. , 
 
l 
 
 II 
 
, 
 
 Refrigeration**^ 
 
 y/ Practical Treatise 
 
 ON THE SCIENTIFIC PRINCIPLES, MECHANICAL OPERATION, AND MANAGE- 
 MENT OF REFRIGERATING PLANTS BASED ON THE VARIOUS 
 MODERN SYSTEMS OF ARTIFICIAL COOLING 
 
 By CHARLES DICKERMAN 
 
 Refrigerating Engineer, Pennsylvania Iron Works Co. 
 
 and 
 FRANCIS H. BOYER 
 
 Constructing Engineer 
 
 ILLUSTRATED 
 
 CHICAGO 
 AMERICAN SCHOOL OF CORRESPONDENCE 
 
 1909 
 
6ENERAL 
 
 COPYRIGHT 1908 BY 
 AMERICAN SCHOOL OF CORRESPONDENCE 
 
 Entered at Stationers' Hall, London 
 All Rights Reserved 
 
Foreword 
 
 recent years, such marvelous advances have been 
 made in the engineering and scientific fields, and 
 so rapid has been the evolution of mechanical and 
 constructive processes and methods, that a distinct 
 need has been created for a series of practical 
 working guides, of convenient size and low cost, embodying the 
 accumulated results of experience and the most approved modern 
 practice along a great variety of lines. To fill this acknowledged 
 need, is the special purpose of the series of handbooks to which 
 this volume belongs. 
 
 C, In the preparation of this series, it has been the aim of the pub- 
 lishers to lay special stress on the practical side of each subject, 
 as distinguished from mere theoretical or academic discussion. 
 Each volume is written by a well-known expert of acknowledged 
 authority in his special line, and is based on a most careful study 
 of practical needs and up-to-date methods as developed under the 
 conditions of actual practice in the field, the shop, the mill, the 
 power house, the drafting room, the engine room, etc. 
 
 C, These volumes are especially adapted for purposes of self- 
 instruction and home study. The utmost care has been used to 
 bring the treatment of each subject within the range of the com- 
 
 179722 
 
mon understanding, so that the work will appeal not only to the 
 technically trained expert, but also to the beginner and the self- 
 taught practical man who wishes to keep abreast of modern 
 progress. The language is simple and clear; heavy technical terms 
 and the formulae of the higher mathematics have been avoided, 
 yet without sacrificing any of 'the requirements of practical 
 instruction; the arrangement of matter is such as to carry the 
 reader along by easy steps to complete mastery of each subject; 
 frequent examples for practice are given, to enable the reader to 
 test his knowledge and make it a permanent possession; and the 
 illustrations are selected with the greatest care to supplement and 
 make clear the references in the text. 
 
 C. The method adopted in the preparation of these volumes is that 
 which the American School of Correspondence has developed and 
 employed so successfully for many years. It is not an experiment, 
 but has stood the severest of all tests that of practical use which 
 has demonstrated it to be the best method yet devised 'for the 
 education of the busy working man. 
 
 C, For purposes of ready reference and timely information when 
 needed, it is believed that this series of handbooks will be found to 
 meet every requirement. 
 
Table of Contents 
 
 PRINCIPLES OF REFRIGERATION, AND FREEZING AGENTS . Page 3 
 
 Unit of Refrigeration (B. T. U.) Specific Heat Latent Heat Units of 
 Plants Thermometers (Fahrenheit, Reaumur, Centigrade) Freezing 
 Agents (Ammonia, Carbonic Acid, Sulphur Dioxide, Compressed Air) 
 
 AMMONIA COMPRESSION SYSTEM v. s . . . . . Page 5 
 
 Evaporators Brine Tank (Rectangular with Flat Coils, Circular with 
 Spiral Coils) Washout Opening Bracing Brine Cooler (Enclosed-Shell 
 and Double-Pipe Types) Compressors (Single-Acting, Double-Acting ; Ver- 
 tical, Horizontal) Valves (Inlet, . Discharge) Piston Stuffing-Box 
 Packing Erection of Plant Water-Jacket Lubrication bosses and their 
 Avoidance Ammonia Condenser (Submerged, Atmospheric, Double-Pipe) 
 Water-Distributing Devices Slotted Water Pipe Oil Separator or .Inter- 
 ceptorAmmonia Receiver or Storage Tank (Vertical, Horizontal) Pipes 
 and Joints Gasket Fittings Ells, Tees, Return Bends Valves (Globe, 
 Angle, Gate; Screwed and Flanged) Pressure Gauges (Discharge or Con- 
 densing Pressure, and Evaporator or Return-Gas Pressure) Brine 
 (Chloride of Calcium, Chloride of Sodium or Common Salt) Baume Scale 
 Direct Expansion System Baudelot Cooler Purging and Pumping Out 
 Connection Testing and Charging -Air-Pressure Test Vacuum Test 
 Operation and Management of Plant Prevention of Ammonia Losses 
 Proportion between Parts of a Refrigerating Plant Useful Tables (Ther- 
 mometer Scales, Properties of Saturated Ammonia, Properties of Calcium 
 and Salt Brine 
 
 CARBONIC ANHYDRIDE, COMPRESSED-AIR, 
 
 AND ABSORPTION SYSTEMS . Page 81 
 
 Refrigeration by Carbonic Anhydride Gas Temperature of Liquefied Gas 
 Refrigeration by Compressed Air Expansion of Air Air-Compressor Re- 
 lief of Valves Unbalanced Valve Pressure Oil and Water Traps Ice- 
 Making Tank Refrigerator Box Water "Butt" or Cooler Ammonia Ab- 
 sorption System Carre's First Ice Plant Reabsorbing Circuit of Weak 
 Water Glass Gauges Gas Foreign to Ammonia 
 
 INDEX . .' , . ... , , , . , . Page 107 
 
REFRIGERATION 
 
 PART I. 
 
 Refrigeration may be defined as the process of cooling. It 13 
 artificially or mechanically performed by transferring the heat 
 contained in one body to another, thereby producing a condition 
 commonly called cold, but which is in fact an absence of heat. 
 This transfer of heat is most rapidly and economically accomplished 
 by evaporation, but Defore considering the apparatus used a few 
 important definitions sihould be reviewed. 
 
 Unit of Refrigeration. The unit or basis of measurement 
 of refrigeration, is the x.nit of heat, and in the United States and 
 England is the British thermal unit (B. T. U.) which is equiva- 
 lent^to raising or towering tlie temperature of one pound of water 
 1 Fahrenheit when at or near 00 Fahrenheit. 
 
 Specific Heat. Specific Heat, or capacity for heat, is the 
 relative capacity of a substance for heat, and is stated or expressed 
 relative to that of water, since water has the greatest heat capacity 
 of any known substance except Hydrogen. 
 
 Latent Heat. "W hen a body changes from a solid to a liquid, 
 or a liquid to a gaseous state, a certain amount of heat must be 
 supplied to it in order to effect the change. This amount is called 
 its latent heat, and is expressed in thermal units. Thus we have 
 in the melting of one pound of ice a latent heat of 142 thermal 
 units, and we understand by this that in order to melt a pound of 
 ice it must absorb into itself, in making the change, 142 B. T. U., 
 or the equivalent of one pound of water changing 142 degrees 
 Fahrenheit. 
 
 Units of Machines or Plants. The unit (or capacity) of 
 refrigerating plants is ordinarily stated in tons, that is, the equiva- 
 lent of so many tons of ice (of 2000 pounds) at 32 F melted into 
 water at 32 F. The unit is equivalent to 142x2000=284,000 
 British thermal units. 
 
 Thermometers. For ordinary use, a mercury tube having a 
 graduated surface or scale at its back with a bulb at its lower end 
 
REFKIGEKATION 
 
 and containing a quantity of mercury is used to denote the tem- 
 
 ureiqlits surroundings. 
 
 c Two "different scales are commonly used in the refrigerating 
 :r tfae v Fahrenheit and Reaumer. The Centigrade or 
 French standard is used for chemical or technical purposes. In 
 the United States and England the Fahrenheit scale is generally 
 accepted as standard except in breweries where the German or 
 Reaumer scale is quite often found. 
 
 The Fahrenheit scale is divided in such manner that the 
 boiling point of water at at- 
 mospheric pressure is 212 
 and the freezing point 32. 
 It is said that F was the 
 lowest temperature Fahren- 
 heit was able to produce by 
 the melting of ice by salt. 
 
 The Reaumer scale is grad- 
 uated by making the boiling 
 point of water 80 while the 
 freezing point is at 0. 
 
 The Centigrade has the 
 freezing point of water at 
 as the .Reaumer, while the 
 boiling point is fixed at 100. 
 This graduation is typical of 
 the French system of meas- 
 urement. 
 
 To transpose the temperature of one scale to that of the others 
 the table on page 77 will be found convenient. 
 
 Let us now take an illustration from a branch of engineering 
 with which almost every one is familiar. 
 
 If we place a glass of water in contact with heat at a temper- 
 ature of 212 F or more, heat will pass from the source and be 
 absorbed by the water until its own temperature reaches that of 
 212, after which evaporation of the water commences and con- 
 tinues until the water has all been transformed into steam. During 
 this time an amount of heat corresponding to this duty has been 
 transferred from the source of heat to the water and its vapor 
 
 Fig. 1. 
 
EEFEIGEEATION 
 
 called steam. This process is familiar to all engineers, in the 
 steam boiler, and is similar to that of refrigeration as ordinarily 
 applied, except that the one is going on at or above a temperature 
 of 212 F (the boiling point of water) while refrigeration is accom- 
 plished by the evaporation of a liquid having a boiling or evapor- 
 porating point sufficiently low to obtain the desired temperature. 
 
 Agents. Among .the most commonly used agents for obtain- 
 ing artificial refrigeration may be mentioned Ammonia, Carbonic 
 Acid, Sulphur Dioxide and Compressed Air, the first named being 
 the most generally used and approved, while the others have 
 advantages for use on ship-board and other places where the fumes 
 of ammonia would prove objectionable. Ammonia, however, 
 appears to present the most favorable qualities for general use, 
 and will, therefore, be the principal a'gent considered. 
 
 Fig. 2. 
 
 Of the two types of ammonia machines, the absorption and 
 the compression, the latter will be the first described. The primi- 
 tive process of refrigeration is represented by a glass or receptacle 
 (Fig. 1) in which a quantity of anhydrous ammonia is placed, and 
 which, so long as its own temperature and that of its surround- 
 ings remain at or above 28 F or 28 below zero (its boiling 
 .point) will continue to take heat over to itself, and therefore con- 
 tinue to evaporate and produce a cooling effect upon its surround- 
 ings, or what is commonly known as refrigeration in the body or 
 substance with which it is in contact. 
 
 In Fig. 2 we have such a receptacle to which is attached a 
 drum or flask filled with the refrigerating agent; if it were possi- 
 ble to procure a cheap volatile liquid, having a sufficiently low 
 
6 
 
 EEFEIGEHATIOK 
 
 CO 
 
 bb 
 
KEFittGERATION 
 
 boiling or evaporating point, the complex systems of refrigeration 
 would be reduced to the above parts, or equivalent simple system. 
 The system would consist of an evaporator, and a receptacle for 
 the refrigerant, with a connecting pipe between, provided with an 
 expansion valve to regulate the flow of the liquid to the evaporator. 
 The cost of ammonia or the refrigerating agent renders this waste 
 impracticable, at least at the present time; and to make refriger- 
 ation a commercial success it becomes necessary to recover and 
 put in condition to be used again the gases arising from the evap. 
 orating ammonia. We have seen how the ammonia absorbed a 
 certain amount of heat from its surroundings during evaporation; 
 it is evident that this heat must be taken from it before it can be 
 again effective as a refrigerant, and for this purpose the com 
 pressor, condenser and other adjuncts to the plant are required. 
 
 The gas pump or compressor is the means employed to 
 recover and compress the gas from the evaporator. In order, 
 therefore, to continue the process of refrigeration in a commercial 
 manner, it becomes necessary to connect to the evaporator and 
 ammonia tank shown in Fig. 2, a gas pump with its engine or 
 other form of power. This is illustrated by Fig. 3. The top of 
 the evaporator is closed and provided with a connecting pipe to 
 the compressor; upon the downward stroke of the compressor 
 piston the gas from the evaporator follows and fills the cylinder 
 above the piston, and upon reaching the bottom of its stroke this 
 valve is closed by a spring, preventing the return of the gas to the 
 evaporator. The return or upward stroke of the piston discharges 
 the gas through the outlet valve and pipe. 
 
 Having described the evaporation of the ammonia and re- 
 covery of its gases by the compressor, we now supply the apparatus 
 necessary to extract the heat with which it is laden, and thereby 
 cause it to resume its initial state ready to again enter the evapo- 
 rator and continue the cycle. The apparatus referred to is called 
 the Ammonia Condenser. Fig. 4 illustrates its construction and 
 connection with the balance of the apparatus. 
 
 The discharge of the ammonia gas from the compressor is 
 continued through the pipe E, the oil separator F, and into the 
 condenser C, which is composed of a series of pipes over which 
 water flows to take up the heat given out by the compressing of 
 
8 
 
 REFKIGEEATION 
 
 the gas. and which combined effect pauses the gas to liquify and 
 flow from the bottom pipe of the condenser through the pipe II to 
 the receiver or storage tank I. This completes the cycle and per* 
 forms the practical process of refrigeration. 
 
 The principle or method of refrigeration has now been de- 
 
 scribed without going into details of construction. The next step 
 is the construction, proportion and combination of the several 
 parts making up the refrigerating plant, and as the evaporator is 
 the foundation or basis of the system, let us first consider this 
 part of the plant. 
 
 EVAPORATORS. 
 Evaporators may be divided into two classes: The first is 
 
15 TO 20 TON REFRIGERATING MACHINE. 
 
 Frick Company. 
 
EEFEIGEEATION 
 
 9 
 
 operated in connection with the brine system. In this evaporator 
 salt brine (or other solution) is reduced in temperature by the 
 evaporation of the ammonia or other refrigerant and the cooled 
 brine circulated through the room or other points to be refriger- 
 ated. In the second, the direct-expansion system, the ammonia 
 or refrigerant is taken directly to the point to be cooled, and there 
 evaporated in pipes or other receptacles, in direct contact with the 
 object to be cooled. Which of the two systems is better, is a much 
 disputed and debated point; we can state, in a general way, that 
 
 Fig. 5. 
 
 both have their advantages, and each is adapted to certain classes of 
 duty. 
 
 The cooling of brine in a tank by a series of evaporating 
 coils, (one of the earliest methods) is common to-day, A descrip- 
 tion of the many methods of construction and equipment would 
 require much space. Let us, therefore, discuss the two most 
 general types only, viz: the rectangular with flat coils, and the 
 circular with spiral coils. 
 
 Fig. 5 shows a sectional view of a brine tank. Flat or zig- 
 zag evaporating coils are connected to manifolds or headers; the 
 pipe connections leading to and from these manifolds for the 
 proper supplying of the liquid ammonia and the taking away or 
 return of the gas to the compressor are also shown. For coils of 
 
10 KEFKIGEKATION 
 
 this type, 1-inch or IJ-inch pipe is preferable, owing to the 
 impossibility of bending larger sizes to a small enough radius to 
 get the required amount into a tank of reasonable dimensions. It 
 is possible to make coils of this construction of any desired length 
 or number of pipes to the coil, "pipes high," the bends being 
 from 3J inches to 4 inches centers for 1-inch pipe, and 4 inches 
 to 5 inches for l|-inch pipe. It is preferable to make the coils of 
 moderate length, (not less than 150 feet in each) and there is no 
 disadvantage (other than in handling) in making them to contain 
 up to 500 or 600 feet each. It will be observed that there is a 
 slight downward pitch to the pipes with a purge valve at the low- 
 est point of the bottom manifold, which is, undoubtedly, valuable 
 and an almost necessary provision. This valve is for removing 
 foreign matter, which may enter the pipes at any time, and by 
 opening the valve and drawing a portion of their contents, the 
 condition of cleanliness can be determined without the necessity 
 of shutting down and removing the brine and ammonia for 
 inspection. The coils are usually strapped or bound with flat bar 
 iron about J inch X 2 inches (or a little heavier for the longer 
 coils) and bolted together with -|-inch square-head machine bolts. 
 The coils are painted with some good water-proof or iron paint. 
 The brine tank is usually constructed of iron or steel plates, 
 varying from T 3 ^- inch to inch in thickness ; the average being ^ 
 inch for tanks of ordinary size. The workmanship and material 
 for a tank for this purpose should be of the very best; without 
 these the result is almost certain to be disastrous to the owner or 
 builder. The general opinion with iron workers (before they have 
 had experience) is that it is a simple matter to make a tank which 
 will hold water or brine, and that any kind of seam or workman- 
 ship will be good enough for the purpose. On the contrary the 
 greatest care and attention to detail is necessary. It is customary, 
 and good practice, to form the two side edges at the bottom by 
 bending the sheets, thereby avoiding seams on two sides, while 
 for the ends an angle iron may be bent to conform to this shape 
 and the two sheets then riveted to the flanges of the angle iron. 
 The edges of the sheets should be sheared or planed bevel, and 
 after riveting, calked inside and out with a round-nosed calking 
 tool. The rivets should be of full size, as specified for boiler con- 
 
EEFEIGERATION 11 
 
 struction and of length sufficient to form a full conical head of 
 height equal to the diameter of the rivet and brought well down 
 onto the sheet at its edges. An angle iron of about 3 inches 
 should be placed around the top edge, and riveted to the side at 
 about 12-inch centers. 
 
 One or more braces (depending on the depth) should extend 
 around the tank between the top and bottom, to prevent bulging; 
 without these it would be impossible to make the tank remain 
 tight, as a constant strain is on all its seams. A very good brace 
 for the purpose is a deck beam. Flat bar iron placed edge-wise 
 against the tank with an angle iron on each side and all riveted 
 through and to the side of the tank with splice plates at the 
 corners or one of each pair long enough to lap over the other 
 makes a good brace; heavy T-iron is also used to some extent. It 
 is usual to rivet up the bottom of the tank and a short distance up 
 the sides, then test by filling with water; if tight lower to its 
 foundation and complete the riveting and calking. It may then 
 be filled with water and tested until proven absolutely tight, when 
 it may be painted with some good iron paint; it is now ready for 
 its equipment of coils and insulation. 
 
 A washout opening with stop valve should be placed in the 
 bottom at one corner; for this purpose it is well to have a wrought 
 iron flange, tapped for the size of pipe required and riveted to the 
 outside of the bottom. If the brine pump can be located at this 
 time, it is well to have a similar flange for the suction pipe riveted 
 to the side or bottom of the tank, as a bolted flange with a gasket 
 is never as durable as a flange put on in this manner. 
 
 O i 
 
 Assuming that the tank is now absolutely tight and painted, 
 the insulation may be put around it, the insulated base or founda- 
 tion having been put in previous to the arrival of the tank. The 
 insulation should be constructed of joists 2 inches or 3 inches X 
 12 inches on edge and filled in with any good insulating material 
 and floored over with two thicknesses tongued and grooved floor- 
 ing with paper between. In putting the insulation on the sides 
 and ends of the tank, place joists 3 inches X 4 inches resting on 
 the projecting edges of the foundation about 2 feet apart. The 
 upper ends should be secured to the angle iron at the top of the 
 tank, its upper flange having been punched with |-inch holes 18 
 
12 REFRIGERATION 
 
 inches to 24 inches centers and to which it is well to bolt a plank, 
 having its edge project the required distance to receive the 
 uprights. Between the braces around the tank blockings should 
 be fitted to secure the frame work at the middle, as the height of 
 some tanks is too great to depend on the support at top and bot- 
 tom alone. 
 
 After the frame work has been properly formed and secured 
 to the base and tank, take 1-inch flooring, rough, or planed on one 
 side, and board up on the outside of the uprights, filling in as the 
 work progresses with the insulating material which may be any 
 one of the usual materials, granulated cork being about the best, 
 all things considered, although charcoal, dry shavings, saw-dust, 
 or other non-conductors may be used with good results. When 
 the first course of boards is in place it is well to tack one or two 
 thicknesses of good insulating paper against the outer surface, 
 care being taken that the joints lap well and that bottoms and 
 corners are filled and turned under at the junction with the 
 bottom insulation. It is then in shape for the final or outer 
 course which is very often made <jf some of the hard woods in 
 2^-inch or 3-inch widths, tongued, grooved and beaded and 
 finished off with a base board at the bottom and moulding at the 
 top, and given a hard wood finish in oil or varnish. If the tank 
 is located in a part of the building in which appearance is of no 
 importance, the outer course may be a repetition of the first, 
 except that the boards are put on vertically instead of horizontally. 
 
