as the trap is generally placed in the rock ballast of the road bed, its exterior is usually given a special finish to give it protection against the elements. (See Page 275.) Railroad terminals are also equipped with extensive systems of water lines for fire protection purposes and these lines, too, must be kept from freezing. The method of prevention (Figure 18-2) found most satisfactory is to run a steam line, carrying from 60 to 80-lb. gauge pressure, parallel with and close enough to each water line that both steam and water lines can be encased in the same insulating covering. Where the water lines terminate, as at hydrant and hose gate outlets, the same dripping of the steam lines and the same thorough removal of condensation with absence of steam cloud are required as with the yard switches. The same type of return trap is used in both cases. Steamship Piers: Steamship piers in cold climates are somewhat similar to railroad terminals in that the Gre lines must be protected. In ad- dition, heat is required for a large number of small enclosures scattered tliroughout for housing the pier clerks. Piers are so built that water of condensation from coils heating water lines and clerk houses cannot be easily returned. The practice is to dis- charge the condensation overboard through the pier deck. The return traps must, therefore, keep the hues clear of condensation to avoid possibility of freezing and at the same time avoid waste of uncondensed steam. Webster Return Traps of similar construction to those previously described for railroad terminals are successfully used for this work. 195 CHAPTER XIX Applications of the Webster System to Vacuum Pans and Similar Apparatus IN processes of manufacture where boiling of the product at a low- temperature is desirable, a special application of the Webster System has been devised for removing air and water of condensation. One of the important uses for vacuum pans is in the milk-condensing industry and in the following pages this particular application of the Webster System is discussed. However, the principles and the Webster apparatus are equally applicable to other processes such, for instance, as the manu- facture of sugar, salt, candy or tartaric acid. The development and growth of the milk industry has reached a point in the last few years where it is now necessary, due to keen competition, to use not only the most modern and efficient machinery in the process of milk treatment, but to install modern power equipment and a perfect system of steam circulation in order to insure the commercial efficiency of the plant. It is essential that each pound of steam (live or exhaust) shall do the maximum of useful work and that all water of condensation shall be returned to the boiler. There are numerous uses for exhaust steam in the modern condensory, such as heating of boiler feed water, heating of water for general use and in the heating system of the building, but as a rule these require only a small portion of the amount of steam available from the exhausts of the engine, compressors, pumps, etc. In a condensory of say 100,000-lb. capacity of milk daily, there will be available at least 200 hp. of exhaust steam, not over 20 per cent of which is required for any of the above uses. The remaining 160 hp. of exhaust steam is available for use in the vacuum pans. The usual i^ractice in the past has been to use live steam in the heating coils of the vacuum pan at a pressure of about 15 to 20-lb. gauge, reducing to this pressure from the high-pressure mains. Very often excess exhaust steam from the engines has been wasted to the atmosphere, being considered a by-product of the engine room with little value excepting for its uses in the boiler room. Exhaust steam at 5-lb. gauge pressure contains about 88 per cent of the heat content of the live steam used to develop power and is as effective in the vacuum pan coils as live steam reduced to the same pressure. To make use of exhaust steam at 5-lb. gauge pressure where live steam was used in the vacuum-pan coils, only shght changes are necessary. Oc- casionally the sizes of coil connections must be increased to the size of the coils themselves and where the steam pressure is decreased, a slight addi- tional amount of heating surface in the coils will be required on account of the lower temperature of the steam at this pressure. In some plants where exhaust steam has been substituted for live steam without changes in the 196 Fig. 19-1. Milk condenser heating surfaces, a slight additional time was required to condense the batch of milk. In most cases this increase was not more than ten minutes. The usual control valve connections, that is, the double globe valve and a gauge attached to each coil connection, will be the same for use with the exhaust steam as with the live steam. The return connections for use with the exliaust steam are very simple. A single Webster High-differential Heavy-duty Trap (see page 249, Chapter 197 24), with a bypass, is connected to each coil outlet. These traps discharge to the return main leading to a vacuum pump in the boiler room. It is essential that each coil shall be drained separately into the vacuum return main in order that the pan operator may have absolute control of the steam pressure in each individual coil. It is necessary when condensing milk to vary the pressure in these coils at will. In some instances the pressure in certain coils must be reduced to atmosphere, while the pressure in other coils is increased to as much as 5 lb. per square inch in order to cause a positive circulation of milk within the pan. Without this positive control of circulation it is impossible for the pan operator to properly manipulate the process. It is also imperative that the water and air of condensation shall be re- moved immediately from the coils of the vacuum pan and that this shall be accomplished independently of any conditions which may affect the opera- tion of the general exhaust steam system in the plant. It is advisable to use an independent pump and return line for the vacu- um pans and not to depend upon other similar equipment which may be used for heating the building. The return line should have a gradual gravity pitch to the vacuum pump and should be so arranged with by-passes and valves that in case the vacuum pump should become inoperative for any reason the return condensation may be discharged by gravity. There must necessarily be no pockets of any nature in this return line. A maintained vacuum of 6 to 8 in. at the outlet of the trap is usually sufficient to insure at all times a positive circulation of steam and the in- stant removal of all water and air of condensation. Not only are much better results obtained by the certainty of this cir- culation, but in many cases where exhaust steam has been substituted for live steam in the milk-condensing process, a marked improvement in flavor of the product has been noted. The great saving in steam consumption in a condensory when equipped with the Webster System will usually pay for the entire installation within a few months. However, a careful analysis must be made of the existing conditions of an old plant or the requirements of a new condensory before any exact arrangement can be determined. There is no other single im- provement to a condensory that will approach the saving obtainable through the economical use of exhaust steam. Figure 19-2 shows an older type of connection for vacuum pans, in which high-pressure steam only is used. The pressure is reduced from 125-lb. per sq. in. boiler pressure to 15 or 20-lb.per sq. in. for use in the pan. The outlet connections are pipes without valves or checks, leading to a header which is piped to a tank located beneath the pan. The tank is a receptacle for water and air of condensation. The air is vented through the small vent valve while the water is drained to a high-pressure positive return trap which discharges the water to an open hotwell or to a feed- water heater. The difficulties encountered in this construction will be short-circuiting of the steam from one return to the other and the impossibility of maintain- ing independent or separate pressure control on each coil in the pan. 198 pressure reducing Valve -^r i Gauges ^ By-pass- HiQh-pressure Main ■Qt Vent Valve Positive Return Trap o To 8oiler Room Fig. 19-2. Drainage system for a vacuum pan using a positive return trap and receiving tank The system of piping, however, is in common use in most of the smaller condensories at the present time. Figure 19-3 shows another construction \Vhere the inlet connections are similar to those in Figure 19-2, but where the outlet connections are con- trolled by means of gate valves and check valves which discharge into a common return hue. This return line is run direct to a pump and receiver which discharges the water back to the boiler. A great many installations are somewhat similar to this and it is evident that there is a great deal of 199 waste of steam due to the inability of the operator to properly throttle the controlling valves on the outlet connections. Figure 19-1 shows the approved application of the Webster System. The exliaust-steam piping includes a Webster Steam and Oil Separator and an auxiliary connection from the high-pressure main with pressure- reducing valve. It is essential that the pressure-reducing valve shall be of such construction that it will maintain constantly the pressure which is de- sired when it is necessary to use live steam for condensing. The back- pressure valve must be of such construction that it is impossible at any time to exceed 10 lb. per sq. in. pressure on the low-pressure mains. The outlet connections from the vacuum pan are run direct to the Pressure- reducing Valve ir—ir Fig. 19-3. Drainage system for a vacuum pan using a pump and recei\er 200 Exhaust Head Return to Vacuum Pump "rip lo Waste Fig. 19-4. Approved manner of applying the Webster System to a vacuum pan Webster High-differential Heavy-duty Traps, which are provided with by- passes and thermostatically controlled air lines and are connected directly to the vacuum return line, which is run through a Webster Suction Strainer to the vacuum pump. These outlet connections also must be equipped with small try-cocks in order that the operator may test the working condition of any coil in the pan at any time. 201 CHAPTER XX Application of the Webster System to Sterilizers, Cooking Kettles and Similar Apparatus HOSPITAL Equipment: All hospital equipment, such as sterilizers for surgical instruments, bandages and dressings, blanket warmers, etc., requires steam at more than the usual heating pressures. As these fixtures are comparatively small consumers of steam, being operated at gauge pressures of 15 to 100 lb., and as they are situated at different parts of the building, it is usual to run a special set of steam supply and return lines for them so that steam may be available at any time throughout the year. For the purpose of insuring rapid removal of condensation and air from each fixture, a Webster Return Trap of similar construction to those described in the preceding chapter is placed on the return of each unit. The operating temperature of the thermostatic members of these traps is close to that of steam at atmospheric pressure; hence it is necessary to provide sufficient exposed piping between the fixture and the trap to allow the con- densation to cool down to the operating temperature of the return trap. This exposed piping is termed cooling surface. Dressing Sterilizer Blanliet Warmer Closet Gate Valves To Waste or Atmosphere 'Dirt Pocl Owing to the high rate of heat transmission through the glass of which greenhouse enclosures are constructed, the heating system must be capable of quick response to the demands for extra heat during nights, cloudy and cold days, and particularly when a sudden cold wind springs up. Co-operating with the ventilators, the heating system must respond quickly to the demand for less artificial heat, when the heat from the sun's rays tends to increase the interior temperature beyond the point desired. Until a few years ago, hot water was con- sidered the best medium for circulation in the heating coils of greenhouses. However, as the size and importance of greenhouses have in- creased, a medium with quicker response in heat flow has become necessary to better meet the many changes in outside temperature and direction and velocity of wind. Steam has proved ideal for this work where the condi- tions of the individual problem have been carefully analyzed and a suitable heating lay- out has been applied. In different types of greenhouses the ar- rangement of the heating coils varies to suit the particular plants or vegetables grown and to meet the needs of forcing, propagation, etc. The conservatory group of the Missouri ; "eTch Botanical Garden at St. Louis, Mo., consisting of palm, economic, cycad, succulent and fern houses (Figures 21-1 to 21-5), is heated by the Webster Vacuum System of Steam Heating. These greenhouses are part of the 125-acre botanical garden presented to the public Fig. 21-2. Plan of half the Conservatory of the Missouri Botanical Gar o .5 s ^ r3 .613 — 'w 5 ^ So o •" 3 -o O I - o T (N si: E 212 Fig. 21-11. View across Orangerie, du Pont Horticultural Group, Mendenhall, Pa Fig. 21-12. Method of heating for growing vines on the walls of the duPont orangerie. Air enters the openings at the bottom of the wall, is heated in passing over the coils at the top and passes into the rooms. The registers in the floor distribute heated air from the indirect heating system 213 week; muslirooms. 2000 pounds per week. The output includes also flower- ing plants, among which are hundreds of thousands of cyclamen, grown for the sale of cut flowers as well as the plants themselves. The temperature requirements of these greenhouses are even more exacting than those of the Missouri Botanical Garden, as shown by the chart. Figure 21-6, taken from the recording thermometer. The steam for heating is taken from a 95-lb. steam hne running through the connecting corridors, and the pressure is reduced in each greenhouse for the Webster Vacuum Heating System, which operates at 5-lb. pressure. The condensation is carried through a vacuum return back to the power plant, where it is delivered by the main vacuum pumps through a tank to a Webster Feed-water Heater and from there pumped to the boilers. The Horticultural Group (Figure 21-10) on the private estate of Mr. Pierre S. du Pont near Mendenhall Pa., is heated by the Webster System. The main buildings comprise the orangerie, exhibition hall, peach houses and display houses. The orangerie is approximately 80 by 180 ft. and the exhibition hall is about 80 by 110 ft. The two peach houses lie on either side of the orangerie and are approximately 50 by 100 ft. in length, with the display house 30 by 50 ft. at the extreme ends. At the rear of the Exhibition Hall is a stage, or rather a veranda, to the future building, which will eventually be the casino. At this end of the building are located the organ and service rooms for entertaining purposes. The heating for this group is remarkable in that the main buildings are heated by a system of indirect radiation with a gravity circulation of air, The indirect surfaces enclosed with copper casings and pans, are placed in a series of tunnels which lie under the walk-ways. Fresh air when required is taken through two sets of primary heaters located in the orangerie and one set of primary heaters for each of the peach and display -house wings. These are furnished with sufficient surface to maintain the air in the tunnels at 60 deg. fahr. 214 CHAPTER XXII M' Installation Details "ANY of the methods of pipe connections which have been developed by Warren Webster & Company during the past 34 years, and have become standard practice, are shown in this chapter and elsewhere in connection with descriptions of specific apparatus. Most of the illustrations have been published as Webster Service Details and are familiar to the profession and trade. These drawings, which indicate the general arrangement of the pipe, fittings and Webster apparatus have been revised from time to time and, as shown here, represent the latest and best thought. They are not to be used for exact layouts of piping, as each individual application presents its own special conditions. No effort has been made to indicate the necessary unions or right and left nipples required for the connections, as these requirements for any case would naturally be best determined by the detail of the layout or by the steamfitter at the job, based upon his skill and upon materials available. Details Applicable to Both the Webster Vacuum System and the Webster Modulation System Rise to new level -Rise to new level WEBSTER CLASS"B' DIRT STRAINER, Reducing Gate Valve Provide at least 3-0 ' pipe cooling surfaci between drip point and return trap Connect into lop or side of return main WEBSTER CLASS "B" DIRT STRAINER Reducing Fig. 22-1. Application of a ^^'ebste^ Return Trap on a low-pressure heat main, at a low point where the main rises. A suflicient length of uncovered pipe must be provirled between the drip point and the return trap Gate Valve _WEBSTER HEAVY DUTY TRAP- Set trap on bracket support ^ on foundation or on Hoot-'' Connect into top or side ol return main Fig. 22-2. The drainage of a low-pressure heat main at a low point, where the line rises, is of such importance that special attention is warranted. This diagram shows a large main with drip through gate valve, Webster Dirt Strainer and Webster Hea\'y-duty Trap 215 Live Steam Irom Boiler \ JL By-pass with Globe or Angle Valve WEBSTER WATER ACCUMULATOR -v Tee for Gauge Connection Straight Pattern Pressure Reducing Valv) Fig. 22-3. Connections for a steam pressure-reducing valve. The control pipe from the low-pressure side of the line must be taken from a point far enough from the valve to insure that the pressure will have been fully expanded. The use of the Webster Water Accuramulator (see Page 267) facilitates a constant static pressure on the diaphragm of the pressure-reducing valve. The pop safety valve prevents pressure building up, particularly at very light loads Return Riser ucer— -"W 1 J4 Pipe uncovered-"* Gate Valve ~; Dirt Pocliet- WEBSTER RETURN TRAP Plug Fig. 22-4. Method of dripping supply risers Fig. 22-5. Three methods of making loops to through a Webster Return Trap into vacuum return provide for expansion movement in risers. The ex- line; the vertical leg acts both as cooling surface and pansion of supply and return risers should have dirt pocket careful study Up to Radiator Dirt Pocliel— _J_4 _ Fig. 22-7. Arrangement for drip- ping a down-feed riser into an over- head return main, showing the un- covered horizontal cooling pipe ' Supply Riser Fig. 22-6. Arrangement for dripping the end of a sup- ply main, which also carries the condensation from the up- feed risers, into an overhead return main. The return trap is located at a point four feet or more from the point dripped WEBSTER RETURN TRAP Overtiead Return IWaJn-^ 216 irt Pocl I Floor Line Fig. 22-30. In the usual down-feed system where the drips of risers are cared for by a separate gravity drip line run near the floor and where the condensation is to be delivered to an overhead vacuum return line through a Webster Heavy-duty Trap, the method shown should be followed 223 Supply Riser - =h^-— 'Return Risei Gate Valve - ^ t,: _ J Reducer- Pipe uncovered. Gate Valve - w Dirt Pocket Cap — > rm ^Ceiling -One size larger than Trap -WEBSTER RETURN TRAP Z^— ""'"a P~ o Steam Supply Main Return Main Fig. 22-31. Arrangement for drip- ping both riser and main where an up- feed riser is fed from the bottom of a supply main. A vertical cooling leg is used Ceiling Steam Supply Main Return Main Fig. 22-32. Arrangement of connec- tions where the up-feed riser is fed from the top of the overhead supply main and the return main is also overhead. A vertical cooUng leg is used Supply Riser WEBSTER RETURN TRAP Plug Floor Line Dirt Pocket Cap Ceiling/ WEBSTER RETURfl TRAP Return Main Return Riser ,'Supply Riser Dirt Pocket Cap Fig. 22-33. Where it is not possible to run a vertical cooling leg on the drip of the riser, cooling surface in the form of a horizontal pipe may be employed as shown 224 Fig. 22-34. Arrangement for removal of condensation from a group of not over 14 sections of vento radiation, where the steam supply enters one end of the group and the returns are taken from the opposite end. The return of each group is separate, the con- densation being carried through a common return line to the Webster Heavy-duty Trap, and the airfromeach group handled separately through a Webster Re- turn Trap connecting to a common discharge line to the vacuum return line. For details of the Webster Heavy-duty Trap see Fig- Blast Heater Sections ure 22-35 WEBSTER RETURN TRAPS Vacuum Air Line Gate Valve VIEBSTER DIRT STRAINER WEBSTER HEAVY DUTY TRAP' Thermostatically Controlled Air Bypass Fig. 22-35. Cross section of Webster Heavy-duty Trap with thermostatically controlled air by-pass, to prevent trap from becoming air-bound 225 Fig. 22-36. The usual method for removal of con- densation from a group of not over 22 sections of vento radiation supplied with steam at each end, is to provide a drip connection also at each end as shown. In some instances, however, where the pressure is low or more than 22 vento sections are used, one of the return Unas should be extended Co„^";'Zs' through the Vento bushing and to about the center ot the group, so that air-binding will be avoided Blast Heater Sections WEBSTER .RETURN TRAPS Drip Connections same as stiown for opposite Side - Blast Heater Sections Gate Valve- WEBSTER DIRT STRAINER > Ecce Bushing niric .dPCj^ WEBSTER RETURN TRAP WEBSTER HEAVY DUTY TRAP Fig. 22-37. Method of dripping double-tierj blast heater sections through Webster Dirt Strainer and Hea\ y-duty Trap WEBSTER RETURN TRAP Vacuum Air Line Ife- WEBSTER HEAVY-DUTY TRAP ±=^ Check Valve & WEBSTER DIRT STRAINER' -..Aiy ^tttt^ Vacuum Return 226 Return Main WEBSTER RETURN TRAP Fig. 22-38. Drip of main and up-feed riser using horizontal cooling surface Supply Steam Connections Blast Heater Sections Eccentric Bushings WEBSTER DIRT STRAINER WEBSTER HETUHN ^TRAPS A -Doorway — Air Pipe Air Pipe must be '/a Diameter ol Return Return toward Vacuum Pump Vacuum Return Near Floor" '/2 Difference I in Levels J t r Floor Line Plugged Tee. T^^^^^^^^^^ Line of Trench Under Doorway Plugged Tee Hot Water Outlet HotWatci Generator Steam Inlet Vacuum Return Fig. 22-39. Arrangement of piping where a vacuum return line is carried along the wall near the floor and passes doorways or other openings. The water is carried under the opening and the air is passed through the line over the opening Fig. 22-40. Method of dripping blast heater section through Webster Return Traps Reducing Ell Gale Valve / WEBSTER HEAVY-DUTY TRAP ^Mud Blow WEBSTER CLASS B" DIRT STRAINER Fig. 22-41. The approved method of draining condensation from the c o i 1 s of a hot-water service heater to the vacuum return line through gate valve, Webster Dirt Strainer and Webster Heavy-duty Trap Trap on Bracket Support on Foundation or on Floor 227 Details Applicable to the Webster Modulation System Only Supply Riser or Supply Connection to Radiator This Connection '/2 when Air Line Valve is 10' O'or less from Dry Return Branch or Main and 3/4 when over 10'0"distant / CeiInQ Line"" 1/2" WEBSTER RETURN TRAP^ 1/2 Socket Supply Mam must be Run Full Size to Drip Point Connection Drop Leg- First Floor Line " Drip to Wet Return at end . of Run in Main Reducing Tee Union above Water Line of Boiler Water Line ot Boiler^ Overhead Djy Return/ Under no Circumstances must the Center Line of this Pipe be less than 6" above Center Line of Return Inlet of Vent Trap ^Never less than 1" — ^Reducing Tee Connect into Wet- Return Main Union above Water Line of Boiler q=rr- /Water Line of Boiler Connection into Wet Return Line - Wet Return near Floor Nv- Wet Return near FIooj;, with space beneath tor Cleaning The Connection into Wet Return must be same size as Dry Return before Rise is made This Connection must be on same Centre as Wet Return Special Swing Check Valve L Floor Linei '-^ i=^ 2 'Floor Line Fig. 22-43. Where a drip is required, at the end of a heating main, the air should usually be vented through a Webster Re- turn Trap into the dry return, as shown in this diagram Fig. 22-42. The dry return in a Webster Modulation System, due to its required grade, must sometimes get down into the head room, in which event it may be drained into the wet return and elevated to a higher level. Certain fundamentals must be observed in do- ing this. The most important is that at the point where the change in elevation occurs, the dry return must never be closer than 6 in. to the level of the inlet to the Webster Modulation Vent Trap 228 WEBSTER RETURN TRAP Above highest point of — Dry Return Supply Main 30 or more If possible Union— '<1-'t' This Connection must Special Swlna be on same Centre as ^^ Check Valve Wet Return ^"^\ \ Fig. 22-44. There is often a demand for hot water for domestic sup- ply where this water can best be heated by transfer of part of the heat from the conden- sation in the steam heating system. The diagram shows one method of doing this in connec- tion with a Webster Modulation System. The hot- water heater and storage tank should be located close to the stCEun boiler so that the steam supply will be available when the plant is being operated at very low pressures Water Line of Boiler^ 'Return from ftot Water Generator. Connect to Wet Return Wet Return near Floor g pMH^ X_ Floor Line -a WEBSTER RETURN TRAP Fig. 22-45. Connections for overhead radia- tion in basement, where there is sufficient drop for gravity flow between the radiation and the water line of the boiler Connect into Wet Return Main" Water Line of Boiler- tjPNP Special Swing Check Valve -This Connection must be on same center as Wet Return Wei Return near Floor 229 V'l"Pipe Sleeve over Rod must — >\\ extend thru Bolt Holes in Diaphram' Portion ol Damper Regulator WEBSTER MODULATION VENT TRAP Overiiead Return from Heating System Fig. 22-46. Typical ap- plication of Webster Damper Regulator Check Valve to a cast-iron sec- tional boiler Fig. 22-47. Method of making connections to boilers operating in parallel. Check valve on vent dis- charge trap only. This is the arrangement of return connections required by many boiler insurance companies 230 WEBSTER MODULATION VENT TRAP Overhead Return from Heating System This Distance to „ be not less than 30 Water Line,of Boilerj Drip from Bottom _of Steam Header to connect to Return Header of Boiler With thermostatic control Lock V2flod Threaded at ends wiih^j 3/4ptpe Sleeve over Rod must extend through Bolt Holes in Diaphragm Portion of Dami Regulator. Remove Pin from Damper^ Regulator. WEBSTER I MODUUTION-- SYSTEM GAUGE Overhead Return from Heating System This Distaince to be not less than 30' Water Line of,, Boiler; Drip from Bottom of Steam Header to Connect to Return Header of Boiler Note:- Oamper Regulator Lever to Rest on Knife Edge in Slot of Damper Regulator With time-clock Control Fig. 22-48. Typical applications of special controlling devices which may be applied to Webster Damper Regulators 231 WEBSTER RETURN TRAP, above Highest Point ol Dry Return .Conned into Top of Return .Supply Line Fig. 22-19. Radiation must sometimes be placed on the side walls of basements, where steam can be circulated only by pro- viding sufficient head for gravity flow be- tween the radiator return outlet and the water line of the boiler. The arrangement shown handles this problem well Ttiis Connection must be on same Center as Wet Return \ Special Swing Check ValveS, ^fW Water Line of Boiler Return Iron Radiator Connect to Wet Return Wet Return near Floo l^i_ Fluor Line"^^ 232 CHAPTER XXIII Capacities and Ratings of Webster Valves and Traps CAPACITY is a basis obtained from tests under one set of conditions from which ratings are deduced for other operating conditions. The term capacity is used in "Steam Heating" to denote the number of pounds of condensation per hour (Wi) which at uniform flow will pass through the specified apparatus when the pressure is maintained at 1 lb. per sq. in. (Pi) above that of the atmosphere and the pressure at the outlet is that of the atmosphere (P2). Having obtained the capacity of any unit of steam-heating apparatus under these standard conditions, ratings may be estimated within a very small error, for other stated conditions of pressure difference, time or amount of heat content in the steam at given initial pressure. For any other pressure difference (P3 - P4) not differing greatly in amount from the standard pressure difference (Pi- P2), the quantity of discharge (W2) varies from the quantity (Wi) discharged under standard conditions in proportion to the square roots of the pressure differences; that is W, = W, P; iK or so nearly as to be within the normal errors of test. The distinction which should be made between capacity and rating, especially where rating is expressed in some indeterminate value like "square feet of radiation," can best be emphasized by examples. Assume a radiator trap, the capacity of which, with a drop from 1-lb. pressure above atmospheric in the radiator and trap, to atmospheric pressure in the trap outlet, has been found by tests to be 60 lb. of condensation per hr. Example 1. At what should this trap be rated in square feet of radia- tion on a coil in a room of 60-deg. average temperature, when the steam pressure in the coil is 4-lb. gauge and the vacuum at the trap outlet is 10-in. or 5-lb. gauge .^* Answer: The pressure difference through the trap would then be 4 + 5, or 9 lb. The flow through the trap would be as the square root of 1 is to the square root of 9, or three times the capacity of the trap at standard 1-Lb. pressure difference. This figures out 180 lb. per hr. Each pound of steam at 4-lb. gauge pressure gives up in condensing in a coil about 963 B.t.u. of latent heat, a total of 963 X 180 or 173340 B.t.u. per hr. Under the temperature due to 4-lb. gauge pressure the coil would probably give off 324 heat units per sq. ft. of surface. Therefore, the rating of this trap under the above conditions would be 324 divided into 173340, or 535 sq. ft. of direct radiation. Example 2. At what would this same trap be rated in square feet of 233 radiation on the same kind of a coil similarly placed when supplied with steam at 3^-lb. gauge, and exhausting to atmospheric pressure at the outlet? Answer: The pressure difference tlirough trap being as stated, 3^ lb. per sq. in., the flow through trap will be as the square root of 1 is to the square root of i<4, or i^ the rate at 1-lb. difference in pressure, or 30 lb. of steam per hr. Each pound of this steam will give up in condensing about 969 B.t.u. of latent heat or 969 X 30 = 29070 B.t.u. per hour. Under the temperature due to 3^-lb. gauge pressure, the coil would probably give off 300 B.t.u. per sq. ft of surface. Therefore the rating of the trap under the conditions of this example would be 29070 divided by 300 = 96.9 sq. ft. of direct radiation. In Example 1, the rating in sq. ft. of radiation is more than five times that in Example 2, the difference being due to the effect of differences in pressure on the same trap, which in both cases had the same capacity. Webster Modulation Supply Valves : Careful consideration should be given to the following facts concerning ratings of this type of apparatus: The capacity of a modulation valve should be based on the quantity of steam expressed in pounds per hour, or the equivalent B.t.u. of latent heat therein at 1-lb. pressure above atmospheric pressure which will flow through the valve when the outlet is at atmospheric pressure. This capacity may be referred to as the number of square feet of radiat- ing surface which will absorb the total latent heat of the steam flowing into the surface in a given time, at the commencement of which the tem- perature of the metal of the radiation and the room are at a stated degree below the normal room temperature. The steam requirements for all types of radiation are greatest during the heating-up period. This is the period during which the cold metal is absorbing heat, while at the same time the radiator as a whole is giving off heat by radiation and convection at approximately one half its normal rate. This statement is approximate because the temperature of the radiating surface is gradually increasing from the cold room temperature to the steam temperature, during this period. Other things being equal, it follows that the longer the allowable heating- up period, the greater is the proportion of capacity which may be expressed in the rating. Each type of radiation having a different weight of metal per square foot of heating surface and a different heat emission rate, will take a different rating of inlet valve of a given capacity. The consensus of opinion seems to be that the rating of a valve should be only such part of its capacity as will permit the heating of the entire radiator to steam temperature from a room temperature of 40 deg. fahr. in 20 minutes from the time the valve is fully opened, and this is taken as the heating-up period in the ratings given in the tables in this chapter. Radiation, according to type, varies in weight between 2.3 and 7 lb. per square foot of surface. This causes a marked difference in the steam requirements during the heating-up period, as well as a marked difference in the rating of any valve of given capacity. In Table 23-1 the warming-up requirements of the various types of 234 direct radiation in general use and, in Table 23-2, the normal heat emission in 70-deg. air, have been averaged under five classifications. From these averages, the factors in column 6 have been derived by which the capacity of any inlet valve in pounds of steam per hour at 1-lb. differential may be converted into rating in square feet of radiation of any of these general classes. Table 23-1. Basis for Rating Inlet Valves Heat required to raise temperature of metal from 40 to 210 deg. fahr. in 20 minutes. Temperature difference 170 deg. fahr. Specific heat, cast iron .12; mild steel .117 Avg. wt. per sq. ft. cast-iron floor radiation 7.00 lb. x .12 x 170 =142.80 B.t.u. per sq. ft. " " " " cast-iron wall radiation 6.50 " x .12 x 170 =132.60 " " " " " " " " sheet-steel radiation 2.30 " x .117 x 170 = 45.75 " " " " " " " " IM-in- coil radiation 5.20 " x .117 x 170 =103.42 " " " " " " " " 1 -in. coil radiation 4.85 " x .117 x 170 = 96.47 " " " " Table 23-2. Rating Values for Modulation Valves For various types of direct heating surface Ccl. 1 Col. 2 Col. 3 Col. 4 Col. 5 Col. 6 B. t. u. per sq. ft. per hr. to maintain 210° in the rad. with room temp, of 70° B. t. u. emitted in 1-3 hour during warming- up period = 1-6 hourly rate B. t. u. per sq. ft. to raise temperature of metal B. t. u. per sq. ft. req'd in 20 minute period. Total of Cols 2 and 3 Combined hourly rate in B. t. u. C01.4X|? Factor for con- verting capacity into rating 970 ^ Col. 5 Cast-iron floor radiation 245 Cast-iron wall radiation 296 Sheet-steel radiation 260 l}^-in. pipe coil radiation 326 1-in. pipe coil radiation 296 40.8 49.33 43.33 54.33 49.33 142.8 132.6 45.75 103.42 96.47 183.6 181.93 89.08 157.75 145.80 551 546 267 473 437 1.76\Avg. 1.78/1.77 3.63 2.05 2. 