 It is well to make the top of the tank in removable sections 
 to facilitate examination or cleaning; for this purpose make a 
 number of sections about 2^ to 3 feet wide of the length or width 
 of the tank, using joists about 2 inches X 6 inches placed on 
 edge, floored over top and bottom and filled in with the selected 
 
 O ' i 
 
 insulating material. It is also well to have a small lid at one end 
 of each (preferably over the headers or manifolds) which will 
 allow of internal examination of the tank to ascertain the height 
 or strength of brine without removing the larger sectionr The 
 tank is now fully equipped and ready for testing and filling with 
 brine. 
 
 For a circular tank the general instructions regarding con- 
 struction and insulation may apply as with the rectangular tank 
 
KEFKIGERATIOtf 
 
 13 
 
 just described; therefore only its special features will be consid- 
 ered. If the tank is small and there is sufficient head room above 
 it for handling the coils there cannot be serious objection to this 
 type as its cost is lower than that of the rectangular tank. This 
 is often an important item in a small installation, but when the 
 tank is of considerable size and the coils large it is not as readily 
 
 Fig. 6. 
 
 handled and taken care of as the other type. The usual construc- 
 tion of a nest of coils for a round tank is to bend the inside coil 
 to as small a circle as possible, which, if it be of 1-inch or 1^-inch 
 pipe may be G to 8 inches. Increase each successive coil enough 
 to pass over the next smaller until the required amount of pipe is 
 obtained. The ends may then be bent up or out and joined to 
 headers at top and bottom and the tank insulated in the manner 
 previously described; it is then ready to test and charge with 
 ammonia and brine. Fig. 6 represents an evaporator of this type. 
 
14 
 
 REFRIGERATION 
 
 Other constructions of tanks and coils are too numerous to de- 
 scribe in detail, and with one exception may be properly classed 
 in one of the preceding types. The one exception referred to is 
 illustrated in Fig. 7. It is quite common and is adopted for 
 large pipe and is often called oval, although not of that shape, 
 but rather a combination of the flat and circular form. It has 
 some good features; it allows the maximum amount of pipe in 
 the smallest space and a large amount of pipe in a single coil. 
 The Brine Cooler at present is a popular and efficient method 
 
 Fig. 7. 
 
 of cooling brine for general purposes. Owing to mechanical 
 defects and the impossibility of obtaining a brine solution which 
 would not freeze, it was abandoned only to be taken up again, and 
 with the aid of modern ideas and better material it has become 
 highly successful. Unlike the brine tank and coil method of refrig- 
 eration, in which the ammonia is evaporated within the coils while 
 the brine surrounds them, the brine passes through a series of 
 coils and the ammonia evaporates within a wrought or cast suell 
 surrounding the coils. Thus the action is reversed. 
 
 Fig. 8 is what is known as the enclosed-shell type of brine 
 cooler, A representing a cast or wrought-iron shell, flanged at each 
 end, to which heads are bolted; a tongue and grooved joint be- 
 
KEFKIGEBATION 
 
 15 
 
 tween, makes the closed cylinder gas tight. B is a series of welded 
 extra strong pipe coils, one with- 
 in the other, having their ends 
 project through the heads and 
 joined to headers at each end 
 with proper unions ; a stop valve 
 is supplied to each coil. Lock 
 nuts or glands are placed around 
 each coil at its opening through 
 the heads and one or more glass 
 gauges with the usual gauge 
 fittings are tapped into the side 
 of the shell to indicate the 
 amount of ammonia. Liquid 
 ammonia is fed into the shell 
 by an ordinary expansion or 
 feed valve near the lower end 
 of the shell at C and the gas 
 taken off through the opening 
 and pipe D to the compressor. 
 A purge valve E for drawing 
 off impurities is placed at the 
 lowest point in the bottom head 
 and a second one F for gas or 
 air in the top head. 
 
 In operation, the discharge 
 pipe from the brine pump is con- 
 nected to the top header or man. 
 ifold, and the bottom header is 
 connected to the main leading 
 to the refrigeration to be per- 
 formed; the return from the 
 cooling system is generally 
 brought to a medium-sized brine 
 tank without coils to which the 
 suction of the pump is con. 
 nected, thereby completing the 
 brine circuit. The heat of the brine passing through the coils in 
 the cooler is taken up by the ammonia during evaporation; the 
 
 Fig. 8. 
 
16 
 
 EEFKIGEEATIOX 
 
 
REFKIGEKATIOE 17 
 
 gas is taken away from the top of the shell to the compressor, and 
 discharged to the condenser and into the receiver to be re-used, as 
 with the system illustrated by Fig. 4. 
 
 The advantages of thejmne cooler over the brine _tank_are 
 due to two features of construction. The brine in passing through 
 the coils is divided into a number of small streams, and while 
 flowing rapidly through a coil of considerable length is churned 
 to such an extent that it is all brought in contact with the coil, of 
 which the outer surface is exposed to the temperature of the evap- 
 orating or boiling ammonia, and thereby gives up its heat much 
 more rapidly to the ammonia than in the brine tank. In the 
 brine tank there is a large body of brine with scarcely any move- 
 ment; the brine immediately in contact with the pipe may be quite 
 cold, but becomes warmer as the distance from the pipe increases. 
 
 The second advantage is that during the evaporation of the 
 ammonia a violent ebullition is taking place, and if this is confined 
 within the pipe coil a certain amount of the liquid is carried for- 
 ward by the escaping gas, and the evaporation within the coil is 
 limited. This limit is reached when the vapor enters the com- 
 pressor in such quantities as to cause too great an expansion in 
 the compressor, or when it becomes difficult to keep the stuffing- 
 box tight, while in the brine cooler properly constructed, the larger 
 diameter of shell allows evaporation to take place place up to 
 practically the theoretical boiling point of the ammonia, without 
 the liquid being carried forward through the gas pipe to the com- 
 pressor. This permits a much higher evaporating pressure or 
 "back pressure" as it is commonly called, than with the brine tank 
 and coils. Also the concentrated or compact shape and construc- 
 tion of the cooler allows greater economy than the large radiating 
 surface of the brine tank. The sides and end of the cooler are in- 
 sulated by some one of the usual methods and very often lagged 
 with finished hardwood strips, tongue, grooved and beaded and 
 bound with finished brass or nickel plated bands. 
 
 Salt brine is commonly used in the brine tank and coil form 
 of refrigerator, but it is unsafe to use it with the brine cooler 
 because when passing through the coil it may freeze and burst the 
 coil. A solution of chloride of calcium is commonly used, its 
 
18 KEFKIGEKATION 
 
 freezing point being 54 below zero Fahr. while salt brine is prac- 
 tically Fahr. 
 
 The second form of brine cooler is what is known as the 
 double=pipe type, the construction of which is illustrated in Fig. 9, 
 In this type one pipe is within another, the brine being discharged 
 from the pump into one or more pipes at A and issuing at B. 
 This connection leads from the main to the point to be refrigerated 
 and the ammonia is expanded or fed into the annular space between 
 the two pipes, and takes up the heat of the brine in evaporating 
 and issuing as gas from the opening D at the top of the cooler 
 From thence the ammonia passes to the compressor and through 
 the cycle of compression, condensation and return to the liquid 
 ammonia receiver as before. The ammonia evaporating between 
 the two pipes will naturally absorb as much heat from the outside 
 surface as from the inner or brine if allowed to do so, and it there- 
 fore becomes necessary to insulate the outside of this from exterior 
 influences. As it is practically impossible to cover the bends and 
 irregular surfaces it becomes necessary to build an insulated room 
 in which the cooler is erected. This is commonly done, but some 
 authorities do not consider it the most practical form. The 
 cooler is equipped with the necessary stands, manifolds and stop 
 valves to properly control the action of any one section when 
 more than one is used. 
 
 As with the enclosed brine cooler, previously described, chlo- 
 ride of calcium brine should be used, as there exists the same lia- 
 bility to freeze, and it is unsafe to operate either type with the 
 ordinary salt solution. These two types of brine coolers and brine 
 tanks and coils are the usual means of cooling or refrigerating 
 brine. 
 
 COMPRESSORS. 
 
 The next step in the process is the recovering of the evaporated . 
 ammonia and its return in liquid form. Compressors may be 
 divided into two principal classes, single acting and double acting; 
 and each class subdivided into vertical and horizontal. They 
 are of the vertical type if single acting, and of both vertical and 
 horizontal if double acting, although the majority of the double 
 acting are of the horizontal type. Machines may also be classed 
 according to the form of driving. The engines used may be hori- 
 
KEFEIGEBATION 19 
 
 zontal or vertical, and within this classification comes almost any 
 machine of modern build. 
 
 Fig. 10 illustrates the vertical single-acting type of com- 
 pressor, two in number, in combination with and driven by a 
 horizontal Corliss engine. It embodies the necessary and usual 
 requisites of an efficient gas pump or compressor. 
 
 As already stated, the function of the compressor is to 
 recover the gas from the evaporator and compress it into the con- 
 denser at a pressure which will cause it to liquify under the 
 action of the cooling; water. It is evident that the gas must 
 
 o o 
 
 follow the piston in its downward stroke and fill the compressor, 
 and upon its reaching the end of its stroke and the pressure being 
 balanced, the strength of the spring in the suction valve causes it 
 to close and the piston begips its return stroke. The compression 
 of the gas within the compressor takes place until its pressure 
 equals or slightly exceeds that above the discharge valve; it then 
 opens and the compressed gas flows into the discharge pipe 
 and thence to the condenser. Two compressors of the single- 
 acting type are almost always used in a machine of this type, and 
 the cranks set opposite, or at 90 to one another, so that one com- 
 pressor is filling and one compressing and discharging at each half 
 revolution of the crank shaft, and the load is accordingly divided 
 into two units, either one of which may be operated independently 
 if necessary. 
 
 As the evaporator is the heart of the refrigerating system, so 
 the piston and valves are the heart of the compressor, and the 
 principal, almost the only, cause of difficulty in the action of the 
 compressor will be found to be in one of the two. 
 
 In the compressor in which the valves operate in a cage, 
 there must of necessity be a gas-tight joint between the bottom of 
 this cage and the compressor head or piston in which it is located* 
 this joint is made in a variety of ways, any one of which will 
 prove effective. A square shoulder is cut into the head with a 
 corresponding shoulder on the cage to match, and a lead gasket 
 about - 6 to J inch in thickness placed between the two. Thia 
 makes a durable joint, except in cases where the joint between 
 the two is of such an amount that the lead is constantly pressed 
 through (a disadvantage of lead as a gasket material). "Without 
 
20 
 
 KEFKIGEKATION 
 
EEFEIGEKATION 
 
 one's being aware of the fact, tlie gasket is gone and a leakage 
 exists. Another objection to a lead gasket is that it compresses 
 and knits into the interstices between the cage and the head. 
 This often makes it impossible to remove the valve or cage from 
 the head without the aid of some kind of a chain block or tackle. 
 Another form of gasket for this purpose, but not popular from a 
 lack of confidence in its permanency, is common lamp or candle 
 wicking saturated with oil and wound tightly and smoothly in 
 the corner against the shoulder on the cage. It is put in place 
 and fully compressed by pulling down on the valve cap until the 
 cage is at the desired height. It is good practice to wind enough 
 on until, when the cage is pressed down by hand, it stands about 
 fa inch above the surface of the head at the top; this amount of 
 compression would make it about even when pulled down. As 
 already stated, this kind of packing is not very popular on ac- 
 count of lack of durability, but it gives very satisfactory results 
 when properly applied, and the valve and cage may be easily 
 removed. Recently the gasket has been omitted and a ground 
 joint made between the cage and the head. Although its efficiency 
 has not yet been proven, from present indications it should be both 
 satisfactory and permanent. 
 
 Assuming that we have made the joint between the cage and 
 the compressor head gas-tight, we must also be certain that the 
 compressor valve forms a perfect joint in closing against the cage. 
 In a vertical compressor, in which the action of the valves is also 
 vertical within their cages, the conditions naturally favor this to 
 the greatest possible extent, as in closing they drop to their seats 
 and it is only necessary to provide for the slight wear taking place 
 in the stems and on the seats due to the rapid opening and closing 
 of the valves. The valve stem must necessarily fit the guides in 
 the cage as closely as possible and still allow free movement, and 
 the seat between the valve disc and cage (preferably made at an 
 angle of 45) must first be machined to the proper angle and then 
 ground in the usual manner. Having made it impossible for the 
 gas to pass the valves and cages, means must be provided for 
 closing the valves at the proper time to prevent loss, as a valve 
 which is slow in reaching its seat presents a double evil loss of 
 efficiency and improper or irregular action on the balance of the 
 
22 REFRIGERATION 
 
 machine. The spring is the usual means of opening the com- 
 pressor valve, and, on the suction or inlet, is commonly placed 
 between the top of the cage and underneath a washer placed at 
 the end of the stem and held in place with one or two nuts; it is 
 frequently reinforced with a buffer spring, or one of greater 
 strength, enough shorter than the length of the stems to allow its 
 opening the proper distance, and then stopping the travel of the 
 valve gently. 
 
 Valves. Fig. 11 illustrates a type of _inlet valve which has 
 stood the test for years and embodies many good qualities. The 
 different points referred to are indicated by the following letters: 
 A, the joint between the cage and head; B, the contact between 
 the valve disc and the cage; C, the spring for actuating the valve, 
 and D, the buffer or stop spring to stop the travel of the valve at 
 the proper point of opening. In the use of this valve the require- 
 ments are that it shall admit the gas to the compressor during the 
 downward stroke of the piston, and close while the piston is at the 
 bottom of stroke and the crank pin is passing the bottom center. 
 It will, therefore, be readily understood that if the spring is 
 stronger than necessary, it will require a certain amount of the 
 pressure of the gas to overcome the strength of the spring, and 
 prevent the filling of the compressor to its fullest limit. In the 
 closing of the valve it would be driven with considerable force 
 against its seat, making a noise in so doing and causing excessive 
 wear. Considerable skill and experience are required to obtain 
 perfect results, but with good judgment and a few trials most of 
 the imperfections can be overcome. Generally the closing spring 
 should not be stronger than is necessary to close the valve when 
 held vertically in the position in which it naturally rests. By 
 taking the valve and cages in the hands and pressing down on the 
 top of the stem with one of the fingers, it will be readily ascer- 
 tained when the springs are of proper strength to close the valve. 
 When put on the compressor, so far as the operation of the inlet 
 valves is concerned, the machine will be practically noiseless and 
 effective in the admission and retention of the gas from that side. 
 
 o 
 
 The discharge valve operates in the reverse direction to that 
 of the suction valve. We know that the suction valve closes 
 while the compressor piston is at its lowest position in the com. 
 
BEFRIGERATIOH 
 
 pressor and while the crank is passing its bottom center. The 
 piston now moves upward compressing the gas until it reaches the 
 pressure in the ammonia condenser, and as it passes this point far 
 enough to overcome the tension of the spring on the discharge 
 valve, it causes it to lift and the contents of the cylinder in its 
 compressed state are discharged through the discharge pipe into the 
 condenser. This continues until the piston reaches its highest 
 
 Fig. 11. 
 
 point and the crank is passing its top center, at which point the 
 valve closes and the suction valve again opens to admit an 
 additional amount of the gas. This process is continued during 
 the operation, of the apparatus. 
 
 It will be noticed that the suction valve opens and closes 
 while the piston is practically without motion, but the discharge 
 valve opens while the piston is nearly at its maximum, and 
 closes while the piston is at tne minimum speed. From this 
 it will be apparent that the thrust or effort on the discharge valve 
 is much greater than on the inlet, that is, in an upward or out- 
 
BEFKIGEKATIOtf 
 
 ward direction ; hence the device for arresting the upward motion 
 of the valve must be more effective than the other. Also the 
 valve must close in a shorter space of time because the great 
 pressure above the valve would cause it to fall with considerable 
 force were it not to reach its seat while the piston was still at the 
 top of its travel, and the pressure above and below equal. Should 
 the piston begin its return or downward stroke before the valve 
 closes it would have the condensing pressure above, and the inlet 
 pressure below, a difference of from 150 to 175 pounds. This 
 pressure would cause it to seat with an excessive blow which 
 would soon cause its destruction, and also cause the escape of a 
 portion of the compressed gas into the compressor resuming in 
 great loss in efficiency of the machine. 
 
 To stop the valve in its opening and prevent shock, it is nee- 
 essa/y to provide a buffer or cushion -in addition to the spring 
 used to close it. The cushion, as usually constructed, is a piston 
 fitting closely in a cylinder and provided with openings for the 
 escape of the gas in front of the piston until it reaches a certain 
 height, which should conform to the lift of the valve ; at this point 
 the pisto'n is prevented from traveling farther by the compression 
 of the gas and the valve is brought to a stop without noise or jar. 
 
 The strength of spring for closing the discharge valve must 
 be nicely gauged; if too light the valve will not be brought to its 
 seat until the piston has started on the return stroke, causing a 
 return to the compressor of a portion of the compressed gas, and 
 the striking on the seat w r ith considerable force due to the pres- 
 sure of the gas above the valve and the removal of the pressure 
 below ; while if the spring is too strong the valve is returned with 
 such force as to cause a harsh sound and rapid wearing. This 
 necessitates more frequent renewals than if moved with a spring 
 of the proper tension. 
 
 Inasmuch as the weight of the moving part of the valve is a 
 factor in determining the required strength, and the diameter, 
 pitch, temper, gauge of spring and material, determine the strength, 
 it becomes practically impossible to lay down a rule for the selec- 
 tion of the proper spring for each condition. Experience shows 
 that one can better determine what spring to use by the sense of 
 feeling than by any rule or standard" 
 
^JWtAR^ 
 
 OP THE 
 
 UNIVERSITY 
 
 Of 
 
REFRIGERATION 25 
 
 Piston. Having provided the inlet and outlet valves with 
 proper opening and closing devices and made them capable of retain- 
 ing the gas passing them, a piston for compressing the gas and 
 discharging it from the compressor must be provided. For the 
 vertical type of single-acting compressor in which both inlet valves 
 are in the upper compressor head, the piston is best made as a 
 ribbed disc with a hub at the center for the piston rod and a peri- 
 phery of sufficient width to be grooved for the necessary snap 
 rings. Three to five of these rings are generally used. 
 
 Fig. 12 illustrates the simplest form of piston of this type, 
 A being the cast head, B the snap rings, and the piston 
 rod. The surface is faced square with the bore of the hub, and 
 
 Pig. 12. 
 
 the rod forced in and riveted over, filling the small counterbore 
 provided for this purpose. The cast head and rod having been 
 previously roughed out, is now finished in its assembled condi- 
 tion, the rod made parallel and true to gauge, threaded to fit the 
 crosshead and the grooves turned for the snap rings, which are 
 made slightly larger than the bore of the compressor. A diagonal 
 cut is made through one side and enough of the ring is cut out to 
 allow it to slip into the cylinder without binding. It is then 
 scraped on its sides until it fits accurately the groove in the piston. 
 It is also well to turn a small half-round oil groove in the outer 
 face of the piston between each ring which gathers and retains a 
 portion of the oil used for lubrication, thus increasing the efficiency 
 
26 EEFEIGEKATION 
 
 of the piston and collecting dust or scale and lessening the liability 
 of cutting of the cylinder due to any of the usual causes. 
 
 The piston rod requires special care both in workmanship and 
 material. In order to be effective it must be true from end to 
 end and to be lasting under the variety of conditions which it 
 operates, should be of a good grade of tool steel. The end which 
 is usually made to screw into the crosshead is turned somewhat 
 smaller, usually from J to J inch in diameter, than the portion pass- 
 ing through the packing or stuffing box principally to allow of 
 returning or truing up the rod when it becomes worn, and also to 
 allow it to pass through the stuffing box. After the rod is screwed 
 into the crosshead it is secured and locked with a nut to prevent 
 turning. The nut also allows the position of the piston to be 
 changed to compensate for wear on the different parts of the 
 machine by simply loosening the lock nut and turning the piston 
 and rod in or out of the crosshead. 
 
 The stuffing box of the compressor, shown in Fig. 13, is one 
 of the most difficult parts to keep in proper order. This is 
 owing principally to one of two causes: not being in line with 
 the crosshead guide or bore of the compressor, or the great dif- 
 ference of temperature to which it is subjected owing to the 
 possible changes taking place in the evaporator. However, w T ith 
 the compressor crosshead guides, and stuffing box in perfect 
 alignment, and a constant pressure or temperature on the evap- 
 orating side, it is a simple matter with almost any kind of 
 packing on a machine of the vertical single-acting type to keep 
 the stuffing box tight and in perfect condition. If, however, 
 either of the above conditions are changed it becomes practically 
 impossible to accomplish this. We have learned that perfectly 
 constructed and operating valves is one of the essential features of 
 a perfect machine. We also know that the alignment of the 
 machine is equally important. 
 
 Erection. Experience in the building, erecting and operation 
 of this class of machinery, shows that more machinery is con- 
 demned, more complaints made and difficulties encountered owing 
 to these two points than all others put together. It is all im- 
 portant to the erecting and operating engineer that they be 
 absolutely certain of these two points. 
 
REFRIGERATION 
 
 After the A frame, the compressor cylinder and its lower 
 head have been placed in position, a fine hard line should be 
 passed through the cylinder and stuffing box down through the 
 guide and to the crank pin in the shaft, drawn tight and secured 
 in some manner at each end and then callipered at each point. 
 The different parts should be brought into perfect alignment 
 before the rest of the machine is assembled. 
 
 Fig, 14 illustrates the methods of obtaining the proper 
 
 Fig. 13. 
 
 results. Assuming that the brasses are central with the connect- 
 ing rod and the connecting rod with the crossliead, the line should 
 of course be central with the crank pin and this condition should 
 exist when the pin is at its top and bottom positions. In other 
 words, when the line is placed midway between the collars on the 
 crank pin when at the bottom stroke, and the shaft is revolved 
 one-half revolution to its top stroke, the line should be exactly 
 midway between them; or the top moved until such is the case, 
 and this should be determined as absolutely correct before pro- 
 ceeding further. When this is accomplished we may proceed to 
 the guides and caliper first at the bottom and then the top 
 between the line and each side of the bore, moving the A frame 
 by dressing the bottoms of the feet or packing under, as may be 
 most desirable,- 
 
28 
 
 REFRIGERATION 
 
 We may now examine the top of the compressor and the 
 bottom of the stuffing box to determine whether or not these are 
 central. By shimming or packing under the side of the com- 
 pressor, the cylinder and the stuffing box may be moved in the 
 
 required direction; this will be found all that is necessary to 
 
 correct the small inaccuracies. Of course, should objection be 
 
 raised to the method, the other remedy is to dress the surfaces. 
 
 Having the different parts in proper alignment, we may now 
 
REFKIGEKATIOff 29 
 
 proceed with the assembling of the balance of the machine, feeL 
 ing assured that with reasonably good workmanship and material, 
 we will have a good running machine. It is well to have a com- 
 pressor stuffing box of any of the several types in two parts or 
 double packed (see Fig. 13), the inner to be of proper proportion 
 to hold the packing against the loss of ammonia and the outer of 
 only slight depth to retain the lubricating oil within the annular 
 space provided between the two, and through which the rod passes 
 in its travel. The packing may be drawn up or tightened by any 
 one of several common devices, although a parallel device or one 
 which causes the gland to move uniformly by tightening at one 
 point is to be preferred. Although three or four separate bolts 
 are very often used they are undesirable from the fact that they 
 may cause a tipping or "cocking" due to the tightening or 
 loosening of one. 
 
 There are innumerable materials for packing, and the " pack- 
 ing man " is encountered every day extolling the "good qualities" 
 of his packing. It is probable that all have good points, but it is 
 doubtful if any one make or kind would meet with the unqualified 
 indorsement of all engineers; also no one packing is best for all 
 conditions or duties. The condition and packing must be suited to 
 one another; this will generally be accomplished by the good 
 engineer. 
 
 In the construction of the stuffing box it is well to bush the 
 bottom of the glands with Babbitt metal, because the rod is often 
 pressed to one side crowding it against the side of the gland 
 or bottom of box, causing the same to cut. When it becomes 
 necessary to turn down the rod, a new bushing is all that is nee- 
 essary to reduce the openings correspondingly. 
 
 Water Jacket. In the vertical single-acting type of com- 
 pressor, it is usual to provide a water jacket, which may be cast 
 in combination with the compressor cylinder or made of some 
 sheet metal secured to an angle, which is bolted to a flange cast 
 on the cylinder. It is usual to have this water jacket start at 
 about the middle of the compressor (or a little below as shown 
 in Fig. 15) and extend enough above to cover the compressor 
 heads, valves and bonnets with water; the principal object of 
 Which is to keep these parts at a normal temperature and thereby 
 
30 
 
 BEFEIGEKATIOK 
 
 improve the operation as well as protect the joints against the 
 excessive heat which would be generated by the continued com- 
 pression. It is also an advantage in the operation of the plant, 
 since by reducing the temperature in the compressor and adjacent 
 parts, the compressor is filled with gas of a greater density. It is 
 also true that the heat extracted or taken up by the water at 
 this point is a certain portion of the worK performed in the con- 
 denser and therefore not a waste. 
 
 In the operation of the plant it is well to have plenty of 
 water flow through the jackets, as 
 the cooler the compressors are kept 
 the better, but in plants in which 
 water is scarce the quantity may be 
 reduced correspondingly until the 
 overflow is upwards of 100 Fahr. 
 In extreme cases of shortage of water 
 the overflow water from the ammonia 
 condenser is sometimes used on the 
 water jackets, that is, the entire 
 amount of available water is deliv- 
 ered to the condenser, and a supply 
 from the catch pan (if it be an at- 
 mospheric type) is taken for the water 
 jackets, in which case a greater quan- 
 
 Fig. 15. 
 
 tity may be used but at a higher temperature. It is customary 
 to admit the water through the flange forming the bottom of the 
 water jacket and overflow near the top into a stand pipe which is 
 connected at its lower end through the flange to a system of pipes 
 to take it away. To prevent condensation on the outer surface of 
 the jacket, and to present a more pleasing appearance, it is fre- 
 quently lagged with hardwood strips and bound with finished 
 brass or nickel-plated bands. It is also well to have a washout 
 connection from each jacket. 
 
 Lubrication. The vertical type of compressor requires the 
 least amount of lubrication from the fact that all moving parts are 
 in equilibrium. The slight amount of oil used is merely to keep 
 the surfaces from becoming entirely dry. Excessive lubrication 
 is an objection, owing to the insulating effect upon the surfaces 
 
EEFKIGEKATICW 
 
 31 
 
 of the condensing and evaporating system. Therefore it is well 
 to feed to the compressors as little as is consistent with the opera- 
 tion of the machinery. A proper separating device should be 
 located in the discharge pipe from the compressor to the con- 
 denser. To properly admit, or feed the lubricant to the com- 
 pressors, sight feed lubricators should be provided, by which the 
 amount may be determined and regulated. These may be of the 
 
 Fig. 16, 
 
 reservoir type, or better still the droppers, fed from a large reser- 
 voir through a pipe and which may be filled by a hand pump 
 when necessary (see Fig. 16). Owing to the action of ammonia 
 on animal or vegetable oils, other than these must be used as a 
 lubricant for the compressor. The principal oil for this purpose 
 (and when obtained pure, a very good one) is the West Virginia 
 Natural Lubricating Oil or Mount Farm, which is a dark-colored 
 oil not affected by the action of the ammonia or the low tempera- 
 ture of the evaporator. Of late years the oil refining companies 
 have put on the market a light-colored oil which appears to give 
 good results for the purpose. Care should be used, however, iw 
 
32 KEFKIGEKATION 
 
 the selection and oil should not be used unless it is of the proper 
 grade, as serious results follow the use of inferior oils. The usual 
 result is the gumming of the compressors and valves or the 
 saponifying under the action of the ammonia through the system. 
 
 LOSSES. 
 
 Having described the compressor and its parts, let us take up 
 the losses due to the improper working or assembling of the 
 parts of the machine, before proceeding with the description of 
 the rest of the plant. As has been stated in a general way, the 
 economy of the compressor lies in its filling at the nearest possible 
 point to the evaporating pressure and then compressing and dis- 
 charging at the lowest possible pressure, as much of the entire 
 contents of the cylinder as possible. If the compressor piston 
 does noc travel close to the upper end (of a single-acting ma- 
 chine) or the machine has excessive clearance, the compressed gas 
 remaining in the cylinder re-expands on the downward stroke of 
 the piston and gas from the evaporator will not be taken into the 
 compressor until the pressure falls to, or slightly below, this point, 
 and the loss due to this fault is equal to the quantity of gas thus 
 prevented from entering the compressor plus the friction of the 
 machine while compressing the portion of the gas thus expanding. 
 
 If we make a full discharge of the gas and there is a leaky 
 outlet valve in the compressor, the escape and re- expansion into 
 the compressor affects not only the intake of the gas at the begin- 
 ning of the return stroke, but continues to affect the amount of 
 incoming gas during the entire stroke and the capacity of the ma- 
 chine will be correspondingly reduced. If the inlet valve is leaky 
 or a particle of scale or dirt becomes lodged on its seat, as the 
 piston moves upward the portion of the gas which may escape 
 during the period of compression is forced back to the evaporator 
 and a corresponding loss is the result. A piston which does not 
 fit the compressor,' faulty piston rings, or a compressor which has 
 become cut or worn to the point of allowing the escape of gas 
 between the cylinder and piston has the same effect as the ill 
 conditioned suction valve. The loss due to leaky or defective 
 cylinders, joints or stuffing boxes, are not included under this 
 head as these more generally effect the loss of the material than 
 the efficiency of the compressor. 
 
KEFKIGEKATIOST 
 
 33 
 
 To present graphically the losses due to the above causes 
 refer to Fig. 17, which illustrates the usual indicator card taken 
 from an ammonia compressor and the effect upon it of the various 
 
 The different mechanisms employed in actuating the com- 
 pressor piston, such as crossheads, connecting rods, pins, crank 
 shaft and bearings, are of usual engine practice. A detailed 
 description will not be given here. It should be stated that owing 
 to the steady load and the continuous service usually demanded of 
 
 Fig. 17. 
 
 a refrigerating plant, and the occasional high pressures encount- 
 ered in the extremely warm W3ather, the construction should be 
 of the best and the wearing surfaces ample to withstand the hard 
 service. The many types of machines and the methods of connect- 
 ing the power or engine are of almost endless variety. It is suf- 
 ficient to state that the general classes of engines are of vertical or 
 horizontal single-cylinder, tandem or cross compound, condensing 
 or non -condensing. 
 
 The horizontal double-acting compressor embodies all the 
 general principles of the vertical single-acting, but having certain 
 modifications to meet the mechanical differences presented. They 
 may be divided into two classes, those having water jackets and 
 
84 KEFRIGEKATION 
 
 those without. The former usually has a water jacket extending 
 about the body of the cylinder but not over the heads and valves 
 as in the single-acting compressor. Compressors not provided 
 with water jackets are internally cooled either by evaporation of a 
 portion of the ammonia, or the injection of ammonia or cooled oil. 
 The claims of both these last named systems are that instead of 
 the curve of compression being close to .the adiabatic it is brought 
 nearly to the isothermal, and that a corresponding economy in 
 horse power required to operate the machine is effected. Owing 
 to the fact that this type of compressor takes in and discharges 
 gas in both directions, it is necessary that inlet and outlet valves 
 be provided in both heads, and that the inner head be provided 
 with a stuffing box also for the piston rod. This renders it im- 
 possible to place the valves horizontally, and as a result, the valves 
 are placed at an angle of from 30 to 45 from the center of the 
 compressor, and the inner face of the heads and pistons made on 
 an angle to conform to this; or sometimes the valves are spherical, 
 to avoid clearance which would result from the difference in their 
 surfaces. The weight of the piston and rod being towards the 
 bottom of the cylinder, it is necessary that the piston be of con- 
 siderable length to provide a greater surface for wear. 
 
 The stuffing box must have sufficient depth to successfully 
 retain the gas .during the period of compression, and lubrication 
 should take place while the rod is passing through the packing. 
 This is accomplished with a small oil pump actuated from the 
 moving parts of the machine or a pressure system regulated by 
 the pressure in the oil separator. In each case oil passes between 
 the double packing thereby causing the piston rod to pass through 
 a chamber of oil. 
 
 The compressor valves and their cages are of the description 
 already given and the same care and caution regarding the con- 
 struction and operation apply to the valves of this type of 
 machine, but the fact that they are horizontal or nearly so makes 
 their construction somewhat different and necessitates springs of 
 different strength. The valves, cages and springs are covered by a 
 dome bolted in place and its union with the compressor head is 
 provided with a gasket to prevent loss of ammonia, it is well to 
 have at hand duplicates of the compressor valves and springs, as 
 
REFRIGERATION 35 
 
 an entire valve can be changed in less time than it takes to repair 
 one out of order. As the machine during this time must remain 
 out of service, it is customary for the builders to supply these in 
 duplicate. After a valve is taken out and replaced, it is well to 
 have the faulty one put in perfect condition, the strength of 
 springs tested, the seat and stem corrected, oiled and put away in 
 readiness to be used again when the occasion requires. 
 
 This type of compressor is usually driven from a rotating 
 shaft with the ordinary connecting rod by a crank and crosshead. 
 Adjustment for wear is provided in the piston rod at the cross- 
 head, and the position of the piston may be adjusted between the 
 heads of the compressor by screwing in or out of the crosshead. 
 The clearance of the compressor piston is important; it should be 
 as small as possible and yet not allow the piston to strike the 
 heads. This naturally cannot be reduced to the small degree pos- 
 sible in the single-acting type, from the fact that it must be ad- 
 justed to both heads, and the expansion and contraction of the 
 piston and connecting rod and wear is of such an amount as to 
 render a close adjustment impossible. Fig. 18 is a sectional cut 
 of a modern type of double-acting compressor with water jacket; 
 Fig. 4 a section of one not using the' water jacket and Fig. 10 an 
 elevation of either in combination with its motive power, a Corliss 
 engine, shaft, fly wheel, etc. 
 
 The stuffing-box oil pump is shown in Fig. 16 which illus- 
 trates the general method of lubricating the compressor piston, the 
 oil being pumped through the box and returning to a catch pan 
 or basin provided in the bed plate. 
 
 THE AMMONIA CONDENSER. 
 
 The Ammonia Condenser, or liquefier, as briefly stated in the 
 description of the system, is that portion of the plant in which the 
 gas from the evaporator, having been compressed to a certain 
 point, is cooled by water and thereby deprived of the heat which 
 it took up during evaporation ; consequently it is reduced to its 
 initial state, that is, liquid anhydrous ammonia. Let us consider 
 the general principles governing the action before describing the 
 types. On account of the duty having been performed, the 
 ammonia as it leaves the evaporator is a gas of low temperature, 
 
36 
 
 REFEIGEEATION 
 
 usually 5 to 10 below that of the 
 brine, or other body upon which 
 it has been doing duty, yet it is 
 laden with a certain amount of 
 heat, although at a temperature 
 not ordinarily expressed by that 
 term. It is a well-known fact 
 that we cannot obtain a refriger- 
 ating agent which can absorb heat 
 from a body colder than itself, 
 and it is therefore , necessary to 
 bring the temperature of the am- 
 monia gas to a point at which the 
 flow of heat from the one to the 
 other will take place. This is 
 done by withdrawing part of the 
 heat in the ammonia in the fol- 
 lowing manner: The cold gas is 
 06 compressed until its pressure 
 ti reaches such a point that at ordi- 
 fe nary temperatures it will condense 
 to liquid form. As it leaves the 
 compressor it is very hot because 
 t)f the fact that it still 'Contains 
 nearly all of the heat it had when 
 it left the evaporator in only a 
 small portion of the space occu- 
 pied before. Thus when it reaches 
 the condenser it is much warmer 
 than the cooling water and will 
 readily give up its heat to the 
 cold water so much that its la- 
 tent heat is absorbed by the water 
 and it condenses into anhydrous 
 ammonia. 
 
 The temperature of water if 
 pumped ironi surface streams will 
 average about 60 F and since we 
 
KEFKIGEEATION 
 
 37 
 
 cannot expect to get the ammonia any colder than this it must be 
 compressed until the boiling point corresponding to the pressure 
 obtained is at about 75 F. 
 
 In the table, page 78, we find that this temperature corre- 
 sponds to a pressure of 144.25 pounds per square inch (absolute) or 
 126.55 pounds per square inch (gauge). 
 
 Thus if the gas is compressed until the gauge reads 126.55 
 and then passed into a condenser where the temperature of tha 
 water is less than 75 F the water will absorb the latent heat and 
 we have accomplished our object which was to remove some of 
 the heat contained in t he ammonia. In this condition it is drained 
 from the condenser into the ammonia receiver to again repeat the 
 cycle of operation. 
 
 E 
 
 /" 
 
 Fig. 19. 
 
 The forms of condenser may be divided into three classes; 
 the submerged, atmospheric, and double-pipe. Of each of these 
 classes a number of different types and constructions are in use. 
 To illustrate the general principles, however, it is only necessary 
 to present one of each type. 
 
 The Submerged Condenser consists of around or rectangular 
 tank with a series of spiral or flat coils within joined to headers at 
 top and bottom with proper ammonia unions. In Fig. 19 is 
 shown a sectional elevation of a popular type of submerged con- 
 denser. A wrought iron or steel tank A is formed by plates from 
 -j^- to T 5 g- inch thick, of the necessary dimensions to contain the 
 coils, and sufficiently braced around the top and sides to prevent 
 bulging when filled with water. A series of welded zigzag pipe 
 
88 
 
 EEFKIGEEATION 
 
 coils B are placed in the tank and joined to headers with 
 ammonia unions D. The ammonia gas enters the top header 
 through the pipe E and an outlet for the liquefied ammonia is 
 provided at F with a proper stop valve. Water is discharged or 
 admitted to the tank at or near the bottom and overflows at outlet 
 
 M. It will be seen that in this type of condenser a complete 
 reverse flow of the current is effected, the gas entering at the top 
 and the liquid leaving at the bottom, while the water enters at the 
 bottom and leaves at the top, thereby bringing the coldest water 
 in contact with the coolest gas . and the warmer water in contact 
 
REFKIGERATION 89 
 
 with the incoming or discharged gas from the compressor, thereby 
 presenting the ideal condition for properly condensing ammonia. 
 
 Owing to the necessarily large spaces between the coils and 
 the distance between the bent pipes, the portion of water coming 
 in contact with the surface of the pipes must be small compared 
 with the total amount passing through; it is, therefore, uneconom- 
 ical as regards amount of water used. With water containing a large 
 amount of floating impurities the deposit on the coils is consider- 
 able, and not easily removed owing to the limited space between 
 the coils, and furthermore, the dimensions of the tank necessary 
 to contain the requisite amount of pipe for a plant of considerable 
 size is so great and its weight when equipped with coils and filled 
 with water requires such a strong support that its use is now lim- 
 ited to certain requirements and localities. 
 
 A better shape for a condenser of this type is one of consid- 
 erable height or depth, rather than low and broad. This is owing 
 to the fact that the greater the length of travel of the water arid 
 gas in opposite directions, the greater the economy. The number 
 of coils used should be such that the combined internal area of 
 the pipes equals, or exceeds the area of the discharge pipe from the 
 compressor. The circular submerged condenser is similar to the 
 above described except that the tank is circular and the coils bent 
 spirally. 
 
 The Atmospheric type of condenser most generally used ia 
 made of straight lengths of 2-inch extra-strong, or special pipe, 
 usually 20 feet long, screwed, or screwed and soldered into steel 
 return bends about 3J-inch centers and usually from eighteen to 
 twenty-four pipes high. The coil is supported on cast or wrought 
 iron stands and placed within a catch pan, or on a Water-tight 
 floor, having a proper waste water outlet and supplied with one of 
 the several means of supplying the cooling water over their sur. 
 faces. Stop valves, manifolds and unions connect with the dis- 
 charge of the compressor and the liquid ammonia supply to the 
 receiver. 
 