22 To ascertain the rating in terms of square feet of radiation of any inlet valve for 20-min. heating-up period, multiply the capacity of the valve ex- pressed in pounds of steam per hour at that given pressure difference by the factor in column 6 corresponding to type of radiation and the result will be the square feet of that surface heated from 40 deg. to 210 deg. in 20 minutes. To ascertain ratings for any other period than 20 minutes, a new table must be prepared retaining columns 1 and 3. New column 2 will be deter- mined by multiplying the B.t.u. in column 1 by one-half the selected warming-up period in parts of one hour. (See seventh paragraph, page 234) . New column 4 will be the sum of new column 2 and standard column 3. New column 5 will be the product of new column 4 by (60 divided by the selected warming-up period in minutes). New column 6 will be the quotient of new column 5 into the latent heat in 1 lb. of steam at pressure. Having the rating for any particular valve for a particular class of radiation at 1-lb. differential, ratings at other pressure differences may be closely approximated by multiplying the 1-lb. rating by the square root of the other pressure difference. The normal average flow to a heated cast-iron radiator is about 250 B.t.u. A properly designed modulation valve, when 0.6 open should supply the radiator with fV of the full-open flow, which is the approximate need 235 for full modulation effect. The balance, or iV of the openmg, is thus available for a quick warming-up period (20 minutes) when the valve is full open. Owing to the wide difference in area between standard pipe sizes, a valve of say 1-in. size must be used on all different sizes of radiators between its own maximum rating and that of the next smaller, or ^-in. valve. The wide-open 1-in. valve will therefore produce a much more rapid heating-up effect when connected to a radiator which is a little too large for a ^-in. valve, and the full modulation effect will be reached much before the valve is 0.6 open, which is the normal position for full modulation effect. This problem might be solved were it not for commercial considerations, by putting a restrictive valve piece in those valve bodies which are used on the lower half of the range. This would limit the flow at 0.6 open to about half way between the maximum for that particular valve and the maximum of the next smaller size. In this way, a valve having a total range of 45 to 78 sq. ft. of radiation at 0.6 open can be limited to 45 to 60 sq. ft. of radiation, thus gaining the whole 0.6 range for controlling the degree of modvdating effect, instead of commencing to modulate only after about "^i closed and having but the remaining Js of the total move- ment for graduating the modulating effect. The ratings of each Webster Type W Modulation Valve for the stated conditions, at various positions of the pointer, are indicated in Figure 23-1, which in conjunction with Table 23-3 will assist in selection of a valve of the proper size for any set of conditions. Initial steam pressure alone is not a correct basis for valve rating or sizing. It is far safer to allow for maximum possible drop in line pressure when figuring the inlet pressure at the valve. Similarly, allowance must be made for variation in return line pressure, especially with vacuum systems. OPEN 10- ^- o / ^^^ "^ ^ / / ^ y ^^ p^^-—-"'^ CO -a CO en 1 r J CH O) - g /// Y 03 U = 9 \lil "en SHUT III 40 SO 120 160 200 240 Square Feet of Average Cast-iron Radiation 280 320 360 400 Fig. 23-1. the Rating of Webster Type W Modulation Valves. Based upon a differential of one pound at valve and fully heating the radiator in 20 minutes in a room temperature of 40 deg. fahr. 236 The condensation rate of radiation varies with the type of radiation or coil, its location, and the difference between outside and room temperatures, and allowance must be made accordingly. Table 23-3. Ratings of Webster Type W Modulation Supply Valves In square feet of average oast-iron direct radiation at various pressure dilTerences. Based on 20-niin. heating-up period from 40 deg. fahr. initial temperature* Pressure difference Size of valves 1 oz. 1 2 oz. 1 4 oz. 6 oz. Soz. 1 lb. Square feet of average cast-iron direct radiation y2" 19 27 38 47 54 76 H" 40 57 80 98 113 160 1" 65 94 132 63 187 265 iH" 112 160 225 76 319 450 Table 23-4. Ratings of Ordinary Angle-pattern Radiator Supply Valves In square feet of average cast-iron direct radiation at various pressure differences. Based on 20-min. heating-up period from 40 deg. fahr. initial temperature* Pressure difference Size of valve 1 oz. ] 2 oz. j 4 oz. 6 oz. 8 oz. lib. Square feet of average cast-iron direct radiation 'A" 21 30 42 52 60 84 H" 44 62 87 107 124 175 1" 77 102 147 180 204 294 IM" 126 180 2.52 308 360 504 iy2" 187 258 364 446 516 728 Table 23-5. Ratings of Webster Double-service Valves In square feet of average cast-iron direct radiation at various pressure differences. Based on 20-niin. heating-up period from 40 deg. fahr. initial temperature * Size of valve Pressure difference 1 oz. 2oz. 4 OZ. I 6 oz. 1 8 oz. lib. Square feet of average cast-iron direct radiation H" 42 60 85 104 120 166 1" 69 97 138 168 195 275 IM" 119 168 238 292 336 475 VA" 172 243 343 420 486 685 * If the quick heading-up feature is disregarded and ratings are desired for normal requirements only, after the radiator has been heated up, multiply the values in the tables by 2.2. Webster Return Traps: Both the Webster Sylphon Return Trap and the Webster No. 7 Return Trap are rated on the basis of the quantity of condensation which they will pass under stated conditions. Owing to the fact that these traps when cold are fully open, the warm- ing-up period of a radiator has no bearing upon the problem of rating return traps even though the discharge of air and water are then at maximum. The thermostatically actuated members of Webster Sylphon and No. 7 Return Traps are sensitive to very slight changes of the temperature of 237 the surrounding medium. The motion of the members is due to the difference in pressure and temperature on a hermetically sealed charge, partially liquid, partially gas and vapor, which responds to changes in temperature with material changes in volume and pressure, and this provides a power- ful force to actuate the valve piece. Table 23-6. Ratings of Webster Return Traps in Pounds of Condensation and B.t.u. per Hour at Various Pressure Differences Size and type Pressure difference of trap 2 oz. 4 oz. 6 oz. 8 oz. lib. Lb. B. t. u. Lb. B. t. u. Lb. B. t. u. Lb. B. t. u. Lb. B. t. u. K"-512 & 712 }^"-522 & 722 Ji"-533 & 733 l"-544 & 744 lM"-545 & 745 14 22 66 133 265 13580 21340 64020 129010 257050 19 31 94 188 ,375 18430 30070 91180 182360 363750 23 38 115 230 459 22310 36860 111550 223100 445230 27 44 132 265 530 26190 42680 128040 257050 514100 38 62 187 375 750 36860 60140 182390 363750 727500 Table 23-7. Initial Steam Pressures and Pressure Drops through Supply Pipes, Modulation Valves and Return Traps of the Heating Systems of Different Tjrpes of Buildings Case Approximate steam pressure in zero weather Pressure drop through supply piping Average pressure differential through valves Modulation supply valve Return trap A }4to%\b. yg lb. with mini- mum run-400 ft. 2oz. 2oz. B ItolJ^U). i<4 lb. with mini- mum run-400 ft. 1 oz. 4 to 6 oz. c 1 to 2 lb. A lb. with mini- mum run-400 ft. 4 oz. 4 to 6 oz. D Vi to 2 lb. J^ to 1 lb. 4 oz. 4 to 6 oz. E VA to 2 lb. 1 lb. 4 to 6 oz. 8 to 12 oz. NOTE: In modulation systems in conjunction with low-pressure boilers of limited water capacity, it is essential that the drop in pressure through the system be kept well below the pressure due to the static head between the modulation vent trap and the water line of the boiler. Special apparatus may be provided to return water to boiler where, owing to structural con- ditions, the above outlined conditions cannot be obtained Note: Webster Water-seal Traps in the few cases where they are used are rated same as the Sylphon and No. 7 Traps. Selection of Modulation Supply Valves and Return Traps: For any given installation the choice of the proper sizes of modulation valves and return traps will depend upon the available pressure differential through the valves. This, in turn, is dependent upon the steam pressure maintained at the boiler and the drop in pressure through the piping system. Wlaile it is not possible to lay down hard and fast rules which are applicable for every installation, the following cases are given as representative types of systems in general use. Cases A to D inclusive, given in table 23-7, relate to 238 modulation systems, with open returns terminating at the boiler in a modulation vent trap or some similar forms of apparatus. Case E is the usual type of vacuum system. The proper sizing of supply and return pipes is explained in detail in Chapter 1 1 and the pressure drops referred to below are found in Table 11-8. Case A: Residences and small apartments where the firing is inter- mittent, frequently extending over eight or perhaps ten-hour periods and where it is necessary to operate at low steam pressure. In mild weather it may be possible to circulate steam through the entire system at or perhaps slightly below atmospheric pressure. In zero weather a pressure will be maintained at the boiler of from 3^ lb. to ^ lb. depending upon the kind of fuel, length of firing period and condition of fire. Case B: Very large residences, apartment houses, small ofiices and public buildings where large size cast-iron sectional or steel boilers are installed, operating at low steam pressure and under the care of a regular attendant, with continuous firing instead of intermittent. Case C: Schools and similar buildings containing large amounts of indirect radiation where there are periods of interruption in maintaining pressure on the system and where quick circulation is desired when starting. Case D: Buildings where the pressure is maintained constant by means of a reducing valve and steam is taken at higher pressure either from its own boiler plant or from a street system. Case E: Ofiice buildings, industrial plants, etc. in which a vacuum system is installed using live steam at reduced pressure, or exhaust steam from engines, pumps and auxiliary apparatus, supplemented by live steam passed through a reducing valve. The steam pressure at the entrance to the supply piping in zero weather will range from IJ^ to 2 lb. and the vacuum on the far end of the return line will be approximately 2-in. Webster Heavy-duty Return Traps: This trap is for use where large quantities of condensation are to be handled at any temperature. It has a cone-shaped float-operated valve piece seating on a sharp-edged orifice, the seat being below the low-water line of the trap. The air entering the trap is allowed to pass to the return line, through a connection controlled by a thermostatically operated trap discharging through a cored passage to the return line. In special cases the opening through the air orifice may be adjusted by hand. Table 23-8. Ratings of Webster Heavy-duty Traps in Pounds per Hour at Various Pressure Differences Through the Valve No allowance made for pressure drop in the connecting piping between radiation and trap or from trap through run-out to return Size Pressure difference of trap MLb. ILb. 2 Lb. 3 Lb. 4 Lb. 5 Lb. 10 Lb. 15 Lb. 0019 019 119 219 700 1250 2100 5600 1000 1800 3000 8000 1400 1700 2500 3050 4200 5100 11200 13600 2000 3600 6000 16000 2200 4000 6700 17900 3150 5700 9500 25300 3900 7000 11700 31100 Webster Series 20 Modulation Vent Traps: Capacities of Series 20 Modulation Vent Traps are based upon the assumption of an air flow of 239 6000 cu. ft. per hour through a vent orifice of 1 sq. in. area from a pressure of 1 lb. above atmosphere to atmospheric pressure. This quantity is obtained as follows: . Velocity of flow in feet per second is V = C ^ 2 gh, and the quantity in cubic feet per Jiotir is Q = 3600 x av. in which Q is the quantity in cubic feet, c is a constant (0.7), h is the height of a column of air in feet, required to produce a pressure of 1 lb. per sq. in., a is the area of the orifice in square feet, v is the velocity in feet per second and g is 32.17. 1 Lb. of air contains approximately 13.2 cu. ft. For any other pressure difference not varying greatly in amount from the above standard pressure difference, the quantity of discharge will be substantially proportional to the square roots of the pressure difference. Assuming that 50 sq. ft. of cast-iron radiation, with connecting supply pipes, will contain 1 cu. ft. of space, from which the air must be discharged before steam will enter, the following basic data applies for Modulation Vent Traps. Table 23-9. Basic Data for Modulation Vent Traps Size of trap 0020 020 120 220 320 Cubic feet of air discharged per hour at 1 lb. differential 85 660 1176 2652 4710 Cubic feet of air discharged per hour at 1 oz, differential 21 165 294 663 1178 Square feet of direct radiation per hour at 1 oz. differential 1050 8250 14700 33150 58900 Referring to page 117, it is to be noted that air vent traps are rated on the basis of flow of initial air from a system in 40 min. with 1-oz. differential pressure through the system. The table below gives the ratings on this basis for which the Webster Modulation Vent Traps should be applied. Table 23-10. Ratings of Series 20 Modulation Vent Traps Size of trap 0020 020 120 220 320 Square feet of direct radiation in 40 min. at 1 oz. pressure 700 5500 9800 22100 39265 No. of *-in. unit vent valves required 1 1 2 3 5 Modulation Vent Valves are required wherever it is desired at times to operate the heating system at a pressure less than atmospheric. Where large heating units are under automatic temperature control, the use of these vent valves is inadvisable unless vacuum breakers are provided at the proper points in the piping system. 240 CHAPTER XXIV Appliances for Webster Systems of Steam Heating WEBSTER Appliances used as parts of heating systems are illus- strated and briefly described in the following pages. These appliances include: Return Traps Gauges Heavy-duty Traps Modulation Vent Traps High-differential Heavy-duty Traps Modulation Vent Valves Modulation Supply Valves Damper Regulators Double-service Valves Hyio Vacuum Controllers Oil Separators Hylo Traps Grease and Oil Traps Conserving Valves Suction Strainers Boiler Feeders Dirt Strainers High-pressure Traps Vacuum-pump Governors Hydro-pneumatic Tanks Lift Fittings Expansion Joints Return Tanks Steam Separators Water Accumulators Feed-water Heaters Vapor Economizers Return Traps for Automatically Removing Water of Condensation and Air from Heating Units The return trap, to be perfect in operation, should — (a) Allow the condensation to escape at a temperature slightly below that of the steam. (6) Drain the radiator thoroughly by gravity, without the assistance of pressm-e or vacuum. A water-logged radiator loses efficiency because part of the heating is being done by the water condensed from steam, which is at lower temperature, and because a water-logged radiator is also an air- bound radiator. (c) Permit continuous removal of air. An air-bound radiator loses efficiency because the steam cannot completely fill it. (d) AutomaticaUy close to prevent loss or waste of steam. (e) Work within the widest necessary range of pressure and vacuum variation. , (/) Require no adjustment under such variations. (g) Be noiseless in operation, if used where noise is objectionable. (h) Be so designed that the valve will close even where dirt may be present in normal quantities. (0 Be durable and require little or no attention or repairs. 241 The efficiency of the radiator will depend upon how nearly the return trap meets these requirements. A return trap working sluggishly will not only hold back the water, but will "bottle up" the air and air-bind the radiator, thus defeating the very purpose of a vacuum system. As different methods must at times be employed in connection with direct radiators, blast sections, riser drips, main drips, dripping hot-water generators, factory coils, etc., Webster Return Traps are made in several forms, at least one of which will meet the requirements of any installation. 100% RADIATOR EFFICIENCY 1 SUCCESSFUL OPERATION AT VARYING PRESSURES 1 1 «« AUTOMATIC REMOVAL OF AIR AND WATER OF CONDENSATION WITH NO LEAK- OF STEAM 99.5 PLUS PER CENT VAPOR EFFICIENCY NO INTERFERENCE BY DIRT WITH THE PROPER FUNC- TIONING OF TRAP Fig. 24-1. The requirements of a perfect radiator trap The type and capacity of the trap required depend upon the point of application, the amount of air and water to be removed, the character of the heating surface and the pressure and vacuum carried. It is important that all of these conditions shall be studied carefully before selection is made of the size and type of trap for specific applications. The Webster Sylphon Trap The Webster Sylphon Trap has been specially designed to meet the requirements for a perfect radiator trap. It maintains the highest possible efficiency within the heating surface by the removal of all of the products of condensation, and as this is effected without loss of steam, it is economical in the highest degree. The economy is especially apparent when reduced- pressure live steam is used in whole or in part, or where, before its appli- cation it has been necessary to waste large quantities of cold water to cool the heating system returns before they enter the vacuum pump. The operating member consists of a Sylphon bellows, which carries a 242 conical-shaped valve piece, closing against a sharp-edged seat. The bellows member is very sensitive, operating to close or open the valve port by the slightest change in the temperature of the sm-rounding medium, and is the most durable form of thermostatic device so far known. The multiple construction of the seamless brass folds forming the bellows distributes the Fig. 24-2. No. 512 Model H Webster Sylphon Trap. Size of pipe connections, ^-in. Fig. 24-3. No. 522 Model H Webster Sylphon Trap. Size of pipe connections, i^-in. Nos. 512 and 522 differ in rating and lift of valve. No. 522 being larger No. 523 has same size body mechanism and rating as No. 522, but has J^-in. pipe connections to meet unusual specifications in that respect strain of movement and increases the hfe of the operating member. In- crease in steam pressure on the outside of the bellows is compensated by the increase in pressure on the inside of the bellows. The sensitiveness of this member is due to the flexibility of the walls 243 of the bellows to movement in the desired direction and the small amount of movement of each fold when acted upon by the pressure surrounding and also that generated within the bellows. The sum of the small movement of each of the many folds gives a greater total lift of the valve than any other device for similar purpose. The conical valve piece and sharp-edged seat give increased capacity Fig. 24-4. No. 533 Model H Webster Sylphon Trap. Size of pipe connections, 54-in. No. 534 has same size body with 1-in. pipe connections to meet unusual specifications No. 544 is similar, but larger throughout for 1-in. pipe connections and greater duty No. 545 is the largest in proportions and ratings. For l}i-in. pipe connections for discharge of water, and the valve does not become inoperative due to presence of dirt and scale. The Webster Sylphon Trap will close quickly and positively when steam reaches the bellows, while the water and air will be freely withdrawn or dis- charged at temperature slightly below that of steam at existing pressure. This means that every radiator in use will be thoroughly efficient in heating, as there will be no "pocketing" of air or "bottling up" of water within the radiator. As the valve is full open when cold, the radiator will be fully drained when steam is turned off, and the vacuum condition existing in the return line will extend within the radiator, assisting circulation when steam is again turned on. Operation : As the steam first flows into the cool radiator, it expels the contained air and initial condensation through the wide-open trap. As the radiator warms up from inflow of steam, the bellows commences to expand, but remains partiaUy open as long as the air and water in the trap are at a lower temperature than that of the steam. The moment the air is entirely expelled from trap body, and replaced with steam, the valve closes. It opens again when water and air at a temperature slightly less than that of the steam accumulate in the trap. Then, as the water and air escape and are replaced in the trap body by steam, the trap again closes, thus complet- ing its cycle. 244 Table 24-1. Models and Dimensions of No. 5 Sylphon Traps for Working Pressure Up to 10 Lb. per Sq. In. For convenience in making pipe connections, Webster Series 5 Sylphon Traps of the smaller sizes Eire made with four types of bodies as shown. Model H or angle is the one most used Model H Angle Model G Straightway offset Model R Right corner Model L Left corner Fig. 2 1-3. Bodies of Webster Series 5 Sylphon Traps ■^-C-^ A Size Trap no. & model A B c D J^" 512H 3" 1^" IKs" 41/9" Vs" 522H 35^" W^' ll%" 5M" %•• 523H W^' 2" lA" 5M" M" 533H 4i^" 2Vs" IM" ^%" 1" 534H 4J/8" 2^" Wi" 5H" 1" 544H 4^" 2^" 2" 6M" IM" .545H xy^- 2,%" 2" 6H" Fig 24-6 Fig. 24-7 Fig. 24-8 Size Trap no. and model A B c D E H" 612G, 512R or 512L 3" IK2" 1" iVi" IH" H" 522G, 522R or 622L 3-i-s" ^Vi" IK" 5=4" 15^" %" 523G, 523R or 523L 3K" nv IK" 5A" IK" M" 533G iA" 2,V" iM" 5%" Not 1" 534G 4H" 2 A" m" 0" made For ratings, see Table 23-6, page 238. 245 The Webster No. 7 Trap Fig. 24-9 Exterior and interior of No. 722 Webster Trap Webster No. 7 Traps also realize all of the requirements for thoroughly satisfactory operation as radiator traps. They are applied at the outlets of steam radiators and coils, at drip points on steam supply hues and risers and at the outlets of blast sections on fan coils and provide continuous free and thorough re- moval of entrained air and water of con- densation, without permitting any live steam to escape to waste in the return lines. The inlet of the trap is attached to the radiator, coil or supply line by means of the union connection, and the outlet is piped into the return line. The thermostatic member is inboard of the valve seat where not affected by pressure or temperature in the return line. The diaphragm, which forms the active part of the operating member, is built of Table 24-2. Models and Dimensions of Webster Series 7 Traps for Working Pressure Up to 10 Lb. per Sq. In. For convenience in making pipe connections, Webster Series 7 Traps are made with four types of bodies as shown. Model H or angle is the one most used Size Trap no. A B c D E y^' 71 2H Wi" ll^" 1^" 015// -16 Vi" 722H W2" lA" IJ^" •■5,^" %" 723H SVs" It^" VA" 3i%" %" 733H 4M" l%" 2H" 4A" 1" 744H 4M" 2" 2K" 4i%" \%" 745H 712G iH" 2" 2y2" 4i%" M" 712R 712L 722G 3M" 2,^" M" 3^" 2H" ¥2" 722RI 722L 33^" 2M" M" ^'A" 2M" For ratings see Table 23-6, page 238 Fig. 24-11 246 four successive phosphor-bronze plates instead of the usual two and for that reason there is greater diaphragm movement and the valve has greater lift than usually found in traps of similar types. The expansion and contraction of the diaphragm member is produced by differences in volume and pressure of a hermetically-sealed fluid charge in response to changes in temperature. Even a very slight temperature change produces a powerful force to actuate the conical valve piece, which in closing, fits tightly on a sharp-edged seat. No part of the valve mechanism is impaired by the quantities of the scale and dirt which normally exist in steam-heating systems. Webster Heavy-duty Traps Fig. 24-12. Series 19T Webster Hea-vry-duty Trap with thermostatically controlled air bypass Series 19T with Thermostati- cally CONTROLLED AlR ByPASS. FoR 15 -LB. Maximum Operating Pressure : The Webster Heavy-duty Trap handles unusually large quantities of conden- sation, and is for dripping main supply risers or mains entering or leaving the building, for draining large sections of blower coils or pipe manifolds, for draining hot-water generators, etc. Insofar as the discharge of condensation is concerned, this trap operates on the float principle and has a large water outlet to withdraw the con- densation as quickly as possible from the unit to be drained. Air is eliminated by means of a thermostatically actuated by-pass, as shown in Figure 24-12. The operating device, the valve piece and seat are the same as used in the Webster No. 7 Trap. 247 The body and cover are of cast iron. The cover is bolted on, easily removable and so designed that all interior parts are exposed for inspection upon its removal. The outlet is in the bottom of the body, and the inlet may be on either end, with the opposite opening plugged. It is recom- mended that wherever practical the inlet farthest away from the valve be used. An opening is provided at the bottom of the float chamber as a clean- out by-pass and for draining the trap when out of use. The float has ample leverage to avoid sticking of the valve. The cone- pointed valve and square-edged seat prevent accumulation of dirt where it might clog the port. The valve is water-sealed at all times, as the water level is always well above the seat. The float lever is kept within the ver- tical plane of action by guide flanges cast into the trap body. This trap can also be furnished special with hand-controlled air and by -pass, where unusual conditions require such construction. In such cases the air port is adjustable for any desired degree of constant leakage. Some of the many practical applications of the Series 19T Trap will be found in Chapter 22. Ratings are given on page 239 and dimensions on page 249. Fig. 24-13. Conventional arrangement of Series 20 Webster High-differential Heavy-duty Trap and Special Webster Dirt Strainer (Inlet pipe may be connected to opposite end if desired) Fig. 2 1-14. Series 20 Webster High-ditferential Heavy-duty Trap for working pressures up_to 50 lb. per sq. in. 248 High-Differential Type, Series 20, For Working Pressures up TO 50 LB. per sq. in.: The Webster High-differential Heavy-duty Trap is recommended for steam pressures higher than 15 lb. and where large quantities of condensation may be discharged. It is particularly applicable to problems like or similar to those described in Chapter 19. The trap body is constructed of cast iron and has an easily removable cover of the same material. The valve is of the balanced type and operates against a steam-brass seat. The ball float is extra heavy to withstand the higher pressures. The Webster High-differential Heavy-duty Trap may be operated with a constant leakage through a hand-adjusted air vent, though the best practice calls for control of the air discharge by means of a thermostatically actuated valve in a by -pass of pipe and fittings as shown in Figure 24-16. It is important to note in this case of higher than ordinary steam pressure, that the thermostatic trap must be of the No. 8 Sylphon type. (See page 275.) Table 24-3. Dimensions of Webster Heavy-duty Traps All dimensions in inches and subject to slight variation Drain Opening Fig. 24-15. Standard type— Series 19T A=Size Outieti.^ ^i Plugged Drain Openino Fig. 24-16. High-differential type — Series 20 For ratings of Heavy-duty Traps see Table 23-8, page 239 Series 19T, with thermostatically controlled by-pass Number A Ai B c D E F G H V V w 0019-T H H 13M 1 ■J'A 12^ iVs 3Vk 2H 9H -^Vh y?. 019-T % H 15M 1 8 15 4H SVs m 9H 6J4 ■H 119-T IVa. iH 193/8 IH 9 18^ 5^/8 VA 4^ ny2 7 1 219-T 2 2 20ys 1^8 10^ 19 J^ 6% m m 13 M 8 1K2 Series 20, high-differential type , Number A Ai B c D E F G H n V W 020 120 220 H IM 2 IM 2 15^ i9ys 20^ 1 8 9 WA 15 183/^ 19}^ 6ys 2% 12M 133^ 6M 7 8 1 1^ 249 The Webster Type W Modulation Valve Fig. :2 1-17. The Webster Type W Modulation Valve — shown in partly open position The Webster Type W Modulation Valve is a special-purpose radiator valve of the quick-opening, non-rising stem, straight-lift type, built for com- plete opening or closing with less than a single turn of the handle. Its manipulation is as simple and its control as effective as the movement that regulates light from a gas jet. As the names implies, the principal function of the Webster Modulation Valve is to facilitate "modulation" of temperature in each room according to the desires of the occupant, by varying the amount of steam admitted to the radiator or coil. A pointer attached to the handle traveling over a graduated dial indicates the amount of valve opening at all times. With the valve full open, the discharge capacity through the ports is nearly equal to that of the outlet connection of the valve. Less than three-fourths of the valve lift and opening movement is re- quired to produce modulation up to normal full heating requirement. The rest is in reserve to admit more steam during the heating-up period, as needed to compensate for the higher condensation rate caused by contact with the cold radiator and its surrounding air. Construction Details : The modulation effect is produced by a pat- ented modulating plug which varies admission of steam in progressive vol- ume with the lift of the valve piece. A Jenkins disc is used to insure tight closing. With the exception of this and the handle, all parts are of brass. The handle is of special composi- tion and so formed that the hand of the operator does not come into contact with the heated surface of the valve body. Application: The Webster Modulation Valve may be used on either hot-water type radiators (having connections from section to section at both top and bottom) or with steam type radiators (bottom connections only), although the former type is preferable from the standpoint of convenience. Where the Webster Modulation Valve is used with the hot-water type of radiator, it should be placed at the top to bring the operating handle in 250 the most convenient location and to permit the steam to circulate across and downward. Air and condensation, being heavier, fall to the bottom in advance of steam and give full efficiency to the heated part of the radiator. Where the Webster Modulation Valve is used with a steam type radiator, it is possible by the use of an inlet section of the hot-water type to secure the con- venience of operation which is obtained where the valve is placed at the top of the radiator. If placed at the bottom of radiators, because other connections cannot be arranged, the inlet bushing should be eccentric and so located that the center line of the radiator or inlet is above that of the radiator outlet. This is essential Fig. 24-18. Typical application of the exten- sion stem principle to prevent condensation from drain- '^^gT Jj ing by gravity through the supply ^'^^ instead of the return connections, thus eliminating water-hammer. Fig. 24-19. Typical appli- cation of chEiin attach- ment to Webster Type W Modulation Valve mi Extension Stem: For attachment to radiators concealed in recesses or under window seats behind grilles, the Webster Modulation Valve is provided with an extension stem and a special dial that may be placed on the face, top or end of the grille or seat (see Figure 24-18). The stem has a universal joint on each end, which permits operation of the valve from a point not directly in line with the valve stem, and at the same time provides enough play to avoid sticking or binding from mis- alignment or shifting caused by expansion and contraction. This con- struction also avoids the necessity for very accurate stem connections. The outside indicator dial, pointer and handle are similar to those used on top of the standard valve. Chain Attachment: The Webster Modulation Valve to be applied to radiators or coils located in skylights, overhead, or on walls near the ceiling, can be fitted with a chain attachment for convenience in obtaining every advantage of the modulation feature (Figures 24-19 and 24-20). The chain wheel is substituted for the handle of the standgu-d type of Modulation Valve and the chain is made just long enough to permit easy grasp from the floor. Tags are attached to bottom of the chain in such positions that the hanging end indicates the degree of valve opening. Table 24-4. Diniensions of Type W Modulation Valve Size A B C D M ■ 2H IK 2Js 4H K Wi Wi 2ys 4^ 1 3M IH 2H 53/8 IM 3 Si o 2H 6 All dimensions in inches and subject to slight variation, o I <>i ^°^ ratings, see Table 23-3, page 237 The Webster Double-service Valve This is one of the latest developments of apparatus for simplifying piping connections in steam heating systems in certain types of construction. Common practice in buildings of only one story and in some other instances calls for a steam supply line along the ceiling of the first floor to feed each radiator or coil through a short down-feed riser, which must be dripped into the return line. This multiplicity of unsightly connections is simplified by the use of Webster Double-service Valves, applied in the manner shown in Figure 24-23. This valve performs "double service, " as a supply valve for the radiator and as a trap for draining the riser. The thermostatically controlled valve is open when there is water or air in the riser, and permits the condensate to flow through a bypass in valve body into the radiator and thence into the return. Upon presence of steam the thermostatic member expands, closes the valve, and thus prevents waste of steam. 252 Fig. 24-22. The Webster Double-service Valve £ ^Supply Main 1 7=^ fe Supply Riser- All Connections to be Irom Bottom of Main Steam is admitted to the radia- tor in amount desired, by means of the quick-opening valve, which is pro- vided with a graduated dial and handle. This valve does not include the modula- tion feature, as the supply valve is designed only for quick opening without respect to modulating effect. The valve body is best-quality cast iron, and all other parts except the valve disc and handle are brass. Nut and nipple are provided only at one end to promote easy installation. AH outside parts are nickel-plated. WEBSTEB DOUBLE SERVICE VALVE Eccentric Bushing 7 WEBSTER RETURN TRAP H Fig. 24-23. Application of a Webster Double-service Valve to a standard cast-iron radiator 253 The thermostatic member, which is built up of four discs of phosphor bronze and filled with a volatile fluid, the conical valve piece and the sharp- edged seat are of standard pat- tern as used in the Webster No. 7 Trap. The inlet valve is provided with a ring seat and Jenkins disc to insure tight closing. Its quick- opening feature is provided by a screw stem of such pitch that the valve will be completely opened with less than a complete tm-n of Fig. 24-24. The Webster Double-service Valve Table 24-5. Dimensions of Webster Double-service Valves Size A B c D E F G H J M 3M 1 2J^ m Wa 2M 2% 9M Vs 1 m IM Wi 5^ I'A 3 3 9H % IM 4 iy2 2% 6M IM 3^ SVs lO^A Vs m 4K Wi 2% 8 IM 3^8 SVs iiM % All dimensions in inches and subject to slight variation. For ratings, see page 237 Webster Oil Separators The Series 21 Webster Oil Separator is made in two patterns — for either horizontal or vertical direction of steam flow. The baffles in the horizontal type are double-hooks so that either nozzle may be used as the steam inlet. The vertical pattern is suitable for up-flow of steam only. An outstanding feature of tliis series of Webster Oil Separators is the position of the manhole cover which makes it possible to inspect or clean the device without disturbing the piping. Septuation of oil and condensation is effected by impact upon and adhesion to baffles and by abrupt changes of direction of flow through the separator. Fig. 24-25. Series 21 Webster Oil Septirator Standard Horizontal Type 254 Fig. 24-26. Series 21 Webster Oil Separator, Standard Vertical Type, lor upflow only There is no unobstructed path through any Webster Oil Separator, yet the free area through which steam must pass is several times greater than inlet and outlet area, thus minimizing pressure loss due to friction. The use of these separators pro- tects boiler heating surfaces and inte- rior surfaces of heating systems from '" "" ""° '^^"'^ """ the oil deposits that otherwise seriously K~] Exhaust /Main WEBSTER OIL SEPARATOR I To Heating Supply Main/ Size of Vent to correspond with Size of Tappino in Top ot Grease Trap WEBSTER GREASE AND OIL TRAP Exhaust MaiRv ize ol Vent to correspond with Size f Tapping in Top of Grease Trap — Hot Well By Pass ' -Laroerthan Drip of Oil Separator t,.y — ^ Free Vent floor Line This Distance Irom Bottom of Oil Separator to the Inlet ot Grease Trap must be at least Five Feet '5'-0'') Gate Valve Floor Line Fig. 24-27. Method of connecting a Webster Grease Trap to a Webster Oil Separator, where a partial vacuum may at times be carried on the heating main Fig. 24-28. Typical method of draining Webster Oil Separator through a Webster Grease Trap, where positive pressure is main- tained at all times impair heat transmission and often cause serious damage. These separators may also be used for such special purposes as removing moisture or oil from compressed air and other gases. That Webster Separators are eflBcient in all their standard and special forms is indicated by absolute satisfaction in over 15,000 installations. 255 The material ordinarily used in the shells is close-grained cast iron, but spe- c al shell of semi-steel, cast steel or other material can be furnished at extra cost. Table 24-6. Maximum Ratings of Oil Sepa- rators in Lb. per Min. at Average Gauge Pres- sures Based on 6000 Ft. per Min. Pipe Velocity Oullel Pressu re, lb. per sq in. Size 5 10 IS 2 5.2 6.7 8.4 10. 3 11.4 15. 18.6 22. 4 19.8 26. 32. 38. 5 31. 40.6 50.2 59.7 6 45. 59. 73. 86.5 8 78. 102. 126. 150. 10 123. 160. 200. 235. 12 176. 231. 285. 339. 14 222. 292. 361. 427. 16 294. 385. 475. 565. 18 375. 492. 608. 720. 20 452. 595. 735. 870. 22 550. 725. 900. 1060. 24 660. 870. 1070. 1270. For lower velocities, the pounds carried will be propor- tional as the lower velocity is to 6000 p- 24-'i0 Table 24-7. Dimensions of Webster Oil Separators All dimensions in inches. Companion flanges furnished only on special order; drilled low-pressure standard unless otherwise ordered Standard Horizontal Type (Fig. 24-30) — for steam flow in either direction Dimensions Flanges SIZE B D E F G Drip Outside diameter Bolt circle No. & sizes of bolts *iy2 10 6ys 33^ iVs (yVs M *9 lOM 8 m 5J/8 7M M 9 12 8 4,3,-8 51/8 7J4 M 6 4M l-Vs 2^ 13 M lOM 5^ 6 8Vs H 7 5}^ -i-H 3 15 11^ 6J^ 63^ 93^ % 7M 6 4r-H ^Vz 15^ 103^8 5 (>h lOK 1 8K 7 4^ys 4 161^ IIM 5}4 6H 1134 1 9 7J^ 8-% 5 iiH 115^ 5h 7 J/2 13M 1 10 834 8-H 6 19 12}^ 6 8M 13^ 1 11 934 8-M 8 21 12K (>H 8^8 18^ IM IW2 iiM 8-M 10 99 16 8J^ 9^8 19M 13^ 16 1434 12-H 12 24H 18^ 9ys WA 22 J^ 2 19 17 12-ys 14 28 99 IVA n]i 22 J^ 9 21 18 M 12- 1 16 31 25 M 13 H 13 233^ 2V2 233^ 2134 16- 1 *Screw connections only. Standard Vertical Type (Fig. 24-29)— for up-flow only Dimensions Flanges SIZE B D E H Drip Outside diameter ly Bolt circle No. & sizes of bolts 3 1334 7^ 334 7M H 6 4-^8 3M uys m 4 9 H 834 i 4-5^ 4 16 9^8 4.34 103^ 1 9 -y-i 8-54 5 16^' 12 534 1234 1 10 834 8-M 6 18 15M 6^8 15M 1 11 9H 8-M 8 2034 1734 83^ 19M IM 13K IIM 8-M 10 2214 21% 103^ 25 ly 16 14M 12-3^ 12 24 24M ny 29S/8 9 19 17 12-K 14 25 M 28^ IWs 335,^ 9 21 183^ 12- 1 16 28 ny, 153/8 3834 2J-^2 233^ 2134 16-1 256 Webster Low-pressure Receiver Oil Separators These separators, acting as eliminators of oil and condensation and as receivers or mufflers, are used chiefly in exliaust steam lines between recipro- cating engines and low or mixed-pressure turbines, or as receivers for the in- termittent exhaust from groups of steam hammers. They are of riveted steel con- struction, with cast-iron nozzles, and, like most of the Webster Oil Separators, are equipped with hooked steel multi-bafBes. The nozzles are of cast iron with flanges drilled low-pressure standard. The fllustration shows one of the many forms of the Webster Low-pressure Receiver Oil Sepa- rator. The inlet and outlet noz- zles may be located to conform with any direction of flow of steeim. The axis of the sheU may be either horizontal or vertical. Inquiries regarding the WelDSter Low-pressure Receiver Oil Separators should be accompanied by a sketch showing the proposed location of and space available for the separator, the sizes and locations of inlet and outlet nozzles and the direction of flow. The inquiry should state the maximum amount of steam to be purified. Webster Grease and Oil Traps Fig. 24-31. The Webster Low-pressure Receiver Oil Separator Fig. 24-32. The Webster Grease and Oil Trap The Webster Grease Trap is for use in draining oil separators on exliaust steam lines or on feed-water heaters, or for removing from the course of the steam any accumulations of oily drips at other points in the low-pressure steam mains or branches. It will operate with equal efficiency under any pressure between atmospheric and 15 lb. per sq. in., above. It is not de- signed for use under high vacuum conditions. As shown in the accompanying sectional fllustration (Figure 24-32) the valve mechanism is simple. The discharge orifice is designed to give the full area of the inlet opening. The valve piece is conical and closes against a sharp-edged seat. 257 The ball float and valve chamber are easily reached for quick cleaning without disturbing pipe connections. Properly installed, the Webster Grease Trap should be provided with a bypass in the piping around it; a check valve should be in the Kne beyond the outlet and bypass, and an equalizing or vent pipe should be run from the top of trap to the exhaust main beyond oil separator. See Figure 24-28. Ratings for Webster Grease Traps: Because the mixture to be discharged is likely to be more or less viscous and sluggish in movement when it is cool it is impossible to rate grease traps on a condensation basis. The size of grease trap to be selected in any case should be that of the drip connection of the oil separator which it is to drain. Table 24-8. Dimensions of Webster Grease and Oil Traps A' Size Outlet A=Size Inlet Number A A' B c D E F G H U V w 016 Va Va 153^ 1 8 15 414 31/^ 2'/^ 81/^ Wa Va 116 IM IH 19 H 1^/s 9 183/s 53/R 3'i/R 4 lOK 7 1 216 2 2 2();/8 \yi lOH 19K 6^8 4^2 m 12M 8 1^2 Fig. 24-33 All dimensions in inches and subject to slight variation The Webster Suction Strainer Fig. 24-34. The Webster Suction Strainer The Webster Suction Strainer is used to prevent the passage to the vacuum pump of dirt and scale brought down with the condensation from a vacuum heating system. The use of this strainer prevents scoring of the pump-cylinder lining, valves and piston rods and the serious efficiency losses and repair bills that would follow such scoring. The strainer is pro- vided with a tapping for the introduction of cold make-up water when same 258 is desired and when specially ordered, a spray nozzle is provided to insure thorough mixture of cold water and vapor in return. Another tapping is provided for a connection to the vacuum gauge and a third plugged outlet is for draining the body when the strainer is not in use. The shell and re- movable cover are of cast iron with composition gasket in the joint. Com- panion flanges, drilled low-pressure standard, are provided for inlet and out- let connections. The basket is of perforated brass, and has at its top rim a casting in which is fastened a handle for hfting out the strainer. The perforations are 0.043 in. in diameter and of sufficient number to provide a total area twice that of the entering pipe. The Webster Suction Strainer is to be placed in horizontal piping only, and should be set so that the axis of the body will be vertical. Water flows to it in the direction of the arrow (see Figure 24-34), and its course through the strainer is evident from the sectional view in the same figure . During the cleaning process it is customary, if the system must be main- tained in operation, to use either the relay pump or the ejector, if there is one, and if not, to temporarily run the returns by gravity to the sewer or waste, closing the stop-valve in the main return. The entire operation oc- cupies but a few minutes. Table 24-9. Dimensions of Webster Suction Strainer K- No. and Size Bolls N Tapped ajid Plugged For maximum working pressm-e of 15 lb. per sq. in. Fig. 24^35 Top view All dimensions in inches and subject to slight variation Size A Bi M 2 5^ 4^/8 12 6 6Vs 5M 4M 4^^x2 y>. Va. 3 6^ m ISH iy2 m 5M 6 4^^x2M y?. Va 4 8A ^a 163^ 9 105^ 7% TA 8-^x2M y-i Va 5 9^ evs 185^ 10 12K 8^ 8M 8-Mx2M y?. Va 6 lOH 1^ 20% 11 13H 9ys 9y2 8-Mx2M y. Va 7 12^ 9A 25 12 J^ 19M 13 lOM 8-Mx3 Va 1 8 UVs 9% 27M 13)^ 21 14>^ IIM 8-Mx3K % 1 10 n]4 11 J4 ^2H 16 243^ 16% 14M 12-Kx3M % 1 12 21 12K 38 19 29 20 17 12-Vsxsy2 % 1 Webster Dirt Strainers Webster Dirt Strainers are used in steam heating systems to prevent dirt from entering radiator traps or traps on drip points, mains or blast coils. They provide convenient receptacles for retention and accumulation of pipe chips, rust, dirt, etc., where impurities can do no harm and where they are easily and quickly removed. 259 Class A (Offset) Webster Dirt Strainers Fig. 24-37. Class B (Straightway) Two models are made : Class A with offset and Class B with straight- way pipe connections. Both have cast-iron shell and cover, the latter made easily removable by means of a yoke and screw. The basket is made from sheet brass perforated with 0.043-in. diameter holes. The total free area through the basket is several times the area of the entering pipe. The sides of the basket are reinforced with strips which are continued upward to form a bale handle. This handle not only serves to make the basket easily removable but acts as a spring against the cover to hold the basket in place. The range of types and sizes offers a selection for any service conditions. The use of these strainers greatly lessens the amount of attention re- quired to keep the system in thoroughly efficient operation and eliminates incentive for the neglect always to be expected with dirt pockets composed of pipe fittings, which cost nearly as much to make and are never as good. Table 24-10. Dimensions of Webster Dirt Strainers, Classes A and B Maximum pressure, 15 lb. per sq. in. Dimensions in inches and subject to slight variation Class A. — Offset (Fig. 24-38) Class A Class B No. I«-H Dia-i Fig. 24-38 018-A 118-A 218-A Size A B 1 or 1M4M IH or 2 6 Bi w-\ c D E F G 15< pJsA 1% 1% 6 2?< 2^4 2l^!65^ 2 2% lii^ 31/^ ■>% I 3 3 9^ 4% 2J^ 3M 4M Class B.— Straightway (Fig. 24-39) Fig. 24-39 No. Size A B Bi B2 c E F G H 018-B 118-B 218-B Hor M 1 orlM lMor2 7M 2M 2J^ 3J4 5t^ 3 6 9A 2M 3H 4M 2V2 4M The Webster Vacuum-pump Governor The vacuum pump of a vacuum heating system should be as nearly automatic in operation as possible. The Webster Vacuum-pump Governor automatically controls the admis- sion of steam to the pump cylinder or cylinders in proportion to the degree of vacuum required. When only part of the heating load is on, just enough 260 steam is admitted into the pump to produce the degree of vacuum required. When the need is greater, the supply of steam is automatically increased. The Webster Vacuum- «i3r-r„.. _ pump Governor can be ad- justed to control the vacuum to any predetermined degree, and may be readjusted when necesscuy. It is remarkably sensitive through a wide range of adjustment. The Webster Vacuum-pump Governor Fig. 24-40 Fig. 24-41 Fig. 24-42 Size A Table 24-11. Dimensions of Webster Vacuum-pump Governors Bi Fi F2 H 2% \% 5 9>^ iy2 lOM 10^ 1^ 2J^ 23H 1 m IH 5 9J^ IVs lOM 11 2 2J^ 241/2 Ik 4 IM 5 9J^ 8 lOM 11}^ 2 2% 24^8 m 4^ IM 5 9% 8^ lOM 1114 2A 2K 2534 2 5V2 IH 5 9% 8K lOM 12 2^ 2J^ 26tV 2J4 6% Wi 5 9% lOM lOM 13% 3M 2J/8 28i/2 3 Wi IH 5 9Vs n^ lOM 14J€ 3>^ 2% 29^2 3^2 8 IM 5 9Vs iiM lOM 14^ 4 2% 30 The Webster Suction Strainer and Vapor Economizer This special device, in addition to its function of protecting the vacuum pump, has a particular advantage in vacuum heating systems where some unusual operating condition results in the return of water to the vacuum pump at a high temperature. Under such conditions, re-evaporation or transformation of water into steam vapor may occur, and the presence of this steam vapor adds to the duty of and may interfere with the proper operation of the pump. If cold water is constantly required for making up the boiler-feed water it can be introduced in the standard Webster Suction Strainer, by the use 261 of the Webster spray-head, without increasmg the cost of plant operation. The special Webster Suction Strainer and Vapor Economizer is designed to meet conditions where cooling water is required, but where the use of it as make- up water would entail waste. The cold water is passed around a nest of copper coils and absorbs the heat of the steam vapor in the main return. This water is not handled by the vacuum pump and does not mix with the condensation in the main return line, as the economizer becomes merely tension of the hot-water piping system, under the available pressure. Fig. 24-43 Fig. 24-44. The Webster Suction Strainer and Vapor Economizer Table 24-12. Dimensions of the Webster Suction Strainer and Vapor Economizer All dimensions in inches and subject to slight variation Size A B B' C D Di E F G J K T' u M 3 5 7 19^ 223^ 28M 6 7^ 22 10 15M lYi 53^ 8=^ 251^ VlYi 187/8 10 dVi 12 iWi Uy2 24J4 121^ 7K 19 6 4^^ X 2M 8^ S-H X 23/4 lOM 8-M X 3 2% 65M 693^ 78 2G2 Fig. 21-i5. Webster Lift Fitting Webster Lift Fittings — Series 20 Webster Lift Fittings are special devices used in pairs at points in vacuum heating systems where con- densation is to be hfted to a higher level. The con- densation is lifted vertically to a higher level in "slugs" on the air-lift principle; the slugs being ob- tained by the use of a comparatively small diameter vertical return with its lower end submerged in the well below the level of the horizontal return which it drains. The lower lift fitting allows the condensa- tion to accumulate in the well below the inlet connec- tion until it seals the vertical passage, thus causing a slight reduction of the vacuum on the inlet side and forcing the water from the well through the vertical lift pipe to the higher level. The upper lift fitting allows the condensation to flow into the horizontal return without falling back into the lifting line. Lifts of six feet or over should be made in steps rather than all in one rise. Steps should be used instead of "drag" lifts through long upwardly inclined pipes. In any case, the pipes between lifts must grade toward pump. Webster Lift Fittings are a big improvement upon and should be sub- stituted for the home-made fittings which in the past have had to be made from combinations of ordinary tees or crosses and plugs, because nothing better was obtainable. Each Webster Lift Fitting is a unit casting, neat in appearance and correctly proportioned for capacity of well and for the area ratio of inlet to outlet. The use of these fittings eliminates all the guess- work and uncertainty about proper operation. They cost less than combi- nations of fittings when the labor cost as well as that of the fittings is con- sidered. Each fitting is provided with a clean-out plug for removing any accu- ^Floor Line Fig. 24-16. Typical application of Webster Lift Fittings (See also Fig. 13-1, page 139) LJ Fig. 24-47. Long screwed lift connection Fig. 24-48. Long flanged lilt connection 26.3 mulation of dirt or other foreign matter from the hft pocket. The larger sizes are flanged and finished and drilled to the low-pressure standard. Fig. 24-49 Table 24-13. Dimensions of Series Webster Lift Fittings in inches 20 Inlet Outle Size A B C D E Drain % Screwed % ¥>, VA 2=/^ 234 v?. 1 " 1 Va Wf. 3 3/h y?. li4 *' \Va 1 5M •iV-?. 334 Va W-?. *' IH 1 6tV ^■h 4^4 Va 2 ** 2 li4 6/s 4/8 4/r 2i/« ** 2y. I'/s 8i/s 5/r 5 '^8 3 Flanged 3 2i/^ 14i4 9 9»/8 4 " 4 3 17i/s 10/8 11^4 5 *• 5 ■iV-?. 19^/ 12/, 121* 6 *' 6 4 2P4 13 /« i4.fV B (( 8 41/, 25 i4 16^4 17 10 ** 10 6 31 /s 20 /s 20/r 12 12 7 34/2 22/8 23A Close screwed lilt connection Fig. 24-50 Table 24-14. Minimum Distance Between Centers %-in. screwed fittings A = 33^ in. 1-in. " " A = 3M in- IJ^-in. " " A = 41^ in. IJ^-in. " " A = Wa in. 2-in. " " A = 5}^ in. 2H-in. " " A = 8 in. 3-in. flanged fittings 4-in. 5-in. 6-in. 8-in. 10-in. 12-in. B = lOj^ in. B = 13,^ in. B = 14,^ in. B = 15if in. B = 18i^ in. B = 22^5 in. B = 23if in. Webster Receiving Tanks — Plain, Water-control and Steam-control Types These tanks are used in connection with vacuum steam heating systems, to provide a place for storage of the condensation discharged by the vacuum pump and for liberation of the air that comes over with this condensation. Each type is designed for pressures not exceeding 30 lb. per sq. in., for installation in horizontal position, and each type has proper receiving capacity and air-hberating surface. The Plain Type receives the condensation and air tlirough an end opening near the top. The air escapes tlirough a vent in the top of the tank, and the water flows by gravity to the bottom outlet and to the feed-water heater or other point of disposal. If the rate of flow of returns to tank ex- ceeds rate of discharge from tank, the excess overflows through an opening on the end near the top. The Water-control and Steam-control Types have regulating valves which are operated by sink pan and rigging similar to those used to regulate the water level in Webster Feed-water Heaters. These two types are also provided with water-troughs, to insure best operation of the sink pan. The Water-control Type has its regulating valve arranged to automati- caUy admit "makeup" at all times when the returns from the heating system are temporarily insufficient to keep the water level in the tank at the pre- 264 Fig. 24-52. Webster Air-separating Tank and Receiver, Steam-control Type Fig. 24-51. Webster Air-separating Tank and Receiver, Water-control Type determined point. The air is vented to atmosphere, the water flows by gravity to the heater or other place of disposal, and any excess of water overflows, as with the Plain Type. The Steam-control Type, which is used where the boiler or boilers are to be fed in proportion to the returns reaching the receiving tank, has its regulating valve installed in the steam supply line to the boiler-feed pump. With water in the tank at or above the predetermined level, the boiler-feed pump is in operation, feeding the returns into the boiler, but when the tank level is below normal, the steam to the boiler-feed pump is shut ofi" and the pump stopped until sufficient returns collect again. Make-up water, if necessary, may be introduced into the tank by hand. The venting of air to atmosphere, delivery of water by gravity flow and provision for overflow of excess water are the same as in the Plain Type. All three types of Webster Receiving Tanks are made from riveted flange steel and have flat heads. The Water-control and Steam-control Types have removable manhole covers and gauge fittings in one end. Each tank is hand-made throughout from best obtainable materials. The sizes hsted are standard. Larger sizes can be made upon special order. 265 Plain Type Table 24-15. Dimensions of Webster Receiving Tanks Note: Openings will be bushed to suit requirements. All dimensions in inches Overflow Fig. 24-53 "^Oullel Size Inlet Outlet Air vent Overflow A B C 18x48 24x72 36 X 96 4 5 8 4 5 8 2 3 4 6 253^ 3834 25 37 49 33^ 6 Water- control Type ^c: D >k D >! Water Regulaling Valve -A -I >l< TtB- Fig. 24-54 ^Outlet to Healer Gauge Glass^^ K E >) Size Inlet Outlet Air vent Overflow Reg, valve A B c D E F G 18x48 24 X 72 36 X 96 4 5 8 4 5 8 134 4 1 2534 2 5 13^ 37^ 3 6 2 503^ 30 >^ 4234 54^ 3M 6 113-2 12 18 18 243^ mi 14 18 24 183^ 23 2834 Steam- control Type ~D H Pump Governor Valve -B- Blank Nipple .Steam OverHow Fig. 24-55 Manhole ^Outlet to Heater K E H Size Inlet OuUet Air vent Overflow Gov. valve A B c D E F G 18 X 18 24 X 72 36x96 I 5 8 4 5 « 134 4 1 2534 2 5 134 375^ 3 6 2 503^ /^ 6% Ws 5^ m 5? 8 10 No. 120 IM 1J€ IM 9A 8t 8 Ws 8M 6H 834 153^ No. 220 IM IM IM 9^ Sii 8 4K ^'A 6M 8M 15^ No. 320 IM IM IM 95% 8^ 8 Ws 8y2 6M 8M 153^ Fig. 24-66. Webster Modulation Vent Valve VgTjt, TraD The Modulation Vent Valve The Webster Modulation Vent Valve This A'^alve has been specially devised to meet the requirement for check against inflow of air to a modula- tion system when it is desired to operate at a pressure less than atmospheric. This check is provided by the seating of a hollow seamless ball which is retained by a cage structure as shown in Figure 24-66. Due to the very slight weight of the ball and the construction of the valve body and seat, a pressure less than one oimce per square inch will serve to lift the valve from its seat, thus permitting the escape of air from the is made in only the 3^^-in. size which 270 may be used as a single unit for installations up to 8500 sq. ft. of direct radiation or equivalent. For larger installations these valves are furnished in multiple units of the necessary number with a fitting such as that shown in Figure 24-67. See Table 23-9, page 240. For use where two vent valves are required Fig. 24-67. Multiple-unit Webster Modulation Vent Valves The Webster Damper Regulator The Webster Damper Regulator is used with the Webster Modulation System and automatically controls the opening of the draft door and check damper of the low-pressure steam- heating boiler. It is extremely sensi- Three-valve pattern Note:-To support Damper Regulate use 4-t/^"Rods with Pipe Separator and malg 7J^ 8-^ 2M 17J^ 5 12 20 10 9Vb 5M 8M 8-M 2M 183^ 6 13 31 M 11 lOM 6,^ 9y2 8-M 2M nVs 8 13M 31 M 1314 llM 7A liM 8-M 2M 24M 10 15 36 ^ 16 12^2 85-8 14 J4 12-K 3,^ 28^ 273 The Webster Low-pressure Boiler Feeder — Series 16 In connection with heating boilers fed from hydro-pneumatic tanks, and under certain other conditions, a Webster Boiler Feeder is useful. This device is shown on Page 147, as part of a Webster Hydro-pneumatic System. WATER INLET EQUALIZING PIPE Fig. 21-74. Webster Low-pressure Boiler Feeder When the water level in the boiler lowers, the ball float opens the feed valve and allows the water to discharge directly to boiler. The valve is of the double-balanced type with large orifice area, because of the low differential between the tank pressure and the boiler pressure. The ball float is large enough to give the lever without excessive difference of water level. An important point in the con- struction of the boiler feeder is that the valve and gear are within the cas- ing. There are no outside glands to keep tight and any leakage which oc- curs is within the body of the device and hence into the boiler. The working parts are easily ac- cessible, but seldom need attention. EQUALIZING '''S- 2'l-75. Conventional pipe; arrangement of Webster Low-pressure Boiler Feeder SUPPORT FDR FEEDER power required to move the valve Fig. 21-76 Table 24-21. Dimensions of Series 16 Webster Low-pressure Boiler Feeder Dimensions in inches and subject to slight variation Number Bi G' 116 1 1 1 1 1 12H 12H 12J4 123^ 2 2 9 2M 253.^ 25?^ 25^ 25?^ UV2 14J/9 6M 6M 6H IM W2 IV2 1}^ VA 2H 11 ?i 11?-^ 11^^ 113^ 10 10 10 10 15^ 15^ 15J^ 216' W2 9 2 2 15 15 21^ 2M 31^ 31 J^ 16K i6y2 2M 2M 2Vs 2% 133/g 13?^ 12 12 19 Ji 19 J^ 316{ 2V2 3 2V2 23^ 19 19 3M 3M 36^ 36M 18J4 8 8 3 3 3 3M 15 15 12 12 21 21 274 The Webster High-pressure Sylphon Trap Fig. 24-7'; The Webster High-pressure Sylphon Trap This trap is in many respects like the standard Webster Sylphon Trap described on Page 242. The body construction is the same except that the position of inlet and outlet opening and the union connection of the inlet are reversed. As the trap must operate at comparatively high steam pressure with resulting high temperature, the thermostatic member or bellows is located outboard of the valve. The sylphon bellows, surrounded in this position with the cooler vapor from the discharged condensate at atmospheric pres- sure, is extremely sensitive to the much higher temperature of the steam, and consequently acts quickly and positively to close the valve against steam passage through the trap. It is pEirticularly important when arranging pipe connections that the manufacturers directions shall be specifically followed. In consequence also of the higher pressure, the valve piece and the seat are constructed of monel metal, which successfully resists wire-drawing and its accompanying wear. The Webster High-pressure Sylphon Trap is made in three sizes and for two pressure ranges — Class 2 for pressure from 15 to .50 lb. per sq. in., and Class 3 for pressures to 100 lb. per sq. in. Application diagrams for this device are shown in Chapters 18 and 20. Fig. 24-78 Table 24-22. Dimensions of Webster High- pressure Sylphon Traps SIZE A B c D 1^"— 822 M —833 1 —844 33g" 4,^ 2^8 3M" 2M 3M 2M" 4H 27.5 Fig. 24-79. Webster Hydro- pneumatic Tank, with Double Control Webster Hydro-pneumatic Tanks Single and Double-control Types Webster Hydro-pneumatic Tanks are used in place of open-vent tanks for receiving returns in steam heating systems where sufficient head room to produce the necessary static head is not available for the installation of a plain receiving tank. The general design is the same as that of Webster Steam-control and Webster Water - control Receiving Tanks, except that in the Single-control Hydro-pneu- matic Tanks the sink pan and rigging control the es- cape of air through the vent pipe, and in the Double- control type this feature is supplemented by an addi- tional sink pan rigged to control a water valve in the discharge piping. In both Single and Double-control types the air is permitted to escape freely until the tank is half filled with condensation, when the vent closes and the remaining air is confined. The air vent is open whenever the con- densation flows by gravity against the resistance in the outlet connection. When the necessary head is greater than that due to the tank being half fuU of condensation, the air vent is closed. Further accumulation of air and water creates additional pressure until this, added to the gravity head, overcomes the resistance and condensation flows tlirough the outlet until the water line reaches the middle of tank. Then the air vent opens to permit escape of air. When the tank has no gravity head to heater or boiler the neces- sary head to overcome resistance in the outlet is by confined pressure only. The Double-control Hydro-pneumatic Tank, in addition, has its water- control valve arranged to close just before the water level reaches the bottom of the tank. The Double-control type serves to prevent admission of air into the system, through discharge from the tank, when the pressure in the open feed-water heater or boiler may be less than that of the atmosphere. Both Single and Double-control Tanks are used under pressure greater than the atmosphere and in most instances must be provided with means for preventing excessive pressure due to obstruction of overflow. For this pur- pose a water-relief valve is provided, which should be piped to an open funnel to facilitate observation and correction of unnecessary waste. Both Single and Double-control types of tanks are made of riveted flange steel plate, have flat heads and are for installation in horizontal position. A water-trough running along the top distributes the water and assures that sink pans are kept filled with water. 276 Manholes and covers and gauge glass fittings Eire regular equipment with both types of tanks. Sizes listed are standard. Others made to order. Table 24-23. Dimensions of Webster Hydro-pneumatic Tanks Openings will be bushed to suit requirements. All dimensions in inches Single-control Type Size Inlet Outlet Vent valve Overflow A B c D E F G 18x48 4 4 % 4 29M 30^ 10 12 24^ 14 18 1 24x72 5 o IH 5 43M 421^ 13 18 36J4 18 22M 36x96 (2)8 8 Wi 6 58 545^ 18 18 483.^ 24 28M Double-control Type Size Inlet Outlet Vent valve Overflow A B c D E F G H J 18 X 48 4 4 % 4 29^ 303^ 10 12 24M 14 18 20 19K 24 X 72 5 5 IH 5 43M 42J^ 13 18 36M 18 22% 22 2S% 36 X 96 (2J8 8 VA 6 58 545^ 18 18 483 8 24 28M 313 s' 35 For ratings, see Table 13-1, page 138. 277 Webster Expansion Joints Webster Expansion Joints are constructed with cast-iron bodies and brass-slip sleeves and in both single and double-slip types. The body of the Webster Expansion Joint is provided with anchors made integral with the body castings for rigid connection to a foundation or a bracket. Service connections are provided for greatest convenience in tapping the steam main for branch piping. Drip outlets also are provided. Fig. 24-82. Class D (at left) Webster Expansion Joint Fig. 24-83. Class DH (at right) Webster Expansion Joint Fig. 24-84. Class G (at left) Webster Expansion Joint Fig. 24-8.5. Class GH (at right) Webster Expansion Joint 278 Fig. 24-86 Table 24-24. Class D Webster Expansion Joints for Low-Pressure Steam Dimensions (in inches) Size B Bi c D Di E F Fi G J= J K' M m 6M 43^ 13'/^ 3 3 5 2^ 015. -16 23 s w^ 1?4 2- M 1 2 6 ■m 13M 3 3 6 2J^ 3 2y2 m 1% 2- M IK 2y?, 6^ 41/8 141^ 3 3 7 3M 3J^ 3H l»4 \-% 2- M 2 3 6Vs 4/8 14^ 3 3 7^ 2Ji 3J^ 2% IM IM 2- M 2 SV?. IVi 41^ 16 4 4 &y2 3}^ 3M 33^ 9 4- Vi 9 4 7^ 41/, 16 5 5 9 4 4M 4 2H 2/, 4- J^ 2/2 5 8^ 4/r i-rVs 5 5 10 41^ 5}^ 4^ 2/^ 2/^ 4- J^ 2/?, 6 8M 4/8 17M 6 6 11 5 5^ 5 3 3 4- ^ 2/2 7 12^ 7 20 j^ 6 6 121^ 6^ 6J^ 534 3 3 4- J^ 3 8 13^ 7'^ 21 J^ 6 8 13,1/^ 7M 7J4 6 5 3 4- % 3/2 10 141^ 7V4 23^ 6 8 16 SVs 8H 7 5 3 4-1 4 12 15J^ 8M 25 K 7 8 19 m 9^ 834 5 33/2 4-1 5 14 ny^ 934 28^ 8 8 21 lOM 10=4 8^4 5 4 4^1^ 6 16 1-7H 9M 281^ 8 8 233^ 12 nVs 10 5 4 4-1^ 6 18 18 9^4 2834 8 12 25 13M 13^ 11 9 4 4-13^ 6 20 18 9M 30^ 8 12 271^ 14)4 141^ 12 9 4 4-134 6 Maximum working pressure, 15 lb. per sq. in. This joint has single slip and maximum traverse of 5 in. and is made with a close-grained cast-iron body and brass tubing or cast-brass sleeve. Standard equipment includes service and drip connections, anchor plates and gland packing. Companion flanges are furnished only when specially ordered. Flanges are drilled low-pressure standard unless specially ordered otherwise. 279 1V4 DRIP' Fig. 24-87 Table 24-25. Class DH Webster Expansion Joints for High-Pressure Steam Dimensions (in inches) Size B Bi c D Di E E2 F Fi J^ P K' M iy2 63/4 4?'8 isi-s 3 3 5 8M 2Js 2il is^' 134 2- H 1 2 6 ■il/H 13M 3 3 6 8H 2J4 3 IM IH 2- M 114 '■i'A by. 4^8 14M 3 3 7 lOH 3}-i 3J^ 13/f \V, 2- M 2 3 (>ys 4J/8 UV2 3 3 7^ 11 2V8 3J^ 1¥ IH 2- ?€ 2 3^2 7J^ 4H 16 4 4 8K 13 i'A 3M 2 2 4^ 3^ 2 4 1V2 4^2 16 5 5 9 12 4 4^ 21^ 214 4- Vs 21/^ 5 ^Vs 4^8 17^ 5 5 10 14M 4H 53^ 2H 21/^ 4- 3^ 2H 6 m 4i/« 17K 6 6 11 15M 5 5^ 3 3 4- % 21^ 7 12>^ 7 20Vs 6 6 12}^ 1714 6^ 6}4 3 3 4^ K 3 8 13M 7i4 22ys 6 8 l^V2 18^ 7J^ 7M 5 3 4- J^ m 10 14^ 7^^ 23}^ 6 8 16 21 M 85^ 8}^ 5 3 4-1 4 12 15^ 8^ 25 J^ 7 8 19 24M 9?i 9J^ 5 3y2 4-1 5 Maximum working pressure, 125 lb. per sq. in. This joint has single slip and maximum traverse of 5 in. and is made with a close-grained cast-iron body and brass tubing or cast-brass sleeve. Standard equipment includes service and drip connections, anchor plates, limit bolts and gland packing. Companion flanges are furnished only when specially ordered. Flanges are drilled low-pressure standard unless specially ordered otherwise. 280 : J t ^^%» K'=NO. AND SiZE OF CORES M = SIZE OF SERVICE CONNECTION^ 1V4DRIP Fig. 24-88 Table 24-26. Class G Webster Expansion Joints for Low-Pressure Steam Dimensions (in inches) Size B C D D' E F F> J- J= Ki M ly?. ilA 22K 3 3 5 2M 2M IM IM 2- Vi 1 2 nys 22 J^ 3 3 6 2J^ 3 IM IM 2- M 1)4 2y?. n% 23H 3 3 7 3M 3^ IM IM 2- M 2 3 12 j^ 25M 3 3 7J^ 2K 3J^ IM IM 2- M 2 ■iy?. 12^ 251^ 4 4 83^ 334 3M 9 2 4^ Jl 2 4 13^ 26M 5 5 9 3^ 4M 2M 23i 4^ Ys 23/2 5 13M 27H 5 5 10 41^ 5H 23^ 23^ 4- Ji 234 6 13J^ 27M 6 6 11 5 53-8 3 3 4- K 2^2 7 14}^ 283^ 6 6 123^ 6^ 63^ 3 3 4- Vs 3 8 15 J^ 31 M 6 8 13H 6H 7M 5 3 4^ 3^ 33^2 10 17 33 J^ 6 8 16 8 83^ a 3 4-1 4 12 18J^ 36}^ 7 8 19 9 9^ 5 3}^ 4^1 5 14 183^ 37M 8 8 21 10>^ 105^ 5 4 4r-iyg 6 16 19^ 38 J^ 8 8 23^ 12 nj^ 5 4 4r-iys 6 18 SOKs 401^ 8 12 25 13M 13}^ 9 4 4-13^ 6 20 22 44 8 12 27y2 14 14}^ 9 4 4^134 6 Maximum working pressure, 15 lb. per sq. in. This joint has double-slip and maximum traverse of 10 in. and is made with a close-grained cast-iron body and brass tubing or cast-brass sleeve. Standard equipment includes service and drip connections, anchor plates and gland packing. Companion flanges are furnished only when specially ordered. Flanges are drilled low-pressure standard unless ordered otherwise. 281 g Eimrngg^ E' \% DRIP K=NO. AND SIZE OF CORES M =SIZE OF SERVICE CONNECTION - -(»| Fig. 24-89 Table 24-27. Class GH Webster Expansion Joints for High-Pressure Steam Dimensions (in inches) Size B> D> El Fi M 1J4 16^8- 8A 22S'g ;^ 3 5 8M 2V4 2|* l?i 13-4 2- h 1 2 163^ 8M 22 H 3 3 6 8M 21/. 3 134 1% 2- M i-'A ^^2 16y2 8^ 23K 3 3 7 103^ 3K ■m. 134 m 2- M 2 3 \W2 9J€ 25M 3 3 7}^ 11 2-/8 ■iV?. 134 m 2- M 2 ■i'A 18 9 25}^ 4 4 9 13 314 334 9 2 4- Vs 2 4 19 9}-^ 26M 5 5 9 12 3V« 414 21^ 2i/? 4- 3^ zy?, 5 19}^ 9M 27}^ 3 .T 10 14M 4H, 51/8 2J4 2/. 4- ^ 2^2 6 19M 9^ 27M 6 6 11 15M 5 53/8 3 3 4- 3^ 2y9. 8 23 11^ 31 M 6 8 131-^ 18>i 63^ 74 5 3 4^ J^ w?. 10 241^ 12^ 33 J^ 6 8 16 21^ 8 8J^ 5 3 4-1 4 12 25 ?i 12K 36M 7 8 19 24M 9 9M 5 sy, 4-1 5 Maximum working pressure, 125 lb. per sq. in. This joint has double-slip and maximum traverse of 10 in. and is made with a close-grained cast-iron body and brass tubing or cast-brass sleeve. Standard equipment includes service and drip connections, anchor plates, limit bolts, and gland packing. Companion flanges are furnished only when specially ordered. Flanges are drilled low-pressure standard unless specially ordered otherwise. 282 Table 24-28. Distance Between Anchor Points and Webster Expansion Joints for Various Steam Pressure Conditions The following table is recommended as a guide in the design of steam piping for determination of the proper points of installation of Webster Expansion Joints. In such design the maximum pressure which the pipe line must sustain during acceptance tests or other special conditions must be selected as the " Gauge pressure" Gauge pressure Temperature difference above zero Expansion Inches per 100 feet Safe maximum distance in feet between anchors for single-slip expansion joints* 212 1.53 260 5.3 227 1.64 245 10.3 240 1.73 225 15.3 250 1.80 220 20.3 259 1.87 215 25.3 267 1.93 210 30.3 274 1.98 202 40.3 286 2.06 195 50.3 297 2.14 190 75.3 320 2.31 175 100.3 337 2.43 166 125.3 352 2..54 160 *For double-slip joints, the safe distance from the joint to an anchor in each direction may be the distance specified for a single joint, provided the body of the double joint itself is securely anchored Webster Series 21 Steam Separators For working pressures up to 200 lb. per sq. in. Webster Steam Separators of the standard types for removing moisture from live steam, have cast-iron corrugated baffles against which the steam impinges, causing a sudden change in direction of flow and consequently freeing the steam of the entrained moisture. The port openings in every Webster Steam Separator are of such size as to minimize loss of steam pressure from unnecessary friction. These separators may also be used for special purposes, as re- moving moisture from compressed air, assuring operation of steam whistles by removing moisture from their steam supplies, etc. The material ordinarily used in the shells is close-grained cast- iron, but special shells of semi- steel, cast steel or other material can be furnished. Gauge-glass fittings and drain valves are usual equipment but are furnished only as extras when ordered. 283 Fig. 24-90. Vertical type Fig. 24-91. Horizontal type Table 24-29. Dimensions of Webster Series 21 Steam Separators All dimensions in inches Companion flanges and gauge and drain fittings furnished only when specially ordered. Flanges are drilled to high-pressure standard unless otherwise ordered ^ Fig. 24-92. Vertical Type Down-flow only Dimensions Flanges Outside Bolt No. & sizes Size B H Drip diameter circle of bolts 2 21k' 7 k 6k 5 4- k W2 223/^ 8 k 7k 5k 4- k 3 23 J^ 9J^ k 8k 6k 8- k 3H 25^ 10 '/g 1 9 7k 8- k 4 26M lOM 1 10 7k 8- k 5 28H 13>^ 1 11 9k 8- k 6 30M 15 1 12k 10k 12- k 8 33 M 20 Ik 15 13 12- k 10 40M 23}^ Ik 17 k 15k 16-1 12 44k 27k Ik 20k 17k 16-lk Fig. 24-93. Horizontal Type D imensions Flanges Size B F G H Drip Outside diameter Bolt circle No. & sizes of bolts 2 9k 3k 12k 8k k 6k 5 4- k 3 Ilk 5k 14k 10k k 8k 6k 8- k 4 13k 5k 16 Ilk 1 10 7 k 8- k 5 14k 7k 17 k 14k 1 11 9k 8- k 6 16k 8k 19k 16 1 12k 10k 12- k 8 20k 10k 23k 20k 1 15 13 12- k 10 24k 12 k 26k 24k Ik 17k 15k 16-1 12 27 k 14k 30 29k Ik 20k 17k 16-lk 284 Special Types of Webster Steam Separators Working pressures up to 150 lb. per sq. in. Fig 24-91 Class L — Angle Type with horizontal outlet Fig. 24-95 Class M— Angle Type with bottom outlet Fig. 24-96 Class N — Angle Type with top outlet Table 24-30. Ratings of Webster Steam Separators Pounds per minute at average gauge pressures. Based upon a pipe velocity of 6000 ft. per min. Gauge pressures Size of 100 Lb. 125 Lb. ISO Lb. 200 Lb. separator per per per per m. sq. inch sq. inch sq. inch sq. inch 2 35. 43.3 51.6 66.6 3 78.3 96.7 112. 141. 4 140. 167. 196. 250. 5 215. 258. 300. 391. 6 317. 383. 450. 583. 7 433. 516. 600. 783. a 550. 660. 800. 1000. 10 883. 1083. 1250. 1580. 12 1250. 1533. 1800. 2333. 285 CHAPTER XXV Specifications for Webster Systems THE following specifications cover typical Webster Systems only in a general way, and are subject to many variations. It is advised that wherever practical a Webster Service Engineer be called into con- sultation during the preparation of plans and specifications for Webster Systems. Specifications for the Webster Vacuum System of Steam Heating (This specification is written for a system of the usual up-feed type. For the variations known as the Webster Conserving System and the Webster Hylo System, revised special clauses will be furnished by Warren Webster & Company on application.) General: (Here specify the general requirements of the contract, such as intent of drawings and specifications; verification of measurements; co-operation with other con- tractors; foreman; ordinances; permits; protectionof work and buildings; rights reserved; extra work; return of specifications and drawings ; payments, etc.) Cutting of Floors and Walls : The [building] [heating] contractor will cut all holes in floors and walls and provide trenches and covers for piping which may be necessary for this work, and at completion make all repairs to floors and walls so cut. Scope of Work: This specification is intended to cover a 2-pipe low-pressure heating system known as the Webster Vacuum System of Steam Heating. It is intended to supply radiation for heating the building to a temperature of .... degrees fahi\ when the outside temperature is or a corresponding equivalent difference in temperature, with doors and windows reasonably tight. Special Apparatus: The basis of this specification being a Webster System, each bidder is required to submit his proposal for furnishing apparatus manufactured by Warren Webster and Company. *Alternate Proposals will be considered for the use of modulation supply valves and thermostatic retmn traps of the same supply and return tappings and as made by , provided each bidder states in his proposal the sum which will be added to or deducted from his main bid in case they are used. Standard Apparatus: In addition to the special apparatus, this contractor is to fur- nish all other material and labor necessary for the complete work as shown on plans or called for in specifications. Radiation: All pipe coils must be made up of full-weight [mild-steel] [genuine wrought iron] pipe and best gray-cast iron fittings and manifolds. All radiators must be of the pattern equal in every respect to that manufactured by and must be of the heights and columns shown on plans. They must be of the [steam] [hot- water] type. (Note: If of hot-water pattern, specify that the radiators "shall be connected with the supply at the top and the return at the diagonally opposite lower corner." If of steam type, specify that they "shall be provided with eccentric bushings and connected so that the bottom of the return connection will be lower than the bottom of the supply connection." Where Webster Modulation Valves are to be used, hot-water type radiators should be specified.) * To be inserted in case the Architect or Engineer desires to obtain, for comparative purposes, an alternate price upon ap- paratus of a make other tiian Webster 286 Contractors supplying radiation ordered for this work shall, if they be called upon to do so, demonstrate to the satisfaction of the owners or their authorized representative, that the radiation furnished contains in each section of the different types supplied the amount of prime heating surface mentioned in the lists published by the manufactui'ers of the respective types. This must be demonstrated by actual measurement and the develop- ment of the exposed surface of the sections. The heating contractor is to instruct the manufacturer of the radiation that he requires same to be thoroughly pickled £md cleaned before shipment and that the outlets are to be plugged with loose wooden plugs. The manufacturer must issue his certificate to the con- tractor showing that these radiators have been so cleaned. These radiators are to be kept plugged until same are connected to the different pipe lines. Air-valve tappings are to be plugged. Radiators must be tapped or bushed for sizes of supplies and returns as shown on plans. Coil Hangers: Overhead radiators are to be himg in special pipe hangers and in no case shall these coil hangers be more than 10 ft. apart. Wall coils are to have spring pieces and are to be hung on cast or wi-ought-iron plates spaced as directed by their manufacturer, screwed to 13^i2-in. strap-iron brackets bent to shape, and securely fastened to the walls with two expansion bolts each. Brackets must be spaced not over 10-ft. centers. Wall radiators must be hung as directed by manufacturers. Straps shall be painted two coats of lead and oil paint of colors as directed by owners before radiators are set in place. Owners must be given opportunity to paint walls or ceil- ings before radiators are set. Return Traps : The return end of every radiator, pipe coil or other form of heating unit must be provided with a Webster Return Trap (of the type selected). The size of the trap shall be governed by the amount of condensation from the radiation unit as called for on plans. The cormections of Webster Return Traps must be made to the approval of Warren Webster & Company, who will provide the contractor with service details showing approved forms of connection. Supply Valves: Each radiation unit must be provided with a Webster Modulation Valve connected to the top supply tapping. The sizes of supply valves, the radiator tappings and the sizes of horizontal bremches from risers to radiators must be as shown on the plans, or as hereafter described in this specification. Pipe: All low-pressure pipe must be full-weight [mild-steel] [genuine wrought-iron] equal to that manufactured by All screwed piping must be fitted with occasional flEinged unions. Where supply pipes are reduced in the run, eccentric reducing couplings must be used. Straighten all pipe, ream all burrs and remove all dirt before erecting pipe or fittings. Have all runs plumb and parallel with building. Provide Webster Expansion Joints of the types and sizes and at the points shown on plans. Support all pipes securely and in such manner as to permit unobstructed movement between anchorages for expansion and contraction. So far as possible, all horizontal runs must be graded in the direction of steam flow. Fittings: All fittings shall be best gray-iron, straight and true and free from blow- holes or other defects; equal to those manufactured by Fittings for low pres- sure shall be standard weight; those for high pressure shall be extra heavy. Valves: All check, gate and globe valves must be equal to those manufactured by Heat Mains: From the low-pressure side of pressure-reducing valve run a pipe to connect into the exhaust steam main where shown on plans. (Here should follow a descrip- tion of the course of the steam main and its branches.) Horizontal runs must grade not less than 1 in. in 25 ft. Live Steam Connection: Connect a . . -in. line from outlet in live steam main (where indicated on plans) to the heating main through the pressure-regulating valve. This valve shall be . . . -in. size and equal to that manufactured by , and shall be set to reduce the steam pressm'e from ... to (1 lb. per sq. in. or less). Provide a 3-valve bypass as shown, the valve in front of the reducing valve to be 287 of the globe pattern. Run a "control pipe" as shown. Place a low-pressure gauge and a ^-in. pop alarm valve set at 10-lb. pressure in the heat main about 10 ft. from the discharge of pressure-reducing valve. Risers : A system of supply and return risers is to be run as shown on plans. Risers are to be run [exposed] [concealed] and are to be of sizes marked on plans. All radiator branches must grade back to risers or mains with as much grade as possible, in no case less than 1 in. in 5 ft. All connections are to be made with ample provision for expansion and contraction and particular care is to be taken thai branches are run without pockets. Return Piping: All return risers and branches are to connect into return mains. Horizontal return piping must be graded toward the vacuum pump not less than 1 in. in 40 ft. Dirt Traps : The bottom of all supply connections taken from the heating main must be dripped into the vacuum return by means of a cooling leg, a gate valve, a Webster Dirt Strainer and a Webster Return Trap of size shown on plans. Note : In large installations it is advisable to run a separate gravity drip line and connect drip of each riser or drip point of main through iJjj-in. line with gate valve to this Une. The discharge of this gravity drip line to be to the feed-water heater through loop seal or to the vacuum return through Webster Heavy-duty Trap. Dirt Strainers: Provide and connect Webster Dirt Strainers of the sizes specified and at the points indicated on the plans. Lift Fittings: Where lifts occur in the vacuum return lines they are each to be pro- vided with a pair of Webster Lift Fittings of the sizes called for on plans and connected according to special service detail furnished by the manufacturer. RoiLERs: (Here specify the make, size and type of boiler or boilers required; also the equipment required for the complete boiler plant, including smoke breeching, damper regulator, gauges, feed pump, injector and any other necessary accessories.) Vacuum Pumps: (Here specify the make, size, type and number of pumps required "to be furnished upon (concrete or other material) foundations to be provided by this contractor." Detail specifications of pumps should describe either the electric-driven type (Nash, etc.) or the steam-driven type (Blake-Knowles, Burnham, Marsh, etc.). For steam- driven pump, specify "simplex, double-acting type, brass lining, and fitted for hot-water service" and that "each pump shall be provided with a forced-feed lubricator of approved make and having a capacity of one quart." Each pump shall have ample capacity for handling the products of condensation from the entire heating system. The discharge from steam-driven vacuum pump must be connected to the proper tapping in the receiving tank. If discharge outlet is located on the side of the steani pump, tap the cover plate above the discharge valves and run ^:4-in. air line, connecting to discharge pipe. All connections must be properly valved and made complete. Suction Strainer: In the suction pipe to the vacuum pump, place a Webster Suction Strainer. This strainer must be connected to accord with special service detail furnished by the manufacturer. Vacuum Governor: In the steam connection to vacuum pump below the lubricator there must be placed a . . .-in. Webster Vacuum-pump Governor with 3-valve bypass. Same must be connected by means of J'2-in. vacuum line to the suction strainer and also to the vacuum gauge on board. Each branch must be provided with a globe valve. Gauges: Furnish and erect at convenient position two 53^-in. compound gauges mounted on a slate board. Connect one gauge to equalizing line between heat main and reducing valve, one gauge to a line connecting vacuum governor with vacuum return at suction strainer. All gauge piping to be H-in. and all branches valved. Air-separating Tank: Furnish a Webster Air-separating Tank ... in. in diameter by . . . in. long. This tank is to be of the type. Erect the separating tank as high above the heater as possible, as shown on plans, and to it make connections from discharge of vacuum pumps and to feed-water heater through long loop seal. From top outlet on tank make a vent connection to atmosphere. 