 In the manner of making the connections to this type of con- 
 denser and the taking away of the liquefied ammonia as well as in 
 the devices for supplying the cooling water, a great variety exists; 
 Fig. 20 represents a side elevation of an ammonia condenser with 
 
40 
 
 EEFEIGEEATION 
 
 the discharge or inlet of the gas from the compressor entering at 
 the top A and the liquid ammonia taken of? at the bottom B 
 while the water is supplied over the coils flowing down into the 
 
 catch-pan or water-tight floor where it accumulates and is taken 
 away by any of the usual means. It will be noticed that the flow 
 of the water and gas with this type of condenser is in the same 
 direction, the coldest water coming in contact with the warmest 
 
REFRIGERATION 41 
 
 ammonia. The temperature governing or determining the point 
 of condensation will be that of leaving the condenser, or at the 
 bottom pipe in which the liquid ammonia is withdrawn. Owing 
 to this arrangement it is not favorable to a low condensing pres- 
 sure or economy in the water used. Fig. 21 represents a type in 
 which an attempt is made to eliminate this undesirable feature, 
 and in which it is expected to use the waste from the condenser 
 proper, in taking out the greater part of the sensible heat from the 
 gas leaving the compressor. 
 
 The construction of this condenser is identical with that shown 
 in the preceding figure except that its uppermost pipe is continued 
 down and under the pipes forming the condenser proper; it passes 
 backward and forward in order that a large proportion of the heat 
 may be removed by the water from the condenser proper, before 
 the ammonia enters the condenser. A supplemental header is 
 sometimes introduced in connection with this pipe f<T emoving 
 any condensation taking place in it. 
 
 A third type of this coitdenser is shown in Fig. 22. In this 
 type a reverse flow of the gas and water takes place. The gas 
 enters the condenser through a manifold or header A at the bottom 
 and continues its flow upward through the pipes to the top; at 
 several points drain pipes are provided for taking off the condensa- 
 tion into the header B. The condensing water flows downward over 
 the pipes. The form is the most nearly perfect condenser of the class. 
 
 The atmospheric type is a favorite, and possesses many feat- 
 ures that make it preferred to the submerged. Its weight is a 
 minimum, being only that of pipe and supports and a small amount 
 of water. The sections or banks may be placed a favorable distance 
 apart to facilitate cleaning and repairs, while the atmospheric effect 
 in evaporating a portion of the condensing water during its flow 
 over the condenser, thereby obtaining the advantage of its latent 
 heat as well as the natural raise in its temperature, adds materially 
 to its efficiency. 
 
 The various devices for distributing the water over the con- 
 denser are numerous: 
 
 Fig. 23 represents the simplest and most easily obtained; a 
 simple trough with perforations at the bottom for allowing the 
 water t.g drip through to the condenser. 
 
REFRIGERATION 
 
 Fig. 24 is a modification of the one shown in Fig. 23. This 
 is intended to prevent the clogging of the perforations, by allow- 
 ing the water to flow into the space at one side of the partition, 
 and then through a series of perforations into the second, and 
 
 thence through a second set of perforations in the bottom to the 
 pipes in the condenser. 
 
 Fig. 25 is a type of trough, or water distributor, designed to 
 overcome the objections to a perforated form of trough, and the 
 consequent difficulties due to the clogging or filling of the perfora- 
 
KEFKIGEKATION 
 
 43 
 
 tions. As will be readily understood from the illustration, this is 
 also made of galvanized sheet metal with one side enough higher 
 
 Fig. 23. 
 
 Fig. 24. 
 
 than the other to cause the water to overflow through the V. 
 shaped notches or openings along the top of the straight or 
 vertical side of the trough, and down and off the serrated bottom 
 edge to the pipes. 
 
REFRIGERATION 
 
 The object of the serrated edges, as will be apparent, is tlie 
 more even distribution of the water, owing to the fact that while 
 it would be practically impossible to obtain a uniform flow of 
 water over a straight and even edge of a trough, particularly if 
 the amount is limited, it is an easy matter to regulate the flow 
 through the Y-shaped openings. 
 
 Fig. 26 is termed the "slotted water pipe." It is a pipe 
 slotted between its two ends, from which the water overflows to 
 the series of pipes below. It is good practice to lead the water 
 supply to a cast-iron box at the center, of the condenser, into the 
 
 Fig. 25. 
 
 sides of which is screwed a piece of pipe (usually 2-inch) reaching 
 the ends of the condenser, and having its outer ends capped, which 
 may be removed while a scraper is passed through the slot from 
 the center towards the ends while the water is still flowing, 
 thereby carrying off any deposit within the pipe. This forms a 
 very durable construction, and not liable, as with the galvanized 
 drip trough, to disarrangement or bending out of shape due to 
 various causes. It is impossible, however, to obtain the uniform 
 flow of water over the condenser with this, as with the serrated or 
 perforated troughs, particularly if tfie supply is limited, from the 
 fact as stated in describing the overflow trough, viz: the impossi- 
 bility of obtaining a sufficiently thin stream of that length. 
 
REFRIGEKATION 
 
 The Double=Pipe Condenser is a modern adaptation of an old 
 idea, given up owing to its complex construction and the imper- 
 feet facilities available for its manufacture. Also, like the Brine 
 Cooler, it has come into use with great rapidity, and has brought 
 forth many novel ideas of principle and construction. It com- 
 bines the good features of the atmospheric as well as the sub- 
 merged; as in the former the weight is small and it is accessible 
 for repairs. It has the downward flow of the ammonia and up- 
 ward flow of the water, effecting a complete counter flow of the 
 two. minimizing the amount of water required and taking up the 
 
 O 
 
 Fig. 26. 
 
 heat of condensation with the least possible difference between the 
 ammonia and water. 
 
 The two general forms of construction are a combination of a 
 IJ-inch pipe within a 2-inch pipe, or a 2-irich pipe within a 
 3-inch. The water passes upward through the inner pipe, while 
 the gas is discharged downward through the annular space; or, 
 the position of the two may be reversed, the ammonia being 
 within the inside pipe while the water travels upward through the 
 annular space. They are also constructed in series, in which the 
 gas enters a number of pipes of a section at one time, flowing 
 through these to the opposite end to a header or manifold, at 
 which point the number of pipes is reduced, and so on to the 
 
BEFKIGERATION 
 
REFKIGEEATION 
 
4S 
 
 REFEIGEEATIOK 
 
 Vinr! Inorf "nnr! FSrf 'nnr{__5^y 
 
REFRIGERATION 
 
 bottom with a constantly reduced area. The theory of this con- 
 struction being that the volume of the gas is constantly reduced 
 as it is being condensed. 
 
 Figs. 27, 28 and 29 illustrate a general range of the various 
 types in use. 
 
 It is usual in the construction of this type to make each 
 section or bank twelve pipes high 
 by about 17J feet long; they are 
 rated nominally at ten tons refrig- 
 erating capacity each, although for 
 uneven units the construction is 
 made to vary from 10 to 14 pipes 
 in each. 
 
 The Oil Separator or Interceptor 
 is a device, or form of trap, placed 
 on the line of the discharge between 
 the compressor and the condenser to 
 separate ths oil from the ammonia 
 gas. It is to prevent the pipe sur- 
 face of the condensing and evapor- 
 ating system from becoming covered 
 with oil which acts as an insulator 
 and prevents rapid transmission of 
 heat through the walls. 
 
 The construction admits of quite 
 a variety of principle, from the plain 
 cylindrical shell with an inlet at one 
 side or end and an outlet at the 
 other, to the almost endless variety 
 of baffle plates, spiral conductors 
 and reverse-current devices. The 
 object is similar to that of the 
 
 Fig. 30. 
 
 or exhaust separator, and generally speaking, that which would 
 be effective in one service would be so in the other. Figs. 30, 31 
 and 3 2 illustrate three of the most common types in use; from these 
 the student will understand the general principles. 
 
 AMMONIA RECEIVER. 
 
 The Ammonia Receiver or Storage Tank is a cylindrical shell 
 
50 
 
 KEFBIGEKATIOlSr 
 
 with heads bolted or screwed on, or welded in each end, and pro. 
 vided with the necessary openings for the inlet and outlet of the 
 ammonia, purge-valve and gauge fittings. They may be vertical 
 or horizontal ; the former type is generally used on account of the 
 saving of floor space, while the horizontal is necessary when the 
 condenser is located so low as to make the flow of the liquid 
 ammonia into the vertical type impossible. A convenient location 
 for the receiver in a plant in which the condenser is located above 
 
 the machine room, is 
 against the wall, or at 
 one side of the room 
 on a bracket or stand 
 at one side of the oil 
 interceptor, the sizes 
 of the tw r o beinof efen- 
 
 o o 
 
 arally the same. They 
 are then more readily 
 under the control of 
 the engineer than if at 
 some out of the way 
 place. 
 
 Fig. 33 illustrates a 
 receiver of the verti- 
 cal type with the usual 
 valves and connec- 
 tions for the proper 
 equipment. The liq- 
 uid ammonia enters at 
 the top and is fed to 
 the evaporator from 
 the side near the bot- 
 tom, the space below 
 this opening being 
 provided for tha accumulation of scale, dirt, or oil, and means are 
 provided for drawing off through the purge valve in the bottom. 
 
 PIPES, VALVES AND FITTINGS. 
 
 Pipes. Extra strong, or extra heavy pipe (so called) is the 
 generally accepted pipe for connecting the various parts of the 
 
 Fig. 31. 
 
 Fig. 32. 
 
EEFKIGEKATIOff 
 
 51 
 
 refrigerating system. "Wrought- iron pipe is generally preferred 
 to steel. Frequently, however, and particularly for the evapor- 
 ating or low-pressure side of the system, a special weight or grade 
 of pipe is used, also standard or common pipe is sometimes em- 
 ployed for this purpose. Without knowing the particular condi- 
 tions under which this is to be used, or the relative value of the 
 material, or manner in which the pipe is made, it is always better 
 to use and insist on having the standard extra-strong grade. The 
 threads should be carefully \jut, with a 
 good sharp die, making sure that the top 
 and bottom of the threads are sharp and 
 true. With this precaution, and an 
 equally good thread in the fitting, it is 
 not difficult to form a good and lasting 
 joint. Particular care should also be 
 taken that the pipe screws into the 
 fitting the proper distance, and forms a 
 contact the entire length, rather than to 
 
 O ' 
 
 screw up against a shoulder without 8 
 perfect fit in the thread. This latto? 
 often causes leaky joints sometime after 
 the plant has been operated the" tempo- 
 rary joint formed by screwing in too 
 deep against the shoulder or ill-fitting 
 threads very often passes the test and is 
 used for some time after until the com- 
 bined effect of heat and cold, and action 
 of the ammonia cause it to break out. 
 It is a safe rule that no amount of solder 
 or other doctoring that is not backed up 
 
 by a good fitting thread to support it can make an ammonia joint. 
 This is particularly true of the discharge or compression side of 
 the plant. 
 
 The manner of making these joints, may be divided into those 
 having a compressible gasket between the thread on the pipe and 
 the fitting into which it screws and the screwed joint formed by a 
 threaded pipe screwed into a tapped flange or fitting. The latter 
 may be divided into those having a soldered joint, or one in which 
 
REFRIGERATION 
 
 the union is formed by the threads only, with some of the usual 
 cements to assist in making a tight joint. 
 
 The two most prominent types of gasket fittings are shown iu 
 Fig. 34 and 35. The former is known in this 'country as the 
 Boyle Union, and is extensively used. As will be observed, the 
 drawing together of the two glands by the bolts, compresses the 
 
 gaskets, (usually rubber) 
 against the threaded sides 
 of the pipe, the bottom 
 and sides of the recess in 
 the flanges, and the edges 
 of the ferrule between the 
 two gaskets. 
 
 Fig. 35 represents a 
 union or joint quite fre- 
 quently used, although not 
 as commonly as the former, , 
 In this the pipe is threaded 
 and screwed into the body 
 of the fitting, but not to 
 form an ammonia-tight 
 joint; leakage is prevented 
 by a packing ring com- 
 pressed by the gland against 
 the pipe thread and the 
 walls of the recess. 
 
 In Fig. 36 (a type ol 
 ammonia coupling), the 
 contact between the pipe 
 and fitting is made to with. 
 stand the leakage of the 
 gas without the aid of pack- 
 ing or other material other than solder or some of the usual 
 cements; the two flanges are bolted together with a tongue and 
 grooved joint having a soft metal gasket. This makes a permanent 
 and durable fitting. 
 
 Other fittings of the class, as ells, tees, and return bends, are 
 usually provided with one of the above methods of connecting with 
 
 34 t 
 

 "I 
 
 W HH 
 
REFRIGERATION 
 
 53 
 
 the system, and the different types described may be obtained of 
 the builders of refrigerating machines. 
 
 Valves for the ammonia system of a refrigerating plant are of 
 special make and construction, being of steel or semi -steel, with a 
 soft metal seat which maybe renewed when worn, and metal gaskets 
 between the bonnets and flanges. 
 
 The usual types are Globe, Angle and Gate, subdivided into 
 screwed and flanged. Fig. 37 is a generally adopted type of the 
 flanged globe ammonia valve, while Fig. 38 represents the angle 
 valve of the same construction. This seems to represent the best 
 elements of a durable and efficient valve. 
 
 Fig. 35. 
 
 For a valve or cock requiring a fine adjustment as is frequently 
 the case in direct -expansion systems, particularly where the length 
 of the evaporating coil or system is short, a Y-shaped opening is 
 desirable. Fig. 39 represents a cock for this purpose which will 
 be found to be effective and meet the most exacting requirements. 
 
 Pressure Gauges. Two gauges are necessary for an ammonia 
 plant of a single system; one to indicate the discharge or con- 
 densing pressure, and one for the evaporator or return gas pressure 
 to the compressors. 
 
 Owing to the action of ammonia on brass and copper the 
 gauges for this purpose differ from the ordinary pressure gauge in 
 that it is made with a tube and connections of steel instead of brass, 
 and this construction is the general choice of gauge makers; in 
 other respects the construction is similar. For machines of small 
 
REFRIGEKATION 
 
 capacity instruments with 6 -inch dials are common, while for larger 
 plants 8 -inch is the generally adopted size. The graduation for 
 the high pressure gauge is usually to 300 pounds pressure, and if 
 a compound gauge is used, it is made to read to a vacuum also. 
 This latter is only needed on certain occasions and frequently 
 omitted from the high-pressure gauge. Owing to the necessity of 
 removing the contents of the system at certain times and usually 
 through the evaporating side of the plant, the gauge for this 
 
 portion of the system is graduated 
 to read from a vacuum to 120 pounds 
 pressure. 
 
 In connecting the gauges to the sys- 
 tem, it is customary to locate the 
 opening in the discharge and return 
 gas lines near the machine within the 
 engine room, placing a stop valve at 
 some convenient point and carrying 
 a line of ^ or -J inch extra strong 
 pipe to the gauges, making the joints 
 with the usual ammonia unions. On 
 account of the possibility of leakage 
 of ammonia gas from the gauge tube, 
 it is often considered advisable to fill 
 the gauge pipe with oil (of the kind 
 used for lubricating the ammonia 
 compressor) for a short distance above 
 the gauges, upon which the pressure 
 of the gas will act, causing the gauge 
 to move properly but without allowing the ammonia gas to enter 
 the gauge. This is an application of the same principle as the 
 steam syphon or bent-pipe arrangement in use with steam gauges, 
 for the purpose of keeping the heat and action of steam from the 
 gauge mechanism by the retaining of water in the gauge con- 
 nection. 
 
 Other gauges used about the refrigerating plant are of the 
 ordinary pressure or vacuum types and do not need a special de- 
 scription, as their construction and manner of applying to the 
 different parts of the system are well known to the engineer. It 
 
KEFKIGEEATION 
 
 Fig. 37. 
 
KEFKIGEEATION 
 
 may be well, however, to caution the user on the importance of 
 testing the gauges often enough to be sure they are accurate, as 
 serious damages may result from a wrong indication of pressure. 
 
 BRINE. 
 
 Brine is used in refrigeration as a medium for the transmis- 
 sion of heat from the point or object 
 to be refrigerated, to the ammonia or 
 other refrigerant, and accordingly may 
 be found in plants in which the appli. 
 cation is indirect. 
 
 In the refrigerating practice of today, 
 two kinds of brine are in use, chloride 
 of calcium, and chloride of sodium 
 (common salt). Either one is dissolved 
 in water making a solution of the 
 proper density; it is then pumped from 
 the brine tank or cooler to the objects to 
 be refrigerated, and returned by a sys- 
 tem of pipes to be recooled and again 
 circulated through the refrigerating 
 system. 
 
 Chloride of calcium brine may be 
 made of such density that its freezing 
 point is 54 Fahr. (54 below zero) 
 while chloride of sodium (salt) brine of 
 maximum density or strength freezes 
 at Fahr. It will, therefore, be seen 
 that for very low temperatures calcium 
 brine should be used. For brine 
 coolers in which the briiie passes 
 through the pipes, and the ammonia is 
 evaporated on the outside with a tern- 
 perature of a few degrees below zero, and the brine not in active 
 circulation, salt brine would be frozen, bursting the pipes and 
 
 causing a considerable loss. The calcium brine may be made of 
 such density or strength as to make this impossible. It will, 
 therefore, be evident that for use in connection with a brine 
 
 Fig. 39. 
 
BEFRIGEEATION 57 
 
 cooler, the chloride of calcium brine is necessarily the choice 
 It also has no corroding effect on pipes, pumps or other connec- 
 tions, and while the cost is somewhat more than that of salt, the 
 general advantages are decidedly in its favor. 
 
 For the brine tank and coil system of refrigeration salt brine 
 may be safely used, and is largely used at the present time. The 
 evaporation of the ammonia, being within the pipes, can only 
 effect the freezing of a small portion on the outer surface, and 
 without damage to the plant. As its temperature may be reduced 
 to zero, or even below (if circulation be maintained) it is effective 
 for practical purposes wherein the temperature required is not 
 below that point. The proper density, or strength of brine, either 
 calcium or salt is determined by the temperature to which it is 
 necessary to be reduced, and the tables on pages 79 and 80 will be 
 found valuable in determining the proper strength for different 
 requirements. It should be remembered, however, that a differ- 
 ence of from 5 to 10 Fahr. exists between the temperature of 
 the brine and that of the evaporating ammonia, and that while the 
 strength of the brine may appear ample for the temperature at 
 which it is carried, the lower temperature of the evaporating 
 ammonia may cause it to solidify within or upon the surface of 
 the evaporator, thus causing it to separate, or freeze, and act as an 
 insulator and prevent the transmission of heat through the surface. 
 It is, therefore, necessary in examining into the strength of the 
 brine, to consider it with reference to the evaporating pressure of 
 the ammonia as well as its own temperature. 
 
 In the last column of the tables is given the gauge pressure, 
 corresponding to the freezing point of the brine of different 
 strengths. 
 
 The usual and proper instrument for determining the strength 
 of brine is the Beaume scale, for chloride of calcium brine. A 
 weighted glass tube and bulb (Fig. 40) is graduated to 100, the 
 former being its floating point in w r ater and the latter the floating 
 point in a saturated solution of salt brine. By comparison of the 
 two in the table of calcium brine it will be observed that the ratio 
 of the two scales are as 1 to 4 which makes it possible to obtain 
 one from the other. 
 
 In using the scales it is customary to draw a sample of the 
 
REFRIGERATION 
 
 brine in a glass test tube, raising its temperature to approximately 
 60 Fahr. and insert the scale; it will then float at the point on its 
 scale corresponding with its strength. 
 
 Brine Systems. In the use of the foregoing tables for cal- 
 cium or salt brine, allowance should be made for the difference in 
 the grades obtained. The quantity required per gallon, or cubic 
 foot of brine, will vary accordingly. The average quantity required 
 however, should nearly correspond with the tables. 
 
 In making brine it is well to lit up a box with a perforated 
 false bottom, or, a more readily obtained and equally effective 
 mixer may be made by taking a tight barrel or hogshead, into 
 which is fitted a false bottom four to six inches above the bottom 
 head, and which is bored with one-half inch 
 holes. Over the false bottom lay a piece of 
 coarse canvas or sack to prevent the salt fall- 
 ing through. A water connection is made in 
 fjjj^jlijp the side of the barrel near the bottom, between 
 
 the bottom head and the false bottom, and a 
 controlling valve placed nearby to regulate 
 the amount of water passing through. An 
 overflow connection is made near the top of 
 the cask, with its end so placed that the brine 
 will flow into the tank, and a wire screen 
 placed across its end inside the cask with a 
 liberal space between it, and the opening, to 
 allow of cleaning. See Fig. 41. The cask or 
 barrel is now filled with the calcium or salt, 
 which dissolves and overflows into the brine 
 tank. 
 
 A test tube and Beaume scale, or salom- 
 eter, should be kept at hand, and frequent 
 tests made; the strength may be regulated 
 by admitting the water more or less rapidly. After the first 
 charge it is well to allow the mixer to remain in position for 
 future requirements. A connection should be made from the 
 return brine line from the refrigerating system to the cask, with a 
 controlling valve by the use of which the strength or density of the 
 brine may be increased without adding to the quantity, keeping 
 
 Fig. 40 
 
KEFKIGEKATION 
 
 59 
 
 the cask full of the calcium or salt, and allowing a portion of the 
 return flow of brine to pass through the cask, dissolving the con- 
 tents and flowing into the tank. 
 
 Calcium is usually obtained in sheet-iron drums, holding 
 about 600 pounds each; it is in the shape of a solid cake within 
 the drum. It is advisable to roll these onto the floor or top of 
 tank in which the brine is to be made and pounded with a sledge 
 hammer before removing the iron casing, this process breaking it 
 up into small pieces without its flying about the room. After 
 breaking it up the shell may be taken off and the contents shov- 
 
 into the mixer. 
 
 Fig. 41. 
 
 It is also sold and shipped in liquid form, in tank cars, 
 generally in a concentrated form (on account of freight charges) 
 and diluted to the proper point upon being put into the plant. 
 Where proper railroad facilities exist, this is probably the most 
 desirable way of obtaining the calcium. 
 
 Salt is sold and may be obtained in .a number of forms. The 
 usual shape for brine is the bulk, or in sacks of about 200 pounds 
 each. "Where it is possible to handle salt in bulk, direct from the 
 car to the tank, this is most generally used on account of the 
 price, being about $1.00, per ton less than if sacked. If it is 
 necessary for it to be carted or stored before using, the sacjs form 
 is preferable. The coarser grades of salt are used for this pur- 
 pose, No. 2 Mine being the grade commonly used. The finer 
 
60 REFRIGERATION 
 
 salts are higher in price, without a corresponding increase iu 
 strength of the brine formed. 
 
 The proper density or strength of the brine must be deter- 
 mined for various temperatures. As a rule its freezing point should 
 be equal to, or slightly below, the temperature of the evaporating 
 ammonia, rather than the temperature of the coldest brine, as is 
 common. Referring to the table of salt brine solution, page 80; 
 if we wish to carry a temperature of 10 Fahr. in the outgoing 
 brine, it is necessary that the temperature of the evaporating am- 
 monia be from 5 to 10 degrees below that point, in order that 
 the transfer of heat from the brine to the ammonia will be rapid 
 enough to be effective, which would mean that the ammonia would 
 be evaporating at a temperature of practically Fahr. To pre- 
 vent the brine freezing against the walls 'of the evaporator its 
 strength or density should be made to correspond with this, or 
 from 95 to 100 on the salometer. This should be cared for 
 more especially in connection with plants using the brine cooler, in 
 which the brine is within the coil, than in the brine tank system 
 in which the ammonia is inside the pipe and the brine outside; 
 here the only danger or loss would be in efficiency. 
 
 In examining into the causes of failure in a plant to perform 
 its usual or rated capacity, it is advisable, unless there is every 
 evidence that the trouble is elsewhere, to make an examination of 
 the brine and determine that its strength and condition is suited 
 to the duty to be performed. 
 
 DIRECT EXPANSION. 
 
 As its name would imply, this system of refrigeration is one 
 in which the refrigerant is expanded or evaporated in direct contact 
 with the duty to be performed, without an intermediate agent for 
 the transfer of the heat. Its application admits of quite a variety 
 of apparatus to meet the requirements of refrigerating practice, the 
 most general of which is the expansion within a pipe system placed 
 in a room to be refrigerated, or within or between a series of pipes 
 over or within which the substance to be refrigerated is passed. 
 
 While the former system admits of a variety of arrangements 
 of the pipes within the room or chamber to be refrigerated, it is 
 confined to the simple principle, however, of the evaporation of the 
 refrigerant within the pipes, by the transfer of heat through the 
 
REFRIGERATION 
 
 61 
 
 walls of the pipe, thereby reducing the temperature in the room or 
 chamber to the desired point, and for certain purposes is a very 
 satisfactory means of producing the desired results. This is prin- 
 cipally true with large rooms in which the temperature and duty 
 to be performed is constant, such as a brewery, packing house, and 
 cold-storage rooms. For rooms requiring an unusually low tem- 
 perature, as freezers of fish and poultry, direct expansion is desir- 
 able, because it is possible to more nearly reach the temperature of 
 
 Fig. 42. 
 
 the refrigerant direct, than with an intermediate agent, as brine; 
 this is due to the fact that there must necessarily be a difference of 
 from 5 to 10 between the temperatures. 
 
 Fig. 42 illustrates a direct expansion construction in which the 
 liquid anhydrous ammonia is expanded by the valve or cock A into 
 the coil or system of pipes B and the gas returning to the com- 
 pressor through the pipe C. 
 
 Fig. 43 represents a fish-freezing room on either side of which 
 is arranged a series of pipe shelves, through which the ammonia is 
 evaporated. The fish are laid on tin trays and placed on the pipe 
 
KEFK1GEKAT1OK 
 
 shelves until the room is filled. It is then closed, the ammonia 
 turned on and left until the freezing has been accomplished. 
 
 It is apparent from the arrangement of the coils being both 
 above and below the trays holding the fish, and close together, that 
 the effect must be very rapid. 9 
 
 In the cooling of J?eer^or other liquids, two forms of apparatus 
 are used : one (the most common), being a series of a 2-inch pipe with 
 return bends, stands, etc., over which the liquid to be cooled is flowed 
 
 Fig. 43. 
 
 and within which the ammonia is evaporated, the product being 
 accumulated in an iron pan or other receptacle in which the cool- 
 ing pipes are placed. In brewery practice it is customary to pro- 
 vide a double series of coils, one above the other, cold water being 
 circulated through the upper section, and the ammonia through 
 the lower, the effect of which is first to remove the heat from the 
 wort as far as possible by the use of water, and the remainder of 
 the cooling being accomplished by the evaporation of the ammonia. 
 This apparatus is called the Baudelot Cooler and is illustrated in 
 Fig. 44. 
 
 Fig. 45 represents a section of a double -pipe cooler for water 
 or other liquids and is similar to the form of double-pipe con- 
 denser or cooler already described. It varies only in the construc- 
 tion of the inner tube which is corrugated to prevent bursting by 
 freezing, which becomes possible when used to cool a congealable 
 
.REFRIGERATION 63 
 
 liquid. In the operation of this type of cooler, when used as an 
 evaporator or direct -expansion cooler, it is usual to reverse the 
 two currents, by feeding or expanding the ammonia into the bot- 
 tom of the coil the gas issuing from the top, while the liquid to 
 be acted upon enters at the top of the coil and issues from the 
 bottom. This type of cooler is largely used in cooling carbonated 
 ale, as it must be kept from the atmosphere, and for cooling drink- 
 ing water in circulating systems now installed in hotels, office 
 buildings and department stores. 
 
 Purging and Pumping out Connection. A common cause of 
 failure to operate properly and effectively is the introduction of 
 some foreign substance into the system. This will be readily 
 understood and appreciated by engineers and those familiar with 
 the requirements of a steam boiler. Clean surfaces on the shell 
 or tubes are necessary for the maximum evaporation of water, or 
 the transfer of heat through the walls of pipe or other forms of 
 heat-transmitting surface. The most common difficulty encoun- 
 tered in a refrigerating plant is oil, either in its natural condition, 
 or saponified by contact with the ammonia, water or brine. It 
 enters the system in many ways: through leakage, condensation in 
 blowing out the coils or system, foreign gas arising from decom- 
 position of the ammonia through excessive heat and pressure, or 
 the mingling of air which may enter the system through pumping 
 out below atmospheric pressure or the air may have remained in 
 the system from the time of charging, never having been fully 
 removed. It is also probable, though hard to determine with cer- 
 tainty owing to the various conditions surrounding the operation of 
 plants, that impurities are introduced with the ammonia, either as a 
 liquid, gas or air which afterwards becomes impossible to'condense. 
 
 The oil in a system forms a covering or coating on the evap- 
 orating surface which acts as an insulation and prevents the ready 
 transfer of heat through the walls of the evaporator. The pres- 
 ence of water or brine causes an absorption of a portion of the 
 ammonia into the water or brine, forming aqua ammonia which 
 raises the boiling point of the ammonia and causes material loss in 
 the duty. Air or other non -condensable gas in the system, excludes 
 an equal volume of the ammonia gas, thereby reducing the avail- 
 able condensing surface in that proportion. 
 
64 
 
 KEFEIGEEATIOK 
 
 For the purpose of cleaning the system and removing the 
 different impurities which may appear, purge and blow-off valve? 
 and connections are provided. One of these is placed at or nea) 
 the bottom of the oil interceptor, which is located between the 
 
 compressors and the condenser; it is used to draw of? the oil used 
 as a lubricant in the compressor and precipitated to the bottom. 
 This oil should not be allowed to accumulate to any great extent 
 as it may be carried forward to the condenser by the current of 
 the gas. 
 
REFKIGERATIOK 65 
 
 If the liquid ammonia receiver be placed in a vertical position 
 it is customary to place a purge valve in the bottom for drawing 
 off oil or other impurities. The supply of liquid to the evaporator 
 being taken off at a short distance above the bottom say 4 to 6 
 inches. 
 
 The next point for the removal of impurities is at the bottom 
 of the brine cooler, or lowe" manifold of the coil system in a brine- 
 tank refrigerator. These may be tried as often as necessary to 
 determine the state of cleanliness of the system. If the system is 
 charged with any of the common impurities, they should be blown 
 out and the system cleansed at the earliest possible moment, as 
 they cause a decided loss. 
 
 Air or foreign gases accumulate in the condenser because the 
 constant pumping out of the evaporating system tends to remove 
 them from that part of the system to the condenser. This point, 
 therefore, is the most natural place for their removal. For this 
 purpose it is customary on the best condensers to place a header or 
 manifold at the top at one end, and connect each of the sections or 
 banks with a valved opening. A valve is also placed at each 
 end of the header, and a connection from one end of this header 
 made to the return gas line between the evaporator and the com- 
 pressors. By closing the stop valves on the gas inlet and liquid 
 outlet of any one of the sections and opening the purge or pump- 
 ing-out line into the gas line to the compressors, the section or 
 bank may be emptied of its contents for repairs or examination 
 arid then connected up and put into service without shutting down 
 the plant, or a material loss of ammonia. For purging of air or gas, 
 the valve should be closed between this header and the machine, 
 and the valve on the opposite end opened to the atmosphere, the 
 valves on each section opened slightly in turn while the foreign 
 gases are expelled. This process should not be used while the 
 compressor is in operation, as the discharge of the ammonia into 
 the condenser would keep the gas churned to the extent that it 
 would become impossible to remove the foul gases, without remov- 
 ing a considerable portion of the ammonia also. 
 
 For this reason it is customary before blowing off the con. 
 denser to stop the compressor and allow the water to flow over the 
 condenser until it is thoroughly cooled. Sufficient time should 
 
EEFEIGEBATION 
 
REFRIGERATION 67 
 
 elapse for the ammonia to liquefy and settle towards the bottom, 
 while the air and lighter gases rise to the top, at which point they 
 may be blown out through the purge valve to the atmosphere. If 
 doubt exists as to whether ammonia or impurities are being blown 
 out attach a piece of hose to the end of the purge valve and im- 
 merse its other end in a pail of water. If it is air, bubbles will 
 rise to the surface, while if it is ammonia, it will be absorbed into 
 the water; the mingling of the ammonia with the water will cause 
 a crackling sound, and the temperature of the water will increase 
 owing to the chemical action. 
 
 TESTING AND CHARGING. 
 
 Having described the different parts of the refrigerating plant 
 and their relations to one another, let us consider the process of 
 testing and charging, or introducing the ammonia into the system. 
 After the connections are made between the different parts, whether 
 the system is brine or direct expansion, it is necessary to introduce 
 air pressure into it to determine the state of the joints. This may 
 be done in sections or altogether. It is customary, however, to put 
 a higher pressure on the compression side of the plant than on the 
 evaporator owing to the difference in the pressure carried in opera- 
 tion. Adjacent to each compressor is placed a main stop valve, on 
 both the inlet and outlet sides, while on either side of these it is 
 customary to place a by-pass or purge valve. 
 
 Before starting the compressor, the main stop valve or valves 
 (if there be two) on the inlet or evaporating side of the compressor, 
 is closed, the small valve between the compressor and the main 
 stop valve opened, and all of the other valves on the system opened 
 except those to the atmosphere. The compressor may then be 
 started slowly, air being taken in through the small by-pass valves 
 and compressed into the entire system. It is well to raise a few 
 pounds pressure on the entire system, before admitting water into 
 the compressor water jackets or other parts of the system, because 
 if a joint were improperly made up, it would be possible for the 
 water to enter the compressors, or coils of the condenser or evap- 
 orator, and serious damage or loss of efficiency in the plant occur 
 which it might be impossible to locate afterwards. While if pres- 
 sure exists within the system when the water is admitted, ltd 
 
68 KEFKIGERATIOJST 
 
 entrance into the coils or system is impossible while the pressure 
 exists, and the leak is at once visible, and may be remedied before 
 proceeding farther. 
 
 In starting the test it is also well to try the two pressure 
 gauges and see that they agree as to graduation, as it has occurred 
 that owing to a leakage between the discharge pipe and the high 
 pressure gauge, an enormous pressure has been pumped into the 
 system causing it to explode, resulting in loss of life and property. 
 If, however, the pressures are found to be equal on the two gauges 
 it is safe to assume that they are recording properly and their con- 
 nections are tight. After these preliminaries it is safe to put an 
 air pressure of 300 pounds on the compression side of the plant, 
 care being taken to operate the compressor slowly, not raising the 
 temperature of the compressed air too much, as with the utmost 
 care in making up joints and in selecting material, certain weak- 
 nesses may exist, and under such high pressure it is well to proceed 
 with caution. 
 
 After the desired pressure has been reached, the entire system 
 should be gone over repeatedly until it is absolutely certain that it 
 is tight. Parts which can be covered with water, such as a sub- 
 merged form of condenser or brine tank with evaporating coils, 
 should be so covered that the entire surface may be gone over at once 
 and with almost absolute certainty. The slightest leakage will 
 cause air bubbles to ascend to the surface ; they may be traced by 
 allowing the water to flow from the tank while the air pressure is 
 still on the coils or system, watching the points w T here it stops and 
 marking them, to be taken up or repaired when empty. For parts 
 which cannot be covered with water, it is customary to apply with 
 a brush a lather of such consistency that it will not run off too 
 readily; upon coming in contact with a leak, soap bubbles are 
 formed, and by tracing to the starting point the leak may be located. 
 After the compression system has been subjected to a pressure of 
 300 pounds and found to be tight, the air may be admitted through 
 the liquid ammonia pipe to the evaporating side of the plant, care 
 being taken that the pressure does not rise above the limit of the 
 gauge which as previously stated is usually 120 pounds and the 
 same process of testing as applied to the opposite side of the plant 
 gone over. 
 
KEFKIGERATION 69 
 
 Many engineers require the vacuum test as well as the fore- 
 going, and although if the former is gone over thoroughly, there can 
 be little chance of leakage afterwards, it is better to be over-exacting 
 than otherwise in the matter of testing and preparation of the plant, 
 thus preventing the possibility of leaks that may prove disas- 
 trous. Open the main stop valves on the inlet line and close the 
 main valves above the compressor on the discharge line, closing 
 the by-pass valves in the suction line, and opening those in the 
 discharge line between the main stop valve and the compressor. 
 Have all the other valves on the system open as before for testing. 
 Starting the compressor draws in the air filling the system through 
 the compressor and discharging it at the small valve left open. 
 Assuming the system to be tight, continuing the operation will 
 finally exhaust the air (or nearly so), when the small valves should 
 be closed and the pressure gauges watched to determine whether or 
 not leakage exists. 
 
 Assuming that the system and apparatus is tight in every 
 particular and that it is otherwise ready to be placed in operation, 
 we are now ready to charge the ammonia into the plant. 
 
 If the air has been exhausted from the system in testing, this 
 usual step need not be taken before charging, and it is only neces- 
 sary to put the machine in proper condition to resume the pump- 
 ing of the gas, and attach a cylinder of ammonia to the charging 
 valve to enable the refrigeration to be commenced. The main 
 stop valves above the compressor which were closed in expelling 
 the air should now be opened and by- pass and other valves to the 
 atmosphere closed. Close the outlet valve from the ammonia 
 receiver and start the machine slowly, at the same time opening 
 the feed valve between the drum of ammonia and evaporator. 
 The anhydrous liquid ammonia will flow into the evaporator 
 through the regular supply pipe, the gas resulting from. evapora- 
 tion being taken up by the compressors and discharged into the 
 condenser and finally settling down into the receiver, when a 
 sufficient quantity has been introduced to form a supply there. 
 Upon closing the valves between the drum from which the sup- 
 ply is being drawn, and opening the outlet valve from the re- 
 ceiver, the process of refrigeration by the compression system is 
 regularly in operation. 
 
70 EEFKIGEBATION 
 
 OPERATION AND MANAGEMENT OF THE PLANT. 
 
 Assuming that the plant has been properly erected, tested, 
 and charged with ammonia of a good quality, and (if a brine system) 
 with brine of proper strength or density, as already explained, it 
 only remains to keep the system or plant in that condition. As all 
 forms of- mechanism are liable to disarrangement and deterioration 
 from various causes, repairs and corrections from time to time 
 must be made to keep them in good condition. Let us now consider 
 the most important points requiring attention. 
 
 It is absolutely necessary for the good working of any type of 
 plant or apparatus that it be kept clean. As a steam boiler must 
 be clean to obtain the full benefit of the fuel consumed, so must 
 the surfaces of the condenser and evaporator be clean to obtain the 
 proper results from the condensing water and evaporation of the 
 ammonia or other refrigerant. 
 
 For satisfactory work the sjstem should be purged of any 
 foreign element present in. the pipes, such as air, water, oil, or 
 brine. Foreign matter is the most common among internal causes 
 for loss of efficiency, and the valved openings which have been 
 shown and described should be used for cleaning the system. 
 
 Oil is used as a lubricant in nearly if not quite all compres- 
 sors, and the quantity should be the least amount that will lubri- 
 cate the surfaces and prevent undue wear. This is considerably 
 less than the average engineer is inclined to think necessary, and 
 consequently a coating forms on the walls of the pipes or other 
 surfaces of the condensing or evaporating systems, and a propor- 
 tionate decrease in the duty obtained. It is also necessary that the 
 oil be of such a nature that it is not saponified by contact with the 
 ammonia. Such a change would choke or clog the pipes, coating 
 their surfaces with a thick paste which causes a corresponding loss 
 as the amount increases. The purge valve in the bottom, of the oil 
 interceptor may be opened slightly about once each week, and the 
 oil discharged from the compressors drawn off into a pail or can, 
 unless a blow-off reservoir is provided. After the gas with which 
 it is charged has escaped, the oil should be practically the same as 
 when fed into the compressors. If, however, the oil is not of the 
 proper quality it will remain thick and. pasty, or gummy, showing 
 
EEFKIGEKATIOJT 71 
 
 ;t to have been affected by the ammonia. Its use should not be 
 
 continued. 
 
 By opening the purge valves, which are usually provided at 
 the bottom manifold or header of the brine tank and the bottom 
 head of the brine cooler, oil or water, if any be in that part of the 
 system, may be drawn off. These valves, however, should not be 
 opened unless there is some pressure in that part of the system, as 
 air would be admitted if the pressure within the apparatus is 
 below that of the atmosphere. Air may enter the system through 
 a variety of causes and its presence is attended with higher con- 
 den sing pressure and a falling off in the amount of work performed. 
 For the removal of air from the apparatus a purge valve is placed 
 at the highest point in the condenser or discharge pipe from the 
 compressors near the condenser, which may be tried when the 
 presence of air or foreign gases is suspected. This should be done 
 after the compressor has been stopped. When the condenser has 
 fully cooled and the gases separated, a small rubber hose or pipe 
 may be carried into a pail of water and the purge Valve or valves 
 slightly opened. If air or other gases exist in the system bubbles 
 will rise to the surface of the water so long as it is escaping, while, 
 if ammonia is being blown off, it will be absorbed in the water 
 and not rise to the surface. 
 