288 Feed-water Heater: Furnish and erect on foundation one Webster Feed-water Heater of sufficient capacity for heating the required feed water to within 5 deg. of the tem- perature of the steam entering same. The drip from oil separator is to connect to waste hne through a Webster Grease Trap with 3-valve bypass and check valve as shown in special service detail. The contractor is to make all necessciry stecmi, water and drain connections as shown or called for. Steam Separator : Furnish and connect Webster Steam Separators of approved type to steam lines as shown or called for. The drip from bottom of each separator is to be connected into a high-pressure trap of approved make. Each trap is to be provided with a 3-valve bypass. The discharge lines from these traps are to be connected into the feed-water heater. Covering : After all piping and apparatus have been tested and made tight to the approval of the [ai'chitect] [engineer] or his representative, the following covering is to be applied. (Here specify necessary covering for boilers, heater, separator, and all [specify which] piping, valves and fittings.) Painting and Bronzing : AH radiators, coils and exposed piping throughout the build- ing, after being tested, are to be painted or bronzed as follows : All radiators, coil and exposed piping are to be painted one coat of sizing and then [bronzed] [painted] [two] coats; color as selected by architect or owner. All exposed parts of boiler and heater to be painted two coats of black asphaltum paint. Tests: All concealed pipes and risers shall be tested and made tight under an hydrauUc pressure of 50 lb. per sq. in. before being covered in. The entire system shall be tested and made tight under 10-lb. steam pressure. Thoroughly blow out the pipes to free them from all accumulation of dirt, chips and other material, making temporary piping connections for this purpose. Fuel and Labor: The heating contractor will furnish all fuel and labor required for testing and adjusting boilers and apparatus and for drying out covering on boilers (and smoke breeching). He will also remove water and ashes resulting therefrom. Temporary Setting of Radiators : Upon written request of the [architect] [engineer] the contractor shall connect up for temporary heat such radiators as shall be designated. These radiators shall afterwards be disconnected, moved, cleaned, and afterwards recon- nected permanently. Wall radiators and radiators without leg sections shall be supported on wooden blocks. Each radiator is to have two pipe connections and no supply or return valves are to be attached at this time. Each bidder will state in his proposal a unit price which he will charge for making temporary connections as described above. Inspection: This job is to be inspected by a representative of the manufacturer of the return traps before acceptance and he shall submit a written report of the same to the Archi- tects. Guarantee : The contractor must agree to make good at his own expense any defects in labor or material furnished by him for this work which may develop within one year from the completion of this contract, reasonable wear and tear excepted. The entire system when completed is to be tested in the presence of the [architect] [engineer] or his representative, and made tight without caulking. The contractor will be held liable for any damage to the building or its contents due to leaks or other defects in his work which may develop during the period of installation and test. Specifications for the Webster Modulation System of Steam Heating (This specification is written for a large residence. It is, of course, subject to modifications and variations for other kinds of buildings, for other sources of steam than house boiler, etc., for which revised typical specifica- tion clauses will be furnished by Warren Webster & Company on request.) General: (Here specify the general requirements of the contract such as intent of drawings and specifications; verification of measurements; co-operation with other con- 289 tractors; foreman; ordinances; permits; protection of work and buildings; rights reserved ; extra work; return of specifications and drawings; payments, etc.) Cutting of Floors and Walls : The [building] [heating] contractor will cut all holes in floors and walls and provide trenches and covers for piping which may be necessary for this work, and at completion make all repairs to floors and walls so cut. Scope of Work: This specification is intended to cover a 2-pipe open-return heating system known as the Webster Modulation System of Steam Heating. It is intended that sufficient radiation shall be supplied for heating the building to a temperature of . . . deg. fahr. when the outside temperature is ... deg. fahr. or a corresponding equivalent difference in temperature, based upon all doors and windows being fitted reasonably tight to prevent excessive infiltration of cold air. Special Apparatus: The basis of this specification being a Webster System, each bidder is required to submit his proposal for furnishing apparatus manufactured by Warren Webster and Company. *Alternate Proposals will be considered for the use of modulation supply valves and thermostatic return traps of the same supply and return tappings and as made by , provided each bidder states in his proposal the sum which will be added to or deducted from his main bid in case they are used. Standard Apparatus : In addition to the special apparatus, this contractor is to fur- nish all other material and labor necessary for the complete work as shown on plans or called for in specifications. Boilers: (Here specify the make, size and type of boiler or boilers required, specifying also the equipment required for the complete boiler plants, including smoke breeching and other necessary accessories.) (Indicate what contractor is to build boiler foundation.) Note: Boilers and auxiliary equipment must be installed in accordance with Warren Webster & Company's standard service details. Damper Regulator: Furnish one Webster Damper Regulator for each boiler; to be connected in accordance with the manufacturer's standard details. Gauges: A special compound gauge for Webster Modulation System is to be installed for each boiler. This gauge will be furnished by the manufacturers of the system. Radiators: All radiators throughout the building shall be of or equal approved make; all radiators to be of the hot-water type with supply tapping at top and return tapping eccentric at diagonally opposite lower corner. Radiators to be of the height and columns and to contain the surface indicated on plams. In no case is radiation to pro- ject above window sill. In connecting all radiators, the inlet end shall be placed next to feed risers, if possible. The indirect stacks are to be (make and type) cast-iron radiation, to be of the size and contain the number of sections as called for on plans. The heating contractor is to instruct the manufacturer of the radiation that same is to be thoroughly pickled and cleaned before shipment and that the outlets are to be plugged with loose wooden plugs. The manufacturer must issue his certificate to the contractor showing that these radiators have been so cleaned. These radiators are to be kept plugged until they are installed and connected. Air valve tappings are to be plugged. Radiators must be tapped or bushed for sizes of supplies and returns as shown on plans. Hangers : Hangers for indirect stacks are to be strong wrought-iron or pipe supports. Enclosures for Radiators: The enclosures and grilles for enclosed radiators will be furnished by Return Traps: The return end of every radiator, pipe-coil or other form of heating unit must be provided with a Webster Return Trap (of the type selected). The size of the trap for each radiation unit shall be as shown on plan or called for in specification. The connections of Webster Return Traps must be made to the approval of Warren Webster & Company, who will provide the contractor with service details showing approved forms of connection. Supply Valves: Each radiation unit must be provided virith a Webster Modulation Valve connected to the top supply tapping. * To be inserted in case the Architect or Engineer desires to obtain, for comparative purposes, an alternate price upon ap- paratus of a make other than Webster 290 The sizes of supply valves, the radiator tappings and the sizes of horizontal branches from risers to radiators must be as shown on plans. Each overhead radiator must be provided with a Webster Modulation Valve with chain attachment. Provide a Webster Modulation Extended-stem Valve for each radiator behind a grille. Modulation Vent Trap: Furnish and install [one] No Webster Modulation Vent Trap for separating the air from the condensation in the heating system. [The] [Each] trap is to be vented through Webster Vent Valve[s] placed in the top. Pipe : All pipe must be full- weight [mild-steel] [genuine wrought iron] equal to that manufactured by All screwed piping must be fitted with occasional flanged unions. Where supply pipes are reduced in the run, eccentric reducing couplings must be used. Straighten all pipe, ream all burrs and remove all dirt before erecting pipe or fittings. Have all runs plumb and parallel with building. Allowance for expansion and contraction must be provided. Support all pipes securely and in such manner as to permit unobstructed movement between anchorages for expansion and contraction. So far as possible, all horizontal runs must be graded in the direction of steam flow; where this is not possible, the pipe lines shall be materially increased in size as shown on plans. Fittings: All fittings shall be best gray-iron, straight and true and free from holes or other defects; equal to those manufactured by Fittings shall be standard- weight. Valves: All gate valves must be equal to those manufactured by All check valves must be special, of balanced type with vertical seat, and of approved make. Fresh- AIR Inlets: Fresh-air inlets for indirect heating are to be taken from openings provided in walls. Another contractor will provide heavy copper wire screens having 3/2-in. mesh, and sheet metal louvers over the mouth of each inlet. Sheet Metal Work: The ducts supplying fresh air to the indirect stacks, the indirect stack casings and the hot-air flue from indirect stacks to registers are to be made of gal- vanized iron. They are to be properly braced and locked tight to prevent air leakage. An adjustable lock quadrant hand damper is to be provided in cold-air connection to each indirect stack. The metal used for all ducts and flues is to conform to the following gauges: Ducts that have one dimension over 48 in., . . . gauge. Ducts that have one dimension from 30 to 48 in., ... gauge. Ducts that have one dimension from 12 to 30 in., . . . gauge. Ducts that have one dimension smaller than 12 in., . . . gauge. The indirect stack casings are to be made of . . . gauge iron and are to be built neatly around stacks and provided with cleanout doors above and below radiators in bottom or side. Registers: The registers for the outlets of hot-air flues from indirect stacks will be furnished by ; their installation is included within this contract. Steam Piping: From the steam outlets on boiler rise and connect to a steam header over boiler. From top of header take branches as shown. The steam lines are to be run close to ceiling of cellar with a grade of 1 in. in 25 ft. The branches for risers are to be taken from top of mains. Steam header and main are to be dripped to wet drip line where shown. Risers : A system of supply and return risers is to be run as shown. Risers are to be run [exposed] [concealed], tmd are to be of sizes marked on plans. Unless otherwise noted on plans, branches to radiators above first floor are to be run concealed in floor construc- tion and branches to first floor radiators are to be run overhead in cellar as close to ceiling as possible. All radiator branches are to grade back to risers or mains with as much grade as possible, in no case less than 1 in. in 5 ft. All connections are to be made with ample provision for expansion and contraction and particular care is to be taken that branches are run without pockets. Return Piping : All return risers and returns from first floor radiators are to connect into overhead return mains. The return mains are to start as high as possible and grade toward the Webster Modulation Vent Trap 1 in. in 25 ft. The vent trap (or traps) to be located where shown and at least 30-in. above the water line and as much higher as possible. 291 [The] [Each] vent trap will be provided with a tapping near the top into which the dry return main must be connected, a tapping in the bottom from which a ... in. pipe must be run to below boiler water line and connected into the wet return through a horizontal swing check valve of make. Make a full size bypass connection around [each] vent trap. IVIake a . . .-in. city water supply connection to boiler with check valve and cock, also a . . . -in. drain to waste through gate valve from the return header of boiler as directed. Check valves are to be installed where shown. A wet drip line is to be run on wall near floor as shown, and connected to boiler. To this line connect drips of mains, indirect radiators and lines from vent trap as shown. Covering: After all piping and apparatus has been tested and made tight to the ap- proval of the [architect] [engineer], the following covering is to be applied. (Here specify necessary covering for boilers, and all steam, return and drip piping, valves and fittings.) Painting and Bronzing : All radiators, coils and exposed piping throughout the build- ing, after being tested, are to be [painted] [bronzed] as follows: All radiators, coils and exposed piping throughout the building are to be painted one coat of sizing and then bronzed or painted [two] coats ; color as selected by architect or owner. All exposed parts of boiler to be painted two coats of black asphaltum ptiint. Radiators or ducts which are visible through grilles or registers are to be painted two coats of dull black. Tests: All concealed pipes and risers shall be tested and made tight under an hydraulic pressure of 50 lb. per sq. in. before being covered in. The entire system shall be tested under 10 lb. steam pressure. The entire system shall be thoroughly washed out before final test, wasting condensation to sewer or other point of disposal. Cleaning Boilers : Remove safety valve, place inside the boiler a sufficient quantity of soda ash to cause saponification of oils and grease. Run temporary overflow pipe to waste, from safety valve outlet or from highest point of boiler and start moderate fire so that foam- ing of boiler will cause flow of oil and grease to waste, at the same time feeding the boiler with water to prevent injury to same. After thoroughly boiling out the boiler, draw the fire and when cool draw off all water from the boiler and thoroughly wash same with clean water to remove dirt and chemicals. The treatment of boiler should be repeated if water line fluctuates abnormally or shows signs of foaming. Fuel and Lador: The heating contractor will furnish all fuel and labor required for testing and adjusting boilers and apparatus and for drying out covering on boilers (and smoke breeching) . He will also remove water and ashes resulting therefrom. Temporary Setting of Radiators: Upon written request of the [architect] [engineer] the contractor shall connect up for temporary heat such radiators as shall be designated. These radiators shall afterwards be disconnected, moved, cleaned, and afterwards recon- nected permanently. Wall radiators and radiators without leg sections shall be supported on wooden blocks. Each radiator is to have two pipe connections and no supply or return valves are to be attached at this time. Each bidder will state in his proposal a unit price which he will charge for making temporary connections as described above. Inspection : This work is to be inspected by a representative of the manufacturer of the return traps before acceptance and he shall submit a written report of the same to the Architects. Guarantee : The contractor must agree to make good at his own expense any defects in labor or material furnished by him for this work which may develop within one year from the completion of this contract, reasonable wear and tear excepted. The entire system when completed is to be tested in the presence of the architect or his representative, and made tight without caulking. The contractor will be held liable for any damage to the building or its contents due to leaks or other defects in his work which may develop during the period of installation and test. 292 CHAPTER XXVI Webster Sylphon Trap Attachments 1. For "Sylphonizing" Webster Traps of Earlier Types STEAM heating, like almost every other science, has developed pro- gressively tlirough experience. Being pioneers in this field Weirren Webster & Co. have had ample incentive and opportunity for experimental research and development, and have constantly improved their product and methods, discarding and abandoning earlier types of apparatus as improved forms were adopted. The Webster Sylphon Trap (shown and described on pages 242-5) is now generally recognized by leading architects and engineers to be the most satisfactory type of device for return line systems. It is in its eleventh year of success and the total number in use has passed the million mark. Owners of buildings and plants in which old-style Webster Valves are in use will be vitally interested in knowing that such valves can be readily converted into Webster Sylphon Traps by means of the Webster Sylphon Attachments described in this chapter. The conversion necessary to brirtg the heating system thoroughly up to date can be made at a very moderate cost. No breaking or touching of pipe connections is involved, as the old valve bodies are utilized. The advantages to be derived from the "changeover" will be evident from the description of the Webster Sylphon ^_ " '■»,. i Fig. 26-1. The No. 422 Thermostatic Valve in its original form and same valve changed over. Pipe connections untouched 293 Trap, on page 242, which description will equally fit the earlier Webster Valves after they are converted by means of Webster Sylphon Attachments. The time required for changing over any valve is only a few minutes. Conversion of No. 422 Webster Thermostatic Valves: The method of changing over by means of the 5-A-13 Webster Sylphon Attach- ment is indicated by the illustrations. It is only necessary to remove the old bonnets and interior parts, tap- ping the body for the insertion of a new brass seat by means of a tapping tool. The Webster Sylphon Trap Attachment may then be inserted and the old valve has become a new Webster Sylphon Trap equal in performance to the standard Webster Sylphon Traps which are furnished to thousands of new customers each year. For conversion of Multiple-unit Thermostatic Valves, see page 296. Conversion of Webster Motor Valves: This is practically the same as with the No. 422 Webster Thermostatic Valve except that a slightly different Sylphon Attachment is used. The illustrations show the No. 522 M Sylphon Attachments for j/^-in. motor-valves of the disc-air-port type. The No. 533 M Attachment for ^-in. motor-valves is of exactly the same construction. These same Sylphon Attachments may be applied to the '03 motor-valves of the pin- air-port type where this special type of valve is to be changed over. For conversion of Multiple-unit Motor Valves, see page 296. Fig. 26-2. Jf-Inch Webster Motor-Valve, Disc- Porl Type, in its original form and same valve changed o\er. is Pipe connections untouched ^ Conversion of No. 422 Webster Water-seal Motors: The method of changing over, as illustrated, involves the use of the same attach- ment as for changing over the Webster Thermostatic Valve as just de- scribed. In the case of the Water-seal Motor, however, the operation is simplified through the old body being already tapped for the valve seat. It is only necessary to remove the old bonnets and interior parts, and insert the new brass seat. The Webster Sylphon Trap Attachment may then be inserted and the old valve becomes a new Webster Sylphon Trap. For conversion of Multiple-unit Valves, see page 296. 294 Fig. 26-3. The No. 422 Water-seal Motor in its original form aijd same motor changed over. Pipe connections untouched Fig. 26-4. No. 5-C-15 Sylphon Attach- ment for 522 or 523 Water-seal Trap where the discharge rating is low Conversion of No. 522 Water-seal Traps: The change-over in this instance re- quires only removal of the old bonnets and interior parts, and inserting the new Webster Sylphon Trap Attachments. Re-tapping is not necessary for the new seat. For conversion of Multiple-unit Water- seal Traps, see page 296. Similar Webster Sylphon Attachments can be fiu"nished for all the other sizes of Webster Water-seal Traps as follows: Fig. 26-5. No. 522 Webster Water-seal Trap in its original form and same trap changed over, using 522 Sylphon Attachment for higher discharge rating 295 The No. 522 and No. 523 take the same Sylphon Attachment. Another attachment applies equally for No. 533 and No. 534. No. 544 and No. 545 each have an individual attachment. rTTi /J^ A rfn rfri =iM= -Unil .^ \ / r m rf^ jfii \ffT\ 5-Unil JQL rfti rfti rBi rf?i rsx 6-Unit Fig. 26-6. Multiple-unit Thermostatic Valve with No. I Type bodies changed over by means of Webster Sylphon Attachments. Pipe connections untouched. Note how intervening openings are blanked out by new cap and solid seat Conversion of Multiple-unit Webster Valves of Earlier Types: On units of radiation beyond the capacity of a single valve it was the practice 296 ill the past to recommend and use a Multiple-unit Valve, made up of a special body having multiple openings to receive two or more bonnets similar in all respects to those used in the standard single-unit valve. For changing these Multiple-unit Webster Valves by means of Sylphon Attachments, the use of Sylphon Attachments is recommended only for the alternate openings in the valve body, the intervening outlets being plugged as shown in Fig. 26-6. Multiple Valves were made up to 6-unit. It is necessary to deter- mine whether attachments are for 2-unit, 3-unit, etc., so that proper num- ber of attachments, solid seats and blanking-out caps may be furnished. The Multiple-unit Valve, when changed, will have capacity equal to (and possibly in excess of) the requirements of the original installation. II. For "Sylphonizing" Radiator Outlet Valves of Other Makes Fig. 26-7. 5-A Extension Attachments (Five-fold Sylphon bellows) applied to valve bodies of various makes 297 A great demand has developed for Webster Sylphon Attachments, not only in connection with early types of Webster Valves, but for other makes of valves and traps, and in the converting of old gravity systems in which the ordinary hand- wheel shut-off valve was employed. To meet the requirements of a wide variety of sizes and types of valve and trap bodies the Attachments described in the following pages have been designed. The principle is the same with each attachment. The variation is only in the work of application. With the instructions furnished and the tools loaned for the purpose, the work of Websterizing, by means of these attachments, is so simple that it can be done in a few minutes for each radiator, and so cleanly that there is no disturbance or damage to surroundings or furnishings. The use of these Webster Sylphon Attachments, properly applied throughout the building, will often effect the same advantages as extensive changes in piping and at a small fraction of the cost. And further, the whole work of change-over can be done without interrupting the operation of the system as a whole. Series 18 Webster Sylphon Attachments are of two general forms: Class A in which the attachment parts are fitted in an extension body which screws into the old trap or valve body; and Class C in which the at- tachment parts are fitted into a special brass cap which is threaded to fit the old valve or trap body. The Class A Extension Attachments are made with extension bodies to receive 5-fold Sylphon Bellows (symbol 5-A) and to receive 12-fold Sylphon Bellows (symbol 12- A). The extension bodies of both the 5-A and 12-A classes are made with a Fig. 26-8. Typical Class A Sylphon Attachments having extension bodies. Where necessary for securing correct final adjustment, a screw fit or push fit seat is used. A typical push fit seat is shown at the right. 298 Fig. 26-9. Typical Extension bodies 12-A threaded opening at the top to receive a standard cap, but of varying diam- eters of the lower part of the body, so that the lower end may be threaded to fit the thread of the old body. The illustrations show the full series of Extension Attachments from 5-A-12 to 5-A-27 inclusive. The 12-A Extension Attachments are similarly made in sizes 12-A-12 to 12-A-27 inclusive, although the application of only two of this type is shown. The capacity required as indicated by size of radiator determines whether a 5-A or 12-A Extension Attachment should be used. It will be noted that the valve stem attached to the Sylphon Bellows varies in length with the type of valve body, but is similar in all cases. The seat requires a little explanation. It is impractical to use a threaded seat, as a constant distance must be maintained from body face to seat face and this cannot be done with a threaded seat because of the variations in the distance mentioned, which will occur in bodies of same make and size. The seat is made to push-fit in the body opening which is previously prepared by reaming to the desirable diameter. Final attachment to gauge depth to meet any variation in the depth of the valve body is made by means of a push-in tool which is loaned for the purpose. In the case of ordinary globe or angle valve bodies and in various makes of float traps where preparation in this respect was not previously provided, the push-fit seat described above provides means to obtain the correct final adjustment without difficulty. The valve stem is a solid brass rod with a conical taper for seating and is of varying length as determined: (1) by the gauge depth of the old body from bonnet face to seat, (2) by the diameter of orifice in the seat; and (3) by the rating of the radiation unit to which the valve is connected. Where necessary to provide greater vapor space through the neck of the extension body, the rod is turned down to smaller diameter at such points. The Class C Cap Sylphon Attachments are designed for those forms of old valve and trap bodies in which the expanding member (Sylphon Bellows) and conical valve piece may be placed entirely within the old body without the use of an extension body. With this class of attachment it is necessary to provide a special cap, threaded to fit the existing body, but the design has been standardized so that few patterns need be used to meet a wide variety of bodies. 299 Fig. 26-10. Typical Class C Sylphon Cap Atlachnients placed entirely with- in the old bodies and push-fit seats in- stalled for correct final adjustment At the left is a 5-C Attachment (Five-fold Sylphon bellows) At the right is a 12-C Attachment (Twelve-fold Sylphon bellows) Note this special case of a new screwed-in seat with a pushed-in fer- rule for insuring accurate adjustment The Class C Cap Attachments, hke the Extension Attachments, are made to receive either the 5-fold or 12-fold Sylphon Bellows to fp^ which the symbols 5-C and 12-C are given. The illustrations above show the applica- tion of Class C Cap Attachments to tw o differ- ent shapes of valve bodies. The description given previously in refer- ence to the valve stem and seat for the Extension Attachments, applies equally to the Cap Attachmputs. 300 CHAPTER XXVII Fuel Saving by Preheating Boiler-Feed Water WHERE exhaust steam is available and would otherwise be wasted, a considerable saving of fuel may be effected by utilizing a direct- contact (open) feed-water heater to transfer heat from the exhaust steam to the cold feed water. The saving amounts to approximately one per cent of fuel for each 11 deg. increase in the feed-water temperature. This is the figure taken for ordinary calculations. A more accurate method of computing this saving takes into considera- tion the total heat in the steam generated in the boiler, as well as the final and initial temperatures of the feed water. This formula is Total saving in per cent = „ , o'o — t~ ' ^^^ which H= total heat above 11. ~r oZ to 32 deg. fahr. per lb. of steam at boiler pressure, t,= temperature of water after heating, and t2= temperature of water before heating. Table 27-1. Percentage of Total Heat of Steam Saved per Degree Increase in Feed-water Temperature for Various Pressures of Saturated Steam Gauge pressure i in boiler— -Lb. per sq. in. ft . S ft 10 25 50 75 100 125 1.50 175 200 225 l;S Value of H 1^ 1150.4 1160.2 1169.2 1178.4 1184.3 1188.8 1192.2 1195.0 1197.3 1199.2 1200.9 Per cent saved per d egree increase in temperature 32 .0869 .0862 . 0855 .0849 .0844 .0841 .0839 .0837 .0835 .0834 .0833 40 .0875 .0868 .0861 .0854 . 0850 .0847 .0844 .0843 .0841 .0840 .0839 50 .0883 .0875 .0869 .0862 .0857 .0854 .0852 .0850 .0848 .0847 .0846 60 .0891 .0883 .0876 .0869 .0865 .0862 .0859 .0857 .0855 .0854 . 0853 70 .0899 .0891 .0884 .0877 .0872 .0869 .0866 .0864 .0863 .0861 .0860 80 .0907 .0899 .0892 .0884 .0880 .0877 .0874 .0872 .0870 .0869 .0867 90 .0915 .0907 .0900 .0892 .0888 .0884 .0882 .0879 .0878 .0876 .0875 100 .0924 .0916 .0908 .0900 .0896 .0892 .0889 .0887 .0886 .0884 .0883 110 .0932 .0924 .0916 .0909 .0904 .0900 .0897 .0895 .0893 .0892 .0891 120 .0941 .0933 .0925 .0917 .0912 .0909 .0906 .0903 .0902 .0900 .0899 130 .0950 .0941 .0934 .0925 .0921 .0917 .0914 .0912 .0910 .0908 .0907 140 .0959 .0950 .0942 .0934 .0929 . 0925 .0922 .0920 .0918 .0916 .0915 150 .0968 .09.59 . 0951 .0943 .0938 .0935 .0931 .0929 .0927 . 0925 ,0924 160 .0978 ,0969 .0960 .0952 .0947 .0943 .0940 .0937 .0935 . 0934 .0932 170 .0987 .0978 .0970 .0961 . 0956 .0952 .0948 .0946 .0944 .0942 .0941 180 .0997 .0988 .0979 .0970 . 0965 .0961 . 0957 . 0955 . 0953 .0951 .0950 190 0.1008 .0998 .0989 .0980 .0974 .0970 .0967 .0964 .0962 .0960 .0959 200 0.1018 0.1008 .0999 .0990 . 0984 .0980 .0976 .0974 .0972 .0970 .0968 210 0.1028 0.1018 0.1009 .0999 .0994 .0990 .0986 .0983 .0981 .0979 .0978 220 0.1039 0.1029 0.1019 0.1010 0.1004 .0999 .0996 .0993 .0991 .0989 .0987 301 Example: Assume a boiler pressure of 140 lb. per sq. in. absolute, and initial and final temperatures of 40 deg. fahr. and 210 deg. fahr. respectively. The total saving according to this formula is 14.36 per cent, where by the "one per cent for each 11-deg. increase" rule, the saving for the same condi- tions figures 15.45 per cent. For convenience the results as figured from the more accurate formula have been reduced in Table 27-1, to a basis of per cent of saving per degree increase of temperature. Webster Feed- water Heaters: Webster Feed-water Heaters, for obtaining the fuel savings just mentioned and other benefits not so easily measured , are made in the following types : Series 100, Class B, with overflow seal: The standard type for utilizing Fig. 27-1. Series 100 Class B Webster Feed -water Heater Fig. 27-3. Series 400 Class EBP and Fig. 27-2. Series 200 Class EB and geries 500 Class EBPH Webster Feed- Series 300 Class EBH Webster Feed- water Heater. Preference Cut-out Type water Heater. Standard Type. Smaller sizes Fig. 27-4. Series 800 Class EF Webster Feed-water Heater, Standard Type Fig. 27-5. Series 900 Class EFP Webster Feed- water Heater. Preference Cut-out Type 302 exhaust steam at atmospheric pressure and for a maximum steam pressure of 3^-lb. per sq. in. May be operated on either induction or thoroughfare principle. Series 200, Class EB: The standard type for use in connection with ex- haust steam systems under pressures not exceeding 5-lb. per sq. in. Best operated on induction principle. Series 300, Class EBH: Same as Series 200, Class EB, but suitable for pressures up to 10-lb. per sq. in. maximum. Tested to 15-Lb. per sq. in. Series 400, Class EBP: Same as Series 200, Class EB, but with inde- pendent oil separator large enough to purify all exhaust. Specially designed for use with exhaust steam heating or drying systems under pressures not exceeding 5-lb. per sq. in. Series 500, Class EBPH: Same as Series 400, Class EBP, but suitable for pressures up to 10-lb. per sq. in. maximum. Tested to 15-lb. per sq. in. Series 800, Class EF: This type is for smaller capacities, 50 to 350 hp., and is similar to Series 200, Class EB, except that the shell is a one- Vent 4t= WEBSTER AIR SEPARATING TANK Discharge from Vacuum Pump To Drain A ^^ Nole:- The Area of Pipe B to be tw ce that of Pipe A -M To Heating System Multiply Maximum Back Pressure carried in Heater by 3 to determine least Bimension in Feet Water Inlet Valve Make up Water Supply ' To Atmosphere Suction Outlet Note:- With Reciprocating Type Boiler Feed Pumps o allow at least 24 inches (as much more as ^ practicable) from C.L. of Suction Outlet to u Pump Valves. With Centrifugal Pumps Consult Pump Manufacturer. , To Boiler Feed Pump ^ Drain ' x:i ^^.gX^ 13 To Sewer Fig. 27-6. Webster Feed-water Heater installation in connection with a Vacuum Heating System. Water inlet automatically controlled. The heater shown is of the standard type. Any other type of Webster Heater would be connected in the same way 303 piece casting and is supported by a framework made from pipe and fittings. It is suitable for working pressures up to 10-lb. per sq. in. Series 900, Class EFP: Same as Series 800, Class EF, but including the large size oil separator and the cut-out valve. Webster Feed-water Heaters, Standard Type: The heater shell as illustrated in this chapter, is made of close-grained cast-iron plates. Web- ster Heaters are also made with shells of genuine old-fashioned puddled wrought-iron, or of other sheet metals such as flange steel or the so-called copper-bearing steels. Wrought-iron heaters are specially recommended as they are proof against the minor accidents of operation which fre- quently crack cast-iron heaters. The heater is easily cleaned, as the interior is accessible without dis- tvubing any of the pipe connections. The large hinged doors may be quickly opened, and the trays withdrawn. The lower chamber, containing the Vent Ph 4t WEBSTER AIR SEPARATING TANK Ife Discharge from Vacuum Pump Note:- The Area of Pipe B to be twice tliat of Pipe A To Drain -fit m^P . Exhaust to Atmosphere To Heating System Multiply Maximum Back Pressure carried in Heater by 3 to determine least Dimension in Feet Regulating Valve I Returns Inlet Back Pressure Valve To Atmosphere From Source of Water Supply Note:- With Reciprocating Type Boiler Feed Pumps allow at least 24 inches (as much more as . practicable) from C.L of Suction Outlet to Pump Valves. With Centrifugal Pumps Consult Pump Manufacturer. To Boiler Feed Pump Drain ^ ^md^ 3Ta Sewer Fig. 27-7. This W ebster Feed-water Heater installation differs from usual practice in that the make-up water supply is manually controlled. A float within the heater operates a valve in the steam-pipe sup- plying the boiler-feed pump to stop the pump when the water level is below a pre-deterniined point .•?04 filter, is accessible through the filter doors. Where the doors are bolted to the heater body, the shell is suitably reinforced, the faces being machined to insure tight joints. LOW PRESSURE RETURNS INLET jROUGH a WATER SEAL HEATIN6 TRAYS OIL SEPARATOR ' EXHAUST STEAM INLET 5CRE1 PUMP m HIGH PRESSURE T OVERFLOW SINK PAN SKIMMER FOR URFACE BLOWOFf OIL SEPARATOR DRIP OVERFLOW OUTLET «*-W TER SCREENS Fig. 27-8. Series 200 Class EB and Series 300 Class EBH Webster Feed-water Heater, Standard Type 305 mg The water supply to the heater is controlled automatically, the regulat- valve being operated by a series of levers connected to an open copper sink pan (performing the functions of a float), placed within the heater shell. Any dangerous excess of water automatically passes out of the heater when the water reaches the overflow level. Except in the case of the 100 Series, the excess water is automatically passed out through a valve actuated in the same manner as the cold water supply-valve, that is, by another open sink pan placed within the heating chamber. This valve is normally closed, preventing loss of steam. The Webster Oil Separator which forms a part of each heater is well Fig. 27-9. Series 800 Class EF Webster Feed-water Heater, Standard Type 303 known and extensively used as an independent unit for removing oil from exhaust steam mains, hence its use in the Webster Feed-water Heater. The feed water, entering the heater through the automatically con- trolled valve inlet, passes into the water-sealed distributing trough, which has two wide, extended lips. The water, overflowing from this trough in even sheets, is distributed over a series of oppositely inclined, finely per- forated metal trays, arranged one above the other as shown in the illustra- tion below. The water in its downward course falls from one tray to the other, part of it passing through the tray perforations and the balance WATER INLET REGULATING LOW EXHAUST 5TEAM INLET ' BAFFLE ./WEBSTER PREFERENCE SEPARATOR MMER FOR SURFACE BLOWOFF DRAIN' , SCREEN FOR PUMP FILTER SCREENS CHAMBER FILTER CHAMBER Fig. 27-10. Series 400 Class EBP and Series 500 Class EBPH Preference Cut-out Type Webster Feed-water Heaters 307 falling from the lower edge of the tray to the tray immediately below. This method of water travel provides the necessary surface contact for the steam and water so that the highest possible temperature is imparted to the water, causing a liberation of gases and precipitation of solids. Ample space is provided for uniform distribution of steam around the trays. By reason of the large storage chamber it is possible to utilize the heater as a receiver for condensation from heating systems, dry kilns, heating apparatus, etc. Between the level at which the cold water supply-valve is closed and the overflow there is ample space for the accumulation and storage of such returns. The filter is located in the lower compartment of the heater. In this settling chamber, opportunity is given for the precipitation and filtration of the particles of sediment and impurities and for frequent drainage through a quick-opening drain valve. The filter bed is commonly composed of coke or other suitable material, which is contained between the perforated division screens already mentioned. This material can be renewed whenever necessary. The large doors at the front allow ready access for charging and cleaning. The Webster Preference Cut-out Heater: This type, as may be noted from the illustrations, combines a Webster Heater and a large oil separator with a cut-out gate valve intervening. The oil separator has sufficient capacity to remove the oil from the exhaust steam delivered from the engines, pumps and other sources. This arrangement is therefore especially desirable where exhaust steam is to be utilized in heating or drying systems, cooking kettles or other industrial processes. A Webster Grease Trap is used in draining the separator. Steam from the engines and auxiliaries should be combined in a common exhaust pipe before reaching the heater. This exhaust pipe may enter the separator horizontally or vertically, the latter condition being usual with the exhaust steam current upward. Upon reaching the preference oil separator the steam flows horizontally through the baffles, which are of the standard Webster design (see Figure 27-11), comprising a number of hooked steel plates interposed in the course of the steam, causing separation by contact, by change of direction and by adhesion. The ports through which the steam is guided and the free area through the baffles are especially designed to prevent any considerable loss of pressure. After passing through the baffles, the steam may pass to the heater, or to the outlet into the heating system or other apparatus using exliaust steam or to the atmosphere. Particularly valuable advantages of the Webster Preference Cut-out Heater are: 1. The considerable saving in piping connections and additional ap- paratus accomphshed by its use as compared with the Standard Heater. 