 To prevent the possibility of air getting into the system, the 
 evaporating pressure should never be brought below that of the 
 atmospheric, or on the gauge, as at such times, with the least 
 leakage at any point, it is sure to enter. Should it become neces- 
 sary to reduce the pressure below that point, it is well first to 
 tighten the compressor stuffing boxes and allow the pressure to 
 remain below only the shortest possible time as not only air 
 may enter, but if it be ,the brine system and a leak exists, brine 
 also will be drawn in. 
 
 From the foregoing it is evident that in order to obtain satis- 
 factory results, the interior of the system must be kept clean by 
 purging at the different points provided for this purpose; and it 
 need only be added in this connection, that when the presence of. 
 oil or moisture becomes apparent in any quantity, the coils or 
 other parts should be disconnected and blown out with steam 
 until thoroughly clean and afterwards with air to make certain 
 
72 EEFKIGEEATIOK 
 
 that condensation from the steam does not remain, arter which the 
 parts may again be connected and tested ready for operation. 
 
 If the plant be a brine system it is necessary that the brine 
 be maintained at a proper strength or density to obtain satisfac- 
 tory results, for if it becomes weakened it freezes on the surfaces 
 of the pipes or evaporator, acting as an insulator and preventing 
 the rapid transmission of heat through the walls. 
 
 Frequently the engineers or owners in looking about for the 
 cause of a falling off in the capacity of a plant, overlook the fact 
 that the strength of the brine is the sole difficulty, and the addi- 
 tion of salt or chloride of calcium is a remedy. Referring to the 
 tables of brine solutions, there should be no difficulty in determin- 
 ing the proper strength of the brine for the different temperatures 
 at which the plant may be operating; but as already stated, this 
 should be made to correspond to the temperature of the evaporat- 
 ing ammonia rather than the temperature at which the brine may 
 be handled. 
 
 It is of great importance to know at all times whether or not 
 the gas taken into the compressors is fully discharged into the 
 condenser, aa the slightest loss at this point is certain to make 
 itself felt in the operation of the plant. The compressor or valves 
 seldom need be taken apart to determine their operation. The 
 engineer should be able to discern the slightest change in tem- 
 perature from the normal, when the compressors are working at 
 their best, by placing the hand on the inlet and outlet pipes or the 
 lower part of the compressors. Should the inlet pipe to one com- 
 pressor be warmer than that to the other (of a pair), or the frost on 
 the pipe from the evaporator reach nearer one compressor than the 
 other, it is then certain that the one with the higher temperature, 
 or from which the frost is farthest, is not working properly or 
 doing as much duty as the other, and it is equally certain that 
 some condition exists which prevents the complete filling and dis- 
 charge of its contents; possibly it has more clearance or leaky 
 valves. 
 
 The most common difficulties experienced with ammonia con- 
 densers are those of keeping the external surfaces clean and free 
 from deposits, and preventing the accumulation of air or foreign 
 gases within. Deposits on the surface are usually of two kinds, one 
 
REFEIGEEATION 73 
 
 which remains soft and may be washed off with a brush or wire 
 scraper such as is used for cleaning castings in a foundry, the other 
 a hard deposit which must be loosened with a hammer or scraper. It 
 is hardly necessary to explain in detail the methods employed in 
 cleaning the condenser as this is a matter that each engineer will be 
 able to accomplish in his own way. It should not, however, be 
 overlooked, and with a condensing pressure higher than ordinary, 
 this should be the first point to be examined after the water supply. 
 
 Air, or foreign gases due to decomposition of the ammonia or 
 other causes find their way into the condenser and make them- 
 selves manifest generally in a higher condensing pressure, or a 
 falling off in the duty to be obtained from the plant. They should 
 be blown off through the purge ^alve at the top of the condenser 
 in the manner already described. 
 
 It is possible, through leakage of^the coils or other parts of the 
 apparatus, that the ammonia may become mixed with brine or 
 water, thereby retarding its evaporation and interfering with the 
 proper or usual operation of the plant. If this is suspected, a 
 sample may be drawn off into a test glass through the charging 
 valve or purge valve of the brine tank or ammonia receiver, and 
 allowed to evaporate, in which case the water or brine will remain 
 in the glass and the relative amount be determined. Through 
 careful evaporation, and continued purging of the evaporator at 
 intervals, this may in time be eliminated, and care should be 
 taken to prevent future recurrence. 
 
 Loss of ammonia should be constantly guarded against. It is 
 watchfulness which determines between a wasteful and an econom- 
 ical plant in this particular, and the engineer who allows the 
 slightest smell of ammonia to exist about the plant is certain to be 
 confronted with excessive ammonia bills; while he who is constantly 
 on the alert and never rests until his plant is as free from the 
 smell of ammonia as an ordinary engine room, will be referred to 
 as the one who ran such and such a plant without addition of more 
 ammonia for so many years. 
 
 The escape of ammonia into the atmosphere is readily de- 
 tected; but where a leakage occurs in a submerged condenser, 
 brine tank or brine cooler it is necessary to examine the surround- 
 ing liquid to determine whether or not it exists. For this purpose 
 
74 REFRIGERATION 
 
 various agents are employed, and may be obtained of druggists or 
 from the manufacturers of ammonia. Red Litmus paper when 
 dipped into water or brine contaminated with ammonia will turn 
 blue. Nessler's solution causes the affected water to turn yellow 
 and brown, while Phenolphthalen causes a bright pink color with 
 the slightest amount of ammonia present. 
 
 The stopping of a leakage of ammonia in the brine tank or 
 cooler may be possible while the plant is in operation, by shutting 
 off the coil in which it occurs, or, if the point is accessible a 
 clamp and gasket may be put in place temporarily. 
 
 PROPORTION BETWEEN THE PARTS OF A REFRIGER- 
 ATING PLANT. 
 
 There is necessarily a certain ratio or proportion between the 
 several parts of a refrigerating plant, as there is between the 
 boiler, engine, and parts of a steam or power plant, in order to 
 obtain the most economical results. It is first necessary that the 
 evaporator be provided with heat-transmitting surface sufficient to 
 conduct 284,000 B. T. U. from the brine to the ammonia, for 
 each ton of refrigeration to be performed. "Without going into a 
 theoretical calculation of this amount, we shall state in both lineal 
 feet of pipe and square feet of pipe surface the commercial sizes 
 and amounts ordinarily in use. 
 
 The coil surface in a brine-tank system of refrigeration, should 
 contain approximately 50 square feet of external pipe surface, to 
 each ton in refrigerating capacity of the plant, when it is to be 
 operated at a temperature of 15 Fahr. This is an ample allow- 
 ance and will be found under general working conditions to give 
 readily the required capacity. While tests have been made in 
 which 40 square feet of pipe surface has been found sufficient for 
 one ton of refrigeration, it will be safer to use the former amount, 
 owing to the varied conditions under which a plant may be oper- 
 ated. This would amount in round figures to 150 linear feet of 
 1-inch pipe, 115 feet of IJ-inch, 100 feet of l-|-inch, or 80 feet of 
 2-inch pipe. 
 
 The brine tank should contain from 40 to GO cubic feet (de- 
 pending on the amount of storage capacity desired) for each ton in 
 capacity of the plant. The brine cooler should contain 12 square 
 
REFKIGEKATIOff 75 
 
 feet of external pipe surface for each ton, from which, in comparison 
 with the amount required for the brine- tank system, the statements 
 regarding the relative efficiency of the two methods of cooling brine 
 may be more readily understood. This amount of surface would 
 practically correspond to 35 linear feet of 1-inch pipe, 28 feet of 
 ll-inch, 25 feet of IJ-inch or 19 feet of 2-inch pipe. The shell of 
 the cooler is made sufficiently large to contain only the number of 
 coils necessary, there being no advantage in a larger shell. 
 
 The submerged type of ammonia condenser should contain 
 approximately 85 square feet of external surface which nearly cor. 
 responds to 100 linear feet of 1-inch pipe, 80 feet of IJ-inch, 70 feet 
 of IJ-inch and 56 feet of 2-inch pipe. 
 
 The atmospheric type of condenser should contain 30 square 
 feet of external pipe surface which corresponds to 87 linear feet 
 of 1-inch pipe, 69 feet of l|-inch, 60 feet of l|-inch and 48 feet 
 of 2-inch pipe. 
 
 The double-pipe type of condenser, as usually rated, contains 
 7 square feet of external pipe surface for the water circulating pipe 
 and about 10 square feet of internal surface of the outer pipe and 
 corresponds to approximately 20 linear feet each of 1^-inch and 
 2 -inch sizes for each ton of refrigerating capacity. 
 
 The above quantities are based on a water supply of average 
 temperature (60) and quantity. In cases of a limited supply or 
 higher temperature than ordinary, a greater amount should be used. 
 
 The ammonia compressor should be of such dimensions that 
 it will take away the gas from the brine cooler, evaporating coils, 
 or system, as rapidly as formed by the evaporation of the liquid 
 ammonia, and unless the temperature at which the plant is to be 
 operated be known, it is impossible to determine the volume of 
 gas to be handled and the necessary sizes of the compressor. 
 
 As stated before, the unit of a refrigerating plant is usually 
 expressed in tons of refrigeration equal to 284,000 B. T. U. Up 
 to the present time, however, a standard temperature at which 
 this duty shall be performed has never been established, and 
 therefore the rating of a machine, evaporator, or condenser by 
 tonnage is a merely nominal one and misleading to the purchaser, 
 a range of as great as 50 per cent very often existing in the 
 tenders for certain contracts. Upon the basis, however, of the 
 
76 REFRIGERATION 
 
 average temperature required of the refrigerating apparatus that 
 of 15 Fahr. is probably the mean; and at this temperature in the 
 outgoing brine, it is necessary to take away from the evaporator 
 nearly 7,000 cubic inches of gas per minute for each tori of 
 refrigeration developed in twenty-four hours. This may be con- 
 sidered as a fair basis for the rating of the displacement of the 
 compressor or compressors of the plant, unless a specific tempera- 
 ture is stated at which the plant is to operate. At Fahr. it is 
 necessary to calculate on approximately 9,000 cubic inches, while 
 At 28 Fahr. about 5,000 will be the required amount. 
 
 For example, if we have two single acting compressors 12 
 inches diameter by 24 inches stroke operating at 70 revolutions 
 per minute, we would have 113.09 (inches, area of 12-inch circle) 
 X 24 (inches stroke) X 2 (number of compressors) X 70 (revolu- 
 tions) -r- 7,000 (cubic inches displacement required) = 54.28 (tons 
 refrigeration per 24 hours of operation), while if the same machine 
 is to be operated at or near a temperature of zero and we 
 divide the product by 9,000 we have a capacity of 42.22 tons only 
 in the same length of time. The above quantities are given as 
 approximate only, but they have been deduced from the average 
 results obtained from years of practice and will be found reliable 
 under average conditions. It is to be hoped, however, that a 
 standard will soon be adopted which will rate machines or plants 
 by cubic inches displacement at a certain number of revolutions 
 or a stated piston speed, and the cooling of a certain number of 
 gallons of brine per minute through a certain range of tern- 
 perature. 
 
KEFKIGEKATION 
 
 77 
 
 THERMOMETER SCALES. 
 
 Fahr. 
 
 Cent. 
 
 Reau. 
 
 Fahr. 
 
 Cent. 
 
 Reau. 
 
 Fahr. 
 
 Cent. 
 
 Reau. 
 
 212 
 
 100 
 
 80 
 
 120 
 
 48.9 
 
 39.1 
 
 30 
 
 1.1 
 
 0.9 
 
 210 
 
 - 98.9 
 
 79.1 
 
 118 
 
 47.8 
 
 38.2 
 
 28 
 
 2.2 
 
 1.8 
 
 208 
 
 97.8 
 
 78.2 
 
 116 
 
 46.7 
 
 37.3 
 
 26 
 
 3.3 
 
 2.7 
 
 206 
 
 96.7 
 
 77.3 
 
 114 
 
 45.6 
 
 36.4 
 
 24 
 
 4.4 
 
 3.6 
 
 204 
 
 95.6 
 
 76.4 
 
 112 
 
 44.4 
 
 35.6 
 
 22 
 
 56 
 
 4.4 
 
 202 
 
 94.4 
 
 75.6 
 
 110 
 
 43.3 
 
 34.7 
 
 20 
 
 67 
 
 5.3 
 
 200 
 
 93.3 
 
 74.7 
 
 108 
 
 42.2 
 
 33.8 
 
 18 
 
 7.8 
 
 6.2 
 
 198 
 
 92.2 
 
 73.8 
 
 106 
 
 41.1 
 
 32.9 
 
 16 
 
 8.9 
 
 7.1 
 
 196 
 
 91.1 
 
 72.9 
 
 104 
 
 40 
 
 32 
 
 14 
 
 10 
 
 8 
 
 194 
 
 90 
 
 72 
 
 102 
 
 38.9 
 
 31.1 
 
 12 
 
 11.1 
 
 89 
 
 192 
 
 88.9 
 
 71.1 
 
 100 
 
 37.8 
 
 30.2 
 
 10 
 
 12.2 
 
 9.8 
 
 190 
 
 87.8 
 
 70.2 
 
 98 
 
 36.7 
 
 29.3 
 
 8 
 
 13.3 
 
 10.7 
 
 188 
 
 86.7 
 
 69.3 
 
 96 
 
 35.6 
 
 28.4 
 
 6 
 
 44.4 
 
 11.6 
 
 186 
 
 85.6 
 
 68.4 
 
 94 
 
 34.4 
 
 27.6 
 
 4 
 
 15.6 
 
 12.4 
 
 184 
 
 84.4 
 
 67.6 
 
 92 
 
 33.3 
 
 26'. 7 
 
 2 
 
 167 
 
 13.3 
 
 182 
 
 83.3 
 
 66.7 
 
 90 
 
 32.2 
 
 25.8 
 
 
 
 17.8 
 
 142 
 
 180 
 
 82.2 
 
 65.8 
 
 88 
 
 31.1 
 
 24.9 
 
 2 
 
 18.9 
 
 15.1 
 
 178 
 
 81.1 
 
 64.9 
 
 86 
 
 30 
 
 24 
 
 4 
 
 20 
 
 16 
 
 176 
 
 80 
 
 64 
 
 84 
 
 28.9 
 
 23.1 
 
 6 
 
 21.1 
 
 16.9 
 
 174 
 
 78.9 
 
 63.1 
 
 82 
 
 27.8 
 
 222 
 
 8 
 
 22.2 
 
 17.8 
 
 172 
 
 77.8 
 
 62.2 
 
 80 
 
 267 
 
 21.3 
 
 10 
 
 233 
 
 18.7 
 
 170 
 
 76.7 
 
 61.3 
 
 78 
 
 25.6 
 
 20.4 
 
 12 
 
 24.4 
 
 19.6 
 
 168 
 
 75.6 
 
 60.4 
 
 76 
 
 24.4 
 
 19.6 
 
 14 
 
 25.6 
 
 20.4 
 
 166 
 
 74.4 
 
 59.6 
 
 74 
 
 23.3 
 
 18.7 
 
 16 
 
 26.7 
 
 21.3 
 
 164 
 
 73.3 
 
 58.7 
 
 72 
 
 22.2 
 
 17.8 
 
 18 
 
 27.8 
 
 22.2 
 
 162 
 
 72.2 
 
 57.8 
 
 . 70 
 
 21.1 
 
 16.9 
 
 20 
 
 28.9 
 
 23.1 
 
 160 
 
 71.1 
 
 56.9 
 
 68 
 
 20 
 
 1.6 
 
 22 
 
 30 
 
 24 
 
 158 
 
 70 
 
 56 
 
 66 
 
 18.9 
 
 15.1 
 
 24 
 
 31.1 
 
 249 
 
 156 
 
 68.9 
 
 55.1 
 
 64 
 
 17.8 
 
 14.2 
 
 26 
 
 32.2 
 
 25.8 
 
 154 
 
 67.8 
 
 54.2 
 
 62 
 
 16.7 
 
 13.3 
 
 28 
 
 333 
 
 26.7 
 
 152 
 
 66.7 
 
 53.3 
 
 60 
 
 15.6 
 
 12.4 
 
 30 
 
 34.4 
 
 27.6 
 
 150 
 
 65.6 
 
 52.4 
 
 58 
 
 14.4 
 
 11.6 
 
 32 
 
 35.6 
 
 28.4 
 
 148 
 
 64.4 
 
 51.6 
 
 56 
 
 13.3 
 
 10.7 
 
 34 
 
 36.7 
 
 29.3 
 
 146 
 
 63.3 
 
 50.7 
 
 54 
 
 12.2 
 
 9.8 
 
 36 
 
 37.8 
 
 30.2 
 
 144 
 
 62.2 
 
 49.8 
 
 52 
 
 11.1 
 
 8.9 
 
 38 
 
 38.9 
 
 31.1 
 
 142 
 
 61.1 
 
 48.9 
 
 50 
 
 10 
 
 8 
 
 40 
 
 40 
 
 32 
 
 140 
 
 60 
 
 48 
 
 48 
 
 8.9 
 
 7.1 
 
 42 
 
 411 
 
 32.9 
 
 138 
 
 58.9 
 
 47.1 
 
 46 
 
 7.8 
 
 6.2 
 
 44. 
 
 42.2 
 
 33.8 
 
 136 
 
 57.8 
 
 46.2 
 
 44 
 
 6.7 
 
 5.3 
 
 46 
 
 43.3 
 
 347 
 
 134 
 
 56.7 
 
 45.3 
 
 42 
 
 5.6 
 
 4.4 
 
 48 
 
 44.4 
 
 35.6 
 
 132 
 
 55.6 
 
 44.4 
 
 40 
 
 4.4 
 
 3.6 
 
 50 
 
 45.6 
 
 36.4 
 
 130 
 
 54.4 
 
 43.6 
 
 38 
 
 3.3 
 
 2.7 
 
 52 
 
 46.7 
 
 373 
 
 128 
 
 53.3 
 
 42.7 
 
 36 
 
 2.2 
 
 1.8 
 
 54 
 
 47.8 
 
 38.2 
 
 126 
 
 52.2 
 
 41.8 
 
 34 
 
 .1.1 
 
 0.9 
 
 56 
 
 48.9 
 
 39.1 
 
 124 
 
 51.1 
 
 40.9 
 
 32 
 
 
 
 
 
 58 
 
 50 
 
 40 
 
 122 
 
 50 
 
 40 
 
 
 
 
 
 
 
78 
 
 EEFKIGEEATIOK 
 
 TEMPERATURE, PRESSURE, LATENT HEAT AND WEIGHT OF AMMONIA, 
 OR PROPERTIES OF SATURATED AMMONIA. 
 
 Temp. 
 
 Pres 
 
 sure 
 
 Latent 
 
 TJtvo 4- 
 
 Volume in 
 Cu. Ft. of 
 
 Volume in 
 Cu. Ft. of 
 
 Weight of 
 1 Cu. Ft. 
 
 F. 
 
 Absolute 
 
 Gauge 
 
 xieat 
 
 1 Lb. Vapor 
 
 1 Lb. Liquid 
 
 Vapor 
 
 40 
 
 10.69 
 
 4.01 
 
 579.67 
 
 24.38 
 
 .0234 
 
 .0411 
 
 35 
 
 12.31 
 
 2.39 
 
 576.69 
 
 21.32 
 
 .0236 
 
 .0471 
 
 30 
 
 14.13 
 
 .57 
 
 573.69 
 
 18.69 
 
 .0237 
 
 .0535 
 
 25 
 
 16.17 
 
 1.47 
 
 570.68 
 
 16.44 
 
 .0238 
 
 .0609 
 
 20 
 
 18.45 
 
 3.75 
 
 567.67 
 
 1448 
 
 .024 
 
 .069 
 
 15 
 
 20.99 
 
 6.29 
 
 564.64 
 
 12.81 
 
 .0242 
 
 .0775 
 
 10 
 
 23.77 
 
 9.07 
 
 56161 
 
 11.36 
 
 .0243 
 
 .088 
 
 5 
 
 27.57 
 
 12.87 
 
 558.56 
 
 9.89 
 
 .0244 
 
 .1011 
 
 
 
 30.37 
 
 15.67 
 
 555.5 
 
 9.14 
 
 .0246 
 
 .1094 
 
 + 5 
 
 34.17 
 
 19.47 
 
 552.43 
 
 8.04 
 
 .0247 
 
 .1243 
 
 10 
 
 38.55 
 
 23.85 
 
 549.35 
 
 7.2 
 
 .0249 
 
 .1381 
 
 15 
 
 42.93 
 
 28.23 
 
 546.26 
 
 6.46 
 
 .025 
 
 .1547 
 
 20 
 
 47.95 
 
 33.25 
 
 543 15 
 
 5.82 
 
 .0252 
 
 .1721 
 
 25 
 
 53.43 
 
 38.73 
 
 540.03 
 
 5.24 
 
 .0253 
 
 .1908 
 
 30 
 
 59.41 
 
 44.71 
 
 536.92 
 
 4.73 
 
 .0254 
 
 .2111 
 
 35 
 
 65.93 
 
 51.23 
 
 533.78 
 
 4.28 
 
 .0256 
 
 .2336 
 
 40 
 
 73. 
 