2. The cut-out valve used in the Webster Preference Cut-out Heater is most rehable for its piu-pose. When the heater is cut out for internal inspection or cleaning, the course of the exhaust steam through the oil 308 separator is such that no steam is in contact with the side wall of the heater. Steam passes through the separator and on to atmosphere or the heating system without warming up the heater body to a degree that would endanger or discomfort the man who may have to enter. A thorough clean-out is possible at any time without having to wait until the whole plant is shut down. 3. The grease and oil trap too is not integral with the overflow of the heater, so that if its outlet becomes temporarily deranged, oil cannot get back into the heater through the overflow opening. Fig. 27-11. Series 900 Class EFP Preference Cut-oat Type Webster Feed-water Heater 309 Table 27-2. Dimensions of Series 200, Class EB, Webster Feed-water Heaters For working pressure up to 5 lb. per sq. in. Specifications Capacity Heating trays Cubic contents Weights, lb. Drawing no. Filter Wkg. pres. No. Horsepower * Lb. mln. Area sq. ft. Ma- terial Total cu. ft. Water cu. ft. Shipping Max. 203 to 400 II V 9247 12.5 24.4 14.7 2600 3600 205 425 to 650 9203 16.5 o 40.0 25.5 3700 5400 207 675 to 900 9250 24.0 c 60.0 40.0 o 4700 7300 210 925 to 1.350 .s ° 9254 33.0 2 80.5 52.0 c 5700 9000 215 1375 to 1850 - s 9252 51.6 o ^ 121.3 80.0 ■f. 8000 13100 220 1875 to 2400 OJ O 9257 63.8 ^n 152.5 101.0 "2 9000 1.5700 225 2425 to 3000 9256 82.0 .5 a 180.0 128.1 s S 10300 18400 230 3100 to 4000 ■s.^ 22457 95.7 240.0 133.5 c s o o. 13000 21300 235 4100 to 5500 ^ g 13377 121.5 .2 316.0 140.0 — 15000 23600 250 5600 to 7500 13626 160.1 g < 400.0 179.0 Q in 20000 31400 285 7600 to 9.500 4 ° 22196 201.5 482.0 222 22000 36000 299 9600 to 12000 z 18779 243.0 268.0 25000 41700 ' One rated horsepower^capacity for heating 30 lb. of water per hour from 40 deg. fahr. to a temperatvu-e within 5 deg. of the steam temperature ,® ® 1 IH 2 2 ®|® ® ® ®!® ® 203 6 205 8 2071 8 21010 4 4 5 5 2}^ 3 3K 3^ IH 2 2K2K 32K 43 53 1 1 1 1 21512 22014 225il6 230,18 2H 2H 3 64 6'4 85 86 1 IK IK 2H 4 4 53 55 55 2-55 IK iH IH 235 20 25022 285 24 299 28 5 108 108 128 1210 2-lH 2-lH 5 5 5 5 2-35 2-3'5 2-46 2-68 2 Comb. Vent and Vacuum Breaker- (D ® Pump Outlet Live Steam Drips DDQ] D D © Drain"' ' 1^ J^ annn D n D No. Trays Foundation rer- an Dimensions No. i Size Lg. Wd. Hgt. A A' B c DBF G 1 H J 9 K j L M , N P 5H R 203 5 15 x24 35 35 SOU 2fi 26 HOV, 66 54j^ 65i 4H 7.iH 18H 21 H 21 '4 25 K 16 9 205 5 151^x30^ 41 41 88 32 32 88 72 .57=/« 7K'5K 7934 2m im 27 26'/, 28M 19 H 7K 8K 207 6 16 x36 45 45 101=^ 36 36 101 H 84 69 '4 7K 93M 25 i-iH 28 H 2VH 34 21H 9^8 U 210 12 10 x40K 51 51 101^ 42 42 lom 84 67 M 7% 6 93M 28 15H 3IV2 31 H 3/ 'M% 8 10^2 215 12 13}^x46 57 57 115K 48 48 115H 9fi 77 VS 8U 7 104 M 33K 16 36 36K 41J^'275^ 8K 1334 220 12 16Kx47 69 57 115^^ 4S 60 115V^ 96 81 H SW 7 105H'4O IS ay? 4b 47 Mi ■i-iyn 10=4 1334 225 24 17Hx28 69 66 117=4,57 61) ]1T'4 96 82H 9 7K 106,H 40K 19% 42 42^8 46'4 33^/8 lOH 16 230 18 I6%%i7 93 57 U5M 48 84 116K 9(5 77 9 7H 1051^ 52 20 bV bb 53ys 45/8 UK 12H 235 24 15Hx47 105 57 120^ 48 96 120H 96 77 ^2'A 9K 105K 61 K 2334 64 61 63 K 51 H 12 1334 250 4S 151^x31 105 72 122K 63 96 122H 96 75 11 U \tH W7H\61H 25 '/s 6b 67 K 63H 51^8 12 20 285 48 15^x39 105 89 122M SO 96 122M 96 75 «K 107?^ 61J4 27 6b 6VK 63 Hi 12 16 299 48 15)^x47 105 105 124?^ 96 96 124?/8 96 75 8H'107H'61i!i 4U 60 67J4 67)^ .... 12 ■iH'A All sizes and dimensions in inches Note: The above data (except weights) applies also to Extra-heavy 300 Series Class EBH Heaters for working pressures up to 10 lb. per sq. in. 310 Table 27-3. Dimensions of 400 Series Class EBP Webster Feed-water Heaters For working pressure up to 5 lb. per sq. in. Specifications Capacity Drawing no. 13166 13188 13167 13165 13171G Heating trays Cubic contents Filter Wkg. pres. Weights, lb. No. Horsepower * Lb. min. Area sq. ft. Ma- terial Total cu. ft. Water cu. ft. Shipping Max. 403 405 407 410 415 to 400 425 to 650 675 to 900 925 to 1350 1375 to 1850 =9'il~-gl 12.5 16.5 24.0 33.0 51.6 ^11 •^.S o 24.4 40.0 60.0 80.5 121.3 14.7 25.5 40.0 52.0 80.0 1 c o s = o Q 5 lb. per sq. in. 3500 4950 6700 8050 10800 4500 6650 9300 11350 15900 * One rated horsepower =capacity for heating 30 lb. per hour from 40 deg. fahr. to a temperature within 5 deg. of the steam temperature Returns- Inlet ® Drain-' Comb. Vent and Vacu um Breaker © Live Steam Drips Exhaust Outlet DIAGRAM FOR PREFERENCE OIL SEPARATORS CLASS H [ Inlet Cut-out Gate Valve WEBSTER CLASS H PREFERENCE OIL SEPARATOR WEBSTER CUSS C PREFERENCE OIL SEPARATOR Exhaust Outlet ® Exhaust Inlet ® Note:- The Table of Dimensions below refers to Heaters with Standard Equipment, Separators smaller or larger than Standard will be furnish ed if desired. The table at right shows sizes of all Prefer WEBSTER ^^^^ ^'' Separators which V GREASE TRAP can be used with this type DIAGRAM FOR STANDARD^Ove^tlow/T^ Heater EQUIPMENT ^^ •^IZE CAPACITY LBS. STEAM PER MIN. DIMENSIONS SIZE DRIP Q R S T U 6 -16 S 11 13 9X 10-X 1 S 80 9)4 23S{ IK 20 475 ■iOH 23 Si 30 5i 25; CO > 6 tniJ 1 ® 10 ® 1 ® 4 ® 21/, ® ® ® ■2Vo ® 2 1/9 ® d Size 5 35 403 10 5 15 x24 35 80^4 405 12 8 1 12 Wo 4 3 1 IH 3 21/4 5 1514^30 Vs 41 41 88 407 16 8 iH 16 2 5 31/4 1 9 4 3 6 16 x36 45 45 101^ 410 18 10 W9. 18 9 5 31/4 1 9 5 3 12 10 x403^ 51 51 101^ 415 20 12 IVi 20 2K2 6 4 1 2H 5 3 1^' 12il3i/4x46 57 .1. 1151/^ Dimensions c V CO A A' B c D 545/R E 6% F G H J 9 K L M N P V 403 26 26 803/j- 66 7314 18 14 213/., 1714 2514 16 534 9 lOH 405 32 32 88 72 57 yk 7 1/4 5H 79^4 2114 1114 27 2014 2834 1914 714 8M IIM 407 3b 36 101 5/g 84 691/4 714 6 9314 25 133/, 2814 221/2 34 2114 914 11 11^2 410 42 42 101 ?/R 84 67 W r'/. 6 9314 28 1514 3114 2514 37 2454 8 101/2 13 415 48 48 1151/8 96 771/5 8 1/2 i 10434 33I/4' 16 36 281/2 4114 27^ 8J4 13^ 14 Note: The dimeusions aud data above, except weights, may be used also for the 500 Series Class EBFH Extra-heavy Pattern Webster Feed-water Heaters 311 Table 27-4. Dimensions of 900 Series Class EFP Webster Feed-water Heaters For working pressure up to 10 lb. per sq. in. Specifications Capacity Drawing no. Heating trays Cubic contents Filter Wkg. pres. Weights, lb. No. Horsepower* Lb. min. Area sq. ft. Ma- terial Total cu. ft. Water cu. ft. Shipping Max. 900 901 9011-^ 902 to 90 95 to 150 155 to 225 230 to 300 No. of lb. per n]in.= Yi of rated horsepower 17198 16837 16724 17203 4.5 5.0 5.6 9.0 American ingot iron or copper 7.1 9.8 11.6 16.4 4.2 5.9 7.3 11.08 & o c. 1675 1780 2200 2700 1925 2140 2600 3425 Returns InletX © ©Comb. Vent and Vacuum Breaker ' One rated horsepower = capacity for heating 30 lb. per hour from 40 deg. fahr. to a temperature within 5 deg. of the steam temperature DIAGRAM FOR PREFERENCE OIL SEPARATORS DIAGRAM FOR STANDARD EQUIPMENT Nole:- The Table of Dimensions - below refers to Heaters Ij with Standard Equipment. ^Separators smaller or larger than Standard wil be furnished if desired. The table at right shows sizes of all Preference Oil Separators which can be used with this type Heater SIZE CAPACITY LBS. STEAM PER MIN. DIMENSIONS SIZE ORIF Q R S T U 3 11 0^6 5V 7^ 6« b^ X 4 20 liJi 7'4 9X 7% V4 'i 5 32 7»6 9 UM 4l'!l'4 H Jj lU I'.IU H h l'4l'ill2 M % 1M2 IH H Returns Inlet ® Cold Water Inlet Comb. Vent and. Vacuum Breaker © Pump Outlet ® Live Steam Drips ( Oil Separator Drips Pop Alarm Valve Exhaust Inlet ® Fig. 27-15 Drain Trays Water line 1 ilter Dimensions No. Cn No. , Size O'er Pow. Rec. Th. 6 At. 2.0 ft. .9 A 16 A' 18 B 62 C D £ 20;^ F 55K G 3H H 18V? J 14 K 7K L 9% M lOV^ N 3H 800 4 i 10x16 39K 35H32H 44MI38M 35H 43 V^ 48 57 801 4 i 10x18 6 2.5 1.2 18 20 68H 47M 54 J1 23 Hl»/f ■m IHV, 171/8 9V« WH nvs m 63 V, 801M 4 10x20 48H 42M 35H 6 2.8 1.4 20 20 V2H 51 ■58K 23 65 i'. *■'/, 19J/, ITA 9H 10»4 nv. 4J1,73!^ 802 4 14x23:551^ 4934 3651 1 6 3.6 1.8 22M 22M 79 56K,63^f 24K 71H 5 21 19JlKn^lvVv*'^Uu.;H,| Fig. 27-17. Typical chart from a Webster-Lea Heater Meter Part III— Addenda CHAPTER XXVIII Miscellaneous Useful Information THE tables in the following pages cover many subjects for which the Heating Engineer must have readily available data. They have been selected after careful consideration and will be found reliable and suf- ficiently accurate in every respect to meet the requirements of good practice. The tables on any subject can be readily located by reference to the back of the book, where they are included both in the general index and the special index of tables. Table 28-1. Diameters and Weights of Seamless Brass and Copper Tubes Iron Pipe Size and Plumber's Size Iron pipe size Regular Extra heavy Diameter, in. Weight in pounds per foot Iron pipe size Diameter, in. Weight in pounds per foot Outside Inside Brass Copper Outside Inside Brass Copper' .405 .281 .246 .259 H" . 105 .205 . 3.53 .371 .540 .375 .437 . 459 H" . 540 . 294 .593 .624 .675 .491 .612 . 644 %" .675 .421 .805 .847 .840 .625 .911 .9.58 Vi' .840 .542 1.191 1 . 2.53 1.050 .822 1.235 1.298 K" 1 . 0.50 .736 1.622 1.706 1.315 1.062 1 . 740 1.829 I" 1.315 .951 2.386 2.509 1.660 1.368 2.557 2.689 IK" 1.660 1.272 3.291 3.460 1.900 1.600 3.037 3 193 1 Vi" 1.900 1.494 3.986 4.191 2.375 2.062 4.017 4.224 «>" 2.375 1 . 933 5 . 508 5.791 2.875 2.500 5.830 6.130 2J--2" 2.875 2.315 8.407 8.839 3.500 3.062 8.311. 8 741 3" 3. 500 2.892 11.24 11.82 4.000 3. 500 10.85 11.41 3^" 4.000 3.358 13.66 14.37 4. 500 4.000 12.29 12.93 4" 4.500 3.818 16.41 17.25 5.000 4.500 13.74 14.44 iV2" 5.000 4.250 20.07 21.10 5.563 5.062 15.40 16.19 5" 5. 563 4.813 22.51 23.67 6.625 6.125 18.44 19.39 6'; 6.625 5 . 7.50 31 . 32 32.93 7.625 7.062 23.92 25.15 7" 7.625 6.625 41.22 43.34 8.625 8.000 30.05 31 . 60 8" 8.625 7.625 47 . 00 49.92 9.625 8.937 36.94 38.84 9" 10.750 10.019 43.91 46.17 10" Plumber's size .654 .521 .452 .475 Vs" .768 .631 ..554 .583 K" .875 .728 .682 .717 H" 1.000 .836 .871 .916 1" * Amei ican Brass Co 1 . 245 1.060 1 . 233 1.297 1J4" 1.508 1.311 1 . 606 1 . 689 W2" 1.756 1 . 564 1 . 84 4 1.939 m" 2.007 1.815 2.123 2.232 O" .•51.5 Table 28-2. Dimensions of Standard Wrouglit-Iron Pipe"'* Black and galvanized for temperatures up to 450 deg. lJ4-In. and smaller proved to 300 lb. per sq. in by hydraulic pressure IJ^-In. and larger proved to 500 lb. per sq. in. by hydraulic pressure Nominal diameter Actual outside diameter Actual inside diameter Inside circum- ference Outside circum- ference Length of pipe per sq. ft. of inside surface Length of pipe per sq. ft. of outside surface Inside area Outside area Length of pipe con- taining one cubic foot Weight per ft. In. In. 0.405 0.54 0.675 0.84 In. 0.270 0.364 0.494 0.623 In. 0.848 1.144 1 . 552 1.957 In. 1.272 1.696 2.121 2.652 Ft. 14.15 10.50 7.67 6.13 Ft. 9.44 7.075 5.657 4.502 In. 0.0572 0.1041 0.1916 0.3048 In. 0.129 0.229 0.358 0.554 Ft. 2.500. 1385. 751.5 472.4 Lb. 0.243 0.422 0.561 0.845 1 1.05 1.315 1.66 1.90 0.824 1.048 1.380 1.611 2.589 3.292 4.335 5.061 3.299 4.134 5.215 5.969 4.635 3.679 2.768 2.371 3.637 2.903 2.301 2.01 0.5333 0.8627 1 . 496 2.038 0.866 1.357 2.164 2.835 270. 166.9 96.25 70.65 1.126 1.670 2.258 2.694 9 3 3J^ 2.375 2.875 3.50 4.00 2.067 2.468 3.067 3.548 6.494 7.754 9.636 11.146 7.461 9.032 10.996 12.566 1.848 1 . 547 1.245 1.077 1.611 1.328 1.091 0.955 3.355 4.783 7.388 9.887 4.430 6.491 9.621 12.. 566 42.36 30.11 19.49 14.56 3.600 5.773 7.547 9.055 4 4K 5 6 4.50 5.00 5.563 6.625 4.026 4.508 5.045 6.065 12.648 14.153 15.849 19.054 14.137 15.708 17.475 20.813 0.949 0.848 0.757 0.63 0.849 0.765 0.629 0.577 12.730 15.939 19.990 28.889 15.904 19.635 24.299 34.471 11.31 9.03 7.20 4.98 10.66 12.34 14.50 18.767 7 8 9 10 7.625 8.625 9.625 10.75 7.023 7.982 9.001 10.019 22.063 25.076 28.277 31.475 23.9.54 27 096 30,433 33.772 0.544 0.478 0.425 0.381 0.505 0.444 0.394 0.355 38.737 50.039 63.633 78.838 45.663 58.426 73.715 90.762 3.72 2.88 2 26 1.80 23.27 28.177 33.70 40.06 11 12 14 15 12.00 12.75 14.00 15.00 11.25 12.000 13.25 14.25 35 343 38.264 41 . 268 44.271 37.699 40.840 43.982 47.124 0.340 0.313 0.290 0.271 0.318 0.293 273 0.254 98.942 116.535 134.582 155.968 113.097 132.732 153.938 176.715 1 . 455 1 . 235 1.069 .923 45.95 48.98 53.92 57.89 16 18 20 16.00 18.00 20.00 15.25 17.25 19.25 47 . 274 53.281 59.288 .50.265 56. 548 62.832 0.2.54 0.225 0.202 0.238 212 0.191 177.867 225.907 279.720 201.062 254.469 314.160 .809 .638 .515 61.77 69.66 77.57 * Walworth Manufacturing Company Table 28-3. Standard Pipe Threads (Briggs Formula) Taper of pipe end = J^-in.perft. = ^-in. per in. Depth of thread (D) = 0.8 x no. of threads per in I Perfect Bottom r<-Fl3t Top and Bottom->t^— but — ^ Perfect Thread Top and Bottom i— f^3Lrop_^j_ h;2Tlireads->« — F-(0.8 Dia.+4.8) ) ^°.S "1 ft c E - -d «'S.S is- pe nto in. Norain insid diam. pipe, i «'2 ^ — f5 ft "-a « o cl 5|| •Oft 2 o ? c o a oj'S o C.2 ft ei'~-aft Ot3 C o a> M «|ft 5 "-I C O Kl St: 4* Oil 'A 27 0.393 0.334 0.19 3 8 3.441 3.241 0.95 H 18 0.522 . 433 0.29 3J^ 8 3.938 3.738 1.00 Yi 18 0.656 . 568 0.30 4 8 4.434 4.234 1.05 Vi 14 0.815 0.701 0.39 4>^ 8 4.931 4.731 1.10 % 14 1.025 0.911 0.40 5 8 5.490 5.290 1.16 1 UJ^ 1.283 1 144 0.51 6 8 6.546 6.346 1.26 IM IVA 1.626 1 . 488 0.54 7 8 7., 540 7'. 340 1.36 IJ^ wVi 1.866 1.728 0.55 8 8 8.534 8.334 1.46 2 WYi 2.339 2.201 0.58 9 8 9.527 9.327 1.57 2^ 8 2.819 2.619 0.89 10 8 10.645 10.445 1 68 316 Table 28-4. Dimensions of Black and Galvanized Wrought-Iron Pipe Extra strong Double extia strong Size Diameters Weight Diameters Weight Thickness per foot Plain ends Thickness per foot Plain ends External Internal External Internal Vs .405 .215 .095 .314 H .540 .302 .119 .535 Vs .675 .423 .126 .738 Vi .840 .546 .147 1.087 .840 .252 .294 1.714 Vi 1.050 .742 .154 1.473 1.050 .434 .308 2.440 1 1.315 .957 .179 2.171 1.315 .599 .358 3.659 IM 1.660 1.278 .191 2.996 1.660 .896 .382 5.214 IM 1.900 1.500 .200 3.631 1.900 1.100 .400 6.408 2 2.375 1.939 .218 5.022 2.375 1.503 .436 9.029 2^ 2.875 2.323 .276 7.661 2.875 1.771 .552 13.695 3 3.500 2.900 .300 10.252 3.500 2.300 .600 18.583 W2 4.000 3.364 .318 12.505 4.000 2.728 .636 22.850 4 4.500 3.826 .337 14.983 4.500 3.152 .674 27.541 Wi 5.000 4.290 .355 17.611 5.000 3.580 .710 32.530 5 5.563 4.813 .375 20.778 5.563 4.063 .750 38.552 6 6.625 5.761 .432 28.573 6.625 4.897 .864 53.160 7 7.625 6.625 .500 38.048 7.625 5.875 .875 63.079 8 8.625 7.625 .500 43.388 8.625 6.875 .875 72.424 9 9.625 8.625 .500 48.728 10 10.750 9.750 .500 54.735 11 11.750 10.750 .500 60.075 12 12.750 11.750 .500 65.415 13 14.000 13.000 .500 72.091 14 15.000 14.000 .500 77.431 15 16.000 15.000 .500 82.771 Table 28-5. 1 1 Length of tube Diameter | Circumference Transverse area per square foot Nominal Nominal thickness Nearest no. f weight external internal jPer External Internal B. Wire Gauge External Internal External Square Internal Square Metal Square surface surface Inches Inches Inches Inches Inches inches inches inches ' Feet Feet Pounds IM 1.560 .095 13 5.498 4.901 2.405 1.911 .494 2.182 2.448 1.679 9 1.810 .095 13 6.283 5.686 3.142 2.573 .569 1.909 2.110 1.932 2M 2.060 .095 13 7.069 6.472 3.976 3.333 .643 1.697 1.854 2.186 W2 2.282 .109 12 7.854 7.169 4.909 4.090 .819 1..527 1.674 2.783 m 2.532 .109 12 8.639 7.955 5.940 5.036 .904 1.388 1.508 3.074 3 2.782 .109 12 9.425 8.740 7.069 6.079 .990 1.273 1.373 3.365 3M 3.010 .120 11 10.210 9.456 8.296 7.116 1.180 1.175 1.269 4.011 3M 3.260 .120 11 10.996 10.242 9.621 8.347 1.274 1.091 1.171 4.331 m 3.510 .120 11 11.781 11.027 11.045 9.677 1.368 1.018 1.088 4.652 4 3.732 .134 10 12.566 11.724 12.566 10.939 1.627 .954 1.023 5.532 iV2 4.232 .134 10 14.137 13.295 15.904 14.066 1.838 .848 .902 6.248 5 4.704 .148 9 15.708 14.778 19.635 17.379 2.256 .763 .812 7.669 * Crane Go. Table 28-6. Surface Factors for Pipes Factors for Factors for Factors for Factor for Factors for Factors for Size reducing lin- reducing sq. Size reducing lin- reducing sq. Size reducmg lin- reducing sq. of pipe eal ft. to ft. to of pipe eal ft. to ft. to of pipe eal ft. to ft. to sq. ft. lineal ft. sq. ft. lineal ft. sq. ft. lineal ft. H .27 3.64 3 .92 1.09 7 2.00 .50 1 .33 2.90 W% 1.05 .96 8 2.23 .44 IM .43 2.30 4 1.19 .85 9 2.50 .40 iy2 .50 2.01 4}^ 1.31 .76 10 2.85 .36 2 .62 1.61 5 1.61 .63 12 3.33 .30 W2 ,75 1.33 6 1.75 ..58 317 Table 28-7. Expansion of Wrought-Iron Pipe on the Application of Heat* pipe is'fitTed"^ Increase in length in inches per foot when heated to Deg. fahr. 160 180 200 212 220 228 240 274 .0128 .0144 ,016 .017 .0176 .0182 .0192 0219 32 .0102 .0118 .0134 .0144 .015 .0157 .0166 0194 50 .0088 .0104 .012 .013 .0136 .0142 .01.52 0179 70 .0072 .0088 .0104 .0114 .012 .0126 .0136 .0163 Coefficient;— .0000067 per deg. fahr. * Holland Heating Manual Table 28-8. Heat Units Per Pound and Weight Per Cubic Foot of Water Between 32 Deg. Fahr. and 340 Deg. Fahr.f S 0) 11 P.O +. o V V 11 u P.O 51 Is +. o u no *. o J5 11 Co *- o O MO ■J Id t£ s" •So i.^ ■B |& K a- rt ^ EB, bflu •S2 ^•s kI &3 K£ &g 108 a£ &3 Htj KU. ^3 0) „ H-o 184 Kd. ^3 222 J3 V &3 32 0.00 62.42 70 38.06 62,30 75.95 61.90 146 113.86 61.27 151,89 60.49 190.1 59.58 33 1.01 62.42 71 39,06 62.30 109 76,94 61.88 147 114,86 61.25 185 1.52.89 60,47 223 191.1 59.55 34 2.01 62.42 72 40,05 62,29 110 77,94 61.86 148 115.86 61,24 186 153.89 60,45 224 192.1 59.53 35 3,02 62.43 73 41.05 62.28 111 78,94 61,85 149 116,86 61.22 187 154.90 60.42 225 193.1 59.50 36 4.03 62.43 74 42,05 62.27 112 79,93 61,83 150 117,86 61,20 188 155.90 60.40 226 194.1 59.48 37 5,04 62.43 75 43.05 62.26 113 80,93 61,82 151 118,86 61.18 189 156.90 60 38 227 195.2 ,59.45 38 6,04 62,43 76 44,04 62,26 114 81,93 61,80 152 119,86 61,16 190 157,91 60.36 228 196.2 59.42 39 7.05 62,43 77 45,04 62,25 115 82.92 61,79 153 120.86 61 , 14 191 158,91 60.33 229 197.2 59.40 40 8.05 62,43 78 46.04 62.24 116 83,92 61,77 154 121.86 61,12 192 1.59,91 60.31 230 198.2 59.37 41 9.05 62.43 79 47.04 62,23 117 84,92 61.75 155 122.86 61.10 193 160,91 60.29 231 199.2 59.34 42 10,06 62.43 80 48.03 62,22 118 85,92 61.74 1.56 123.86 61,08 194 161.92 60.27 232 200.2 59.32 43 11,06 62.43 81 49.03 62,21 119 86.91 61.72 157 124.86 61,06 195 162.92 60.24 233 201.2 59.29 44 12.06 62.43 82 50.03 62.20 120 87.91 61.71 1,58 125,86 61 , 04 196 163.92 60.22 234 202.2 59.27 45 13.07 62,42 83 51.02 62,19 121 88,91 61,69 159 126,86 61.02 197 164.93 60.19 235 203.2 ,59.24 46 14,07 62,42 84 52.02 62,18 122 89.91 61,68 160 127.86 61.00 198 165.93 60.17 236 204.2 .59.21 47 15.07 62,42 85 53.02 62,17 123 90,90 61.66 161 128.86 60.98 199 166.94 60.15 237 205.3 59.19 48 16,07 62,42 86 54.01 62.16 124 91,90 61.65 162 129.86 60,96 200 167.94 60.12 238 206.3 .59.16 49 17.08 62,42 87 55,01 62.15 125 92.90 61.63 163 130,86 60,94 201 168,94 60.10 239 207.3 59.14 50 18.08 62.42 88 56,01 62.14 126 93,90 61.61 164 131,86 60.92 202 169.95 60.07 240 208.3 59.11 51 19,08 62.41 89 57.00 62.13 127 94,89 61.59 165 132,86 60.90 203 170.95 60.05 241 209.3 59.08 52 20,08 62.41 90 .58,00 62,12 128 95.89 61.58 166 133,86 60,88 204 171,96 60,02 242 210.3 59.05 53 21,08 62,41 91 59.00 62.11 129 96,89 61.56 167 134,86 60.86 205 172.96 60,00 243 211.4 .59.03 54 22,08 62,40 92 60,00 62.09 130 97,89 61.55 168 135,86 60.84 206 173,97 59,98 244 212.4 59.00 55 23.08 62.40 93 60,99 62,08 131 98.89 61.53 169 136.86 60.82 207 174,97 59,95 245 213.4 58.97 56 24.08 62., 39 94 61,99 62.07 1,32 99.88 61,, 52 170 137,87 60.80 208 175,98 59,93 246 214.4 58.94 57 25,08 62,39 95 62,99 62,06 133 100.88 61,50 171 138.87 60.78 209 176,98 59.90 247 215.4 .58.91 58 26,08 62.38 96 63,98 62,05 134 101.88 61,49 172 139.87 60.76 210 177,99 59.88 248 216.4 58.89 59 27.08 62,37 97 64.98 62.04 135 102.88 61.47 173 140.87 60.73 211 178.99 59.85 249 217.4 58.86 60 28.08 62,37 98 65.98 62,03 136 103.88 61.45 174 141.87 60.71 212 180.00 59.83 250 218.5 58.83 61 29,08 62,36 99 66,97 62,02 137 104.87 61.43 175 142.87 60.69 213 181.0 59.80 260 228.6 58.55 62 30.08 62,36 100 67,97 62,00 138 105,87 61.41 176 143.87 60.67 214 182.0 59.78 270 238.8 58.26 63 31.07 62,35 101 68,97 61.99 139 106,87 61.40 177 144.88 60.65 215 183,0 59.75 280 249.0 57.96 64 32.07 62,35 102 69.96 61,98 140 107,87 61.38 178 145.88 60.62 216 184,0 59.73 290 259.3 57.65 65 33.07 62. 34 103 70.96 61,97 141 108,87 61.36 179 146.88 60.60 217 185,0 59.70 300 269.6 57.33 66 34.07 62.33 104 71.96 61,95 142 109,87 61 . 34 180 147.88 60.58 218 186.1 59.68 :U(I 279.9! 57.00 67 35.07 62.33 105 72.95 61.94 143 110,87 61,33 181 148.88 60.56 219 187.1 59.65 320 290.2 56.66 68 36.07 62.32 106 73.95 61.93 144 111.87 51,31 182 149.89 60.53 220 188.1 59.63 330 J00.6 56.30 69 37.06 62.31 107 74.95 61.91 145 112.86 51.29 183 150.89 50.51 221 189.1 59.60 340 Jll.O 55.94 i Steam, Babcock & Wilcox Co. 318 Table 28-9. Dimensions of Cast-Iron Screwed Fittings* "^ ^^4- h A A n A r' J s r - ■<-A— {-A-*- <— A— ~A- Size, inches 1 . IM. 13^. 2 . 2^. 3 . 3M. 4 . 434. 5 . 6 . 7 . 8 . 9 . 10 . 12 . Standard A B Inches Inches lA Hi 2M 3,^ 3,^ 3M 4iV 4t^ 6J4 7^ 13^ lA 1 j- A 16 1 ii 1 1^ .*■ 16 0_3_ - 16 2H Ol3 -16 ^16 3i^ 3J^ 4}4 4H >'l6 6 Extra heavy A B Inches Inches 2 2M 2^ 3 3>i 43^ 4H 53^ 53^ 63/8 734 83^ 113/g 133.i 1?^ 13^ m 2H 2V2 3 3i^ 3M 4 4M 4% 53^ Standard and extra heavy C D E F Inches Inches Inches Inches 2M 3 334 434 5J€ 63€ 7J^ 83^ 9M 115^ 11^ 13iV 15M leu 20 ii 20H 241^ IJ^ 2M 2M 334 3M 43^ 63/8 6K 934 934 lOM 1234 13^ 16M 16^ 19J^ 215 16 33^ Wi 3^ 3% 43^ 4M 534 6A 7H 2A 2^ 2% 2% 33^ 3^ 3^ 434 Note — The above dimensions are subject to a slight variation Table 28-10. 45-Degree Offset Connections *Cr; iCo. __ Pipe size Centre to centre A Centre to face B Face to face of 45's C i Offset D fi \ W- /^ ) 1^ 2 23^ 3 33^ 4 434 5 6 7 8 3^ 33^ Wi SVs 53^ 6 7ys 8M 10 li% 1^ 1-4 -16 2?^ 2J^ 2M 3,^ 3i^ 3^8 43^ ¥2 ¥2 % % H % 1 1 1 1 2M 2H tl 3^ 3J^ m Pipe size Centre to centre A Centre to face B Face to face of 45's C Offset D 434 43^ 5A 5il 6A 7f6 ¥2 M ■ 1 134 234 23^ 2M 33^ y% 1 13^ lA 141 Iff ifi 2-h NOTE: The Offset D is equal to the distance A -=- 1.414 319 Table 28-11. Rules for Standard Weight Flanged Fittings American 1915 Standard, 125-lb. working pressure Shell thickness in inches 13L T->-U- s 1 X^ Size fitting, Shell Size fitting. Shell Size fitting, Shell inches thickness inches thickness inches thickness o 7 rs 5 Yi 12 Yi 2J^ tV 6 9 14 if 3 Vi 7 ^ 15 ^ W2 Yi 8 H 16 H 4 Yi 9 M 18 1 4J^ Y2 10 13. 16 20 . lA 1. Standard reducing elbows carry same dimensions center-to-face as regular elbows of largest straight size. 2. Standard tees, crosses and laterals, reducing on run only, carry same dimensions face-to-face as largest straight size. 3. Where long-turn fittings are specified, it has reference only to elbows which are made in two center-to-face dimensions and to be known as elbows and long-turn elbows, the latter being used only when so specified. 4. All standard weight fittings must be guaranteed for 125-lb. working pressure, and each must have mark cast on indicating maker and guaranteed working steam pressure. 5. Standard weight fittings and flanges to be plain faced, and bolt holes to be 3^ in. larger in diameter than bolts ; bolt holes to straddle center lines. 6. Size of all fittings scheduled indicates inside diameter of ports. 7. Square head bolts with hexagonal nuts are generally recommended for use. 8. Double-branch elbows, side-outlet elbows and side-outlet tees, whether straight or reducing, carry same dimensions center-to-face and face-to-face as regular tees and elbows. 9. Bull-head tees or tees increasing on outlet, will have same center-to-face and face- to-face dimensions as a straight fitting of the size of the outlet. 10. Tees, crosses and laterals 16-in. and smaller, reducing on the outlet, use the same dimensions as straight sizes of the larger port. {ConUnued on next page) 15 Standard, ] Table 2 25-lb. working 8-12. Stand pressure ard Flanges and Bolts 19 Pipe Flange Bolts Bolt Holes -■•It k- ^ Size P Diam. D Thick- ness T No. Size Diam. Bolt circle B.C. m o Diam. 8 nY?. lYs 8 Y IWa Yh ■^ — > r - '— — —. 9 15 Wh 12 Ya 13 K Yh 10 12 16 19 12 12 Yh Yh 14M 17 1 1 Pipe Flange Bolts Bolt Boles 14 21 Wi 12 1 1834 114 Size Diam. No. Size Size 15 2214 Wh 16 1 20 Wh P D T Diam. B.C. Diam. 16 2-iY?. 1t^ 16 1 21 K Wh 18 25 Itv 16 l/s 22Ya Wi 1 4 T% 4 7 T6 3 g 16 IH 41/, y?. 4 Vs •AYh fk 20 27 y, 14 20 Wh 25 Wa lY?. 5 fk 4 Y?. ■iYn Yh 22 29 H i~i 20 IH 27^4 Wh 2 6 Ys 4 Yh m Y4 24 32 1/8 20 Wa 29 K, Wh 26 UY4 2 24 Wa 31^4 Wh 2y?. 7 H 4 Yh 5Y?. H 3 lY?. K 4 Yh 6 K 28 ■i(>Y?. 2A 28 Wa 34 Wh ■iY?. »Y, H 4 Yh 7 Ya 30 ■i8H •2.Yi 28 Wh 36 W?. 4 9 lA 8 Yh TY?. % 32 'HYa. 2K 28 W?. ■iSY?. Wh 34 i-iH 2A 32 W?. 40 i4 Wh 4H 9Y4 s 8 Ya r% Yh 5 10 5 8 Y4 »Y2 Yh 36 46 2^ 32 W?. 42^4 Wh 6 11 1 8 H 9Y?, Yh 38 48^4 Wi 32 Wh 4514 Wa 7 12^2 llV 8 H lOYi Ys 40 5054 2Y2 36 Ws 47K Wi 320 Sizes 18-in. and laiger, reducing on the outlet, are made in two lengths, depending on the size of the outlet, as given in the table of dimensions. 11. For fittings reducing on the run only, a long-body pattern will be used. Y's are special and made to suit connections. Double-branch elbows are not made reducing on the run. 12. Steel flanges, fittings and valves are recommended for superheated steam. 13. If flanged fittings for lower working pressure than 125 lb. are made, they shall conform in all dimensions, except thickness of shell, to this standard and shall have the guaranteed working pressure cast on each fitting. Flanges for these fittings must be stand- ard dimensions. Table 28-13. Standard Flanged Reducing Laterals 1915 Standard, 125-lb. Working Pressure , .1 1 1 1 - 5 -T 1 \ll lu_ _1LJ/ u H -< 1, 1 / Reducing lateral Reducing-on-run lateral Reducing-on-run and branch lateral Run-R Size Dimensions, inches M N Flanges Diam. Thickness 1 — — — — — 4 A IM V-A or less 8 61^ \% 6K 414 A. W2 W2 " " 9 7 9 7 5 ^ 2 2 " " lOJ^ 8 2H 8 6 'A 2J^ 21^ " " 12 9J4 2K 93^ 7 a 3 3 " " 13 10 3 10 ^'A M 3J^ 3^ " " 14M 11>^ 3 11 K2 834 Hi 4 4 " " 15 12 3 12 9 a 4^ Wi " " 15}^ \W2 3 123^ 9H 15. 5 5 " " 17 13^ 33^ 13^ 10 15 T6 6 6 " " 18 14J^ 3J^ 14^ 11 1 7 7 " " 201^ \W2 4 16H 12 3^^ ll^ 8 8 " " 22 viVi 4>i 171/2 1334 134 9 9 " " 24 i9y2 4}^ 1934 15 1^ 10 10 " " 25}^ 203^ 5 2034 16 1^ 12 12 " " 30 24>^ Wi 24J4 19 IM 14 14 " " 33 27 6 27 21 Ws 15 15 " " 34H 28J^ 6 28 >4 223^ 154 16 16 " " 36^ 30 (^Vi 30 2334 lA 18 9 " " 26 25 1 2734 25 1,^ 18 18 to 10 inc. 39 32 7 32 25 l^ 20 10 and less 28 27 1 2934 273^ Hi 20 20 to 12 inc. 43 35 8 35 27y2 Hi 22 10 and less 29 283^ Vi 31}/2 29 J^ m 22 22 to 12 inc. 46 3714 SV2 37^2 29^ Hi 24 12 and less 32 si'A V2 34^ 32 VA 24 24 to 14 inc. 49M m/i 9 4034 32 iVs 26 12 and less 35 35 38 3434 2 26 26 to 14 inc. 53 44 9 44 343^ 2 28 14 and less 37 37 40 36 H 2^ 28 28 to 15 inc. 56 46^ 9H 46^ 3634 2^ 30 15 and less 39 39 42 3«M 2% 30 30 to 16 inc. 59 49 10 49 38 34 2ys 321 Table 28-14. Standard Flanged Bull-Head Reducing Tees and Crosses 1915 Standard, 125-lb. Working Pressure Reducing tee h^^=1 ^r^rrli i L'^^ \l-z: Reducing cross ^ — A >j< A > £ Reducing- on-run tee ^citi Bull-head tee ->|< — J > mr rrm - Reducing-on-run and Branch tee cross "T cr- c:^^^ ^ FP- Reducing-on-run branch Size Branch b A & J Dimensions, inches Flanges Diam. Thickness 1 - — — — 4 1^ IM 1 or less 3M 3M 4J^ ¥2 iy2 IM " 4 4 5 ^ 2 I'A I'A 4}^ 6 H 2^ 2 " 5 5 7 H 3 2M " 5^ 5M Note — A reduction in size on 7M H 3J^ 3 " 6 6 the run does not affect the 8M 13 4 3J^ " ■ 6H 6>i dimensions but branch out- 9 iS. lets of small size such as are 4,14 4 " 7 7 • listed below will reduce the 9li T* 5 4M '* ■7V2 7J^ dimensions of fittings 18 in. 10 a 6 5 ** 8 8 or over in size 11 1 7 6 " 8M 8M 12 "4 1,^ 8 7 " 9 9 13M IVb 9 8 '* 10 10 15 IVs 10 9 " 11 11 16 1t% 12 10 " 12 12 19 m 14 12 " 14 11 21 Ws 15 14 15 " 14>^ 15 15 Branch b J K 22 K 23J^ Wi 16 ll^ 18 18 to 14 inc. 16>^ 16K 12 or less 13 15V^ 25 1 9 1t6 20 20 to 15 inc. 18 18 14 " " 14 17 271^ 1 11 J- 16 22 22 to 16 inc. 20 20 15 " " 14 18 29}^ IH 24 24 to 18 inc. ■22 22 16 " " 15 19 32 Wi 26 26 to 20 inc. 23 23 18 " " 16 20 34M 2 28 28 to 20 inc. 24 24 18 " " 16 21 3614 2t^ 30 30 to 22 inc. 25 25 20 " " 18 23 38M 2}^ 32 32 to 22 inc. 26 26 20 " " 18 24 41 M m 34 34 to 24 inc. 27 27 22 " " 19 25 43M 2^ 36 36 to 26 inc. 28 28 24 " " 20 26 46 2^8 38 38 to 26 inc. 29 29 24 " " 20 28 48M ^% 40 40 to 28 inc. 30 30 26 " " 22 29 50M 2^ 322 Table 28-15. Standard Flanged Elbows, Crosses, Laterals and Reducers 1915 Standard, 125-lb. Working Pressure Long-turn elbow Reducing elbow Double-branch elbow _□! Straight tee T^P" J" Straight cross Straight lateral l< G- Reducer Size Run-R Dimensions, inches C D Flange Biam. Thickness 1 33^ 5 IM I'A 5M — 4 7 T6 IM m ^Vo 2 8 63€ — ■ 434 J4 I'A 4 6 23i 9 i — 5 ffe 2 4H 6,^ 23^ 103-^ 8 — 6 ^ 23^ 5 7 3 12 934 — . 7 . H 3 5J^ 7% 3 13 10 6 734 M iy2 6 8J^ 33^ 14^ 1134 63^ 834 il 4 6y2 9 4 15 12 7 9 H 4}^ 7 93^ 4 1534 1234 734 934 il 5 7V2 lOK 43^ 17 1334 8 10 15 6 8 IIM 5 18 1434 9 11 1 7 8M 12M 53^ 203^ 16H 10 1234 ll^ 8 9 14 5^ 22 173^ 11 1334 Wi 9 10 isu 6 24 1934 ll"^ 15 IVs 10 11 \6V2 63^ 2534 2034 12 16 l^ 12 12 19 73^ 30 24M 14 19 IK 14 14 21H 73-^ 33 27 16 21 IVs 15 14H 22M 8 343^ 2834 17 22M m 16 15 24 8 3634 30 18 2334 lA 18 16H 261^ 83^ 39 32 19 25 1^ 20 18 29 934 43 35 20 2734 Hi 22 20 313^ 10 46 373^ 22 2934 Hi 24 22 . 34 11 4934 4034 24 32 V/s 26 23 363^ 13 53 44 26 3434 2 28 24 39 14 56 46 28 3634 2A 30 25 413^ 15 59 49 30 38M 234 32 26 44 16 — — 32 41 M 23€ 34 27 463'2 17 — — 34 43 M 2A 36 28 49 18 36 46 254 38 29 513^ 19 — — 38 48^ ZVs 40 30 54 20 — 40 50M 2^ 323 Table 28-16. Rules for Extra-Heavy Flanged Fittings American 1915 Standard 250-lb. Working Pressure Shell thickness in inches Size fitting, Shell Size fitting, Shell Size fitting. Shell inches thickness inches thickness inches thickness 2 Vs 5 % 12 w% "i 2J^ Vi 6 13. 14 lA -1) 3 Ys 7 % 15 ^Vx 3}^ Vs 8 15 T6 16 lA 4 % 9 1 18 1=^ 41^ 16 10 li^ 20 1^ 1. Extra heavy reducing elbows carry same dimensions center-to-face as regular elbows of Itirgest straight size. 2. Extra heavy tees, crosses and laterals, reducing on run only, carry same dimensions face-to-face as largest straight size. 3. Where long-turn fittings are specified, it has reference only to elbows which are made in two center-to-face dimensions and to be known as elbows and long-turn elbows, the latter being used only when so specified. 4. Extra heavy fittings must be guaranteed for 250-lb. working pressure, and each fitting must have some mark cast on it indicating the maker and guaranteed working steam pressure. 5. All extra heavy fittings and flanges to have a raised surface i^ in. high inside of bolt holes for gaskets. Thickness of flanges and center-to-face dimensions of fittings include this raised surface. Bolt holes to be Y^ in. larger in diameter than bolts. Bolt holes to straddle center lines. {Continued on next page.) Table 28-17. Extra-Heavy Pipe Flanges and Bolts 1915 Standard, 250-lb. Working Pressure -A^ Pipe Size Flange Bolts Bolt holes /y^ §^ i " Diam. Thick- Bolt ^k } P D ness T No. Size circle B. C. hole ^^ 8 15 15/^ 12 K 13 r 9 \6H 1% 12 1 14 \v^ 10 12 14 20,1^ 23 1^8 2 2H 16 16 20 1 1.1 8 I^Va 17M 20M IM Pipe Flange Bolts Bolt holes Wa Siie Diam. Thick- No. Size Bolt Bolt hole 15 241^ 2^ 20 IH 21 J^ w^ P D T B.C. 16 2b/, 2K 20 IH 22/, IH 18 28/, 2V, 24 lyA 24^4 l^s 1 4K« H 4 y?. 3K Vs I'/i 5 H 4 y?. ZH % 20 30 ^ 2y?, 24 IH 27 \y-? IH 6 i3. 4 y« 4,1/, Va 22 33 2yH 24 ly?, 2914 1^/8 2 (>y?. Vh 4 'A 5 Va 24 36 2^4 24 IVh 32 VYa 26 3814 2H 28 m 34/, IYa •2yo, -iy?. 1 4 % SVh Vs 3 m IH 8 ■% 6V8 14 28 40^4 21* 28 i-% 37 m ■sy?. y Ifk 8 H 7i4 % 30 43 3 28 VH 39^4 1% 4 10 li4 8 ■% r/n % 32 45 '4 ■m 28 \% ^\y■?. 2 34 47/, 3K 28 i% 43/, 2 'iV?. tOH: lA 8 Va 8'/s Vs 5 11 Ws 8 Va 9^4 Vs 36 50 3^, 32 IVh 46 2 6 i2y?. 1t^ 12 Va loys Vb 38 5214 3,^ 32 IV, 48 2 7 14 1^2 12 % liK 1 40 54}^ 3t% 36 \y% 5014 2 324 6. Size of all fittings scheduled indicates inside diameter of ports. 7. Square head bolts with hexagonal nuts are generally recommended for use. 8. Double branch elbows, side outlet elbows and side outlet tees, whether straight or reducing sizes, carry same dimensions center-to-face and face-to-face as regular tees and elbows. 9. Bull-head tees or tees increasing on outlet, will have same center-to-face and face-to- face dimensions as a straight fitting of the size of the outlet. 10. Tees, crosses and laterals 16-in. and smaller, reducing on the outlet, use the same dimensions as straight size of the larger port. Sizes 18 in. and larger, reducing on the outlet, are made in two lengths, depending on the size of the outlet as given in the table of dimen- sions. 11. For fittings reducing on the run only a long body pattern will be used. Y's are special and made to suit connections. Double branch elbows are not made reducing on the run. 12. Steel flanges, fittings and valves are recommended for superheated steam. Table 28-18. Extra-Heavy Flanged Reducing Laterals 1915 Standard, 250-lb. Working Pressure Reducing lateral Reducing-on-run lateral Reducing on-run and Branch lateral Size Branch b Dimensions, inches M Flanges Diam. Thickness 1 — — 4>i 11 IH \\i and less Wz ■7M 2}^ iVi 5 Vi W2 W2 " " 11 83^ W2 SV2 6 H 2 O ft It 11?^ 9 2y2 9 6H % 2^ 2K " " 13 10}^ Wi 10V2 7y2 1 3 3 " " 14 11 3 11 8H Wi 3J^ 3M " " 15}^ 123^ 3 12)^ 9 lA 4 4 " " 16H 133^ 3 13}^ 10 IM 41^ 41^ " " 18 14)^ Wi 14>^ 10^ lA 5 5 " " 18M 15 W2 15 11 Ws 6 6 " " 21 J^ yiVi 4 17}^ 12J^ \ii 7 7 " " 23J^ 19 m 19 14 iy2 8 8 " ■' 25 J^ 20^ 5 201^ 15 1% 9 9 " ■' 27>^ 22K 5 22 J^ 16J4 m 10 10 " " 29}^ 24 5K 24 17^ m 12 12 " " 33J^ 27 J^ 6 2iy2 20^ 2 14 14 " " 373^ 31 6H 31 23 2H 15 15 " '■ 39>^ 33 (^Vi 33 24>^ 2A 16 16 " •' 42 34^ iy2 341^ 25}^ 2K 18 9 •' " 34 31 3 32y2 28 2^ 18 16 to 10 inc. 45>^ 37J^ 8 37M 28 2ys 20 10 and less 37 34 3 36 3oy2 2y2 20 18 to 12 inc. 49 401^' &y2 401^ 30}4 2M 22 10 and less 40 37 3 39 33 2J^ 22 20 to 12 inc. 53 433^ W2 43 J^ 33 2^ 24 12 and less 44 41 3 43 36 2H 24 22 to 14 inc. 57'^ 47^ 10 47M 36 2M 325 Table 28-19. Extra-Heavy Flanged Bull-Head Reducing Tees and Crosses 1915 Standard, 250-lb. Working Pressure k — ^J — >|' II ._i- \<'b->\ Reducing tee <— J — »l<— J — . n 1 I ! r 1 fill T,. 1. \<-b>\ Reducing cross 4 'A Reducing- on- run tee --T 'JZ Bull-head tee i±± 5-1- Reducing-on-run and branch tee ■J ><— J — >■ I I I I I I I I ^ Reducing-on-run and branch cross Run-R Size Branch b Dimensions, inches K Flanges Diam. Thickness 1 — — — 44 fi IM 1 or less 4M 414 5 H iy2 IK " " 4M 4}-^ 6 H 2 IK " " 5 5 6y2 . Vs 2y2 2 " " 5H 5,4 7J^ 1 3 2K " " 6 6 SH 1}^ 3J^ 3 " " 6J^ 6,'i 9 lA 4 iVz " " 7 1 Note — A reduction in size on 10 IH the run does not alTect the 4J^ 4 " " 7>i ^'A dimensions but branch out- 104 l^ 5 m " " 8 8 lets of smaller size than those 11 Wi 6 5 " " SV2 S14 listed below will reduce the 12,4 li^ 7 6 " " 9 9 dimensions of or over in size fittings 18 in. 14 14 8 7 " " 10 10 15 1^ 9 8 " " 10>4 10 14 16}^ IM 10 9 " " iVA 113-^ 174 VA 12 10 " " 13 13 204 2 14 12 " " 15 15 23 24 15 14 " " 153^ 15 H B anch J K 244 2A 16 15 " " 163^ 16M 254 2J4 18 18 to 14 inc. 18 18 12 or less 14 17 28 2?^ 20 20 to 15 inc. 19J^ 194 14 " " ■154 18,4 304 24 22 22 to 16 inc. 20M 204 15 " " 164 20 33 254 24 24 to 18 inc. 22y2 224 16 " " 17 21,4 36 2M 26 26 to 20 inc. 24 24 18 " " 19 23 38M 2H 28 28 to 20 inc. 26 26 18 " " 19 24 403^ 21i 30 30 to 22 inc. 27}^ 274 20 " " 204 254 43 3 32 32 to 22 inc. 29 29 20 " " 204 264 45 J4 34 34 34 to 24 inc. 30,14 30 K .^.^ ti «t 22 28 474 34 36 36 to 26 inc. 32M 324 24 " " 234 294 50 354 38 38 to 26 inc. 34 34 24 " " 234 304 .52 K 3i% 40 40 to 28 inc. 35, ^ 354 26 " " 25 314 544 35^ 326 Table 28-20. Extra-Heavy Flanged Elbows, Crosses, Laterals and Reducers 1915 Standard, 250-Ib. Working Pressure Double-branch elbow -( i I J I Straight tee Straight cross Straight lateral If cr- Size Run-R Dimensions, inches C D Flange Diam. Thickness 1 4 5 2 S'A 6A — 43^ H IM 4M 5^ 23^ 9A ■^H — 5 % IJ^ 4^ 6 2M 11 &A — 6 *t 2 5 6J^ 3 iiA 9 — 63^ Vs 2^ 5J^ 7 W2 13 lOH 73^ 1 3 6 7H S'A 14 11 6 834 \v% sy2 6V2 8^ 4 15}-^ 121^ 6 14 9 lA 4 7 9 4>^ 163^ 133^ 7 10 IM m I'A 9^ 43^ 18 14 U 73^ 103^ lA 5 8 lOK 5 WA 15 8 11 1^8 6 SV2 n'A 53i 21H nji 9 1234 1t^ 7 . 9 12H 6 23}^ 19 10 14 13-2 8 10 14 6 25}^ 203^ 11 15 VA 9 10}^ 15M 6}^ 27}^ 2234 113^ 163i IH 10 11^ 161^ 7 291^ 24 12 173^ VA 12 13 19 8 33}^ 273^ 14 203^ 2 14 15 2iy2 83^ 373^ 31 16 23 2^ 15 15}^ 22M 9 3914 33 17 243^ 2^ 16 16>^ 24 9;^ 42 343^ 18 251.^ 234 18 18 26M 10 45}^ 373^ 19 28 25/8 20 19H 29 IOI2 49 403^ 20 303^ 23^ 22 20J^ 31^ 11 53 433^ 22 33 2% 24 22 J^ 34 12 57 H 4734 24 36 2M 26 24 36M 13 26 3834 2H 28 26 39 14 28 40M 2if 30 27^ 4114 15 — — 30 43 3 32 29 44 16 — _ 32 4534 33^ 34 30K 46H 17 — — 34 473-^ 334 36 321^ 49 18 36 50 5% 38 34 51 J^ 19 — — 38 52 3i 3A 40 35H 54 20 — — 40 543^ 3^ ■327 Table 28-21. Properties of Saturated Steam Reproduced by permission from Marks and Davis Steam Tables and Diagrams. Copyright, 1909, by Longmans, Green & Co. Pressure, lb. absolute Temperature, deg. fahr. Specific volume, cu. ft. per lb. Heat of the liquid, B.t.u. Latent heat of evap., B.t.u, Total heat of steam, B.t.u. Pressure, lb. absolute 1 101.83 333.0 69.8 1034.6 1104.4 1 o 126.15 173.5 94.0 1021.0 1115.0 2 3 141.52 118.5 109.4 1012.3 1121.6 3 4 153.01 90.5 120.9 1005.7 1126.5 4 5 162.28 73.33 130.1 1000.3 1130.5 5 6 170.06 61.89 137.9 995.8 1133.7 6 7 176.85 53.56 144.7 991.8 1136.5 7 8 182.86 47.27 150.8 988.2 1139.0 8 9 188.27 42.36 156.2 985.0 1141.1 9 10 193.22 38.38 161.1 982.0 1143.1 10 11 197.75 35.10 165.7 979.2 1144.9 11 12 201.96 32.36 169.9 976.6 1146.5 12 13 205.87 30.03 173.8 974.2 1148.0 13 14 209.55 28.02 177.5 971.9 1149.4 14 14.7 212.0 26 79 180 970.4 1150.4 14.7 15 213.0 26.27 181.0 969.7 1150.7 15 16 216.3 24.79 184.4 967.6 1152.0 16 17 219.4 23.38 187.5 965.6 1153.1 17 18 222.4 22.16 190.5 963.7 1154.2 18 19 225.2 21.07 193.4 961.8 1155.2 19 20 228.0 20.08 196.1 960.0 1156.2 20 22 233.1 18.37 201.3 956.7 11.58.0 22 24 237.8 16.93 206.1 953.5 1159.6 24 26 242.2 15.72 210.6 950.6 1161.2 26 28 246.4 14. 67 214.8 947.8 1162.6 28 30 250.3 13.74 218.8 945.1 1163.9 30 32 254.1 12.93 222.6 942.5 1165.1 32 34 257.6 1*^ 22 226.2 940.1 1166.3 34 36 261.0 11.58 229.6 937.7 1167.3 36 38 264.2 11.01 232.9 935.5 1168.4 38 40 267.3 10.49 236.1 933.3 1169.4 40 42 270.2 10.02 239.1 931.2 1170.3 42 44 273.1 9.59 242.0 929.2 1171.2 44 46 275.8 9.20 244.8 927.2 1172.0 46 48 278.5 8.84 247.5 925.3 1172.8 48 50 281.0 8.51 250.1 923.5 1173.6 50 52 283.5 8.20 252.6 921.7 1174.3 52 ■ 54 285.9 7.91 255.1 919.9 1175.0 54 56 288.2 7.65 257.5 918.2 1175.7 56 58 290.5 7.40 259.8 916.5 1176.4 58 60 292.7 7.17 262.1 914.9 1177.0 60 62 294.9 6.95 264.3 913.3 1177.6 62 64 297.0 6.75 266.4 911.8 1178.2 64 66 299.0 6.56 • 268.5 910.2 1178.8 66 68 301.0 6.38 270.6 908.7 1179.3 68 70 302.9 6.20 272.6 907.2 1179.8 70 72 304.8 6.04 274.5 905.8 1180.4 72 74 306.7 5.89 276.5 904.4 1180.9 74 76 308.5 5.74 278.3 903.0 1181.4 76 78 310.3 5.60 280.2 901.7 1181.8 78 80 312.0 5.47 282.0 900.3 1182.3 80 328 Table 28 -21. Properties of Saturated Steam — Continued Pressure, lb. absolute Temperature, deg. fahr. Specific volume, cu. ft. per lb. Heat of the liquid, b.t.u. Latent heat of evap., b.t.u. Total heat of steam, b.t.u. Pressure, lb. absolute 82 84 86 88 313,8 315.4 317.1 318.7 5.34 5.22 5.10 5.00 283.8 285.5 287.2 288.9 899.0 897.7 896.4 895.2 1182.8 1183.2 1183.6 1184.0 82 84 86 88 90 92 94 96 320.3 321.8 323.4 324.9 4.89 4.79 4.69 4.60 290.5 292.1 293.7 295.3 893.9 892.7 891.5 890.3 1184.4 1184.8 1185.2 1185.6 90 92 94 96 98 100 105 110 326.4 327.8 331.4 334.8 4.51 4.429 4.230 4.047 296.8 298.3 302.0 305.5 889.2 888.0 885.2 882.5 1186,0 1186.3 1187.2 1188.0 98 100 105 110 115 120 125 130 338.1 341.3 344.4 347.4 3.880 3.726 3.583 3.452 309.0 312.3 315.5 318.6 879.8 877.2 874.7 872.3 1188.8 1189.6 1190.3 1191.0 115 120 125 130 135 140 145 150 350.3 353.1 355.8 358.5 3.331 3.219 3.112 3.012 321.7 324.6 327.4 330.2 869.9 867.6 865.4 863.2 1191.6 1192.2 1192.8 1193.4 135 140 145 150 155 160 165 170 361.0 363.6 366.0 368.5 2 920 2.834 2.753 2.675 332.9 335.6 338.2 340.7 861.0 858.8 856.8 854.7 1194.0 1194.5 1195.0 1195.4 - 155 160 165 170 175 180 185 190 370.8 373.1 375.4 377.6 2.602 2.533 2.468 2.406 343.2 345.6 348.0 350.4 852.7 850.8 848.8 846.9 1195.9 1196.4 1196.8 1197.3 175 180 185 190 195 200 205 210 379.8 381.9 384.0 386.0 2.346 2 290 2.237 2.187 352.7 354.9 357.1 359.2 845.0 843.2 841.4 839.6 1197.7 1198.1 1198.5 1198.8 195 200 205 210 215 220 225 230 388.0 389.9 391.9 393.8 2.138 2.091 2.046 2.004 361.4 363.4 365.5 367.5 837.9 836.2 834.4 832.8 1199.2 1199,6 1199.9 1200.2 215 220 225 230 235 240 245 250 395.6 397.4 399.3 401.1 1.964 1.924 1.887 1.850 369.4 371.4 373.3 375.2 831.1 829.5 827.9 826.3 1200.6 1200.9 1201.2 1201.5 235 240 245 250 Table 28-22. Indicated Horsepower of an Engine A = area of the piston in square inches. P = niean efTeclive pressure of the steam on the piston, lb. per sq. in. L = length of stroke in ft. N=number of working strokes per min.= 2 X r. p. m. for double-acting cylinder. PLAN Then i.hp.= 33,000 The mean pressure in the cylinder of a non-condensing engine when cutting off at }4, stroke = boiler pressure multiplied by . 597 J^ stroke = boiler pressure multiplied by . 919 ^ " = " " " " .670 J^ " = " " " " .937 3^ " = " " " " .743 3^ " = " " " " .966 J^ " = " " " ■• .847 Va " = " " " " .992 329 Table 28-23. Dimensions of Horizontal Return Tubular Boilers"" Corresponding to Am. Soc. M. E. Standards Horse power 34 36 39 36 30 45 42 35 52 48 40 47 45 43 55 53 50 63 60 58 85 73 68 96 82 77 111 95 83 125 106 93 136 123 107 153 138 120 169 153 134 178 167 145 197 186 161 Heat- ing sur- face Sq. ft. SheU 370 430 470 430 360 540 500 420 620 570 480 560 540 510 660 630 600 750 720 700 1021 872 822 1147 980 924 1338 113 993 1504 1272 1116 1632 1474 1289 1834 1657 1448 2037 1839 1608 2139 2001 1745 2375 2232 1938 Dia. In. 42 42 48 48 48 48 48 48 48 48 48 54 54 54 54 54 54 54 54 54 60 60 60 60 60 60 66 66 66 66 66 66 Lgth Feet 12 14 12 12 12 14 14 14 16 16 16 12 12 12 14 14 14 16 16 16 16 16 16 18 18 18 16 16 16 18 18 18 16 16 16 18 18 18 20 20 20 18 18 18 78 20 78 20 78 20 THICKNESS OF SHELLS AND HEADS Tubes No. X 34 34 44 34 24 44 34 24 44 34 24 54 44 36 54 44 36 54 44 36 76 54 44 76 54 44 102 72 54 102 72 54 126 96 72 126 96 72 126 96 148 118 148 118 88 Dia. In. 3 3 3 4 3 Wi 4 3 3J4 4 3 3}-; 4 3 3V'2 4 3 33-2 4 3 S}4 4 3 3}4 4 3 3^2 4 3 3>^ 4 3 3}'> 4 3 4 3 4 3 4 3 ■i'A 4 Lgth Feet 12S-Lb. working pressure Shell Heads In. In. 12 , ,. u a 14 14 16 16 16 12 12 12 14 14 14 16 16 16 16 16 16 18 18 18 16 16 16 18 18 18 16 16 16 18 18 18 20 20 20 18 18 18 20 20 20 5yi Vb y% % Yb Vb Yb Long joint SheU In. 150-Lb. working pressure Quad Butt. Quad Butt. Quad Butt. Quad Butt. Double Butt, Double Butt. Double Butt. Double Butt. Double Butt. Double Butt. Double Butt. Double Butt. Double Butt. Double Butt Double Butt Triple Butt. Triple Butt, i^ Triple Butt. Triple Butt. Triple Butt. Triple Butt. Triple Butt. Triple Butt. Triple Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. H Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. H Hds In. X2 Yi Y% Yb Yb Yb Yb Long joint Triple Butt. Triple Butt. Triple Butt. Triple Butt. Triple Butt. Triple Butt. Triple Butt. Triple Butt. Triple Butt. Triple Butt. Triple Butt. Triple Butt. Triple Butt. Triple Butt. Triple Butt. Triple Butt. Triple Butt. Triple Butt. Triple Butt. Triple Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. Quad Butt. .M c v.,H 6S .1?: Q'^ at 4 1 4 1 4 1 4 1 4 1 4 1 4 1 4 1 4 1 4 1 4 1 4 Wi 4 Wa 4 Wa 4 1'4 4 IM 4 Wa 4 \Va 4 Wa 4 IM 5 m D l'/2 m 5 lJ/2 5 m 5 Wo 6 9 6 2 6 o 6 9 6 -9 6 O 6 O 6 9 6 9 6 9 6 O 6 ■■> 6 o 6 9 6 9 7 9 O 7 9 9 7 '1 9 2H W2 2U ■^Y2 W2 Wt "-Yi 2M 2 3^' W2 2M 2M W2 2H •W2 2J^ 2M 2J/2 ^-Yi 2Y2 2J^ ■2Y2 2Y2 2Y2 2Y2 *Coatesville Boiler Works, Philadelphia, Pa. tFor heating boilers, a boiler horsepower is assumed in this table to be equivalent to 12 sq. ft. of heating surface JA boiler of 48-in. diameter and larger has a manhole in the front head below the tubes in addition to the regular manhole in the upper part of the shell or front head 330 Table 28-24. Properties of Air Temper- ature, deg. fahr. Vol. of dry air with unity at 32 deg. fahr. Cubic feet per lb. of air Weight per cu. ft. of dry air in lb. Zero 0.935 11.58 0.0864 12 0.960 11.87 0.0842 22 0.980 12.14 0.0824 32 1.000 12.40 0.0807 42 1.020 12.64 0.0791 52 1.041 12.88 0.0776 60 1.057 12.39 0.0764 62 1.061 13.13 0.0761 70 1.078 13.34 0.0750 72 1.082 13.39 0.0747 82 1.102 13.64 0.0733 92 1.122 13.90 0.0720 100 1.139 13.95 0.0710 102 1.143 14.14 0.0707 112 1.163 14.40 0.0694 122 1.184 14.65 0.0682 132 1.204 14.90 0.0671 142 1.224 15.15 0.0660 152 1.245 15.40 0.0649 162 1.265 15.65 0.0638 172 1.285 15.90 . 0628 182 1.306 16.17 0.0618 192 1.326 16.42 0.0609 202 1.347 16.67 0.0600 212 1.367 16.92 0.0591 0.267 0.388 0.522 0.556 0.754 0.785 1.092 1.501 1.929 2.036 2.731 3.621 4.752 6.165 7.930 10.099 12.758 15.960 19.828 24.450 29.921 Elastic force of Cubic feet of vapor in in. of mer- cury vapor from 1 lb. of water 0.044 0.074 0.118 0.181 3289 2252 1595 1227 1135 819 600 444 356 334 253 194 151 118 93.3 74.5 59.2 48.6 39.8 32.7 27.1 B.t.u. ab- sorbed per cu. ft. of air per deg. fahr. Dry air 0.02056 0.02004 0.01961 0.01921 0.01882 0.01847 0.01818 0.01811 0.01777 0.01767 0.01744 0.01710 0.01690 0.01682 0.01651 0.01623 0.01596 0.01571 0.01544 0.01518 0.01494 0.01471 0.01449 0.01426 0.01406 Sat. air 0.02054 0.02006 0.01963 0.01924 0.01884 0.01848 0.01822 0.01812 0.01794 0.01790 0.01770 0.01751 0.01735 0.01731 0.01711 0.01691 0.01670 0.01652 0.01634 0.01616 0.01.598 0.01580 Cu. ft. of air raised 1 deg. fahr. by 1 b.t.u. Dry air 48.5 50.1 51.1 52.0 53.2 54.0 55.0 55.2 56.3 56.5 57.2 59.1 59.5 60.6 61.7 62.5 63.7 65.0 66.2 67.1 68.0 68.9 69.5 71.4 Sat. air 48.7 50.0 51.0 51.8 52.8 53,8 54.6 54.7 55.5 55.8 56.5 57.1 57.8 57.8 58.5 59.1 59. 60. 61. 62.4 63 64 Table 28-25. Volume and Weight of Air at Atmospheric Pressure at Temperatures Between 212 and 850 Deg. Fahr. Temperature, degrees fahrenheit Volume of one pound in cubic feet Weight one cubic foot in pounds Temperature, degrees fahrenheit Volume of one pound in cubic feet Weight one cubic foot in pounds Temperature, degrees fahrenheit Volume of one pound in cubic feet Weight one cubic foot in pounds 212 16.925 . 059084 320 19.647 . 050898 550 25.444 .039302 220 17.127 . 058388 340 20.151 . 049625 575 26,074 .038352 230 17.379 . 057541 360 20.655 . 048414 600 26.704 . 037448 240 17.631 . 056718 380 21.159 .047261 650 27.964 .035760 250 17.883 .055919 400 21.663 .046162 700 29 224 . 034219 260 18.135 . 055142 425 oo ^93 . 044857 750 30.484 . 032804 270 18.387 . 054386 450 0.7 923 . 043624 800 31 . 744 .031502 280 18.639 .053651 475 23.554 . 042456 850 33.004 .030299 290 18.891 . 052935 500 24.184 .041350 300 19.143 .052238 525 24.814 .040300 331 Table 28-26. Weight of Water at Temperatures Used in Physical Calculations Temperature, Degrees Fahrenheit Weight per cubic foot, pounds Weight per cubic inch, pounds At 32 degrees or freezing point at sea level . . . At 39.2 degrees or point of maximum density. At 62 degrees or standard temperature At 212 degrees or boiling point at sea level. . . 62.418 0.03612 62.427 0.03613 62.355 0.03608 59.846 0.03469 Table 28-27. Volume and Weight of Distilled Water at Various Temperatures" Tem- per- ature, deg. fahr. 32 39.2 40 50 60 70 80 90 100 110 120 130 140 150 Relative volume water at 39.2 deg.= l 1.000176 1.000000 1.000004 1.00027 00096 00201 00338 1.00504 00698 00915 01157 01420 1.01705 1.02011 Weight in lb. per cubic foot Tem- per- ature, deg. Jahr. 62.42 160 62.43 170 62.43 180 62.42 190 62.37 200 62.30 210 62 22 212 62.11 220 62.00 230 61.86 240 61.71 250 61.55 260 61.38 270 61.20 280 Relative volume, water at 39.2 deg. = l 1.02337 1 . 02682 1 . 03047 1.03431 03835 04256 04343 , 0469 0515 , 0562 .0611 1.0662 1.0715 1.0771 Weight in lb. per cubic foot 61.00 60.80 60.58 60.36 60.12 59.88 59.83 59.63 59.37 59.11 58.83 58.55 58.26 57.96 Tem- per- ature, deg. fahr. 290 300 310 320 330 340 350 360 370 380 390 400 410 420 Relative volume, water at 39.2 deg. = 1 1.0830 1 . 0890 1.0953 1.1019 1.1088 1.1160 1 . 1235 1.1313 1.1396 1483 1573 167 177 187 Weight Tem- Relative in lb. per- volume, per ature, water at cubic deg. 39.2 deg. foot fahr. = 1 57.65 430 1.197 57.33 440 1.208 57.00 450 1.220 56.66 460 1.232 56.30 470 1.244 55.94 480 1.256 55.57 490 1.269 55.18 500 1.283 54.78 510 1.297 54.36 520 1.312 53.94 530 1.329 53.5 540 1.35 53.0 550 1.37 52.6 560 1.39 Weight in lb. per cubic foot 52.2 51.7 51.2 50.7 50.2 49.7 49.2 48.7 48.1 47.6 47.0 46.3 45.6 44.9 * Marks and Da Table 28-28. Boilins; Point of Water at Various Altitudes Boiling point, degrees fahrenheit Altitude above sea level, feet Atmospheric pressure, pounds per square inch Barometer reduced to 32 degrees, inches Boiling point, degrees fahrenheit Altitude above sea level, feet Atmospheric pressure, pounds per square inch Barometer reduced to 32 degrees, inches 184 15221 8.20 16.70 199 6843 11.29 22.99 185 14649 8.38 17.06 200 6304 11.52 23.47 186 14075 8.57 17.45 201 5764 11.76 23.95 187 13498 8.76 17.83 202 5225 12.01 24.45 188 12934 8.95 18.22 203 4697 12.26 24.96 189 12367 9.14 18.61 204 4169 12.51 25.48 190 11799 9.34 19.02 205 3642 12.77 26.00 191 11243 9.54 19.43 206 3115 13.03 26.53 192 10685 9.74 19.85 207 2589 13.30 27.08 193 10127 9.95 20.27 208 2063 13.57 27.63 194 9579 10.17 20.71 209 1539 13.85 28.19 195 9031 10.39 21.15 210 1025 14.13 28.76 195 8481 10.61 21.60 211 512 14.41 29.33 197 7932 10.83 22.05 212 Sea Level 14.70 29.92 198 7381 11.06 22.52 332 Table 28-29. Pressures Corresponding to Given Heads of Water in Feet Water at maximum density. Temperature, 39.2 deg. fahr. h = head in feet. P= pressure in lb. per sq. inch = .443 h h P h P h p h P h P h p h p 1 .433 16 6.928 31 13.42 46 19.92 61 26.41 76 32.91 91 39.40 2 .866 17 7.361 32 13.86 47 20.35 62 26.85 77 33.34 92 39.84 3 1.299 18 7.794 33 14.29 48 20.78 63 27.28 78 33.77 93 40.27 4 1.732 19 8.227 34 14.72 49 91 22 64 27.71 79 34.21 94 40.70 5 2.165 20 8.660 35 15.15 50 21.65 65 28.14 80 34.64 95 41.13 6 2.598 21 9.09 36 15.59 51 22.08 66 28.58 81 35.07 96 41.57 7 3.031 99 9.53 37 16.02 52 22.52 67 29.01 82 35.51 97 42.00 8 3.464 23 9.96 38 16.45 53 22.95 68 29.44 83 35.94 98 42.43 9 3.897 24 10.39 39 16.89 54 23.38 69 29.88 84 36.37 99 42.87 10 4.330 25 10.82 40 17.32 55 23.81 70 30.31 85 36.80 100 43.30 11 4.763 26 11.26 41 17.75 56 24.25 71 30.74 86 37.24 12 5.196 27 11.69 42 18.19 57 24.68 72 31.18 87 37.67 13 5.629 28 12.12 43 18.62 58 25.11 73 31.61 88 38.10 14 6.062 29 12.56 44 19.05 59 25.55 74 32.04 89 38-54 15 6.495 30 12.99 45 19.48 60 25.98 75 32.47 90 38.97 Table 28-30. Pressure, in Oiuices Per Square Inch Corresponding to Various Heads of Water, in Inches" Head Decimal parts of an inch .4 .5 .06 .12 .17 .23 .29 .35 .40 .46 .52 1 .58 .63 .69 .75 .81 .87 .93 .98 1.04 1.09 2 1.16 1.21 1.27 1.33 1.39 1.44 1.50 1.56 1.62 1.67 3 1.73 1.79 1.85 1.91 1.96 2 02 2.08 2.14 2.19 2.25 4 2.31 2.37 2.42 2.48 2.54 2.60 2.66 2 72 2.77 2.83 5 2.89 2.94 3.00 3.06 3.12 3.18 3.24 3.29 3.35 3.41 6 3.47 3.52 3.58 3.64 3.70 3.75 3,81 3.87 3.92 3.98 7 4.04 4.10 4.16 4.22 4.28 4.33 4.39 4.45 4.50 4.56 8 4.62 4.67 4.73 4.79 4.85 4.91 4.97 5.03 5.08 5.14 9 5.20 5.26 5.31 5.37 5.42 5.48 5.54 5.60 5.66 5.72 *Suplee's Mechanical Engineers' Reference Book, published by J. B. Lippincott Co. Table 28-31. Comparison of Measures of Pressure and Weight f 1 lb. per sq. in. 1 oz. per sq. in. 1 atmos- p h e r e = (14.7 lb. persq. in.) 144 lb. per sq. ft. 2.0416 in. mercury at 62 deg. fahr. 2.309 ft. water at 62 deg. fahr. 27.71 in. water at 62 deg. fahr. 0.1276 in. mercury at 62 deg. fahr. 1.732 in. water at 62 deg. fahr. 2116.3 lb. per sq. ft. 33.947 ft. water at 62 deg. fahr. 30 in. mercury at 62 deg. fahr. 29.922 in. mercury at 32 deg. fahr. 1 in. water at 62 deg. fahr. 0.03609 lb 5.196 lb. per sq 5774 oz. ft. per sq. in. ft. water at 62 deg. = fahr. 0.433 lb. per sq. in. 62.355 lb. per sq. ft. in. mer- f 0.491 lb. or 7.86 oz. per sq. in. cury at = ■! 1.132 ft. water at 62 deg. fahr. 62 deg. fahr. [ 13.58 in. water at 62 deg. fahr. IKent's Mechanical Engineers' Pocket Book 333 Table 28-32. Conversion of Mercury and Vapor Pressures Inches of mercury to pounds per square inch Tenths 1 2 3 4 5 6 7 8 9 Inches Lb. Sq. in. Lb. Sq. in. Lb. Sq. in. Lb. Sq. in. Lb. Sq. in. Lb. Sq. in. Lb. Sq. in. Lb. Sq. in. Lb. Sq. in. Lb. Sq. in. 0. 0.49 0.98 1.47 1.96 2.46 2.95 3.44 3.93 4.42 10 4.91 5.40 5.89 6.39 6.88 7.37 7.86 8.35 8.84 9.33 20 9.82 10.32 10.81 11.30 11.79 12.28 12.77 13.26 13.75 14.24 30 14.74 15.2 15.7 16.2 16.7 17.2 17.7 18.2 18.7 19.1 40 19.6 20.1 20.6 21.1 21.6 22.1 22.6 23.1 23.6 24.1 50 24.6 25.1 25.5 26.0 26.5 27.0 27.5 28.0 28.5 29.0 60 29.5 30.0 30.5 30.9 31.4 31.9 32.4 32.9 33.4 33.9 70 34.4 34.9 35.4 35.9 36.3 36.8 37.3 37.8 38.3 38.8 80 39.3 39.8 40.3 40.8 41.3 41.8 42.2 42.7 43.2 43.7 90 44.2 44.7 45.2 45.7 46.2 46.7 47.2 47.6 48.1 48.6 100 49.1 49.6 50.1 50.6 51.1 51.6 52.1 52.6 53.0 53.5 Pounds per square inch to inches of mercury Tenths 1 2 3 4 5 6 7 8 Pounds In. Hg. In. Hg. In. Hg. In. Hg. In. Hg. In. Hg. In. Hg. In. Hg. In. Hg. In. Hg. 0. 2.0352 4.0704 6.10.56 8.1408 10.1760 12.2112 14.2464 16.2816 18.3168 10 20.352 22.3872 24 4224 26.4576 28.4928 30.528 32.. 5632 34.5984 36.6336 38.6688 20 40.704 42.7392 44.7744 46.8096 48 . 8448 50.8809 52.91.52 54.9504 56.9856 59.0208 30 61.056 63.0912 65.1264 67.1616 69.1968 71.2.320 73.2672 75.3024 77.3376 79.3728 40 81.408 83.4432 85.4784 87.5136 89.5488 91.5840 93.6192 95.6544 97.6896 99.7148 50 101.76 103.795 105.830 107.865 109.900 111.9.36 113.971 116.006 118.041 120.077 60 122.11 124.145 126.180 128.215 130.250 132.286 134.321 136.356 138.391 140.427 70 142.46 144.495 146.530 148.565 150.600 152.636 1.54.671 156.706 158.741 160.777 80 162.81 164.945 166.880 168.915 170.9.50 172.986 175.021 177.056 179.091 181.127 90 183.16 185.195 187.230 189.265 191.300 193.336 195.371 197.406 199.441 201.476 100 203.53 205.565 207.600 209.635 211.670 213.706 215.741 217.776 219.811 221.846 Table 28-33. Comparison of Measures of Pressure Name of units Atmospheres On square inch Inches mercury at 32 deg.fahr. Feet of water at 60 deg. fahr. Millimeters of mercury at 32' fahr. Pounds per square foot Kilograms per square meter Atmosphere 1. .068,03 .033,42 .029,47 .001,316 .000,472,6 .000,096,77 14.7 1. .491,3 .433,2 .019,34 .006,947 .001,423 29.922 "2!036 1. .881,8 .039,37 .014,13 .002,895 33.94 2.309 1.134 1. .044,64 .016,03 .003.283 760. 51.7 25.398 22.399 1. .359,2 .073,-55 2,116. 143.946 70.7 62.35 2.784 1. .204,8 10,333 Pounds per square inch In. mercury at 32° fahr. . Feet of water at 60° fahr. . MilUmeters of mercury at 32° fahr Pounds per square foot. . Kilograms per sq. meter 702.925 345.331 304.565 13.596 4.883 1. Table 28-34. Reasonable Economic Performance of Stationary Steam Plants* Central station Mfg. power plants Heating plants Type of plant Large 10,000 kw. and up Small 2000-10,000 kw. Small up to 100 hp. Medium 100-500 hp. Large 500-2000 hp. Central 1000 hp. and up Office and public bldgs. Residence Efficiency of boiler and Furnace in per cent 70-76 68-74 60-70 68-72 68-74 68-74 50-70 50-65 Coal per hour in lb. Per kw-hr. Per 1 hp. Per boiler hp. 2-3 1 2^-4 5-8 3-5 2J4-4 3-4 1 3-6 i * L. P. Breckenridge. Lecture on Fuel Conservation 334 Table 28-35. Weight in Pounds of One Gallon of Water at Temperatures from 32 Deg. to 420 Deg. Fahr. Temp. wt. Temp. wt. Temp. Wt. Temp. Wt. 32 8.344 105 8.279 185 8.084 270 7.788 35 8.345 110 8.270 190 8.069 280 7.748 39.2 8.3454 115 8.260 195 8.053 290 7.707 40 8.345 120 8.250 200 8.037 300 7.664 45 8.345 125 8.239 205 8.021 310 7.620 50 8.343 130 8.229 210 8.005 320 7.575 55 8.341 135 8.218 212 7.998 330 7.527 60 8.337 140 8.206 215 7.988 340 7.486 65 8.333 145 8.193 220 7.971 350 7.429 70 8.329 150 8.181 225 7.954 360 7.376 75 8.323 155 8.168 230 7.937 370 7.323 80 8.317 160 8.155 235 7.929 380 7.267 85 8.311 165 8.141 240 7.920 390 7.211 90 8.304 170 8.127 245 7.893 400 7.152 95 8.296 175 8.113 250 7.865 410 7.085 100 8.288 180 8.099 260 7.828 420 7.032 Table 28-36. Contents of Round Tanks in U. S. Gallons, for Each Foot in Depth To find capacity of a tank of any size: Given dimensions of a cylinder in inches, to find its capacity in U. S. gallons: Square the diameter, multiply by the length and by .0034 Diameter Ft. In. Gallons, 1 foot in depth 1 1 3 1 6 1 9 2 2 3 2 6 2 9 5.8735 9.1766 13.2150 17.9870 23.4940 29.7340 36.7092 44.4179 52.8618 62.0386 73.1504 82.5959 93.9754 106.1200 118.9386 132.5209 146.8384 161.8886 177.6740 194.1913 211.4472 229.4342 248.1564 267.6122 Diameter Ft. In. Gallons, 1 foot in depth 7 7 3 7 6 7 9 8 8 3 8 6 8 9 11 11 11 11 12 12 12 12 13 13 13 13 14 14 14 14 287.8032 308.7270 330.3859 352.7665 375.9062 399.7666 424.3625 449.2118 710.6977 743.3686 776.7746 810.9143 848.1890 881 . 3966 917.7395 954.8159 992.6274 1031.1719 1070.4514 1108.0645 1151.2129 1192.6940 1234.9104 1277.8615 Diameter Ft. In. Gallons, 1 foot in depth 15 15 15 15 16 16 16 16 17 17 17 17 21 21 21 21 22 22 22 18 18 3 18 6 18 9 1321.5454 1365.9634 1407.5165 1457.0032 1503.6250 1550.9797 1599.0696 1647.8930 1697.4516 1747.7431 1798.7698 1850.5301 1903 02.54 1956.2537 2010.2171 2064.9140 2590.2290 2652.2532 2715.0413 2778.5486 2842.7910 2907.7664 2973.4889 3039.9209 Diameter Ft. In. Gallons, 1 foot in depth 23 23 23 23 24 24 24 24 25 25 25 25 27 27 27 27 28 28 26 26 3 26 6 26 9 3107.1001 3175.0122 3243.6595 3313.0403 3383.1563 3454.0051 3525.5929 3597.9068 3670.9596 3744.7452 3819.2657 3894.5203 3970.5098 4047.2322 4124.6898 4202.9610 4281.8072 4361.4664 4441.8607 4522.9886 4604.8.517 4686.4876 4770.7787 4854.8434 335 o o 3 61) c ^ Oj ^ be <;m o o CTv n s ■^ o o i t^ «*-< Uh o CO Oi N r^ K CO CO :3 o (M tfl V 1 o 1 ;::::::::::::::::::; :iS^§§§§222SS : : : : a) 1 :::::::::■■:■■■ •SSggSSSSSSg^Sg "3 > d > :::::::■::■■■ •§?5§2§S:n^2§2K2 : : : 0) •s d in 6 l24 > •s a • .' ■' .' •' : o o o o o o o o o rf ^ ci ci w • •' ■ ■ ■' •' ■' ■ .' .' .■ "3 > ^COOSOnO*OOCO'^|-OCO ■ - PC4 - ■ ■ O O O O O O O -— 1 r-H (M (M - .' - '. ' ' > « 1 -• o d — \ O O O O O O -— 1 r-H CI (M - .' ' * > MVOOMrO^LOCOCO'^O 0} d ■i ■ ■ ■ ■ O O O O O O O 1— 1 (M rc - .' > •O^OLOOr— (LOOLOO ■ ■ CJ\ ^O LO ^ O ■* rH On CO o d ' ■ ■ o o o o o o o d rH .■.'.".':: > 0) •8 d 2^ PC o o o o o o ^ rH f-i : .'.■:.':: : "aJ > b OOOOr-H-HClrO "3 ^1 d ^1 lOOiOOiOOmOLOOOOOOiOOOOOOOOOOOOOOOOOOOOOO 336 Table 28-38. Friction of Water in Pipes Giving velocity in feet per second, friction head in feet and friction loss in pounds per square inch for each 100 ft. of pipe discharging a given quantity of water in gallons per niinute (Weisbach Formula) 0) 3 a S Pi •s? •SI •0 J3 [A d ai3 ■- a T3 J3 in d •SI ■0 s n d w — ^1 •0 s J3 " 9 Ml d-o — d s .d o* "^ (fl m £•8 d a " >■?, a a " £?S a p » >>S a d "" £■3 d a " >.o a d . d k. *^ u v-i 0*^ ^ *j ** >-• *^ ^ W U *-• "S '71 '^ .2 ^ .S 9i •3 0) .z a> .S .S QJ 'u !> .2 •£ .S 0) S 8" " tSft g» ■5£ Sa g» ".S 2 * 0" ■3JS tja 0" "£ ■S n g" ".£ tSa o > a, £.a &s >• P. £.S ££ s > a £.5 '&a II £.3 &£ 11 £.s £5 u S > a S.S '&a M"Pipe 1" Pipe l} 28%, c = 4. Also, when C and Gi are the percentages of fixed and volatile carbon, respec- tively, and H the percentage of hydrogen, E.t.u. per lb. = (14,600 C + 20,390 Ci + 62,000 H) + 100 340 Table 28-47. Composition and Heat Values of Anthracite Coal Locality Fixed car- bon Vola- Mois- tile ture Sul- pliur B.t.u. per lb. of dry coal Anthracite Pennsylvania 78 . 60 Buckwheat 81. 32 Wilkes-Barre 76. 94 Scranton 79. 23 Scranton 84.46 Cross Creek 89. 19 Lehigh Valley 75.20 Lykens Valley 76 . 94 Lykens VaUey 81.00 Wharton 86.40 Buck Mt 82.66 Beaver Meadow . 88.94 Lackawanna 87 . 74 Rhode Island 85. 00 Arkansas 74. 49 Semi-Anthracite Pennsylvania, Loyalsock 83 . 34 Bernice 82.52 Bernice . 89.39 Wilkes-Barre 88.90 Lycoming Creek 71 . 53 Virginia, Natural Coke 75. 08 Arkansas 74 . 06 Indian Territory 73.21 Maryland, Easby 83. 60 14.80 0.40 3.84 3.88 10.96 0.67 12,200 6.42 1.34 15.30 11,801 3.73 3.33 13.70 • . • < 12,149 5.37 0.97 9.20 .... 12,294 1.96 3.62 5.23 13,723 7.36 1.44 16.00 12,423 6.21 .... 15,300 5.00 15,300 3.08 3.7i 6.22 6.58 15,000 3.95 3.04 9.88 0.46 15,070 2.38 1.50 7.11 0.01 3.91 2. 12 6.35 7.00 0.12 0.90 14.73 i.52 9.26 13,217 8.10 1.30 6.23 1.03 15,400 3.56 0.96 3.27 0.24 15,050 8.S6 0.97 9.34 1.04 15,475 7.68 3.49 14,199 13.84 0.67 13.96 6.03 12.44 1.12 11.38 0.47 14.93 1.35 9.66 13.65 5.11 8.03 i.is 13,662 16.40 11,207 *Harding & Willard Table 28-48. Weight of Materials Dry woods Weight in Material lb. of one cu. ft. Ash 43-53 Beech 43-53 Birch 40-46 Boxwood 57-83 Cork 15 Ebony 70-83 Elm 34-45 Weight in Material lb. of one cu. ft. Fir, Spruce 30-44 Greenheart 70 Hornbeam 47 Larch 31-37 Lignum-vitae 83 Mahogany — Honduras. 35 " Spanish . . 53 Weight in Material lb. of one cu. ft. Oak — American red 54 " English 48-58 Pin(^-red 30-44 white 27-34 yellow 29-41 Teak 41-55 Stones, earth, etc. Weight in Material lb. of one cu. ft. Asphaltum 64-112 Brick — common 100-125 fire 137-150 Cement— Portland 80-90 Clay 120 Concrete 120-140 Earth 77-120 Glass — crown 156 Weight in Material lb. of one cu. ft. Glass— flint 187 plate 169 Granite 164-175 Gravel 90-125 Grindstone 134 Lime — quick 52 Limestone and marbles 150-179 Mortar— hardened .. . . 88-118 Weight in Material lb. of one cu. ft. Mud— dry and close . . . 80-110 wet and fluid . . . 104-120 Sand— dry 88-110 wet 118-129 Sandstone 130-170 Victoria stone (crushed "1 granite, Portland ce- > 144 ment. silica) ) 341 Table 28-49. Weight of Materials — Continued Metals and Alloys Material Specific gravity Weight in lb. of one cu. ft. cu. in. Cu. in. in one lb. Aluminum — cast wrought " bronze Antimony Arsenic Bismuth {from to average " Muntz metal " naval (rolled) " sheet " wire {from to average Copper — cast hammered " sheet " wire Gold (pure) " standard 22 carat fine (Gold 11— Copper 1) {from to average I from Iron — wrought Uo [average Lead — cast sheet . . Manganese Nickel — cast " rolled Platinum Silver (from to average Tin White Metal (Babbitt's) Zinc — cast " sheet 2.569 160 .093 10.80 2.681 167 .097 10.35 7.787 485 .281 3.56 6.712 418 .242 4.13 5.748 358 .207 4.83 9.827 612 .354 2.82 7.868 490 .284 3.53 8.430 525 .304 3.29 8.109 505 .292 3.42 8.221 512 .296 3.37 8.510 530 .307 3.26 8.462 527 .305 3.28 8.558 533 .308 3.24 8.478 528 .306 3.27 8.863 552 .319 3.13 8.735 544 .315 3.18 8.622 537 .311 3.22 8.927 556 .322 3.11 8.815 549 .318 3,15 8.895 554 .321 3.12 19.316 1203 .696 1.44 17.502 1090 .631 1.59 6.904 430 .249 4.02 7.386 499 .266 3.76 7.209 464 .260 3.85 7.547 470 .272 3.56 7.803 486 .281 3.68 7.707 480 .278 3.60 11.368 708 .410 2.44 11.432 712 .412 2.43 8.012 499 .289 3.46 8.285 516 .299 3.35 8.687 541 .313 3.19 21. 516 1,340 .775 1.29 10. 517 655 .379 2.64 7.820 487 .282 3.55 7.916 493 .285 3.51 7.868 490 .284 3.53 7.418 462 .267 3.74 7. 322 456 .264 3.79 6.872 428 .248 4.04 7.209 449 .260 3.85 Table 28-50. Specific Heat and Densities of Building Materials ' Building materials Specific heat Brickwork . 1950 Concrete 0.2700 Masonry . . 2159 Plaster." 2000 Pinewood 4670 Building materials Specific heat Oakwood 0.5700 Birch 4800 Glass 1977 Steel 1165 Densities in 16 per cu. ft. .Stonework 160 Wood 40 Slate 170 Plaster 90 * Harding and Willard .142 Table 28-51. Specific Heats of Various Substances f Solids Temperature,* „ .„ degrees Speciflc fahrenheit '•««' Copper 59-460 0. 0951 Gold 32-212 . 0316 Wrought iron 59-212 . 1152 Cast iron 68-212 . 1200 Stee\ (hard) 68-208 . 1175 Steel (soft) 68-208 . 1165 Zinc 32-212 .0935 Brass (vellow) 32 .0883 Temperature,* degrees Specific fahrenheit heat Glass (normal ther. 16"'). • • • 66-212 0. 1988 Lead 59 .0299 Platinum 32-212 .0323 Silver 32-212 .05.59 Tin 105-64 .0518 Ice 5040 Sulphur (newly fused) .2025 Liquids Temperature,* c-„--fi„ degrees S?"'^'^ fahrenheit Water. . Alcohol 59 /32 1176 Mercury 32 Benzol j^So Glycerine 59-102 Lead (melted) to 360 heat 1 . 0000 0.5475 .7694 .3346 .4066 .4502 .0410 Temperature,* gpecific * degrees *; , fahrenheit "^^ Sulphur (melted) 246-297 0. 2350 Tin (melted) . 637 Sea-water (sp. gr. 1.0043) 61 . 980 Sea-water (sp. gr. 1.0463) 64 . 903 Oil of turpentine 32 .411 Petroleum 64-210 . 498 Sulphuric acid 68-133 . 3363 Olive oil 309 Gases Air Oxygen . . . Nitrogen . . Hydrogen . Tempera- ture,* degrees fahrenheit Specific heat at constant pressure Specific heat at constant volume 32-392 5.5-405 32-392 54-388 0.2375 .2175 .2438 3.4090 0.1693 .1553 .1729 2.4141 Tempera- Specific Specific ture,* heat at heat at degrees constant constant fahrenheit pressure volume Carbon monoxide. . . . 41-208 Carbon dioxide 52-417 Methane 64-406 Blast-fur. gas (approx.) Flue gas (approx.) 0. 2425 0.1728 2169 .1535 5929 .4505 2277 2400 * When one temperature alone is given the "true" specific heat h given; otherwise the value is the "mean" specific heat for the range of temperature aiven tHarding and Willard Table 28-52. Tensile Strength of Materials Average value in pounds per square inch Antimony 1053 Aluminum — castings 15000 sheet 24000 bars 28000 Brass — yellow 26880 Bronze — cast 34000 delta metal— cast 44800 " rolled 67200 gun metal 32000 phosphor 40000 " manganese 62720 Tobin 78500 Copper — cast 22400 sheet 30240 wire 40000 Cast Steel. .80000 Gold 20384 Iron— cast 25000 " 18000 wrought 4.5000 Lead— cast 1800 rolled sheet 3320 Platinum wire 53000 Puddled semi-steel 35000 to 42000 Silver— cast 40000 Steel— cast 60000 to 80000 forgings. . . 60000 to 95000 Tin— cast 3360 Zinc — cast 3360 sheet 15680 Woods Ash 11000 to 17000 Beech 11500 to 18000 Cedar 10300 to 11400 Chestnut 10500 Elm 13000 to 13489 Hemlock 8700 Hickory 12800 to 18000 Locust 20500 to 24800 Maple 10500 to 10584 Oak— white 10253 to 19500 Pine— white 10000 to 12000 yellow 12600 to 19200 Spruce 10000 to 19500 Walnut, black... 9286 to 16000 .34.S Table 28-53. Lineal Expansion of Solids at Ordinary Temperatures (Tabular values represent increase per foot per 100-deg. increase in temperature, fahr. or cent.) Substance Temperature conditions* deg. fahr. Coefficient per 100 deg. fahr. Coefficient per 100 deg. cent. Brass (cast) Brass (wire) Copper Glass (English flint) . Glass (French flint) . Gold. Granite (average) . . . Iron (cast) Iron (soft forged) . Iron (wire) Lead Mercury Platinum. '. Limestone Silver Steel (Bessemer rolled, hard) . Steel (Bessemer rolled, soft) . . Steel (cast, French) Steel (cast annealed, English) 32 to 212 32 to 212 32 to 212 32 to 212 32 to 212 32 to 212 32 to 212 104 to 212 32 to 212 32 to 212 32 to 212 104 32 to 212 104 to 212 to 212 104 104 001042 .001875 001072 .001930 000926 .001666 000451 .000812 000484 . 000872 000816 .001470 000482 . 000868 000589 .001061 000634 .001141 000800 . 001440 001505 .002709 0099841 .017971t 000499 . 000899 000139 . 000251 001067 .001921 00056 .00101 00063 .00117 000734 . 001322 000608 . 001095 * Where range of temperature is given, coeflicient is mean over range t CoefiGcient of cubical expansion Table 28-54. Deciir^al^^qiiivalents of Fractions of an Inch Fractions 3^ ■^ iV H ^ A , . 7 M 9 A 11 32 Decimals .015625 .03125 .046875 .0625 .078125 .09375 .109375 .125 .140625 .15625 .171875 .1875 .203125 .21875 .234375 .25 .265625 .28125 .296875 .3125 .328125 .34375 '■■ 'Fraiipons Decimals .359375 .375 .390625 .40625 .421875 .4375 .453125 .46875 .484375 .5 .515625 .53125 .546875 .5625 ..578125 .59375 .609375 .625 .640625 .65625 .671875 .6875 Fractions .703125 .71875 .734375 .75 .765625 .78125 .796875 .8125 .828125 .84375 .859375 .875 .890625 .90625 .921875 .9375 .953125 .96875 .984375 1.00 344 Table 28-55. Decimals of a Foot for Inches and Fractions of an Inch Inch 0" 1" 2" 3" 4" S" 6" 7" 8" 9" 10" 11" -. ^ .0833 .1667 .2500 .3333 .4167 .5000 .5833 .6667 .7.500 .8333 .9167 A .0026 .0859 .169S .2526 .3359 .4193 .5026 .5859 .6693 .7526 .8359 .9193 ^ .0052 .0885 .1719 .2552 .3385 .4219 .5052 .5885 .6719 .75.52 .8385 .9219 ^ .0078 .0911 .1745 .2578 .3411 .4245 .5078 .5911 .6745 .7578 .8111 .9245 Vs .0104 .0937 .1771 .2604 .3437 .4271 .5104 .5937 .6771 .7604 .8437 .9271 A -0130 .0964 .1797 .2630 .3464 .4297 .5130 .5964 .6797 .7630 .8464 .9297 ^ .0156 .0990 .1823 .2656 .3490 .4323 .5156 .5990 .6823 .7656 .8490 .9323 ^ .0182 .1016 .1849 .2682 .3516 .4349 .5182 .6016 .6849 .7682 .8516 .9349 M -0208 .1042 .1875 .2708 .3542 .4375 .5208 .6042 .6875 .7708 .8542 .9375 ^ .0234 .1068 .1901 .2734 .3568 .4401 .52,34 .6068 .6901 .7734 .8.568 .9401 A .0260 .1094 .1927 .2760 .3594 .4427 .5260 .6094 .6927 .7760 .8594 .9427 a .0286 .1120 .1953 .2786 .3620 .4453 .5286 .6120 .6953 .7786 .8620 .9453 % .0312 .1146 .1979 .2812 .3646 .4479 .5312 .6146 .6979 .7812 .8646 .9479 M .0339 .1172 .2005 .2839 .3672 .4505 .5339 .6172 .7005 .7839 .8672 .9505 1^ .0365 .1198 .2031 .2865 .3698 .4531 .5365 .6198 .7031 .7865 .8698 .9531 a .0391 .1224 .2057 .2891 .3724 .4557 .5391 .6224 .7057 .7891 .8724 .9557 }4 .0417 .1250 .2083 .2917 .3750 .4583 .5417 .6250 .7083 .7917 .8750 .9583 a .0443 .1276 .2109 .2943 .3776 .4609 .5443 .6276 .7109 .7943 .8776 .9609 ^ .0469 .1302 .2135 .2969 .3802 .4635 .5469 .6302 .7135 .7969 .8802 .9635 If .0495 .1328 .2161 .2995 .3828 .4661 .5495 .6328 .7161 .7995 .8828 .9661 ^ .0521 .1354 .2188 .3021 .3854 .4688 .5521 .6354 .7188 .8021 .88.54 .9688 a .0547 .1380 .2214 .3047 .3880 .4714 .5547 .6380 .7214 .8047 .8880 .9714 H .0573 .1406 .2240 .3073 .3906 .4740 .5573 .6406 .7240 .8073 .8906 .9740 U .0599 .1432 .2266 .3099 .3932 .4766 .5599 .6432 .7266 .8099 .8932 .9766 K .0625 .1458 .2292 .3125 .3958 .4792 .5625 .6458 .7292 .8125 .89.58 .9792 If .0651 .1484 .2318 .3151 .3984 .4818 .5651 .6484 .7318 .8151 .8984 .9818 M .0677 .1510 .2344 .3177 .4010 .4844 .5677 .6510 .7344 .8177 .9010 .9844 M .0703 1536 .2370 .3203 .4036 .4870 .5703 .6536 .7370 .8203 .9036 .9870 Ji .0729 .1562 .2396 .3229 .4062 .4896 .5729 .6562 .7396 '8229 .9062 .9896 .5755 .6.589 .7422 .8255 .9089 .9922 .5781 .6615 .7448 .8281 .9115 .9948 .5807 .6641 .7474 .8307 .9141 .9974 1.0000 Table 28-56. Decimals of a Foot Equivalent to Inches and Fractions of an Inch 0729 .1562 .2396 .3229 .4062 .4896 0755 . 1.589 .2422 . 3255 .4089 .4922 0781 .1615 .2448 .3281 .4115 .4948 0807 .1641 .2474 .3307 .4141 .4974 Inches 0" M" M" H" H" %" %" Vs" .01042 . 02083 .03125 .04166 .05208 . 06250 .07292 1 .0833 .0937 .1042 .1146 .1250 .1354 . 1459 .1563 2 .1667 .1771 .1875 .1979 .2083 .2188 .2292 .2396 3 .2500 .2604 .2708 .2813 .2917 .3021 .3125 .3229 4 .3333 .3437 .3542 .3646 .3750 3854 .3958 .4063 5 .4167 .4271 .4375 .4479 .4583 .4688 .4792 .4896 6 .5000 .5104 .5208 .5313 .5417 .5521 .5625 .5729 7 .5833 .5937 .6042 .6146 .6250 .6354 .6459 .6563 8 .6667 .6771 .6875 .6979 .7083 .7188 .7292 .7396 9 .7500 .7604 .7708 .7813 .7917 .8021 .8125 .8229 10 .8333 .8437 .8542 .8646 .8750 .8854 .8958 .9063 11 .9167 .9271 .9375 .9479 .9583 .9688 .9792 .9896 345 Table 28-57. Circumferences and Areas of Circles Advancing by Eighths Diam. Circum. Area Diam. Circum. Area Diam. Circum. Area Diam. Circum. Area A . 04909 . 00019 2.ii 8.44,30 5.6727 7. 21.991 .38,485 14. M 44.768 1,59.48 ■h .09818 .00077 ^4 8.6394 5.9396 Ys 22.384 39.871 Ys 45.160 162, 30 A .14726 .00173 M 8.8357 6.2126 M 22.776 41 . 282 Yi 45.553 165.13 T^ .19635 . 00307 y% 9.0321 6,4918 Ys 23.169 42,718 Ys 45.946 167.99 A .29452 . 00690 15 16 9.2284 6,7771 Yi 23., 562 44,179 Yi 46.3.38 170.87 Vs .39270 .01227 Ys 23.9,55 45,664 Ys 46.731 173.78 ^ .49087 .01917 3. 9.4248 7.0686 Yi 24.347 47.173 A . 58905 . 02761 1^ 9.6211 7.3662 Ys 24.740 48.707 15. 47.124 176.71 3^ . 68722 . 03758 J 8 9.8175 7.6699 Ys 47,517 179.67 3 16 10.014 7.9798 8. 25.1.33 50.265 Yi 47.909 182.65 H . 78540 .04909 M 10.210 8.29,58 Ys 25., 525 51.849 Ys 48.302 185.66 A .88357 .06213 h 10.407 8.6179 M 25.918 ,53.456 Yi 48.695 188.69 A .98175 .07670 % 10.603 8.9462 Ys 26.311 55.088 Ys 49.087 191,75 11 32 1.0799 .09281 ^ 10.799 9.2806 Yi 26.704 ,56.745 Yi 49.480 194,83 H 1.1781 .11045 Vi 10.996 9.6211 Ys 27.096 ,58.426 Yi 49.873 197.93 ¥ 1.2763 .12962 9 16 11.192 9.9678 Yi 27.489 60.132 1.3744 . 1,5033 Yi 11. 388 10.321 Ys 27.882 61 . 862 16. ,50.265 201 . 06 a 1.4726 . 17257 H 11, 585 10.680 Vs ,50.6,58 204.22 % 11.781 11.045 9, 28.274 63.617 Yi 51.051 207.. 39 ^2 1.5708 . 19635 M 11.977 11.416 Ys 28.667 65, 397 Ys 51 . 414 210.60 H 1.6690 .22166 Vi 12.174 11.793 Yi 29.060 67.201 Yi 51 . 836 213.82 A 1,7671 .24850 16 12.370 12 177 Ys 29.452 69.029 Ys 52.229 217.08 19 32 1.8653 . 27688 Yi 29.845 70.882 Yi 52.622 220.35 5^8 1.9635 . 30680 4. 12.. 566 12.566 Ys .30.2,38 72 . 760 Ys 53,014 223,65 21 37 2.0617 . 33824 T^ 12.763 12.962 Yi 30.631 74.662 11 2.1598 .37122 J'8 12.9.59 13.364 Ys 31 . 023 76.589 17, 53.407 226.98 M 2.2580 . 40574 _3_ 16 13.155 13.772 Ys ,53.800 230.33 M 13.3,52 14.186 10. 31.416 78.540 Yi 54.192 233.71 M 2.3562 .11179 A 13.548 14.607 Ys 31 . 809 80.516 % .54.. 585 237.10 ft 2.4544 . 47937 % 13.744 15.033 Yi ,32.201 82.516 Yi 54.978 240.53 2.5525 . 51849 ^ 13 941 15.466 Ys 32, 594 84.541 Ys 55.371 243.98 32 2.6507 ..5.5914 Y2 14.137 15.904 Yi .32.987 86, 590 Yi 55.763 247.45 Fs 2.7489 .60132 9 16 14.334 16. 349 Ys .33.379 88.664 Ys 56.156 250.95 29 32 2.8471 .64504 Y% 14., 530 16.800 Yi 33.772 90.763 tf 2.9452 . 69029 H 14.726 17.257 Ys 34.165 92.886 18. 56., 549 254.47 fi 3.0434 . 73708 Y^ 14.923 17.721 Ys ,56.941 258.02 if 15.119 18.190 11. 34.. 558 95.0.33 Yi 57.3,34 261, 59 1. 3.1416 .7854 y% 15.315 18.665 Ys .34.9.50 97.205 % ,57.727 265.18 16 3.3379 .8866 13 16 15.512 19.147 Yi 35.343 99.402 Yi 58.119 268.80 Ks 3.5343 .9940 % 35.736 101 . 62 Ys .58.512 272.45 A 3.7306 1.1075 5. 15.708 19.635 Yi 36.128 103.87 Yi ,58.905 276.12 J€ 3.9270 1.2272 1^ 15.904 20.129 Ys 36, 521 106.11 Ys ,59.298 279.81 A 4.1233 1 . 3530 Yi 16.101 20.629 Yi 36.914 108.43 ?^ 4.3197 1 . 4849 3 T6 16.297 21.1.35 Ys 37.306 110.75 19. 59.690 283.53 A 4. 5160 1 . 6230 M 16.493 21 648 Ys 60.083 287.27 y2 4.7124 1.7671 A 16.690 22.166 12. 37.699 113.10 Yi 60.476 291.04 ^ 4.9087 1.9175 Yi 16.886 22.691 Ys 38.092 115.47 Ys 60.868 294.83 Yi 5.1051 2.0739 A 17.082 23.221 Yi 38.485 117.86 Yi 61.261 298.65 H 5.3014 2.2,365 M 17.279 23.7,58 Ys 38.877 120.28 Ys 61 . 654 302.49 M 5.4978 2.40,53 9 17.475 21.301 Yi 39.270 122.72 Yi 62.046 306.35 it 5.6941 2, 5802 Yi 17.671 21 8,50 Ys .39.663 125^19 Ys 62.439 310.24 K 5.8905 2.7612 11 16 17.868 25 . 406 Yi 40.0.55 127.68 if 6.0868 2.9483 Y^ 18.064 25.967 Ys 40.448 130.19 20. 62.832 314.16 13. 16 18.261 26, 535 Ys 63.225 318.10 9 6.2832 3.1416 y% 18.4.57 27.109 13. 40.841 132.73 Yi 63.617 322.06 "'a 6.4795 3.3410 M 18.653 27.688 Ys 41 . 233 135.30 ?-8 64.010 326.05 y% 6.6759 3, 5466 Yi 41 . 626 137.89 Yi 64.403 330.06 A 6.8722 3.7583 6. 18.850 28.274 % 42.019 140.50 Ys 64.795 334.10 M 7.0686 3.9761 J-8 19.242 29.465 Yi 42.412 143.14 Yi 65.188 338.16 A 7.2649 4.2000 Y4. 19.635 30.680 Ys 42.804 145.80 Ys 65.581 342.25 ?^ 7.4613 4.4301 % 20.028 31.919 Yi 43 197 148.49 A 7.6576 4.6664 Yi 20.420 33.183 Ys 43.590 151.20 21. 65.973 346.36 j^ 7.8540 4.9087 Ys 20.813 34.472 Yk 66.366 3,50.50 T^ 8.0503 5.1572 H 21 . 206 35.785 14. 43.982 1,53.94 Yi 66.7,59 354.66 ^ 8.2467 5.4119 Ys 21.. 598 37.122 Ys 44.375 1,56.70 Ys 67.152 358.84 346 Table 28-57. Circumferences and Areas of Circles Advancing by Eighths — Continued Diam. Circum. Area Diam. Circum. Area Diam. Circum. Area Diam. Circum. Area 21. Ji 67.544 363.05 28.^4' 90.321 649.18 .36. 113.097 1017.9 13. J^ 135.874 1469.1 'A 67.937 367.28 Vs 90.713 654.84 }8 113.490 1025.0 Vs 136.267 1477.6 H 68.330 371, 54 Vi 113.883 1032.1 V2 136.659 1486.2 Vs 68.722 375.83 29. 91.106 660.52 8 8 114.275 1039.2 Vs 137.052 1494.7 J-8 91.499 666.23 Vi 114.668 1046.3 Vi 137.445 1503.3 69.115 380.13 % 91.892 671.96 ?8 115.061 10.53.5 Vs 137.837 1511.9 'Vs 69.508 .384.46 Js 92.284 677.71 % 115.454 1060.7 M 69.900 388.82 Vi 92.677 683.49 Vs 115.846 1068.0 44. 138.230 1.520.5 Vs 70.293 .393.20 Vs 93.070 689.30 Vs 138.623 1.529.2 K 70.686 397.61 H 93. 162 695.13 37. 116.239 1075.2 Vi 139.015 1537.9 H 71.079 402.04 Is 93.855 700.98 ^8 116.632 1082.5 Vs 139.408 1.546.6 H 71.471 406.49 Vi 117.024 1089.8 Vi 139.801 1.555.3 H 71.864 410.97 ,30. 94.248 706.86 H 117.417 1097.1 Vs 140.194 1.564.0 Vs 94.640 712.76 Vt 117.810 1104.5 Vi 140, 586 1.572.8 23. 72.257 415.48 Va 95.033 718.69 Vs 118.202 1111.8 Vs 140.979 1581.6 Vs 72.649 420.00 Vs 95.426 724.64 H 118. 596 1119,2 H 73.042 424.56 Vi 95.819 730.62 Vs 118.988 1126.7 15. 141.372 1590.4 y% 73.435 129.13 Vs 96.211 736.62 Vs 141.764 1599.3 Yi 73.827 133.74 H 96.604 742.64 38. 119.381 1134.1 Vi 142.1.57 1608.2 y% 74.220 138.36 Vs 96.997 748.69 Vs 119.773 1141.2 Vs 142.550 1617.0 M 74.613 443.01 Vi 120.166 1149.2 V2 142.942 1626.0 Vi 75.006 447.69 31. 97.389 7,54.77 ?8 120.. 5.59 11,56.6 Vs 143.335 1634.9 Vs 97.782 760.87 Vi 120.951 1164.2 % 143.728 1643.9 24. 75.398 452.39 H 98.175 766.99 Vs 121 . 344 1171.7 Vs 144.121 1652.9 Vi 75.791 457.11 Vs 98.. 567 773.14 Vi 121.737 1179.3 M 76.184 161.86 Vi 98.960 779.31 Vs 122.129 1186.9 16. 144.513 1661 . 9 y% 76.576 466.64 Vs 99.353 785.51 Vs 144.906 1670.9 Vi 76.969 171.44 V 99.746 791.73 .39. 122. 522 1191.6 Vi 145.299 1680.0 Vs 77.362 476.26 Vs 100.1.38 797.98 Is 122 '915 1202.3 Vs 145.691 1689.1 H 77.754 481.11 - Vi 123.308 1210.0 V2 146.084 1698.2 - Vs 78.147 485.98 32. 100., 531 804.25 H 123.700 1217.7 Vs 146.477 1707.4 Ys 100.924 810.54 V2 124.093 1225.4 Vi 146.869 1716.5 25. 78.. 540 190 87 H 101.316 816.86 Vs 124.486 1233.2 Vs 147.262 1725.7 Vs 78.933 495.79 % 101.709 823.21 Vi 124.878 1241.0 Vi 79.325 ,500.74 Vi 102.102 829. 58 Vs 125.271 1248.8 17. 147.6.55 1734.9 Vs 79.718 .505.71 Vs 102.494 835.97 Vs 148.048 1744.2 Vi 80.111 510.71 Vi 102.887 812.39 10. 125.664 12.56.6 Vi 148.440 1753.5 Vs 80. 503 515.72 Vs 103.280 848.83 ?8 126.056 1264.5 Vs 148.833 1762.7 H 80.896 .520.77 Vi 126.449 1272.4 V2 149.226 1772.1 Vs 81 . 289 .525.84 33. 103.673 8.55.30 ?8 126.842 1280.3 Vs 149.618 1781.4 Vs 104.065 861.79 Vi 127.235 1288.2 Vi 1.50.011 1790.8 26. 81.681 .530.93 Vi 104.4.58 868.31 Vs 127.627 1296.2 Vs 150.404 1800.1 Vs 82.074 .536.05 ?8 104.851 874.85 Vi 128.020 1301.2 Va 82.467 541 . 19 Vi 105.243 881.41 • Vs 128.413 1312.2 18. 150,796 1809.6 Vs 82.860 .546.35 Vs 105.636 888.00 Vs 151.189 1819.0 Vi 83.252 551 . 55 Vi 106.029 894.62 11. 128.805 1320.3 Vi 151.. 582 1828.5 Vs 83.645 .5.56.76 H 106.421 901.26 Vs 129.198 1328.3 Vs 151.975 1837.9 Vi 84.038 .562.00 Vi 129.591 1336.4 V2 152.367 1847.5 Vs 84.430 567.27 34. 106.814 907.92 ?8 129.983 1344.5 Vs 152.760 1857.0 J-8 107.207 914.61 Vi 130.376 13.52.7 Vi 153.153 1866.5 27. 84.823 .572.56 Vi 107.600 921.32 5-8 130.769 1360.8 Vs 153.545 1876.1 Vs 85.216 577.87 H 107.992 928.06 Vi 131.161 1369.0 Vi 85.608 .583.21 Vi 108.385 931.82 Vs 131 . 5.54 1377.2 19. 153.938 1885.7 Vs 86.001 .588.57 Vs 108.778 9U.61 Vs 154.331 1895.4 Vi 86.394 .593.96 H 109.170 918.42 12. 131.917 1385.4 Vi 154.723 1905.0 Vs 86.786 .599.37 H 109., 563 9,55.25 y% 132.340 1393.7 Vs 155.116 1914.7 M 87.179 601.81 Vi 132 732 1402.0 V2 155, 509 1924.4 Vs 87.572 610,27 35. 109.956 962.11 H 133.125 1410.3 Vs 155.902 1934.2 Vs 110.348 969.00 Vi 133.518 1118.6 Vi 156.294 1943.9 28. 87.965 615.75 Vi 110.741 975.91 Vs 133.910 1427.0 Vs 156.687 1953.7 Vs 88.357 621.26 58 111.134 982.84 % 134.303 1135.4 Vi 88.750 626.80 Vi 1 11. 527 989.80 Vs 134.696 1443.8 .50. 157.080 1963.5 Vs 89.143 632.36 Vs 111.919 996.78 Vi 89.. 535 6.37.94 Vi 112.312 1000.38 13. 135.088 14.52.2 Vs 89.928 643. 55 Vs 112.705 1010.8 Vs 135.481 1460.7 347 Table 28-58. Fractional Equivalents, Powers and Roots of Numbers Num- ber Frac, equiv. Square root Cube root Square Cube 1 X Num- ber Frac. equiv. Square root Cube root Square Cube d H O > > .01 .0156 .02 .03 ^ .1 .125 .1414 .1732 .2154 .25 .2714 .3107 .0001 . 0002441 .0004 .0009 .000001 . 000003815 . 000008 . 000027 .802 1.003 1.134 1.389 .3281 .33 34 3438 21 64 11 32 .5728 .5745 .5831 .5863 .6897 .6910 .6980 .7005 .1077 .1089 .1156 .1182 . 03533 . 03594 .03930 . 04062 4,594 4.607 4.677 4.702 .0313 .04 .0469 .05 A ^ .1768 .2 .2165 .2236 .3150 .3420 . 3606 . 3684 . 0009766 .0016 .002197 .0025 . 00003052 . 000064 .000103 .000125 1.418 1.604 1 . 756 1.793 .35 3594 .36 .37 a .5916 .5995 .6 .6083 . 7017 .7110 .7114 .7179 .1225 1292 '.vm .1369 , 04288 , 04:641 .04666 . 05065 4.745 4.808 4.812 4.879 .06 .0625 .07 .0781 1^ 5 64 .2449 .25 .2646 .2795 .3915 .3968 .4121 .4275 .0036 . 003906 . 0049 .006104 . 000216 . 0002441 . 000343 . 0004768 1.965 2.005 2 122 2.242 .375 .38 .39 .3906 25 64 .6124 . 6164 .6245 .625 .7211 . 7243 .7306 .7310 . 1406 . 1444 .1521 .1526 . 05273 . 05487 . 05932 .05960 4.911 4.944 5,009 5.013 .08 .09 .0938 .1 'i- .2828 .3 .3062 .3162 .4309 .4481 .4543 .4642 . 0064 .0081 . 008789 .01 . 000512 . 000729 . 0008240 .001 2.269 2.406 2.456 2.537 .4 . 4063 .41 .42 'a .6325 .6374 . 6403 .6481 .7368 . 7406 . 7429 .7489 ,16 .1650 ,1681 ,1764 .64 . 