 58.3 
 
 530.63 
 
 3.88 
 
 .0257 
 
 .2577 
 
 45 
 
 80.66 
 
 65.96 
 
 527.47 
 
 353 
 
 .026 
 
 .2832 
 
 50 
 
 88.96 
 
 74.26 
 
 524.3 
 
 3.21 
 
 .02601 
 
 .3115 
 
 55 
 
 97.63 
 
 82.93 
 
 521.12 
 
 2.93 
 
 .02603 
 
 .3412 
 
 60 
 
 107.6 
 
 92.9 
 
 517.93 
 
 2.67 
 
 .0265 
 
 .3745 
 
 65 
 
 118.03 
 
 103.33 
 
 515.33 
 
 2.45 
 
 .0266 
 
 .4081 
 
 70 
 
 129.21 
 
 114.51 
 
 511.52 
 
 224 
 
 .0268 
 
 .4664 
 
 75 
 
 144.25 
 
 12655 
 
 508.29 
 
 2.05 
 
 .027 
 
 .4978 
 
 80 
 
 154.11 
 
 139.41 
 
 50466 
 
 1.89 
 
 .0272 
 
 .5291 
 
 85 
 
 167.86 
 
 153.16 
 
 501.81 
 
 .74 
 
 .0273 
 
 .5747 
 
 90 
 
 182.8 
 
 168.1 
 
 498.11 
 
 .61 
 
 .0274 
 
 .6211 
 
 95 
 
 198.37 
 
 183.67 
 
 495.29 
 
 .48 
 
 .0277 
 
 .6756 
 
 100 
 
 215.14 
 
 200.44 
 
 491.5 
 
 .36 
 
 .0279 
 
 .7353 
 
 105 
 
 232.98 
 
 218.28 
 
 488.72 
 
 .29 
 
 .0281 
 
 .7862 
 
 110 
 
 251.97 
 
 237.27 
 
 485.42 
 
 .2 
 
 .0283 
 
 .8451 
 
 115 
 
 272.14 
 
 257.44 
 
 482.41 
 
 .12 
 
 .0285 
 
 .9042 
 
 120 
 
 293.49 
 
 278.79 
 
 47879 
 
 .04 
 
 .0287 
 
 .9738 
 
 125 
 
 316.16 
 
 301.' 46 
 
 475.45 
 
 .97 
 
 .0289 
 
 1.172 
 
 130 
 
 340.42 
 
 325.72 
 
 472.11 
 
 .9 
 
 .0291 
 
 1.2218 
 
 135 
 
 365.16 
 
 350.46 
 
 468.75 
 
 .84 
 
 .0293 
 
 1.3212 
 
 140 
 
 392.22 
 
 377.52 
 
 465.39 
 
 .79 
 
 .0295 
 
 1.4108 
 
 145 
 
 420.49 
 
 405.79 
 
 462.01 
 
 .74 
 
 .0297 
 
 1.4904 
 
 150 
 
 450.2 
 
 435.5 
 
 458.62 
 
 .69 
 
 .0299 
 
 1.5896 
 
KEFEIGEEATION 
 
 79 
 
 TABLE OF CALCIUM BRINE SOLUTION. 
 
 Deg. 
 Baum6 
 60 F. 
 
 Deg. 
 Salom- 
 eter. 
 60 F. 
 
 Per Cent 
 Calcium 
 by Weight 
 
 Lbs. per 
 Cu. Ft. 
 Sol. 
 
 Lbs. 
 per 
 Gallon 
 
 Specific 
 Gravity 
 
 Specific 
 Heat 
 
 Freezing 
 Point F. 
 
 Amm. 
 Gauge 
 Pressure 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 1 
 
 32 
 
 47.31 
 
 1 
 
 4 
 
 .943 
 
 1.25 
 
 i 
 
 1.007 
 
 .996 
 
 31.1 
 
 46.14 
 
 2 
 
 8 
 
 1.886 
 
 2.5 
 
 i 
 
 1.014 
 
 .988 
 
 30.33 
 
 45.14 
 
 3 
 
 12 
 
 2.829 
 
 3.75 
 
 
 1.021 
 
 .98 
 
 29.48 
 
 44.06 
 
 4 
 
 16 
 
 3.772 
 
 5 
 
 i* 
 
 1.028 
 
 .972 
 
 28.58 
 
 43 
 
 5 
 
 20 
 
 4.715 
 
 6.25 
 
 i 
 
 1.036 
 
 .964 
 
 27.82 
 
 42.08 
 
 6 
 
 24 
 
 5.658 
 
 7.5 
 
 i 
 
 1.043 
 
 .955 
 
 27.05 
 
 41.17 
 
 7 
 
 28 
 
 6.601 
 
 8.75 
 
 if 
 
 1.051 
 
 .946 
 
 26.28 
 
 40.25 
 
 8 
 
 32 
 
 7.544 
 
 10 
 
 i* 
 
 1.058 
 
 .936 
 
 25.52 
 
 39.35 
 
 9 
 
 36 
 
 8.487 
 
 11 25 
 
 if 
 
 1.066 
 
 .925 
 
 24.26 
 
 37.9 
 
 10 
 
 40 
 
 9.43 
 
 12.5 
 
 ii 
 
 1.074 
 
 .911 
 
 22.8 
 
 36.3 
 
 11 
 
 44 
 
 10.373 
 
 13.75 
 
 it 
 
 1.082 
 
 .896 
 
 21.3 
 
 34.67 
 
 12 
 
 48 
 
 11.316 
 
 15 
 
 2 
 
 1.09 
 
 .89 
 
 19.7 
 
 32.93 
 
 13 
 
 52 
 
 12.259 
 
 16.25 
 
 *k 
 
 1.098 
 
 .884 
 
 18.1 
 
 31.33 
 
 14 
 
 56 
 
 13202 
 
 17.5 
 
 2* 
 
 1.107 
 
 .878 
 
 16.61 
 
 29.63 
 
 15 
 
 60 
 
 14.145 
 
 18.75 
 
 1ft 
 
 1.115 
 
 .872 
 
 15.14 
 
 28.35 
 
 16 
 
 64 
 
 15.088 
 
 20 
 
 8| 
 
 1.124 
 
 .866 
 
 13.67 
 
 27.04 
 
 17 
 
 68 
 
 16031 
 
 21.25 
 
 21 
 
 1.133 
 
 .86 
 
 12.2 
 
 25.76 
 
 18 
 
 72 
 
 16.974 
 
 22.5 
 
 3 
 
 1.142 
 
 .854 
 
 10 
 
 23.85 
 
 19 
 
 76 
 
 17.917 
 
 23.75 
 
 8* 
 
 1.151 
 
 .849 
 
 7.5 
 
 21.8 
 
 20 
 
 80 
 
 18.86 
 
 25 
 
 3* 
 
 1.16 
 
 .844 
 
 4.6 
 
 19.43 
 
 21 
 
 84 
 
 19.803 
 
 26.25 
 
 3| 
 
 1.169 
 
 .839 
 
 1.7 
 
 17.06 
 
 22 
 
 88 
 
 20.746 
 
 27.5 
 
 8f 
 
 1.179 
 
 .834 
 
 1.4 
 
 14.7 
 
 23 
 
 92 
 
 21.689 
 
 28.75 
 
 3f 
 
 1.188 
 
 .825 
 
 4.9 
 
 12.2 
 
 24 
 
 96 
 
 22.632 
 
 30 
 
 4 
 
 1.198 
 
 .817 
 
 8.6 
 
 9.96 
 
 25 
 
 100 
 
 23.575 
 
 31.25 
 
 41 
 
 1.208 
 
 .808 
 
 11.6 
 
 8.19 
 
 26 
 
 
 24.518 
 
 32.5 
 
 4* 
 
 1.218 
 
 .799 
 
 17.1 
 
 5.22 
 
 27 
 
 
 25.461 
 
 33.75 
 
 H 
 
 1.229 
 
 .79 
 
 21.8 
 
 2.94 
 
 28 
 
 
 26.404 
 
 35 
 
 4| 
 
 1.239 
 
 .778 
 
 27. 
 
 .65 
 
 29 
 
 
 27.347 
 
 36.25 
 
 4f 
 
 1.25 
 
 .769 
 
 32.6 
 
 l"Vao 
 
 30 
 
 
 28.29 
 
 37.5 
 
 5 
 
 1.261 
 
 .757 
 
 39.2 
 
 8.5"" 
 
 31 
 
 
 29.233 
 
 38.75 
 
 5 
 
 1.272 
 
 
 46.3 
 
 12 
 
 32 
 
 
 30.176 
 
 40 
 
 5^ 
 
 1.283 
 
 
 54.4 
 
 15 
 
 33 
 
 
 31.119 
 
 41.25 
 
 5| 
 
 1.295 
 
 
 52.5 
 
 10 
 
 34 
 
 
 32.062 
 
 42.5 
 
 H 
 
 1.306 
 
 
 39.2 
 
 4 
 
 35 
 
 
 33 
 
 43.75 
 
 5f 
 
 1.318 
 
 
 25.2 
 
 1.5 
 
80 
 
 EEFKIGEKATION 
 
 TABLE OP CHLORIDE OF SODIUM (SALT) BRINE. 
 
 Degrees 
 on 
 Salom. 
 
 Percent- 
 age Salt 
 by Weight 
 
 Pounds 
 Salt per 
 Cu. Ft. 
 
 Pounds 
 Salt per 
 Gallon 
 
 Specific 
 Gravity 
 
 Specific 
 Heat 
 
 Freezing 
 Point F. 
 
 Ammonia 
 Gauge 
 Pressure 
 
 
 
 
 
 
 
 
 
 1 
 
 1 
 
 32 
 
 47.32 
 
 5 
 
 1.25 
 
 .785 
 
 .105 
 
 1.009 
 
 .99 
 
 30.3 
 
 45.1 
 
 10 
 
 2.5 
 
 1.586 
 
 .212 
 
 1.0181 
 
 .98 
 
 28.6 
 
 43.03 
 
 15 
 
 3.75 
 
 2.401 
 
 .321 
 
 1.0271 
 
 .97 
 
 26.9 
 
 41 
 
 20 
 
 5 
 
 3.239 
 
 .433 
 
 1.0362 
 
 .96 
 
 25.2 
 
 38.96 
 
 25 
 
 6.25 
 
 4.099 
 
 .548 
 
 1.0455 
 
 .943 
 
 23.6 
 
 37.19 
 
 30 
 
 7.5 
 
 4.967 
 
 .664 
 
 1.0547 
 
 .926 
 
 22 
 
 35.44 
 
 35 
 
 8.75 
 
 5.834 
 
 . .78 
 
 1.064 
 
 .909 
 
 20.4 
 
 33.69 
 
 40 
 
 10 
 
 6.709 
 
 .897 
 
 1.0733 
 
 .892 
 
 18.7 
 
 31.93 
 
 45 
 
 11.25 
 
 7.622 
 
 1.019 
 
 1.0828 
 
 .883 
 
 17.1 
 
 30.38 
 
 50 
 
 12.5 
 
 8.542 
 
 1.142 
 
 .0923 
 
 .874 
 
 15.5 
 
 28.73 
 
 55 
 
 13.75 
 
 9.462 
 
 1.265 
 
 .1018 
 
 .864 
 
 13.9 
 
 27.24 
 
 60 
 
 15 
 
 10.389 
 
 1.389 
 
 .1114 
 
 .855 
 
 12.2 
 
 25.76 
 
 65 
 
 16:25 
 
 11.384 
 
 1.522 
 
 .1213 
 
 .848 
 
 10.7 
 
 24.46 
 
 70 
 
 17.5 
 
 12.387 
 
 1.656 
 
 .1312 
 
 .842 
 
 9.2 
 
 23.16 
 
 75 
 
 18.75 
 
 13.396 
 
 1.791 
 
 .1411 
 
 .835 
 
 7.7 
 
 21.82 
 
 80 
 
 20 
 
 14.421 
 
 1.928 
 
 1.1511 
 
 .829 
 
 6.1 
 
 20.43 
 
 85 
 
 21.25 
 
 15.461 
 
 2.067 
 
 1.1614 
 
 .818 
 
 4.6 
 
 19.16 
 
 90 
 
 22.5 
 
 16.508 
 
 2.207 
 
 1.1717 
 
 .806 
 
 3.1 
 
 18.2 
 
 95 
 
 23.75 
 
 17.555 
 
 2.347 
 
 1.182 
 
 .795 
 
 1.6 
 
 16.88 
 
 100 
 
 25 
 
 18.61 
 
 2.488 
 
 1.1923 
 
 .783 
 
 
 
 15.67 
 
gs 
 
 
 
 0- 
 
 
REFRIGERATION 
 
 PART II 
 
 REFRIGERATION BY CARBONIC ANHYDRIDE GAS. 
 
 In general design and requirements, the refrigerating ma- 
 chine using carbonic anhydride gas is substantially like the ma- 
 chine using" ether, ammonia, or carbonic dioxide gases in that it 
 liquefies the gas by the removal of the latent heat in condensers 
 and tanks. Where it differs materially is in the pressures required 
 to accomplish the liquefaction of the gas. 
 
 The following table shows the pressure required for lique- 
 faction at different temperatures from an approximate normal 
 condition, of 80 degrees to a point where the gas remains a liquid 
 under the atmospheric pressure of 14.7 pounds from the absolute. 
 
 TEMPERATURE OF GAS LIQUEFIED. 
 
 Temperature 
 Fahrenheit. 
 
 Pressure 
 Pounds per sq. in. 
 
 Temperature 
 Fahrenheit. 
 
 Pressure 
 Pounds per sq. in. 
 
 80 
 
 1000.6 
 
 -60 
 
 134.2 
 
 70 
 
 889.3 
 
 -70 
 
 113.2 
 
 60 
 
 771.7 
 
 -80 
 
 96.2 
 
 50 
 
 689.4 
 
 -90 
 
 81.0 
 
 40 
 
 588.0 
 
 -100 
 
 70.1 
 
 30 
 
 507.1 
 
 -110 
 
 57.9 
 
 20 
 
 433.6 
 
 -120 
 
 47.4 
 
 10 
 
 367.1 
 
 -130 
 
 38.4 
 
 
 
 311.6 
 
 -140 
 
 30.0 
 
 -10 
 
 260.1 
 
 -150 
 
 21.3 
 
 -20 
 
 217.5 
 
 -160 
 
 15.2 
 
 -30 
 
 182 8 
 
 -170 
 
 7.1 
 
 -40 
 
 162.8 
 
 -179.6 
 
 0.0 
 
 -50 
 
 156.8 
 
 
 
 In the operation of refrigerating machines where the gas is 
 rapidly passing through the condensers, it has been established 
 that the temperature of. the gas liquefied is from 8 to 12 degrees 
 above that of the water used for condensing. If the condensing 
 water is 60 degrees, though during the summer days of August 
 
KEFRIGEKATION 83 
 
 or September a temper atiire of 65 to 76 degrees is more common 
 where city service water is in use, a pressure of at least 1,000 
 pounds per square inch is required for the working conditions. 
 
 With this pressure, compressing cylinders and piping must 
 be very strong to withstand the pressure, and the diameter of the 
 gas cylinder must be small compared with that of the steam 
 cylinder. As carbonic anhydride gas does not attack copper or 
 kindred metals they can be used with safety for the working parts 
 of the machine. 
 
 Although as dangerous as any of the other gases, as it excludes 
 the presence of oxygen, the gas is not noticed by smell as is the 
 case with ammonia. In a vapor form, the specific gravity is 
 greater than that of the atmosphere, and the gas escaping in small 
 quantities is not easily detected as it immediately sinks in the 
 cellars, sewers, or loose earth. As life cannot be sustained without 
 the presence of oxygen, any gas that excludes it is dangerous. The 
 presence of ammonia is so pronounced that it is easily detected 
 when but a small amount is in the atmosphere, while the presence 
 of carbonic anhydride gas is difficult to detect even up to the 
 moment of exhaustion of life. 
 
 In the use of carbonic anhydride gas it is necessary that the 
 most careful attention be paid to the joints and stuffing boxes. The 
 compressors are invariably of the single-acting type, as it is almost 
 impossible to maintain tight stuffing boxes under the intense pres- 
 sure necessary for liquefaction 
 
 Compressors are quite extensively made for the liquefaction 
 of carbonic acid anhydride gas, by industries supplying the same 
 in small carboys of steel for recharging soda water or beer, or any 
 beverage which requires the addition of carbonic acid gas for 
 enlivenment. In the better class of these compressors, the cylin- 
 der for compressing the gas is compounded as shown in Fig. 46. 
 By this design the first set of cylinders deliver the gas to a re- 
 ceiver at a pressure between 400 and 600 pounds per square inch. 
 Here the gas is cooled ; from this cylinder the suction of the final 
 pump is taken, which leaves the gas at 1,000 pounds pressure. 
 There is an advantage in machines of this build (compound cylin- 
 ders), as there is a less amount of engine friction than in single- 
 acting cylinders. 
 
 Fig. 47 shows a single-acting horizontal compressing cylinder 
 direct connected to a throttling steam engine "D" valve pattern, 
 
REFRIGERATION 
 
EEFHIGERATION 
 
 85 
 
 FIG. 48 
 DIRECT- CONNECTED VERTICAL REFRIGERATING COMPRESSOR 
 
KEFRIGEKATION 
 
 double cylinder operating on a single shaft. The tail rod of the 
 steam cylinder extends into and forms the piston rod of the com- 
 pressor. 
 
 Fig. 48 shows a vertical stearn engine connected to a single- 
 
 FIG. 49 
 BELT- DRIVEN REFRIGERATING COMPRESSOR 
 
 acting compressor ; the compressor being bolted to the side of the 
 steam cylinder with a double center-crank engine and over-hung 
 fly wheel. 
 
 Fig. 49 shows a single-acting vertical compressor, connected 
 
REFRIGERATION 87 
 
 to a shaft and belt, wheels over hanging. This design is for a belt- 
 driven plant. 
 
 The cycle of operation of the gas is as follows : the gas 
 passes from the compressor into a cylinder in which the oil from 
 the lubricator of the cylinder is separated from the gas. From 
 this tank the gas passes to the condensing coils where the latent 
 heat is taken from it and the gas as it becomes a liquid flows to a 
 receiving tank, being carried there by gravity. 
 
 From this liquid tank, the gas is conducted through piping to 
 the freezing coils, where it is liberated from the condensing pres- 
 sure to the vaporizing pressure, usually 30 to 50 pounds per square 
 inch. A far greater back pressure can be carried than with 
 ammonia when accomplishing the same work. This is due to 
 the much lower vaporizing temperature, (boiling point) of the 
 carbonic anhydride gas in a liquefied form when passing from a 
 liquid to a vapor by the taking up of latent heat. 
 
 Carbonic Anhydride gas when liquefied to be used as a re- 
 frigerant may be applied through a brine tank, cooling the brine 
 which afterwards may be circulated in cooling coils in refrigerator 
 boxes or rooms. This system is known as the indirect. The 
 process of sending the gas direct through the piping suspended 
 in the refrigerating rooms is known as the direct application of 
 refrigerating fluid. 
 
 REFRIGERATION BY COMPRESSED AIR. 
 
 To obtain refrigeration by compressing and expanding air, we 
 resort to the effort of compression, and while air is compressed 
 conduct off the heat which has multiplied in proportion to the 
 amount* of compression. We can convert the heat held by the 
 air into power ; then the air containing but little heat is used for 
 refrigerating purposes. 
 