06705 , 06892 , 07409 5.072 5.112 5.135 5.198 .1094 .11 .12 .125 7 64 Vs .3307 .3317 . 3464 .3536 .4782 .4791 .4932 .5 .01196 .0121 .0144 .01562 . 001308 .001331 . 001728 . 001953 2.653 2.660 2.778 2.836 .4219 .43 . 4375 . 44 27 64 7 16 .6495 .6557 .6614 .6633 .75 .7548 .7591 .7606 .1780 . 1849 .1914 .1936 . 07508 .07951 . 08374 .08518 5.209 5,259 5,305 5,320 .13 .14 . 1406 .15 ^ .3606 .3742 .375 .3873 .5066 .5193 .5200 .5313 .0169 .0196 .01978 .0225 . 002197 . 002744 . 002781 .003375 2.892 3.001 3.008 3.106 .45 . 4531 .46 . 4688 29 64 lA 32 .6708 .6732 .6782 .6847 .7663 ,7681 .7719 .7768 .2025 .2053 ,2116 .2197 ,09113 . 09304 . 09734 .1030 5.380 5.399 5.440 5,491 .1563 .16 .17 .1719 _5_ 32 .3953 .4 .4123 .4146 .5386 . 5429 . 5540 .5560 . 02441 . 0256 .0289 . 02954 .003815 . 004096 .004913 . 005077 3.170 3.208 3 307 3.325 .-47 48 . 481 1 .49 31 6T .6856 .6928 .6960 .7 ,7775 .7830 .7853 ,7884 .2209 . 2304 ,2346 .2401 ,1038 .1106 ,1136 .1176 5,498 5,557 5,582 5,614 .18 .1875 .19 .20 A .4243 .433 .4359 .4472 .5646 . 5724 . 5749 .5848 . 0324 .03516 .0361 .04 . 005832 . 006592 . 006859 .008 3.403 3.473 3.496 3.587 .5 51 .5156 .52 V2 .7071 .7141 .7181 .7211 .7937 .7990 ,8019 ,8042 ,25 ,2601 ,2658 ,2704 .125 ,1327 ,1371 .1406 5,671 5,728 5,759 5.784 .2031 .21 .2188 '■'2 7 32 .4507 . 4583 .4677 .4690 .5878 .5944 .6025 .6037 .04126 .0441 . 04785 .0484 . 008381 . 009261 .01047 . 01065 3.615 3.675 3.751 3.762 .53 .5313 ..54 . 5469 1 7 32 .35 64 .7280 .7289 . 7349 .7395 ,8093 ,8099 ,8143 ,8178 .2809 .2822 '2916 .2991 .1489 ,1499 . 1.575 ,1636 5.839 5.846 5,894 5.931 .23 .2344 .24 .25 M k .4796 .4841 .4899 .5 .6127 .6165 .6215 .6300 .0529 . 05493 .0576 .0625 .01217 .01287 .01382 .01563 3.846 3.883 3.929 4.010 .55 .56 .5625 .57 9 re .7416 .7483 .75 ; .7550 ,8193 1,8243 ,8255 ,8291 . 3025 .3136 .3164 .3249 .1664 .1756 ,1780 .1852 5.948 6.002 6.015 6.055 .26 .2656 .27 .28 H .5099 .5154 .5196 .5292 .6383 .6428 . 6463 . 6542 .0676 , 07056 .0729 ,0784 .01758 . 01874 . 01968 .02195 4.090 4.134 4.167 4.244 .5781 .58 .59 .5938 .7603 .7616 .7681 .7706 ,8330 ,8340 ,8387 , 8405 .3342 ,3364 , 3481 .3525 .1932 .1951 . 2054 .2093 6.098 6.108 6.161 6.180 .2813 .29 .2969 .30 .5303 .5385 .5448 .5477 .6552 .6619 .6671 . 6694 .07910 .0841 . 08814 .09 . 02225 . 02439 .02617 .027 4.253 4.319 4.370 4.393 .6 . 6094 .61 .62 a .7746 .7806 .7810 .7874 ,8434 ,8478 ,8481 ,8527 .36 .3713 .3721 ,3844 .2160 .2263 ,2270 .2383 6,212 6.261 6.264 6.315 .31 .3125 .32 5 16 .5568 .5590 .5657 .6768 .6786 .6840 .0961 . 09766 .1024 . 02979 . 03052 . 03277 4.466 4.483 4.537 .625 .63 .64 % .7906 .7937 .8 , 8550 ,8573 .8618 .3906 ,3969 .4096 ,2441 ,2500 ,2621 6.341 6.366 6.416 348 Table 28-58. Fractional Equivalents, Powers and Roots of Numbers — Continued Num- ber .6406 .65 Frac. equiv, 6.563 ki 66 67 6719 43 64 68 6875 a 69 70 7031 n 71 7188 23 72 73 7344 U 74 75 % 76 7656 ¥i 77 78 7813 ^ 79 7969 M 8 81 8125 M 82 8281 S3 64" 83 84 8438 fJ 85 8594 S 86 87 875 '^ 88 89 8906 f^ 9 9063 29 3T 91 92 9219 AS 61 93 9375 ^ 94 95 9531 a Square root Cube root . 8004 .8062 .8101 . 8124 .8185 .8197 . 8246 .8292 .8307 .8367 .8395 . 8426 . 8478 .8485 . 8544 .8570 .8602 .8660 .8718 .875 .8775 .8832 .8839 .8888 .8927 . 8944 .9 .9014 .9055 .9100 .9110 .9165 .9186 .9219 .9270 .9274 .9327 .9354 .9381 . 9434 .9437 .9487 .9520 .9539 . 9592 .9601 .9644 .9682 .9695 .9747 .9763 .8621 .8662 .8690 .8707 . 8750 . 87.59 . 8794 .8826 .8837 .8879 .8892 .8921 . 8958 .8963 . 9004 .9022 .9045 .9086 .9126 .9148 .9166 .920 .9210 . 9244 .9271 .9283 .9322 .9331 .9360 .9391 .9398 .9435 .9449 .9473 .9507 .9510 .9546 . 9565 .9583 .9619 .9621 .9655 .9677 .9691 .9726 .9732 .9761 .9787 .9796 .9831 .9840 Square .4104 . 4225 . 4307 . 4356 . 4489 .4514 .4624 .4727 .4761 .49 . 4944 .5041 .5166 .5184 . 5329 .5393 .5476 .5625 . 5776 . 5862 . 5929 . 6084 . 6104 .6241 .6350 .64 .6561 .6602 .6724 . 6858 .6889 .7056 .7120 .7225 .7385 .7396 .7569 .7656 .7744 .7921 .7932 .81 .8213 .8281 .8464 .8499 .8649 .8789 .8836 .9025 .9084 Cube .2629 .2746 .2826 .2875 . 3008 .3033 .3144 .3249 . 3285 .3430 . 3476 . 3579 .3713 .3732 .3890 .3961 . 4052 . 4219 . 4390 .4488 . 4565 . 4746 . 4768 . 4930 .5060 . 5120 . 5314 . 5364 .5514 .5679 .5718 .5927 .6007 .6141 .6347 .6361 . 6585 .6699 .6815 ,7050 .7065 .7290 .7443 .7536 .7787 . 7835 .8044 .8240 .8306 .8574 .8659 > 6.419 6.466 6.497 6.516 6.565 6.574 6.614 6.650 6.66 6.710 6.725 6.758 6.799 6.805 6.8.53 6.873 6.899 6.946 6.992 7.018 7.038 7 083 7.089 7.129 7.1.59 7.174 7.218 7.229 7.263 7.298 7.307 7.351 7.367 7.394 7.435 7.438 7.481 7.. 502 7.. 524 7.566 7.569 7.609 7.635 7.651 7.693 7.701 7.734 7.766 7.776 7.817 7.830 Number .96 .9688 .97 .98 . 9844 .99 1. 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.1 2 2 2^3 2.4 2.5 2.6 2.7 2.8 2.9 3. 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4. 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5. Frac. equiv Square root .9798 . 9843 . 9849 .9899 .992 .9950 1. 1 . 049 1 . 095 1.14 1.183 1.225 1 . 265 1 . 304 1 . 342 1.378 1 . 414 449 483 517 1 . 549 581 612 643 1.673 1.703 1.732 1.761 1.789 1.817 1.844 1.871 1.897 1.924 949 975 2. 2' 025 2.049 2.074 2.098 2.121 2.145 2.168 2.191 2.214 2.236 Cube root . 9865 . 9895 .9899 .9933 .9948 .996 1. 1.032 1 . 063 1.091 1.119 1 . 1145 1.170 193 216 239 1.260 281 301 320 1 339 1 . 357 1.375 1.392 1 . 409 1 . 426 1 . 442 1.458 1.474 489 504 518 1.533 1.547 1.560 1.574 1.587 1.601 1.613 1.626 639 651 663 675 687 698 710 Square .9216 . 9385 . 9409 . 9604 .9690 .9801 Cube 21 1 . 44 69 96 25 2.56 2.89 3.24 3.61 4. 4.41 4.84 5.29 5.76 6.25 6.76 7.29 7.84 8.41 9. 9.61 10.24 10.89 11.56 12.25 12.96 13.69 14.44 15.21 16. 16.81 17.64 18.49 19.36 20.25 21.16 22.09 23.04 24.01 25. . 8847 .9091 .9127 . 9412 .9538 .9703 1. 1.331 1.728 2.197 2.744 3.375 4.096 4.913 5.832 6.859 8. 9.261 10.65 12.17 13.82 15.63 17.58 19.68 21 . 95 24.39 27. 29. 79 32.77 35.94 39.30 42.88 46.66 50.65 54.87 59.32 64. 68.92 74.09 79.51 85.18 91.13 97.34 103.8 110.6 117.6 125. H O 7.8.58 7.894 7.899 7.940 7.957 7.980 8.021 8.412 8.786 9.145 9.490 9.823 10.14 10.45 10.76 11.06 11.34 11.62 11.90 12.16 12.43 12.68 12.93 13.18 13.42 13.66 13.89 14.12 14.35 14.57 14 79 15.01 15.22 15.43 15.64 15.85 16.04 16.24 16.44 16.63 16.82 17.01 17.20 17.39 17.57 17.75 17.93 349 Table 28-59. Comparison of Wire Gauges Thickness in decimals of an inch d 4) s £5 ■ils o S bUZi pa 1 i ad c la V ■ss E3 d ll ia g cd ffld If -5 1. 0000000 .490 .500 .5 23 . 02257 .025 . 0258 .024 .027 . 028125 000000 . 5800 .460 .464 .46875 24 . 02010 .022 . 0230 .022 .025 .025 00000 .5165 .430 . 432 . 4375 25 .01790 .020 . 0204 .020 .023 .021875 0000 . 4600 .454 .3938 .400 . 454 . 40625 26 . 01594 .018 .0181 .018 . 0205 . 01875 000 . 4096 .425 . 3625 .372 .425 .375 27 . 01420 .016 .0173 .0161 .0187 .0171875 00 . 3648 .380 .3310 .348 .380 . 34375 28 . 01264 .014 .0162 .0148 . 0165 .015625 . 3249 .340 .3065 .324 .340 .3125 29 .01126 .013 .0150 .0136 . 0155 . 0140625 1 .2893 .300 .2830 .300 .300 . 28125 30 .01003 .012 .0140 . 0124 . 01372 .0125 2 .2576 .284 .2625 .276 .284 . 265625 31 . 008928 .010 .0132 .0116 .0122 .0109375 3 .2291 .259 .2437 .252 .259 .25 32 . 007950 .009 .0128 .0108 .0112 .01015625 4 .2043 .238 . 2253 .232 .238 . 234375 33 . 007080 .008 .0118 .0100 .0102 . 009375 5 .1819 .220 .2070 212 .22 .21875 31 . 006305 007 .0104 .0092 0095 . 008.59375 6 .1620 .203 .1920 '192 ^203 .203125 35 .00.5615 .005 . 0095 .0081 0090 .0078125 7 . 1443 .180 .1770 176 .18 . 1875 36 . 005000 00 1 .0090 0076 . 0075 .00703125 8 . 1285 .165 .1620 .160 .165 . 171875 37 . 004453 . 0085 .0068 0065 . 006640625 9 . 1144 .148 . 1483 144 .148 . 15625 38 . 003965 .0080 .0060 .0057 . 00625 10 .1019 . 134 .1350 .128 .134 . 140625 39 . 003531 . 0075 . 0052 .0050 11 . 09074 .120 . 1205 .116 .12 .125 40 . 003145 .0070 .0018 .0015 12 . 08081 .109 . 10.55 .104 .109 . 109375 41 . 002800 . 001 1 13 .07196 .095 .0915 .092 .095 . 09375 42 . 002494 . 0040 14 .06408 .083 .0800 .080 .083 . 078125 43 .002221 .0036 15 . 05707 .072 .0720 ,072 .072 . 0703125 44 . 001978 .0032 16 0.5082 .065 0625 064 065 0625 45 001761 0028 17 . 04526 .058 .0540 .056 .058 . 05625 46 . 001.568 .0024 18 .04030 .049 .0475 .048 .049 .05 47 .001397 .0020 19 .03589 .042 .0410 .040 .040 . 04375 48 .001244 .0016 20 .03196 .035 . 0348 .036 .035 .0375 49 .001018 .0012 21 . 02846 .032 . 03175 .032 .0315 . 034375 50 . 0009863 .0010 22 . 02535 .028 .0286 .028 . 0295 . 03125 Table 28-60. Useful Factors Igal. (U. S.){l 1 gal (British) = 1 cu. ft. = 1 cu. ft. water at 60 deg. fahr. = 1 gal. water at 60 deg. fahr. = 1 cu. ft. water at 212 deg. fahr. = 1 gal. water at 212 deg. fahr. = 1 barrel water at 60 deg. fahr. 1 inch mercury< ] 1 lb. per sq. in. pressure Height of a column of water in feet X 0.434 A column of water 1 sq. in. and 2J^ ft. high 1 calorie 1 kilogram Calories per kilo X 1.8 1 kilowatt (1000 watts) 1 horsepower 3.97 B.t.u. = 2.2046 lb. = B.t.u. per lb. = 1.3405 hp. = 0.746 kw. lkilowatti=^6,9B.t'i.permin. \ = 3414 B.t.u. per hour 231 cu. in. 0.13368 cu. ft. 277.274 cu. in. 7.4805 gal. 62.37 lb. 8.34 lb. 59.76 lb. 7.99 lb. 31)^ gal. = 262.7 1b. 1}^ ft. or 13.6 in. water 0.491 lb. per sq. in. 2.304 ft. water at 60 deg. fahr. lb. pressure per sq. in. approximately 1 lb. f= 42.4 B.t.u. per min. = 2545 B.t.u. per hour = 33000 ft. lb. per min. 1 boiler horsepower = 33479 B.t.u. per hour 1 B.t.u. = 778 ft. lb. 1 ft. lb. per sec. = 1.356 watts 350 Table 28-61. Standard Causes of Sheet Metal U. S. standard Birmingham or Stubs No. of Thickness, inches Weight per sq. ft, in lb. Thickness, inches Weight per sq. ft. in lb. No. of gauge Fractions Decimals Iron steel Fractions Decimals Iron — ., „ Steel gauge 7-0 1-2 . 5 20.00 20.4 (Approx.) / 7-0 6-0 15-32 . 46875 18.75 19.125 6-0 5-0 7-16 . 4375 17.50 17.85 5-0 4-0 13-32 . 40625 16.25 16.575 29-64 .454 18.16 18.52 4-0 3-0 3-8 .375 15.00 15.30 27-61 . 425 17.00 17.31 3-0 2-0 11-32 . 34375 13.75 14.025 3-8 .38 15.20 15.50 2-0 5-16 .3125 12.50 12.75 11-32 .34 13.60 13.87 1 9-32 . 28125 11.25 11.475 19-64 .3 12.00 12.24 1 2 17-64 . 265625 10.625 10.8375 9-32 .281 1 1 36 11. 59 O 3 1-4 .25 10. 10.2 17-64 .259 10. 36 10.. 57 3 4 15-64 . 23 1375 9.375 9.5625 15-64 .238 9, 52 9.71 4 5 7-32 . 21875 8.75 8.925 7-32 .22 8.80 8.98 5 6 13-61 . 203125 8.125 8.2875 13-64 ^203 8.12 8.28 6 7 3-16 . 1875 7.5 7. 65 3-16 .18 7.20 7.31 7 8 11-64 .171875 6 875 7.0125 .165 6.60 6.73 « 9 5-32 .15625 6.25 6.375 5-32 . 148 5.92 6.04 9 10 9-61 .140625 5.625 5.7375 9-64 . 134 5.36 5.47 10 11 1-8 .125 5. 5.1 1-8 .12 J. 80 4.90 11 12 7-61 . 109375 4.375 4.4625 7-64 .109 1.36 4.45 12 13 3-32 . 09375 3.75 3.825 3-32 .095 3.80 3 88 13 14. 5-6 1 . 078125 3.125 3.1875 5-64 .083 3.32 3.39 11 15 9-128 . 0703125 2.8125 2.86875 .072 2 88 2.91 15 16 1-16 . 0625 2.5 2.55 1-16 .065 2.60 2.65 16 17 9-160 . 05625 2.25 2.295 .0.58 2.32 2 37 17 18 1-20 .05 2 2.04 3-61 .049 1 . 96 2.00 18 19 7-160 . 04375 1 . 75 1.785 . 042 1.68 1.71 19 20 3-80 . 0375 1.50 1 . 53 . 035 1 . to 1. 13 20 21 11-320 .031375 1.375 1 . 4025 1-32 .032 1.28 1.31 21 22 1-32 .03125 1.25 1 . 275 .028 1.12 1.14 22 23 9-320 . 028125 1 . 125 1 . 1 175 .025 1.00 1.02 23 24 1-40 025 1. 1.02 .022 .88 .90 24 25 7-320 . 021875 .875 .8925 .02 .80 .82 25 26 3-160 . 01875 .75 .765 .018 .72 .73 26 27 11-610 .0171875 . 6875 . 70125 1-64 .016 .64 .65 27 28 1-64 .015625 .625 . 6375 .014 .56 .57 28 29 9-640 .0110625 .5625 . 57375 .013 .52 ..53 29 30 1-80 . 0125 . 5 .51 .012 .48 .49 30 31 7-640 . 0109375 .J 375 . 44625 .01 .40 .41 31 32 13-1280 .01015625 . 10625 .414375 .009 .36 .37 32 33 3-320 . 009375 .375 . 3825 .008 .32 .33 33 34 11-1280 . 00859375 . 34375 . 350625 .007 .28 .29 34 35 5-640 . 0078125 . 3125 . 31875 .005 .20 .20 35 36 9-1280 .00703125 .28125 . 286875 .004 .16 .16 36 37 17-2560 . 00664062 . 265625 . 2709375 37 38 1-160 . 00625 .25 . 255 38 Table 28-62. Measures of Weight, Contents and Area Long Measure Square Measure Cubic Measure 12 inches = 1 foot. 144 square inches = 1 square foot. 1728 cubic inches = 1 cubic foot. 3 feet = 1 yard. 9 square feet = 1 square yard. 27 cubic feet = 1 cubic yard. 5 J4 yards = 1 rod. 30 J^ square yards = 1 square rod. 4 rods = 1 chain. 160 square rods = 1 acre. 10 chains = 1 furlong. 640 acres = 1 square mile. 8 furlongs = 1 mile. Liquid Measure 4 gills = 1 pint. 31 H gallons = 1 barrel. 2 pints = 1 quart. 2 barrels = 1 hogshead. 4 quarts = 1 gallon. .351 24.75 cubic feet = l perch. 128 cubic feet = 1 cord. Avoirdupois Weight 16 ounces = 1 pound. 100 pounds = 1 hundredweight. 20 cwt. = 1 ton. Table 28-63. Mensuration of Surfaces and Volumes Area of rectangle = length X breadth. Area of triangle = base X J^ perpendicular height. Diameter of circle = radius X 2. Circumference of circle = diameter X 3.1416. Area of circle = square of diameter X .7854. area of circle X number of degrees in arc. Area of sector of circle = 360 Area of surface of cylinder = circumference X length + area of two ends. To find the diameter of circle having given area: Divide the area by .7854, and extract the square root. To find the volume of a cylinder: Multiply the area of the section in square inches by the length in inches = the volume in cubic inches. Cubic inches -^ 1728 = volume in cubic feet. Surface of a sphere = square of diameter X 3.1416. Solidity of a sphere = cube of diameter X .5236. Side of an inscribed cube = radius of a sphere X 1.1547. Area of the base of a pyramid or cone, whether round square or triangular, multiplied by one-third of its height = the solidity. Diam. X .8862 = side of an equal square. Diam. X .7071 = side of an inscribed square. 5r = proportion of circumference to Radius X 6.2832 = circumference. diameter = 3.1415926. Circumference = 3.5446 X V area of circle. t2 = 9.8696044. Diameter = 1.1283 X Varea of circle. ^^ = 1-7724538. Length of arc = no. of degrees X .017453 radius. Log. t = 0.49715. Degrees in arc whose length equals radius = 57° 2958'. 1/^^ = 0.31831. Length of an arc of 1 deg. = radius X .017543. 1/360 = .002778. Length of an arc of 1 min. = radius X .0002909. 360/- = 114.59. Length of an arc of 1 sec. = radius X .0000048. Table 28-64. Electrical Units Volt — The unit of electrical motive force. Force required to send one ampere of current through one ohm of resistance. Ohm — Unit of resistance. The resistance offered to the passage of one ampere, when impelled by one volt. Ampere — Unit of current. The current which one volt can send through a resistance of one ohm. Coulomb — Unit of quantity. Quantity of current which, impelled by one volt, would pass through one ohm in one second. Farad — Unit of capacity. A conductor or condenser which will hold one coulomb under the pressure of one volt. Joule — Unit of work. The work done by one watt in one second. Watt — The unit of electrical energy, and is the product of ampere and volt. That is, one ampere of current flowing under a pressure of one volt gives one watt of energy. One electrical horsepower is equal to 746 watts. One kilowatt is equal to 1,000 watts. To find the watts consumed in a given electrical circuit, such as a pump motor, multiply the volts by the amperes. To find the volts, divide the watts by the amperes. To find the amperes, divide the watts by the volts. To find the electrical horsepower required by a motor, divide the watts of the motor by 746. To find the mechanical horsepower necessary to generate the required electrical horsepower, divide the latter by the efficiency of the generator. To find the amperes of a given circuit, of which the volts and ohms resistance are known, divide the volts by the ohms. To find the volts, when the amperes and ohms are known, multiply the amperes by the ohms. To find the resistance in ohms, when the volts and amperes are known, divide the volts by the amperes. 352 Table 28-71. Conversion of Fahrenheit and Centigrade Temperatures Formulae: fahr. = — cent. + 32 deg. cent. = ^ (fahr. ■ 32 deg.) FAHR. CENT. 10- "-10 20—- 30- 32- Freezing 40 ; 50- 60- 70- 80- 90 = 100= 10 20 30 FAHR CENT. - 40 110= - '^Z- - 120= 1 50 — — 130 = = 60 140= ISO 70 160 — 170 — 80 180 — — — - 190 - ~ 90 — - — 200 ~- FAHR. 210 : CENT. 212- Boiling_ 220 = 100 230 = 240 = "110 250 — 260 = 270 = 120 130 280 = 290 = 300 = 140 FAHR CENT. - 150 — - 310 = = - 160 320 = = ^^n 170 :^ — 340 — ^ 350— 180 360 — — 370 — ~190 — 380—. 390 — - -200 — ' . 400 — 353 General Index See also the following additional indexes: Tables, page 362; Webster Service Details, page 364; Webster Apparatus, page 366. Accumulator, water (see water accumulator) . . . Acid, tartaric, manufacture of 196 Air, capacity of various sizes of pipes, (table) ... 69 ducts, area of, for indirect radiators 54 ducts, method of sizing 68 ducts, sized by friction loss method 68-69 ducts, sized by velocity method 68 elimination, importance of, in dry kiln coils..... 181,186 heat required to raise temperature of, (tables) 72, 73 infiltration 31-33 infiltration, B. t.u. required for, (table) 33 infiltration, double-hung windows, (chart) .... 32 infiltration, example of 33 infiltration, experiment on 32 pressure loss in ducts, (chart) 70 properties of, (table) 331 quantities required for ventilation, (table) .... 67 recirculation of, in industrial plants 67 removal devices, modulation system 162 removal from coils in dry kilns 184 resistance of elbows, (table) 71 -separating tanks, description and dimensions of 264^266 -separating tanks, discharge of returns through,144 -separating tanks, plain, method of connecting returns from vacuum pump 144 -separating tanks, water-control, method of connection to vacuum pump and to feed- water heater 145 supply, cold, for schools 61 supply for class rooms 61 supply, proper 60 velocities for fan system, public buildings. ... 67 velocities for fan systems, various types of buildings, (table) 68 Altitude, effect upon boiling point of water, (table) 332 effect upon design of chimney 87 Anchor points, allowable distance between 283 Anthracite coal, heat values of, (tables) . . . 340, 341 Apartment buildings, considerations leading to selection of type of heating system for. . .97, 109 operating pressure 239 Architectural features, effect upon selection of type of heating system 103 Area, measures of, (table) 351 Areas of circles, (table) 346-347 Attachments for Sylpbon traps {see Trap attach- ments) Auditoriums, ventilation of 63 Automatic pump and receiver, connections for discharge from vacuum pump 149 Avoirdupois weights, (table) 351 Bain marie (see Kitchen equipment) Ball check valves (see Modulation vent valves) Banquet haU, ventilation of 64 Basement radiation, method of draining, modu- lation system 229, 232 Belt driven vacuum pumps 143 Bends, effect of, upon flow of steam through pipes, (table) 115 Bituminous coal, heat values of, (table) 339-340 Blanket warmers (see Hospital equipment) Blast heaters, connections for 225-227 Blower sections, connections for 225-227 Boiler feed pump and receiver, connections for discharge from vacuum pump 149 feed pump controlled by air-separating tank, connections for , 149 feeder, connections with double-control hydro- pneumatic tank and geared-type vacuum pump 147 feeder, description and dimensions of 274 rooms, size of 94, 108 tubes, dimensions of, (table) 317 Boilers, basis for rating 89 cast iron type 106 efficiency of 91 high-pressure, as used in connection with vacuum systems 107 method for cleaning 93 modulation system connections for thermo- static and for time clock control of damper regulator 231 modulation system connections for parallel operation 230 necessity for withstanding corrosion in 106 priming of 93, 105 proportions of 90 required firing periods for 93 return tubular, dimensions of, (table) 330 selection of proper type of 105-108 water space of 90 Boiling point of water at various altitudes, (table) 332 Botanical gardens (see Greenhouses) Brass tubes, diameters and lengths of, (table) . . . 315 British thermal unit, definition of 9 Building, size and type of, for determining choice of heating system 97 Calorific values of coal 340 Candy, manufacture of 196 Capacitv, air-carrying, of various sizes of pipes, (table) 69 definition of 233 Carpenter, Prof. R. C 112 Ceilings, heat transmission factors for 30 Centrigrade, conversion to fahrenheit scale .353 Central station heat 107 Check valves, special, for modulation systems, application details of 268, 269 Chemical plants, exhaust ventilation for 65-66 Chimney lining, dimensions of standard sizes of. . 75 Chimneys, effect of altitude upon design of 87 for house heating boilers 74 capacity of, (table) 76-77 limngs for, (table) 75 proportioning of 74 for power boilers 78 procedure for proportioning 79 Churches, considerations leading to selection of type of heating system for 100 ventilation of ; 63 Circles, circumferences and areas of, (table) . 346-347 Clearance, vacuum pumps 139 Cloth-drying machines, application of Webster apparatus to 190 354 General Index — Continued Cloth-drying machines, description of 190 Coal, anthracite, heat values of, (table) . . . .340-341 bituminous, heat values of, (table) 339-340 calorific value of, (table) 340 grate areas required for burning, (table) 92 rates of combustion of, (table) 92 Coals, classification of 339-340 Coffee m-ns (see Kitchen equipment) Coils, continuous header type, in dry kilns 182 design of, for lumber dry kilns 183 drainage of 220-221 pipe, Umit of length of 43 pipe, surface in square feet of, (table) 56-57 sectional header type in dry kilns 184 vertical header type in dry kilns 185 Cold air ducts, area of, for indirect radiation ... 54 Combination gauges 267 connections for 268 Combination systems, vacuimi and modulation. 100 Combustion rates for various coals, (table) 92 Computation sheets for example of factory heat reqmrements 40-41 Computation sheets for example of residence heat requirements 38-39 Computations, for direct and indirect radia- tion 55-58 for indirect radiation 53-54 Condensation, losses in steam piping 113 products of 12 saving due to return to boilers. 13 Condensed milk (see Condensories) Condensing engines, bleeding receiver of 175 Condensories, appUcation of Webster system to . . 196 Connections, details of, to indirect radiator 52 offset, (table) .319 Conserving system, description of 173 typical layout of 173 Conserving valves, description and dimensions of. 273 illustration of . . . ^ 174 Contents, measures of, (table) .351 of round tanks, (table) 335 Controllers, Hylo (see Hylo controllers) Cooking, steam appliances for (see Kitchen equipment) Copper tubes, diameters and lengths of, (table) . 315 Costs of direct cast iron radiation, relative .... 51-52 Critical velocities in radiator run-outs 132-134 Critical velocity, definition of 132 Cube roots of numbers, (table) 348-349 Cubic measure, (table) 351 Damper control for boilers 94 Damper regulators, description and dimensions of .271 method of control by thermostat and by time clock 231 use in connection with conserving valve 175 Dampers, air volume, at branch ducts 72 Data required for design of steam heating sys- tems 15 Decimal equivalents of fractions, (table). . .348-349 equivalents of inches, (table) 344-345 Densities of materials, (table) 342 DifferentieJ-type return trap, description of . . . .155 Differential pressures through traps and valves .238 Direct radiation, definition of 11 example of computation of 55, 58 heat emission, (table) 45 heat emission with varying room temperature. 47 heat emission with varying steam pressure. . . 46 relative costs of cast iron, (table) 51-52 with exhaust systems 66 Direct-indirect radiators, data for 55 Direct-indirect radiators, description of 55 Direct-indirect system of ventilation 60 Dirt, effect of, on size of return mains 13 Dirt strainers, description of 259 dimensions of 260 Disposal of condensation in vacuum systems . . . 171 Doors, heat transmission factors for 28 Double-control hydro-pneumatic tanks, descrip- tion and dimensions of 276-277 used in connection with geared-type vacuum pump and boiler feeder 147 Double-service vcdves 164 description and dimensions of 252-254 ratings of 237 typical installation detail of 253 Down-feed riser, definition of 12 draining through radiator 220, 253 Down-feed systems, modulation 163 vacuum 167-168 Draft, chimney, definition of 78 intensity of, (formula) 79 losses 80 losses in boiler, (formula) 84 losses in flues, (formula) 83 losses in furnace, (formula) 84 losses in stack, (formula) 81 required for various fuels, (chart) 85 Drag lifts 263 Dry kibas 179 causes of trouble in 181 design of pipe coils for 183 important features of design of 181 plans showing use of continous-header coil in. 182 plans showing use of sectional-header coil in . . 184 plans showing use of vertical-header coil in. . . 185 temperature with exhaust steam in 181 temperature with live steam in 183 use of exhaust steam in 181 Dry returns, methods of connections for modu- lation systems 228-229 modulation systems 162, 164 Drying, cloth 190 improper methods of lumber 179 paper 192 yarn 188 Ducts, air-carrying, capacity of various sizes of, _ (table) 69 air pressure loss in, (chart) 70 area of, for indirect radiation 54 comparison of friction in round and rectangular 71 hot-air, with hot blast system 66 method of sizing 68 resistance of air in elbows of, (table) 71 trunk line system, sized by friction loss method 68-69 trunk hne system, sized by velocity method . . 68 underground masonry, for schools 62 Economizer, vapor, and suction strainer, des- cription and dimensions of 261-262 Economy, feed-water heaters, (table) 301 Economy of returning condensation to boiler ... 13 Efficiency, increase in, for radiation with shield. 51 decrease in, with enclosed radiators 50 heating tests of return traps for 154 Elbows, friction of water in, (table) 336 resistance of air in, (table) 71 Electrical units, definitions of 352 Electric-driven vacuum pumps 137, 172 for vacuum systems using low-pressure boilers. 173 use of, in schools, churches, etc., for inter- mittent heating 100 35S General Index — Continued Ekiclosed radiator, with grilles 49 decreased efficiency of, (table) 50 Enclosure for radiators 48 Engine, horsepower of 329 Evaporation, boiler, measurement of 313 Expansion, joints, allowable distances between anchor points of 283 joints, description and dimensions of ... . 278-282 loops in risers 216 of solids, lineal, (table) 344 of wrought iron pipe, (table) 318 Ebqposure and protective conditions 15 Extra-heavy fittings, dimensions of, (table), 324^327 flanges, dimensions of, (table) 324 iron pipe, dimensions of, (table) 317 Factories, removal of fumes or dust in 65 Factors, basic, for heat transmission 25 Factory, examples of computation sheet of heat requirements for 40-41 plan showing heat requirements for 37 Fans, sizes and arrangement of 72 Feeder, boiler (see Boiler feeder) Feed-water heater, gravity return to 222 economy of, (chart) 301 steam-control type, typical connections to ... . 304 water-control type, typical connections to ... . 303 Webster, description of 302-313 dimensions. Class EB 310 dimensions. Class EBP 311 dimensions. Class EF 313 dimensions. Class EFP 312 Fire protection for exposed water hydrants 195 Fireplace 60 Fittings, cast iron, screwed, dimensions of, (table) 319 effect of, upon steam flow 115 extra-heavy flanged, dimensionsof, (table) . 324^327 extra-heavy flanged, rules for 324 lift (see Lift fittings) standard flanged, dimensions of, (table) . . 320-323 standard flanged, rules for 320 Flanges, extra-heavy, dimensions of, (table) .... 324 standard, dimensions of, (table) 320 Float-type return trap, description of 154 Floors, above cold space, heat transmission fac- tors for 29 laid on ground, heat transmission factors for . . 30 Flow of steam through pipes 110 Flow of water, through elbows, (table) 336 through pipes, (table) 337 Flues, chimney (see Chimney flues) Food products, manufacture of 204 Fractional equivalents of decimals, (table) . 348-349 Friction, air in ducts, (chart) 70 round and rectangular ducts, comparison of losses, (chart) 71 steam in pipes. Ill water in elbows, (table) 336 water in pipes, (table) 337 Fuel saving by preheating feed water 301 Fuels, draft required for different, (chart) 85 Fumes, remov^ of 65 Furnaces for steam boilers 90 Gallon of water, weight at various temperatures of, (table) 335 Gauges (see Combination gauges) combination (see Combination gauges) Hylo , 178 sheet metal, (table) 351 typical connections of 150 Gauges, wire, comparison of, (table) 350 Geared-type vacuum pump , . 146 connections with boiler feeder and double-con- trol hydro-pneumatic tank 147 with single-control hydro-pneumatic tank .... 146 Generator, hot-water (see Hot-water generator) Glass, roof, heat transmission factors for 29 Governor, vacuum pump (see Vacuum pump governor) typical connections for 151 Grade of pipe, effect upon critical velocity of . . . 133 Grate surfaces for various grades of coal, (table) . 92 Grates for steam boilers 90 Gravity, indirect radiation, definition of 11 drips, hydraulic head for 119 Grease traps, description of 257 dimensions of 258 method of connecting, for draining of oil sepa- rator 255 Greenhouses, application of Webster systems to. 205 GriUe enclosure for radiators 49 Heads of water corresponding to pressures, (table) 333 Heat absorbing capacity of materials 19 absorption by stored materials 10 content 9 emission of direct radiation, (table) 45 percentage of variation of, (chart) 44 with varying room temperatures, (chart) .... 47 with varying steam pressures, (chart) 46 head 21 location and character of source of 15 loss required for air infiltration, (table) 33 losses through monitors 24 required to raise temperature of air, (tables) 72, 73 requirements 10 computation sheet for factory 40-41 computation sheet for residence 38-39 example of factory 36 example of residence 35 for stored materials 35 method of calculating 34 plan of factory 37 where heating is not continuous 35 specific, definition of 9 stratification, iUustration of 23 transmission, basic factors for 25 transmission factors, ceilings 30 doors 28 floors above cold space 29 floors laid on ground 30 interior walls 25 roof construction 28 roof glass and skyUghts 29 walls, brick 26 walls, clapboard 25 waUs, concrete faced with brick 26 walls, concrete faced with stone 27 walls, corrugated iron 26 walls, hard stone or concrete 27 waUs, hollow tile 27 waUs, hollow tUe faced with brick 26 walls, sandstone or limestone 27 walls, stucco on studs 26 windows 28 windows above datum 28 wood partitions 28 transmission rates, fundamental conditions. . . 21 transmitted through steam pipes 116 units, definitions of 9 values of various kinds of coal, (table). . .339-341 356 General Index — Continued Heater-meter, Webster-Lea, description of. 313-314 Heaters, blast (see Blast heaters) feed-water (see also Feed-water heaters) feed-water, connections from water-control air-separating tank 145 method of calculating size of 72 Heating, initial 9 Heating efficiency, tests of return traps for 1.54 surface of pipe coils, (table) 56-57 surface, boiler 90 surface, character and location of 19 surface, method of computing and selecting. . . 42 systems, basic data required for the design of 15 systems, hot blast 66 Heavy-duty traps, connection for coils drained through one trap in lumber dry kilns 187 high-differential type, application to drainage of vacuum pan 201 high-differential type, description and dimen- sions of 249 method of running return pipe in lumber dry kits 187 sectional drawing of 225 Series 19T, description of 247 Series 19T, dimensions of 249 Series 19T, ratings of 239 use in lumber dry kilns 182, 186 High-differential heavy-duty traps (see Heavy- duty high differential traps) High-duty vent trap 163 application of 120 High-pressure Sylphon traps, application for hos- pital equipment 202 application for kitchen equipment 203 application to hydrants to prevent freezing ... 195 description and dimensions of 275 typical installation for railroad switches 194 Horsepower, boiler 89 of an engine 329 of return tubular boilers, (table) 330 Hospital equipment, application of Webster sys- tems to 202 Hospitals, considerations leading to choice of type of heating system for 107 Hot air ducts, area of, for indirect radiation. ... 54 Hot blast heating system for industrial plants . . 66 Hot water generator, connections for 222, 227, 229 Hot water pattern radiation, connections for ... 43 Hotels, considerations leading to selection of type of heating system for 106 Humidity 59 relative indoor 19 HydrauUc head for gravity drips 119 Hydro-pneumatic tanks, description and dimen- sions of 276-277 discharge to. . . 147 double-control, connections with geared-type vacuum pump and boiler feeder 147 selection of size of 138, 142 single-control, connections with geared-type vacuum pump , 146 Hylo controllers 178 controllers, dimensions of . . 272 gauges 178 systems, typical connections of special appa- ratus 177 traps 178 traps, dimensions of 272 vacuum systems, description of 176 Impurities, lack of, in distilled water 13 in condensation 12 Indirect radiation, connection for air supply of. 65 definition of 11 example of computation of 55-58 formulae for computing 54 method of computing 53-54 methods of heating by 53 with exhaust systems 66 Indirect radiator, details of connection to 52 Indirect stacks, connections for 225-227 Indirect system of gravity ventilation 60 Industrial plants, exhaust ventilation for 65 hot blast systems for 66 Infiltration, air 31 B.t.u. reqijired for, (table) 33 double-hung windows, (chart) 32 example of 33 Initial heating period 10 Initial velocity of steam flow, (table) 110 Inleakage of air to piping of vacuum system, effect of 122 Inside temperature requirements, (table) 18 Intermittent use of building, effect upon design of heating system 100 Iron pipe, dimensions of, (table) 316-317 J oints, expansion (see Expansion joints) Kettles, cooking (see Kitchen equipment) Kilns, lumber drying 179 causes of trouble in 181 construction of 180 design of pipe coils for 183 important features in design of 181 plans showing use of continuous header coils in. 182 plans showing use of sectional header coils in. 183 plans showing use of vertical header coils in. , 185 Kitchen, heating equipment for 106 heating equipment, application of Webster systems to 203 ventilating equipment for 64 Laboratory tests of return traps 153 Lift fittings, application for "step-up" Ufts 139 Series 20, description of 263 Series 20, dimensions of 264 typical application of 263 Lift pockets (see Lift fittings) Lifts, drag 263 method of design for "step-up" 139 Liquid measure, (table) 351 Location of building, effect upon selection of design of heating system 101 Lock-shield modulation valves 170 Long measure, (table) 351 Loss, friction, in round and rectangular ducts, (chart) 71 Lubricator, force-feed 170 sight-feed. 170 sight-feed, typical connections of .151 Lumber-drying, improper methods of .179 kihis 179 kilns, causes of trouble in 181 kilns, important features in design of 181 processes 179 tests 180 IVIachinery, heat-absorbing capacity of 19 Mains, dripping, in vacuum system 167 method of dripping 215 ratings for vacuum and modulation return 128-129 357 General Index — Continued Mains, ratings for vacuum cuid modulation supply 128-129 steam (see Risers) supply and return, definition of 12 Material, densities of, (table) 342-343 specific heats of, (table) 342 tensile strength of, (table) 343 weights of, (table) 341 Measures of pressure, comparison of, (table) 334 Mechanical indirect radiation, definition of 11 Mechanical laboratory, illustration of 152 Meeting rooms, ventilation of 64 Mensuration of surfaces and volumes 352 Meter-heater (see Heater-meter) MiUt condensories (see Condensories) Modulation system, advantages of 109 basement, radiators for 162 classes of structures for application of 96 descriptions of 161 down-feed 163 dry return 162, 164 elements of a 95 layout of typical 160 pressiu'e drop in 116 proportioning of return mains for 121 proportioning of steam mains for 121 removal of air in 162 return mains and risers in 162 sizes of supply and return pipes, (table) . .128-129 specification for typical 289 supply mains and risers in 162 taking steam from street, description of 164 up-feed 163 various types of 162 wet return 163-164 with boiler pressures up to 10-lb., description of 162 with boiler pressures up to 50-lb., description of 163 with pump and receiver 164 Modulation valves, lock-shield type 170 omission of 103 Type W, description of 250 dimensions of 252 ratings of 237 with chain attachment, description of 252 with chain attachment, installation details of 251 with extended stem 252 vacuum systems 169 Modulation vent traps 162 description and dimensions of 268-270 typical installation details of 268-269 Modulation vent valves, application details of 268-271 description and dimensions of 270-271 Monitors, heat losses through 24 Motor valves, attachments for 294 Muffler oil separator 257 Multiple-unit valves, attachments for 296 National Dry Kibi Co 187 Noise due to design of run-outs 134 No. 7 Traps, description and dimensions of 246 ratings of 238 Offiee buildings, considerations leading to selec- tion of type of heating system for 97 Offset connections, (table) 319 Oil separator, allowable velocity through 255 method of draining by means of grease trap . .255 receiver and muffler 257 Oil separator, Series 21, description of 254 dimensions of 256 ratings of 256 Open return-line systems 95 Operating pressure 239 Painting, effect of, upon radiation 49 Pans, vacuum (see Vacuum pans) Paper-drying machines, application of Webster apparatus to 191 Partitions, wood, heat transmission factors for. . 28 Performance of stationary steam plants, (table) . 334 Piers, steamship, fire protection for. 195 Pipe, air-carrying, capacity of various sizes of, (table) 69 coils, continuous header type for dry kilns. . . .182 limi t of length of 43 sectional header type for dry kilns 184 surface in square feet of, (table) 56-57 vertical header type for dry kilns 185 copper and brass (see Tubes) expansion of, (table) 318 extra and double-extra strong, dimensions of, (table) 317 friction of water in, (table) 337 standard wrought iron, dimensions of, (table) . 316 threads, standard, (table) 316 Pipes, grading of mains, risers, and run-outs. ... 20 sizes of supply and return for modulation and vacuum systems 128-129 surface factors for 317 Piping, steam, condensation losses in 113 system, down-feed 20 Piston speed in vacuum pumps 140 Plain air separating-tank, description of 264 dimensions of 266 method of connecting discharge from vacuum pump 144 selection of size 138, 142 Plans, necessity for 18 Pockets, lift (see Lift fittings) Power-driven reciprocating vacuum pumps 143 Power load 165 Powers of numbers, (table) 348-349 Pressure, and weight, comparisons of, (table) . . . 333 comparison of measures of, (table) 334 corresponding to water-head, (table) 333 differences 12 drop in modulation systems 116 in steam pipes 114 in vacuum systems through return trap. 120-121 to impart initial steam velocity 110 schedule of 238 drop through radiator trap in modulation sys- tems 117 through return main 117 through vent trap 117 through vent valve 116 in pipes, calculation of air. 69 loss in ducts, (chart) 70 operating 239 -reducing valve, connections for 216 connections to water accumulator 267 vacuum system 166 regulator (see Pressure-reducing valve) Priming of boilers 105 Properties of air, (table) 331 Properties of saturated steam, (table) 328-329 Public buildings, allowable air velocities for fan systems in 67 considerations leading to selection of type of heating system for 98 .358 General Index — Continued Public buildings, operating pressure in 239 Pump £ind receiver, conditions requiring use of.... 99 connections for discharge from vacuum pump to 119 disciiarge of returns from vacuum pump to. . . 148 use of in a modulation system 161 Pump governor, vacuum, description and dimen- sions of 260 Pump, vacuum, sizing, (table) 138 Radiation, cast iron wall, in factory 12, 44 direct, definition of 11 example of computation of 55, 58 heat emission, (table) 45 heat emission with varying room tempera- tiu-es, (chart) 47 heat emission with varying steam pressures . 46 direct and indirect, with e.xhaust systems .... 66 effect of painting on 49 hot water pattern, connections of 43 indirect, definition of 11 formula for computing 54 methods of computing 53-54 methods of heating by 53 hmit of length of wall 43 method of computing and selecting 42 percentage variation in heat emission, (chart) . 44 relative costs of cast iron direct, (table) . . . .51-52 square feet of, definition of 12 Radiators, connections on vacuum system 169 direct-indirect, data for 55 direct-indirect, description of 55 enclosed, decreased efficiency of, (table) . . , 50-51 enclosed with grilles 49 enclosures 48 indirect, details of connection to 52 run-outs, critical velocity in 132-134 transmission rate, variation of 11 traps {see also Return traps) traps, pressure drop through 117 with shield, increased efficiency of, (table) .... 51 valves {see Modulation valves) Railroad switches, method of prevention of freezing 194 Railroad terminals 194-195 Rating, definition of 233 Ratings, angle valves, (inlet) 237 double-service valves 237 heavy-duty traps 238-239 modulation valves 234-237 modulation vent traps 240 modulation vent valves 240 No. 7 traps 237-238 supply and return mains 128-129 supply valves 237 Sylphon traps 237-238 Type W modulation valves 237 Receiver and muffler oil separators 257 Receiving tanks, description and dimensions of 264-266 plain, method of connecting returns from vacuum pump to 144 selection of size of 138, 142 water-control, method of connection with vacuum pump and feed-water heater 145 Reciprocating vacuum pumps, power-driven. . . . 143 proportions of 138 Recirculation of air in industrial plants 67 Reducing valves {see Pressure-reducing valves) Re-evaporation 261 Re-evaporation, chart . ; 157 of discharge from return traps 156 Registers, area of, for indirect radiators 54 Regulators, damper {see Damper regulators) pressure (see Pressure-reducing valves) vacuum {see Vacuum pump governors) Relative humidity 59 Residences, boiler pressure for 239 considerations leading to selection of type of heating system for 97, 108 example of heat requirements for, computa- tion sheet 38-39 heat requirements for, plan showing 36 Resistance, of coils and air washers 72 of fittings to steam flow 113-115 of 90° elbows, (table) 71 of pipes to air flow, calculation of 69 Return mains, definition of 12 for modulation systems, proportions of . . . .121 for vacuum systems, proportions of 122 function of 12 ratings of, (table) 128-129 sizing of 141 piping, location of 20 modulation systems 162-164 tanks {see also Tanks) uses in vacuum system 171 traps, differential type, description of 155 float type, description of 154 method of running return pipe to 187 No. 7, description and dimensions of 246 No. 7, ratings of 237-238 objects of tests in laboratory 153 outboard type 156 pressure drop allowable through 117 requirements for perfect operation of 241 selection of size and type of 238 Sylphon, description of 242-245 Sylphon, dimensions of . . 245 Sylphon, ratings of 237-238 testing 153 tests for heating efficiency of 154 thermostatic type, description of 155 use of, for air removal 186 use of, in lumber dry kilns 182, 18 1-186 tubular boilers, dimensions of, (table) 330 Returns, dry, methods of connections for modu- lation systems 228-229 flashing of 122 intermittent 105 methods of cooling 122 Risers, down-feed, draining through radiator 220,253 drainage of 216-219, 224 dripping, vacuum system 167 method of providing for expansion of 216 modulation systems, methods of draining . 228-229 return, proportions of, for vacuum systems. . .122 up-feed and down-feed, definition of 12 used as heating surface 219 Roof construction, heat transmission factors for 28 Roof glass, heat transmission factors for. 29 Roots of numbers, (table) 348-349 Rotating vacuum pumps 137 Round tanks, contents of, (table) 335 Run-outs, above floor 219 critical velocity in 132-134 in floor 218 sizing of 135-136 under floor 219 vacuum svstems 170 359 General Index — Continued Salt, manufacture of 196 Saturated steam, properties of, (table) 328-329 School rooms, arrangement of diffusers and direct radiation for 62 Schools, considerations leading to selection of type of heating system for 98, 108 operating pressures for 239 ventilating system for 61 Selection of proper type of steam heating system, fundamental considerations leading to 97 Separating tanks (see Air-separating tanks) Separators, oil, allowable velocity through 255 method of draining 255 receiver and muffler type of 257 Series 21, description of 254 dimensions of 256 ratings of 256 Separators, steam. Series 21, description and di- mensions of 283-285 Service details (see separate index) Sheet metal gauges, (table) 351 Shield, radiator, increase in efficiency due to. . . . 51 Single-control hydro-pneumatic tanks, con- nections to geared-type vacuum pump 146 description and dimensions of 276-277 Sizing run-outs for various grades and quan- tities 135-136 Skin-friction 114 Skyhghts, heat transmission factors for 29 Slasher equipment, typical application of 189 Slashers, equipment for 188 Slope of pipe, effect of upon critical velocity. . . . 133 Specific heat, definition of 9 Specific heats of materials, (table) 342-343 Specifications, typical, for modulation system. . .289 for vacuum system 286 Spitzglass, J. M .112 Square feet of radiation, definition of 12 Square measure, (table) 351 Square roots of numbers, (table) 348-349 Stacks (see Chimneys) indirect, connections for 225-227 Standard fittings, dimensions of, (table) .... 320-323 Standard flanges, dimensions of, (table) 320 Standard iron pipe, dimensions of, (table) 316 Stand-pipes, air-separating 144 Stationary steam plants, performance of, (table) . 334 Steam, (tables) 328-329 -control tanks, control of boiler feed pump, connections 149 -control tanks, description of 265 dimensions of 266 -driven reciprocating vacuum pumps, propor- tions of 138 -driven vacuum pumps, typical connections to .' 150, 166 end, vacuum pump, proportioning of 143 exhaust, use of, in dry kilns 181 flow, effect of pipe fittings on 115 flow through standard pipes 112-115 heating systems, types of 95 mains, drainage of 215 mains, dripping, vacuum systems 167 plants, stationary, performance of, (table) 334 requirements for tempering air 61 saturated, properties of, (table) 328-329 separators, ratings of 285 separators. Series 21, description and dimen- sions of .283-285 supply, sources of, effect upon selection of type of heating system 103 supply, vacuum systems, source of 165 Steamship piers, fire protection for 195 Sterilizers (see also Hospital equipment) 107 Storage of returns 142 Store buildings, considerations leading to selec- tion of type of heating system for 97 Strainers, dirt, description of 259 dimensions of 260 suction, and vapor economizer, description and dimensions of 261-262 description of 258 dimensions of 259 selection of size of 138, 141 typical connections to 150 use of, on lumber dry kiln coils 186 Stratification, factors for 24 formula for temperature due to 25 illustration of 23 Street steam, supply 107 system, method of cooling returns 222 system, vacuum 173 Strength, tensile, of materials, (table) 343 Suction strainers 171 and vapor economizer, dimensions and de- scription of 261-262 description of 258 dimensions of 259 selection of size of 138, 141 ty piccd connections to 150 Sugar, manufacture of 196 Supply mains, and risers for modulation sys- tems 162 definition of 12 for modulation systems, proportions of 121 for vacuum systems, proportions of 122 ratings of, (table) 128-129 Supply pipes, location of 20 Supply risers (see also Risers) drainage by means of heavy-duty traps 223 Supply valves (see also Modulation valves) ratings of 237 selection of size and type of 239 Surface factors for pipes, (table) 317 Surfaces and volumes, mensuration of 352 Switches, railroad, method of prevention of freezing 194 Sylphon attachments (see Trap attachments) . Sylphon traps, description of 242-245 dimensions of 245 ratings of 237-238 Tanks, air-separating, description and dimen- sions of _ 264-266 air-separating, selection of size of 138, 141 hydro-pneumatic, description and dimensions of 276-277 selection of .size of 138, 142 single control, connections with geared-type vacuum pump 146 plain air-separating, method of connecting re- turns from 144 plain, selection of size of 138, 142 round, contents of, (table) 335 steam-control, connections to boiler feed pump and vacuum pump 149 selection of size of 138, 142 water-control, method of connection with vacuum pump and to feed-water heater. .145 selection of size of , 138, 142 Temperature, at ceiling, air mechanicaUy agitated 24 at ceiling, high rooms 23 average of high rooms 23 comfortable 59 360 General Index — Continued Temperature, daily maximum and minimum in New York 16-17 difference, factors for, (chart) 22 due to stratification, (formulae) 25 for various rooms, (table) 18 increase in high buildings 23 requirements, inside, (table) 18 Temperatures, lowest recorded, (chart) 14 Tensile strength of materials, (table) 343 Terminals, railroad 194-195 Tests of lumber drying 180 Tests of retinn traps 153 Theatre ventilation 63 Thermometer scales, conversion of 353 Thermostatic-type return trap, description of. . . 155 Thermostatic valve No. 4, trap attachments for. 294 Threads, pipe, standards, (table) 316 Topography 15 Transmission of heat through pipe 113 Transmission rate of radiators, variation of 11 Trap attachments 293 for motor valves 294 for multiple-unit valves 296 for thermo-valves 294 for various types of valves 297 for water-seal motors 294 for water-seal traps 295 Traps (see also Return traps) grease and oil, description and dimensions of 257-258 method of connecting for draining oil sepa- rator 255 Traps, heavy-duty, high differential 249 heavy-duty, beries 19T, description of 247 dimensions of 249 ratings of 239 high-pressure Sylphon (see High-pressure Sylphon traps) Hylo (see Hylo traps) modulation vent (see Modulation vent traps) proper location of thermostatic type on lumber dry kiln coils 186 proper type for lumber dry kilns 184 return, testing 153 water-seal, attachments for 295 Tubes, boiler, dimensions of, (table) 317 brass and copper, diameters and weights of, (table) 315 Tubular boilers, dimensions of, (table) 330 United States Weather Bureau, daily tempera- tures, 1916 to 1920 16-17 lowest temperatures recorded, (chart) 14 Units, heat, definitions of 9 Up-feed risers, definition of 12 Up-feed systems, modulation 163 vacuum 167-168 Vacuum governors, sizing of 138, 143 typical connections of 151 pans, application of apparatus 201 drainage of 196 pumps. . , 137, 170 belt-driven 143 discharging to automatic pump and receiver, connections for 149 electric-driven 137, 172 geared-type 143 governor 170 governor, description and dimensions of . . . .260 reciprocating, proportions of 138 rotating 137 Vacuum governor, sizing of, (table) 138 steam-driven, typical connections of.. .150, 166 steam-ends, proportioning of 143 water-and-air ends, proportioning of 140 regulators (see Vacuum pump governors) systems, advantages of 109 classes of structures for application of 96 degree of vacuum for 122 descriptions of 165 different types of 165 disposal of condensation in 171 down-feed 167-168 dripping mains and risers for 167 elements of 96 Hylo, description of 176 pressure drop through traps in 121 proportions of mains and risers for 122 pumps for 170 radiator connections for 169 radiator supply valves for 169 requirements of 12 run-outs for 170 sizes of supply and return mains, (table) 127-129 sources of steam supply for 165 typical layout of 166 typical problem of sizing pipe for 123 typical specification for 286 up-feed 167-168 using street steam 173 ventilation problems with 172 with boiler pressines from 15 to 50-lb 172 with low pressure boilers 173 with power boilers, description of 165 Valves (see also Modulation valves) conserving (see Conserving valves) effect of, upon flow of steam through pipes. . .115 modulation vent (see Modulation vent valves) radiator outlet, attachments for 297 Vapor economizer and suction strainer, descrip- tion and dimensions of 261 Velocity, air for fan systems in pubfic buildings. 67 air for fan systems in various types of buildings 68 allowable through oil separators 256 critical, in radiator run-outs 132-134 -head factors, (table) 348-349 initial, of steam flow, (table) 110 Vent traps, high-duty, appHcation of 120 location of 120 modulation (see Modulation vent traps) pressure drop through 117 valves, modulation (see Modulation vent valves) pressure drop through 117 Ventilation, apparatus, selection of 72 banquet halls and meeting rooms 64 churches 63 direct-indirect system 60 exhaust, for industrial plants 65 gravity indirect system 60 kitchens 64 methods 60 problems 59 problems in design of vacuum system. ...... .172 schools 61-62 theatres and auditoriums 63 Vento radiation, connections for draining .. 225-227 Volumes and surfaces, mensuration of 352 \Af Type modulation valves, description of 250 dimensions of 252 ratings of 237 WaU radiation, cast iron, in factory 42, 44 361 General Index — Continued Wall radiation, methods of applying 102, 104 illustration of application in factory 44 limit of length of 43 Walls, heat transmission factors for, brick 26 clapboard 25 concrete faced with brick or stone 26-27 corrugated iron 26 hard stone or concrete 27 hollow tile 27 hollow tile faced with brick 26 interior 25 sandstone or Umestone 27 stucco on studs 26 Warming-up period 10 Warp drying 190 Water accumulator, description and dimensions of 267 typical connections to conserving valve 173 typical connections to pressure-reducing valve 267 -and-air end, vacuum pump, proportioning of. 140 benefits of returning to boiler 13 -control tank, description of 264 dimensions of 266 method of connection to vacuum pump and feed-water heater 145 Water-control tank, selection of size of . . . . 138, 142 conversion factors of, (table) 338 cost at stated rates, (table) 338 -seal motors, attachments for 294 -seal traps, attachments for 295 weight and volume at various temperatures, (table) 332 Weather Bureau, United States, lowest tempera- tures recorded, (chart) 14 Webster apparatus (see separate index) systems of steam heating, descriptions of 161 Weight, cuid pressure, comparison of, (table) . . .333 measures of, (table) 351 of 1 gallon of water at various temperatures, (table) 335 Wet-returns, modulation systems 162, 164 Windows, double-hung, air infiltration through, (chart) 32 heat transmission factors for 28 heat transmission factors for, above datum. ... 28 Wire gauges, comparison of, (table) 350 Wood partitions, heat transmission factors for . . 28 Yarns, sizing and drying of 188 Y.M.C.A. buildings, considerations leading to selection of type of heating system for 106 Tables Air, heat required to raise temperature of.. . .72-73 infiltration, B.t.u. required for 33 pressure loss in ducts, chart of 70 properties of 331 quantities required for ventilation 67 resistance of elbows 71 velocities for fan systems in public buildings. . 67 velocities for fan systems in various types of buildings 68 Altitude, effect of, upon boiUng point of water. . 332 Anthracite coal, heat values of 340-341 Area, measures of 351 Areas of circles 346-347 Avoirdupois weight 351 Bends, effect upon steam flow through pipes. . .115 Bituminous coal, heat values of 339-340 Boiler tubes, dimensions of 317 Boilers, return tubular, dimensions of 330 Boiling point of water at various altitudes 332 Brass tubes, diameters and lengths of 315 Calorific values of coal 340 Ceihngs, heat transmission factors for 30 Centigrade, conversion to fahrenheit scale 353 Chimney lining, dimensions of standard sizes. . . 75 Circles, circuniferences and areas of 346-347 Coal, anthracite, heat values of 340-341 bituminous, heat values of 339-340 calorific value of 340 classification of 339-340 grate areas required for burning 92 rates of combustion of 92 Coils, pipe, surface in square feet 56-57 Combustion rates for various coals 92 Connections, offset 319 Contents, measures of 351 of round tanks 335 Copper tubes, diameters and lengths of 315 Cost of direct cast iron radiation, relative 52 Cube roots of numbers 318-349 Cubic measure 351 Decimal equivalents of fractions 348-349 of inches 344-345 Densities of materials 342 Differential pressures through traps and valves . 238 Direct radiation, heat emission 45 heat emission with varying steam pressures .... 46 relative costs of cast iron 52 Direct-indirect radiators, data for 55 Doors, heat transmission factors for 28 Ducts, air-carrying, capacity of various sizes of. 69 air pressure loss in, chart of 70 resistance of air in elbows of 71 Economy of feed-water heaters 301 Efficiency, increase in radiation with shield 51 decrease of, in enclosed radiators 50 Elbows, friction of water in 336 resi-stance of air fine 71 , Electrical units, definitions of 352 Engine, horse power of 329 Expansion, wrought iron pipe 318 solids, fineal 344 Extra-heavy fittings, dimensions of 324-327 flanges, dimensions of 324 iron pipe, dimensions of 317 Factors, basic, for heat transmission 25 Feed-water heaters, economy chart for 301 Fittings, effect of, upon steam flow 115 extra-heavy flanged, dimensions of ..... . 324^327 extra-heavy flanged, rules for 324 screwed cast iron, dimensions of 319 standard flanged, dimensions of 320-323 standard flanged, rules for 320 Flanges, extra-heavy, dimensions of 324 standard, dimensions of 320 Floors, above cold space, heat transmission factors for 29 laid on ground, heat transmission factors for. 30 362 Index of Tables — Continued Flow of water, through elbows 336 through pipes 337 Fractional equivalents of decimals 348-349 Friction, air in ducts, chart of 70 loss, comparison between round and rectan- gular ducts 71 water in elbows 336 water in pipes 337 Gallon of water, weight at various tempera- tures 335 Gauges, sheet metal 351 wire, comparison of 350 Glass, roof, heat transmission factors for 29 Grate surfaces for various grades of coal 92 Heads of water corresponding to pressures 333 Heat, emission of direct radiation with varying room temperatures 47 emission of direct radiation with varying steam pressures 46 emission of radiation, percentage variation .... 44 required to raise temperature of air 72-73 transmission, basic factors for 25 transmitted through steam pipes 114, 116 values of various kinds of coal 339-340 Horsepower, of an engine, 329 of return tubular boilers 330 Hydro-pneumatic tanks, selection of size . . .138, 142 I nfiltration, B.t.u. required for 33 chart for double-hung windows 32 Inside temperature requirements 18 Iron pipe, dimensions of 316-317 Liquid measure 351 Long measure 351 Loss, friction, in round and rectangular ducts. . . 71 IVIains, ratings for return 128-129 ratings for supply 128-129 Materials, densities of 342 specific heats of 342-343 tensile strength of 343 weights of 341 Measures of pressure, comparison of 334 Mensuration of surfaces and volumes 352 Offset connections 319 Partitions, wood, heat transmission factors for . 28 Performance of stationary steam plants 334 Pipe, air-carrying, capacity of various sizes of. . . 69 coils, surface in square feet 56-57 copper and brass {see Tubes) expansion of 318 extra and double-extra strong, dimensions. . . .317 friction of water in 337 sizes of supply and return 128-129 standard wrought iron, dimensions of 316 ■ surface factors for 317 threads, standard 316 Plain air-separating tanks, selection of size. 138, 142 Powers of numbers 348-349 Pressure, and weight, comparison of 333 comparison of measures of 334 corresponding to water heads 333 drop to impart initial steam velocity 110 drops, schedule of 238 loss in ducts, chart of 70 Properties of air 331 Properties of saturated steam 328-329 Public buildings, allowable air velocities in fan systems 67 Pumps, vacuum, sizing of 138 Radiation, direct, heat emission 45 direct, heat emission with varying room tem- peratures 47 direct, heat emission with varying steam pressures 46 percentage variation in heat emission 44 relative costs of cast iron direct 52 Radiators, direct-indirect, data for 55 enclosed, decreased efficiency of 50 with shield, increased efficiency of 51 Ratings of supply and return mains 128-129 Receiving taiiks, selection of size of 138, 142 Re-evaporation chart 157 Resistance, of 90° elbows 71 to steam flow of fittings 115 Return mains, modulation systems, proportions of 121 ratings of 128-129 Return tubular boilers, dimensions of 330 Roof glass, heat transmission factors for 29 Roots of numbers 348-349 Round tanks, contents of 335 Run-outs, sizing of 135-136 Saturated steam, properties of 328-329 Sheet metal gauges 351 Shields, radiator, increase in efficiency due to. . . 51 Sizing run-outs for various grades and quan- tities 135-136 Skylights, heat transmission factors for 29 Specific heats of materials 342-343 Square measure 351 Square roots of numbers 348-349 Standard fittings, dimensions of 320-323 Standard iron pipe, dimensions of 316 Stationary steam plants, economic performance of 334 Steam-driven reciprocating vacuum pump, pro- portions of 138 Steam, flow, effect of pipe fittings on 115 flow through standard pipes 114-115 plants, economic performance of 334 properties of 328-329 saturated, properties of 328-329 Strainer, suction, selection of size of 138, 141 Strength, tensile, of materials 343 Suction strainer, selection of size of 138, 141 Supply mains, for modulation systems, propor- tions of 121 ratings of 128-129 Surface factors for pipe 317 Surfaces emd volumes, mensuration of 352 Tanks, air-separating, selection of size of. .138, 141 hydro-pneumatic, selection of size of 138, 142 plain, selection of size of 138, 142 round, contents of 335 steam-control, selection of size of 138, 142 water-control, selection of size of 138, 142 Temperature difi'erence, chart of factors for .... 22 Temperature for various rooms 18 Temperature requirements, inside 18 Tensile strength of materials 343 Thermometer scales, conversion of 353 Threads, pipe, standard 316 Transmission of heat through pipe 114, 116 Tubes, boiler, dimensions of 317 363 Index of Tables — Continued Tubes, copper, brass, diameters and weights of. . 315 Tubular boilers, dimensions of 330 Vacuum governors, sizing of 138, 143 Vacuum pumps, reciprocating, proportions of. . .138 sizing of 138 Valves, effect of, upon flow of steam through pipes 115 Velocities of air for fan systems in public build- ings 67 Velocity-head factors 348-349 Volumes and surfaces, mensuration of 352 \A/alls, heat transmission factors for, brick 26 clapboard 25 concrete faced with brick 26 concrete faced with stone 72 Walls, corrugated iron 26 hard stone or concrete 27 hollow tile 27 hollow tile faced with brick 26 interior 25 sandstone or Umestone 27 stucco on studs 26 Water, conversion factors 338 cost at stated rates 338 weight and volume at various temperatures . . 332 Water-control tanks, selection of size of.. . .138, 142 Weight, and pressure, comparison of 333 measures of 351 of one gallon of water at various temperatures. 335 Windows, heat transmission factors for 28 Wire gauges, comparison of 350 Wood, partitions, heat transmission factors for. . 28 Webster Service Details Accumulator, water (see Water accumulator) Air-separating tank, plain, method of connecting returns from vacuum pump 144 water-control, method of connecting to vac- uum pump and to feed-water heater 145 Automatic pump and receiver, connections for discharge from vacuum pump 149 Bain marie (see Kitchen equipment) Ball check valves (see Modulation vent valves) Basement radiation, method of draining, modu- lation system 229, 232 Blanket warmers (see Hospital equipment) Blast heaters, connections for 225-227 Blower sections, connections for 225-227 Boiler-feed pump, and receiver, connections for discharge from vacuum pump 149 controlled by air-separating tank, connections for 149 Boiler feeder coimections with double-control hydro-pneumatic tank and geared-type vac- uum pump 147 Boilers, modulation system, connections for ther- mostatic and for time clock control of damper regulator 231 modulation system, method of connection for parallel operation 230 Cloth-drying machines, appUcation of Webster apparatus to 190 Coffee Urns (see Kitchen equipment) Coils, design of, for lumber kilns 183 drainage of 220-221 Combinatibn gauges, connections for 268 Condensed milk (see Condensories) Condensories, appUcation of Webster system to.. 196 Conserving system, typical layout of 173 Controllers, Hylo (see Hylo controllers) Cooking, steam appliances for (see Kitchen equipment) Damper regulators, methods of control by thermostat and by time clock 231 Double-control hydro-pneumatic tank, used in connection with geared-type vacuum pump and boiler feeder 147 Double-service valves, typical installation, de- tail... . _. 253 Down-feed risers, draining through radiator. 220, 253 Dry kilns, design of pipe coils for 183 plans showing use of continuous header coil for 182 plans showing use of sectional header coil for. .184 plans showing use of vertical header coil for . . 185 Dry returns, methods of connections for modu- lation systems 228-229 Expansion loops in risers 216 Feeder, boiler (see Boiler feeder) Feed-water heater, gravity return to 222 typical connections, steam-control type 304 typical connections, water-control type 303 Fire protection for exposed water hydrants 195 Fittings, lift (see Lift fittings) Gauges (see Combination gauges) cornbination (see Combination gauges) typical connections for 150 Geared-type vacuum pump, connections with boiler feeder and double-control hydro- pneumatic tank 147 connections with single-control hydro-pneu- matic tank 146 Generator, hot water (see Hot water generator) Governor, vacuum pump (see Vacuum pump governor) vacuum pump, typical connections of 151 Grease trap, method of connecting for draining of oil separator 255 Heater, blast (see Blast heater) feed-water (see also Feed-water heater) feed-water, connections from water-controlled air-separating tank 145 Heavy-duty trap, connections for coils drained through one trap in lumber kilns 187 sectional drawing of 225 High-differential heavy-duty trap, application to drainage of vacuum pans 201 High-pressure Sylphon trap, appUcation for hos- pital equipment 202 appUcation for kitchen equipment 203 appUcation to hydrants to prevent freezing. . .195 typical installation for railroad switches 194 Hospital equipment, appUcation of Webster system to 202 Hot water generator, connections for. . 222, 227, 229 364 Index of Webster Service Details — Continued Hydro-pneumatic tank, double-control, con- nections with geared-type vacuum pump and boiler feeder 147 single-control, connections with geared-type vacuum pump 146 Hylo systems, typical connections of special apparatus 177 Indirect radiation, connection for air supply. . . 65 Indirect radiator, details of connection to 52 Indirect stack, connections for 225-227 J oint, expansion (see Expansion joint) Kettle, cooking (see Kitchen equipment) Kilns, design of pipe coils for 183 plans showing use of continuous header coils. .182 plans showing use of sectional header coil. . . .184 plans showing use of vertical header coil for. . 185 Kitchen equipment, apphcation of Webster sys- tem to 203 Kitchen, ventilating equipment for 64 Lift fittings, application for "step-up" Ufts. ..139 Lift pockets (see Lift fittings) lifts, method of design for "step-up" 139 Lubricators, sight, typical connections of 151 Mains, method of dripping 215 steam (see Risers) Milk condensories (see Condensories) Modulation system, typical layout 160 system, valves with chain attachment, in- staEation details 251 vent traps, typical installation details 268-269 vent valves, application details 268-271 Oil separators, method of draining by means of grease trap 255 Pans, vacuum (see Vacuum pans) Paper-drying machine, application of Webster apparatus to 191 Pier, steamship, fire protection for 195 Pipe coils, drainage of 220-221 use of continuous header type in dry kilns.. . . 182 use of sectional header type in dry kilns 184 use of vertical header type in dry kilns 185 Plain air-separating tanks, method of connecting discharge from vacuum pump 144 Pockets, hft (see Lift fittings) Pressme-reducing valve, connections for 216 connections to water accumulator 267 Pressure regulators (see Pressure-reducing valve) Pump and receiver, connections for discharge from vacuum pump 149 Radiator traps (see Return traps) valves (see Modulation valves) Radiators, indirect, details of connection to ... . 52 Railroad switch, method of prevention of freez- ing 194 Receiving tanks, plain, method of connecting re- turns from vacuum pump 144 water-control, method of connection to vacuum pump and feed-water heater 145 Reducing valves (see Pressure-reducing valves) Regulators, damper (see Damper regulators) pressure (see Pressure-reducing valves) vacuum (see Vacuum pump governors) Returns, dry, methods of connections for modu- lation system 228-229 Returns tank (see Tanks) Risers, down-feed, draining through radiator 220, 253 drainage of 216-219, 224 method of providing for expansion of 216 modulation system, methods of draining . 228-229 used as heating surface 219 Run-outs, above floor 219 in floor 218 under floor 219 Separating tanks (see Air-separating tank) Separators, oil, method of draining 255 Single-control hydro-pneumatic tanks, connec- tions to geared-type vacuum pump 146 Slasher equipment, typical installation of 189 Stack, indirect, connections for 225-227 Steam-control tanks, control of boiler feed pump, connections 149 Steam-driven vacuum pumps, typical connec- tions of 150, 166 Steam mains, drainage of 215 Steamship piers, fire protection for 195 Sterilizers (see Hospital equipment) Suction strainers, typical connections of 150 Street system, method of cooling returns from. . 222 Supply risers (see also Risers) drainage by means of heavy-duty trap 223 Supply valves (see Modulation valves) Switches, railroad, method of prevention of freezing 194 Tanks, hydro-pneumatic single-control, connec- tions with geared-type vacuum pump 146 plain air-separating, method of connecting re- turns from 144 steam-control, connections showing boiler- feed pump and vacuum pump 149 water-control, method of connection with vac- uum pump and to feed-water heater 145 Traps (see also Return traps) grease and oil, method of connecting for drain- ing oU separator 255 high-pressure Sylphon (see High-pressure Syl- phon traps) Hylo (see Hylo traps) modulation vent (see Modulation vent traps) proper location of thermostatic, on lumber dry kiln coils 186 Vacuum governors, typical connections of 151 pans, appUcation of apparatus 201 pumps, discharging to automatic pump and receiver, connections of 149 pumps, steam-driven, typical connections of 150,166 regulators (see Vacuum pump governors) system, typical layout of 166 Valves (see also Modulation valves) conserving (see Conserving valves) modulation vent (see Modulation vent VcJves) Vent traps, modulation (see Modulation vent traps) valves, modulation (see Modulation vent valves) Ventilating equipment for kitchens 64 Vento radiation, connections for draining. .. 225-227 yN&icT accumulators, typical connections to con- serving valve 173 typical connections to pressure-reducing v£ilve.267 Water-control tanks, method of connection to vacuum pump and to feed- water heater 145 365 Webster Apparatus Accumulator, water {see Water accumulator) Air-separating tanks, description and dimensions of 264-266 Anchor points, allowable distance between 283 Attachments for Sylphon traps (see Trap attach- ments) Ball check valves (see Modulation vent valves) Boiler feeder, description and dimensions of ... . 274 Check valves, special, for modulation systems, application details of 268-269 Combination gauges 267 connections for 268 Conserving valves, description and dimensions of. .._. 273 illustration of 174 Controllers, Hylo {see Hylo controllers) Damper regulators, description and dimensions of... 271 Dirt strainers, description of 259 dimensions of 260 Double-control hydro-pneumatic tanks, descrip- tion and dimensions of 276-277 Double-service valves, description of 252-2.54 dimensions of 254 ratings of 237 typical installation detail of 253 Drag hfts 263 Economizer, vapor, and suction strainer, des- cription and dimensions of 261-262 Economy table, feed- water heaters 301 Evaporation, boiler, measurement of 313 Expansion joints, allowable distances between anchor points of 283 description and dimensions of 278-282 Feeder, boiler {see Boiler feeder) Feed-water heaters, description of 302-313 dimensions, Webster Class EB 310 dimensions, Webster Class EBP 311 dimensions, Webster Class EF 313 dimensions, Webster Class EFP 312 economy chart of 301 typical coimections, steana-control type 304 typical connections, water-control type 303 Fittings, Uft {see Lift fittings) Fuel saving by preheating feed water 301 Gauges {see also Combination gauges) combination {see Combination gauges) typical connections for 150 Governors, vacuum pump {see also Vacuum pump governors) typical connections for 151 Grease traps, description of 257 dimensions of 258 method of connection for draining oil sepa- rator 255 Heater-meter, Webster-Lea, description of .313-314 Heaters, feed-water {see Feed-water heaters) Heavy-duty traps, connection for coils drained through one trap in lumber dry kilns 187 high-differential type, description and dimen- sions of 249 method of running return pipe in lumber dry kilns 187 Heavy-duty traps. Series 19T, description of . . . .247 Series 19T, dimensions of 249 Series 19T, ratings of 239 use in lumber-drying kilns 182, 186 High-differential heavy-duty traps, description and dimensions of 249 High-pressure Sylphon traps, description and dimensions of 275 Hydro-pneumatic tanks, description and dimen- sions of 276-277 selection of .size of 138, 142 Hylo controllers, dimensions of 272 Hylo traps, dimensions of 272 Joints, expansion {see Expansion joints) Lift fittings. Series 20, description of 263 Series 20, dimensions of 264 typical applications of 263 Lift pockets {see Lift fittings) Lifts, drag 263 Ivleter-heaters (see Heater-meters) Modulation system, typical specification for ... . 289 valves. Type W, description of 250 Type W, dimensions of 252 Type W, ratings of 237 Type W, with chain attachment, description of 252 Type W, with extended stem 252 with chain attachment, installation details of 251 vent traps, description and dimensions of .268-270 typical installation details of 268-269 vent valves, application details of 268-271 description and dimensions of 270-271 Motor valves, attachments for 294 Muffler oil separators 257 Multiple-unit valves, attachments for 296 No. 7 traps, description of 246 dimensions of 246 ratings of 238 Oil separators, allowable velocity through 255 method of draining by means of grease trap 255 receiver and muffler 257 Series 21, description of 254 Series 21, dimensions of 256 Series 21, ratings of 256 Plain air-separating tanks, description of 264 dimensions of 266 selection of size 138, 142 Pockets, lift (see Lift fittings) Pressure-reducing valves, connections to water accumulator 267 Pressure regulators (see Pressure-reducing valves) Pump governors, vacuum, description and di- mensions of 260 Pumps, vacuum, table of sizing 138 Radiator traps (see Return traps) Radiator valves (see Modulation valves) Receiver and muffler oil separator 257 Receiving tanks, description and dimensions of 264-266 selection of size of 138, 142 Reducing valves, (see Pressinre-reducing valves) 366 Index of Webster Apparatus — Continued Regulators, damper {see Damper regulators) pressure {see Pressure-reducing valves) vacuum (see Vacuum pump governors) Return traps, method of running return pipe to . 187 No. 7, description and dimensions of 216 No. 7, ratings of 237-238 requirements for perfect operation of 241 Sylphon, description of 242-245 Sylphon, ratings of. 237-238 use for air removal in lumber drv kilns 186 use in lumber dry kilns '. . . . 182, 18 1-186 Return tanks {see Tanks) Separating tanks- {see Air-separating tanks) Separators, oil, allowable velocity through 255 method of draining 255 receiver and muHler type 257 Series 21, description of 254 Series 21, dimensions of 256 Series 21, ratings of 256 Separators, steam. Series 21, description and dimensions of 283-285 Single-control hydro-pneumatic tanks, descrip- tion and dimensions of 276-277 Specifications, typical, modulation system 289 typical, vacuum system 286 Steam-control tanks, description of 265 dimensions of 266 Steam separators, ratings of 285 Series 21, description and dimensions of. .283-285 Strainers, dirt, description of 259 dirt, dimensions of 260 suction, and vapor economizer, description and dimensions of 261-262 description of 258 dimensions of 259 selection of size of 138, 141 use of, on lumber dry kiln coils 186 Suction strainer, and vapor economizer, descrip- tion and dimensions of 261-262 description of 258 dimensions of 259 selection of size of 138, 141 typical connections for 150 Supply valves {see Modulation valves) Sylphon attachments (see Trap attachments) Sylphon traps, description of 242-245 dimensions of 245 ratings of 237-238 Tanks, air-separating, description and dimen- _ sions of 264-266 air-separating, selection of size of 138, 141 Tanks, hydro-pneumatic, description and dimen- sions of _ 276-277 hydro-pneumatic, selection of size of . . . . 138, 142 plain, selection of size of 138, 142 Tanks, steam-control, selection of size of. . .138, 142 water-control, selection of size of 138, 142 Thermostatic valve No. 4, trap attachments for. 294 Trap attachments 293 for motor valves 294 for multiple-unit valves 296 for thermo valves 294 for various types of valves 297 for wat er-sead-motors 294 for water-seal traps 295 Traps (see also Return traps) grease and oil, description of 257 dimensions of 258 method of connecting for draining oil sepa- rator 255 heavy-duty series 19T, description of 247 dimensions of 249 ratings of 239 high-pressure Sylphon {see High-pressure Syl- phon traps) Hylo (see Hylo traps) modulation vent (see Modulation vent traps) proper location of thermostatic type, on lumber dry kiln coils 186 proper type for lumber dry kilns 184 water-seal, attachments for 295 vacuum governors, typical connections for .... 151 pump governors, description and dimensions of 260 regulators {see Vacuum pump governors) system, typical specification for 286 Valves (see also Modulation valves) conserving (see Conserving valves) modulation vent (see Modulation vent valves) radiator outlet, attachments for 297 Vapor economizer and suction strainer, descrip- tion and dimensions of • ■ • . -261 Velocity, allowable, through oil separators 256 Vent traps, modulation (see Modulation vent traps) Vent valves, modulation (see Modulation vent valves) \A/ Type modulation valves, description of . . . .250 dimensions of 252 ratings of 237 Water accumulators, description and dimensions of 267 typical connections to conserving valve .... 173 typical connections to pressure-reducing valve 267 -control tank, description of 264 dimensions of 266 selection of size of 138, 142 -seal motors, attachments for 294 -seal traps, attachments for 295 367 WARREN WEBSTER & COMPANY EXECUTIVE OFFICES AND WORKS CAMDEN, N.J. Branch Offices and Representatives Atlanta, Ga. Atlantic City, N. J. Baltimore, Md. Birmingham, Ala. Boston, Mass. Charlotte, N. C. Chicago, lU. Cincinnati, Ohio Cleveland, Ohio Colmnbus, Ohio Dallas, Texas Denver, Colo. Detroit, Mich. Easton, Pa. Grand Rapids, Mich. Houston, Texas IndianapoUs, Ind. Kansas City, Mo. Los Angeles, Cal. Memphis, Tenn. Milwaukee, Wis. Minneapolis, Minn. New Orleans, La. New York, N. Y. Omaha, Neb. Philadelphia, Pa. Pittsburgh, Pa. Portland, Ore. Rochester, N. Y. Saginaw, Mich. San Francisco, Cal. Seattle, Wash. St. Louis, Mo. Syracuse, N. Y. Toledo, Ohio Washington, D. C. Wilkes-Barre, Pa. Sole Representatives and Manufacturers in Canada DARLING BROTHERS, Limited Head Office and Works, Montreal, P. Q. Branch Offices and Representatives Calgary Ottawa Quebec Vancouver Halifax Toronto Winnipeg London, England THE ATMOSPHERIC STEAM HEATING CO., Ltd. 1; li jj jljiji iii! ii!i IIMi!ili!il J i |f jili,, 'i'ip;';si j> < I :' !! li'inninr 'Ml fill i llll'Kmnr,^r,.F°'^G^^ 8'- ;iii.!|i!iii illiliii'!! 'ii ly