 That this may be more clearly understood let us consider the 
 following : By taking air at atmospheric pressure at sea level, 
 usually 14.7 pounds per square inch (this varies as the pressure 
 increases or diminishes as shown by the mercury column in a 
 barometer) and compressing it to 150 pounds per square inch, 
 ten volumes of air have been compressed into the space occupied 
 by one volume at atmospheric pressure. The heat which was 
 contained in the ten volumes has been forced into the one volume. 
 
KEFKIGERATION 
 
 The temperature is increased because- the total amount of heat 
 is now in the one volume. The increase of heat is in proportion to 
 the compression. This is the important factor which makes possi- 
 ble refrigeration by mechanical means. 
 
 From the compressor, the air is discharged into piping which 
 is surrounded by water 5 the heat is thus carried off and the tem- 
 perature of the air is reduced to that of the surrounding water. 
 

KEFKIGEBATION 89 
 
 Should the air be liberated at this time there would be but a slight 
 reduction in temperature, probably from 20 to 30 degrees Fah- 
 renheit. 
 
 Expansion of Air. From the cooling coils, the air passes 
 to an expanding cylinder which is not unlike a steam engine cylin- 
 der. The air at the pressure of 150 pounds expands and drives a 
 piston which is connected to the driving shaft of the machine and 
 aids in the compression of air. The amount of work accomplished 
 by this cylinder is in proportion to the heat the air contains, and 
 this heat is used up or converted into power. The air is delivered 
 into the cooling pipes for ice-making or refrigeration at a tem- 
 perature of from 40 to 65 degrees below zero, the final condition 
 depending upon the efficiency of the machinery. 
 
 The machinery represented by the accompanying drawings 
 and descriptions is in use in the United States Navy and has been 
 adopted as standard. 
 
 First. Assembled parts of the machine. This can best be 
 understood by reference to Fig. 50. The machine is known as 
 the Allen Dense Air Ice Machine. 
 
 In Fig. 51 we have three cylinders with slide valves, not 
 unlike a steam engine, A in fact representing a steam cylinder, 
 driving the air compressor B. This cylinder is operated by a 
 single D valve and controlled by a throttling governor or by any 
 governor adapted to conditions at sea. Power from the steam 
 cylinder is conducted by connecting rod and disc crank, to which is 
 attached a driving shaft H with a crank in the center of the shaft 
 which drives the air compressor. On the opposite side of the 
 shaft is a disc crank from which the expanding cylinder is at- 
 tached which in turn aids the steam cylinder in its work. F is a 
 plunger piston pump for circulating sea water around the coils 
 in the cooling tank C. G is a priming pump for air. 
 
 In the location of cylinder cranks, the crank driving the air 
 compressor leads the steam cylinder about 30 degrees. This is 
 the practice followed by the best engine and air or gas compressor 
 builders, where they are direct connected. The object of the lead 
 is to apply the greatest pressure attainable to the piston of the air 
 compressor at the time it is completing its stroke, when the angle 
 of the crank pin nears the position exerting the greatest effort on 
 the crank and previous to the time of the closing of the cut-off on 
 the steam cylinders. By this method a much lighter fly wheel 
 
90 
 
 REFRIGERATION 
 
REFRIGERATION 91 ' 
 
 can be used, for the power developed by the engine is applied 
 directly through the shaft and not transmitted to the fly wheel to be 
 given off when the compression of the air cylinder is taking the 
 maximum power and the steam crank is nearly completing its 
 stroke. 
 
 Air Compressor * B." In considering the action of this 
 specially designed air compressor, we find that the suction is taken 
 through the opening in the bottom of the valve chest, the opening 
 being located in the same way as the exhaust on a slide valve 
 engine. The discharge is through the face of the valve chest, 
 the location again being similar to the steam supply to a slide-valve 
 engine. The valves are of the slide design. It is a question with 
 engineers whether or not this design is superior to the poppet 
 valve as used by ammonia and kindred gas compressors. The 
 advantages of using the slide valves are : first, they are compara- 
 tively noiseless ; second, they are not constantly hammering their 
 seats or faces in closing, and third, . there is no unbalanced pres- 
 sure of the valve seat to be overcome by the engine, or to cause 
 the rapid destruction of the metal forming a poppet valve. 
 
 !N"ote : For a description of unbalanced valve operation see 
 page 93. 
 
 In the operation of the valves we find two rocker shafts, each 
 of which is operated by an eccentric from the main shaft. The 
 rocker shaft nearest to. the main shaft operates the valve admitting 
 steam to the engine A; this is a plain D valve. The shaft also 
 operates the rider valve on both air compressor and expander 
 cylinder. 
 
 The second rocker shaft operates the main valve of the com- 
 pressor and the expander cylinder. From the crosshead of the 
 air compressor an arm extending horizontally operates the charg- 
 ing air pump and also the water circulating pump. Water from 
 the water cooler is continuously flowing around the jacket of the 
 air compressing cylinder. The action of the expanding chamber 
 is the same as though steam were used to move the piston, the 
 energy given by this expansion of air aids in driving the air com- 
 pressor, thereby adding to the economy of the operation. This 
 is not, however, the primary cause for this construction. By using 
 the air, which is at high pressure, to obtain power, the heat that 
 it contains is consumed or converted into power and at 60 pounds 
 per square inch, which is the back pressure carried, there is ob- 
 
92 
 
 EEFEIGEKATION 
 
REFRIGERATION 
 
 93 
 
 tained a temperature of from 70 to 90 degrees below zero. This 
 can be obtained with a working initial pressure of 260 pounds per 
 square inch. In no instance is the latent heat of the air affected 
 except to a slight degree, equaling in ratio the ability of the air to 
 carry latent heat due to the different specific temperatures during 
 the compression and expansion. 
 
 Relief of Valves. Should the pressure in the expanding 
 cylinder become greater than the pressure in the discharge cham- 
 ber, due to the distortion of rods or slipping of eccentrics, the 
 valves would spring back from their seats and relieve the pressure. 
 Upon the receding of the piston the valve would close. 
 
 Unbalanced Valve Pressure. In considering this question, 
 let us take a poppet valve for our illustration; this is shown in 
 Fig. 53. 
 
 The design calls for a 
 6-inch compressing cylinder 
 with a valve seat of f inch 
 face giving a bearing surface 
 on top of the valve 6 J inches 
 in diameter. The area of the 
 cylinder equals 28. 274 square 
 inches, while the area of the 
 top of the valves including 
 the seat is 33.183 square 
 inches. Let us consider a 
 working pressure of 150 
 pounds per square inch. To 
 open this valve there must be 
 exerted a pressure of 150 x 
 33.183 = 4977.45 pounds. 
 The power exerted on the 
 under side of the valve, when 
 the pressures are equal to that 
 of the discharge chamber, is 
 
 28.274 x 150 = 4241.1 pounds, or in order to open the valve there 
 must be added 4977.45 4241.1 = 636.35 pounds. In other words, 
 to force the valve from its seat there must be exerted 28.53 pounds 
 per square inch in excess, or a total pressure above the valve of 
 150+28.53=178.53 pounds per square inch on the entire compress- 
 ing piston. This power is overcome by placing springs or com- 
 
 FIG. 53 
 
94 REFEIGEBAtlON 
 
 pressing chambers on top of the valve, the latter by far the most 
 satisfactory. 
 
 The loss caused by this defect in design of poppet valve equals 
 19.02 per cent of the entire requirements for compression of gases. 
 
 Oil and Water Traps. In the main discharge line from the 
 air-expanding cylinder to the ice-making tank, is placed a sepa- 
 rator E, for intercepting water or oil that may be in the system. 
 The water is carried in at any time when fresh air is taken to 
 replenish the air in use in the cycle of operation. These air-blows 
 or vents are used upon starting up a refrigerating plant. The 
 vents in the cooling chamber C, can be blown off at any time but 
 this usually occurs at the starting of the plant. 
 
 The very low temperature of the air congeals any water or oil 
 that may remain in the system ; this freezing taking place in the 
 piping or oil traps. This insures dry air to work with. The 
 jacket around the bottom of 'the trap is to receive steam when it is 
 desired to remove the oil or water, the latter collecting and remain- 
 ing in the separator as snow. These traps hang vertically so that 
 the operation of gathering the water and oil is one of gravity. In 
 the plan (Fig. 51) they are shown as being horizontal. This is 
 never done in practice but shows more clearly the arrangement of 
 different parts. 
 
 Ice Making Tank. The air is ejected from the expanding 
 cylinder, and after passing the trap enters a series of pipes divided 
 up into manifolds and coils to cause the air to travel: many times 
 from one end to the other, to form a long coil. It is not necessary 
 that this should be a continuous coil, as there are no liquids to 
 vaporize. The air takes up specific heat only and conveys it. back 
 to the compressing cylinder for removal in the cooler in the ex- 
 panding cylinder. 
 
 Surrounding the air coils in the ice tank is a solution of brine 
 made from Chloride of Calcium. The ice moulds used are formed 
 of cans made of galvanized iron the same as those used for ice 
 making plants. The condition of the air in passing from the 
 ice-making tank is governed by the quantity of ice withdrawn. 
 This should not be sufficient to raise the temperature of the air 
 above zero Fahr. This increases the amount of heat taken from 
 the tank from 60 degrees below zero to zero, or about two British 
 thermal units for each cubic foot of air passing through the cycle. 
 
REFRIGERATION- 95 
 
 Refrigerator Box. The air from the ice-making tank passes 
 into the refrigerator box coils, entering at a temperature of zero. 
 These coils are made with a manifold at each end with divisions 
 in the manifolds to direct the flow of air, causing a circulation 
 back and forth of three times the length of the box. By this 
 method of distributing the circulation, a small pipe system can 
 be used for the piping, while the headers are of an area equaling 
 the discharge from the expanding cylinder. The required area for 
 the circulating pipes is made up of several of the smaller pipes. 
 This is not a vital or even a necessary point. A large pipe could 
 be erected, giving the entire area of the exhaust cylinder opening. 
 This would increase the friction of the passage of air over the 
 design as illustrated in the plan. 
 
 Water Butt " or Cooler. From the refrigerator box, the 
 air passes through a coil of pipe in a tank filled with water. The 
 object being the cooling of the water for the use of the men. This 
 is the last operation of the air and it is desired to have the air at as 
 high a temperature as is consistent with the work. 
 
 The application of compressed air was first made successful in 
 ocean steamships carrying meat to Europe. The engines were so 
 large that no auxiliary boiler could furnish sufficient steam; so 
 that to cool the refrigerator box it required the starting of one 
 of the ship's main boilers. The air was exhausted from the box 
 at atmospheric pressure, and from the expanding cylinder 
 it was discharged directly into the refrigerator box. The result 
 was that tlie oil used for lubrication became very strong in the 
 air and left a taste in the meat. The moisture in the atmosphere 
 was turned to snow as it came in contact with the cool air; this 
 snow in turn becoming melted when striking the sides or floor of 
 the refrigerator or coming in contact with the merchandise in ship- 
 ment. This has been remedied by enclosing the air in piping and 
 having a continuous cycle of the cooling fluid in operation. 
 
 In no instance does the liquefaction of air enter into the 
 problem of refrigerating with air. 
 
 In the work of construction, iron pipe may be used, with any 
 of the pipe cements for joints common to first class piping. 
 
 The following instructions for starting and operating tho 
 Allen Dense Air Tec Machines are used by the United States Navy. 
 
 On starting the machine, have the blow valves of the expander 
 
96 EEFEIGEEATION 
 
 and the pet-cocks of the various traps open until no more grease 
 or water discharges. 
 
 The two IJ-inch or 2-inch valves of the main pipes must be 
 open and the 1-inch by-pass pipe closed; also the J-inch hot-air 
 valves from the compressor to the expander cylinder must be 
 closed. 
 
 Be sure that the circulating water is in motion. 
 
 The full pressure is 60 to 65 Ibs. low pressure, and 210 to 
 225 Ibs. high pressure. 
 
 During the running, open the pet-cocks of the water-trap 
 which takes the water out of the air from the primer pump, fre- 
 quently enough that it will never be more than half filled. If the 
 water should be allowed to enter the main pipes, it is liable to 
 freeze and clog at the valves. 
 
 By keeping all stuffing boxes well lubricated by the lubricator 
 cups, the pressures are easily maintained with but little screwing 
 up of the packing. 
 
 If the low-air pressure is not maintained, the fault is almost 
 always due to leaks at the stuffing boxes. Under all circumstances 
 it is due to some leak into the atmosphere, as we have never yet 
 found the primer pump valves at fault. 
 
 The packing of valve stems and piston rods consists of a few 
 inner rings of Katzenstein's soft metal packing, then a hollow 
 greasing ring, then soft fibrous packing (Garlock packing). 
 
 The sight feed lubricators of the compressor and expander 
 should only use a light pure mineral machine oil, from which the 
 paraffine has been removed by freezing usually three drops per 
 minute in the compressor and one or two in the expander. 
 
 The pistons of the compressor and expander cylinders are 
 packed with cup leathers, which commonly last about one or two 
 months of steady work. When these leathers give out, the high 
 pressure decreases in relation to the low pressure, and the ap- 
 paratus shows a loss of cold. A leak at any other point of high 
 pressure into low pressure will have the same effect. 
 
 These packing leathers are made of thick kip leather, or of 
 white oak-tanned leather of somewhat less than -J-inch thickness. 
 They are cut f inch larger in diameter than the cylinders. The 
 leathers must be kept soaked with castor oil and must be well 
 soaked in that before using ; and a tin box containing spare leathers 
 and castor oil must be kept on hand. 
 
REFRIGERATION 07 
 
 Once, or sometimes twice, a day, it is necessary to clean the 
 machine by heating it np and blowing ont all the oil and ice 
 deposits. This is done as follows : 
 
 The 1-inch valve of the by-pass is opened. Then the two 1^ 
 or 2-inch valves in the main pipes are closed ; then the two ^-inch 
 valves in the hot air pipe from the compressor chest to the expander 
 are opened, and the l^-inch valve of expander inlet is closed 
 partly; then the live steam is let into the jacket of the oil-trap 
 slowly, keeping the outlet from the steam jacket open enough to 
 drain the condensed steam. 
 
 Run in this manner for about one-half hour, during this time 
 frequently blow out the bottom valve of the oil-trap, also the blow- 
 off from the expander, until everything appears clean. Then 
 shut off the steam and drain connections of the jacket of the trap 
 and the hot air pipe from the compressor to the expander. Then 
 open the two 1^ -inch valves in main pipes. Then close the* 1-inch 
 by-pass pipe and all pet-cocks and run as usual. 
 
 Whenever opportunity offers to blow out the manifolds of 
 the meat-room and the ice-making box (that is, whenever they 
 are thawed), this should be done. 
 
 If it is suspected that a considerable quantity of oil and water 
 have got into the pipe system and are clogging the areas and coat- 
 ing the surfaces, the pipes can be cleaned by running hot air 
 through them as is done during the daily cleaning of the machine. 
 The oil and water are then drawn off at the bottom of the ice- 
 making box and the manifolds of refrigerating coils. 
 
 The clearance of the two air pistons and of the primer plunger 
 is only -J inch ; therefore not much change of piston rods and con- 
 necting rods is permissible, and when the piston nuts are un- 
 screwed to change the piston leathers, the rod should be watched 
 that it does not unscrew from the crosshead. 
 
 Whenever it is noticed that the brine freezes, more chloride 
 of calcium should be added and should be well stirred into the 
 brine. 
 
 ABSORPTION SYSTEM. 
 
 By the rapid vaporization of water in the desert of Arabia, 
 due to the intensely dry atmosphere, the first ice, other than that 
 formed by the natural process of winter freezing, was made. For 
 cooling large quantities of water, this process is in use to-day on 
 a more clearly defined and greatly enlarged plan known as the 
 
98 
 
 REFRIGERATION 
 
 Water Cooling Tower. This method is being extensively used 
 for cooling for condensing ammonia gas or for condensing the ex- 
 haust steam from an engine. 
 
 Carre's First Ice Plant: From the use of this system of 
 vaporization, Carre, a French scientist, constructed the first device 
 for cooling by mechanical means and producing ice, and all devices 
 for absorption refrigeration owe their results to the work so ably 
 accomplished by him. 
 
 A definition of the terms used in the two systems in con- 
 nection with refrigerating machinery is as follows : 
 
 Absorption Refrigeration, In the absorption, as in the com- 
 pression system, it is necessary to maintain pressure upon the 
 
 ammonia gas when freed from 
 water in order that it may 
 become liquefied, and during 
 its period of liquefaction 
 give up the latent heat. 
 
 The Carre original ma- 
 chine consisted of two strong 
 iron jars connected together 
 with an iron pipe as shown in 
 Fig. 54. In the jar A, or 
 ammonia still, was placed a 
 quantity of highly charged aqua ammonia. A spirit lamp E was 
 placed under the jar. An air cock was placed at I, and when the 
 jar became heated, the air cock was opened until the air was ex- 
 hausted. The pressure increased in both jars and connection A, B, 
 C. Jar C was placed in a tank and surrounded by cold water D. 
 The supply of this water was constantly changing so that at all 
 times the water remained cold or at its original temperature, which 
 we may assume at 60 degrees Fahr. The heat from the lamp 
 caused the ammonia to vaporize and a pressure was obtained suffi- 
 cient to liquefy the gas in the jar C. This pressure was about 120 
 pounds per square inch. The intense pressure made by the am- 
 monia gas was sufficient to raise the boiling pressure of the water 
 to 230 degrees Fahr., thereby preventing the vaporization of the 
 water. This temperature was ample to drive out a large amount 
 of gas. 
 
 After the process was complete, which was determined by 
 the length of time that the heat was exposed to jar A, the lamp 
 was removed. The water was drawn off from around jar C and 
 
 Fig. 54. 
 
REFRIGERATION 99 
 
 the tank filled with whatever substance it was desired to freeze. 
 A water pipe allowed water to flow over the jar A and cool its 
 contents, the result being that the pressure was removed from 
 both jars A and C, and the liquid anhydrous gas began to vaporize 
 in jar C, the gas returned to jar A, and was taken up in the water 
 from which it had been expelled. By the passage of the anhydrous 
 ammonia from a' liquid into a gas, the heat which was taken up 
 and caused the vaporization, being held latent by the gas, was 
 taken from the surrounding liquid in tank D. 
 
 This produced a low temperature, the boiling point of liquid 
 anhydrous ammonia being at atmospheric pressure 47 degrees be- 
 low zero Fahr. The ratio of the temperature and pressure deter- 
 mines the temperature at which the gas boils in passing from a 
 liquid to a gaseous condition. 
 
 Reabsorbing. As the expanded gases return to the jar A and 
 come in contact with the water, they are absorbed by the water and 
 in this process of absorption, the heat, which is taken up latent by 
 vaporization in the freezing jar C, is given off. The heat thus 
 given off in the jar A is carried away by the water flowing from 
 connection H. 
 
 It was by this simple device that Carre established the princi- 
 ples of refrigeration. We should remember that it was in 18 58 when 
 this work was done and that the methods of working iron were then 
 very crude. Carre's success was due to his patience and endurance. 
 
 In Fig. 55 is shown a double plant absorption machine, in- 
 cluding an ice making tank, each machine having a capacity of 
 12^ tons, or a 2 5 -ton ice-making output for every twenty-four 
 hours of constant operation. The plants are connected together so 
 that they can be interchangeable in their working parts. 
 
 The following is a brief description : An ammonia still A is 
 built of iron pipe 12 inches in diameter with heavy flanged heads, 
 which are of wrought iron, screwed on to the pipe and soldered 
 where the pipe and metal of the head joins. The object of a 
 flanged head is to admit of coils in the interior. A strong solution 
 of aqua ammonia is placed in the still and heated by a steam spiral 
 coil placed in the interior of the still. In operation, the aqua am- 
 monia still is kept about one-third filled with aqua ammonia. In 
 naming the parts of the apparatus, each designer or builder selects 
 names to suit his fancy. While the part used for applying heat 
 to the aqua ammonia is necessary to all designs of absorption 
 
100 
 
 * ' 
 
 EEFEIGERATION 
 
 QOOOOOO 
 OC^OOOOCD \- 
 
 y.Q- 
 
KEFKIGEKATION 101 
 
 machinery, we find it bearing the following names: '"ammonia 
 boiler/ 7 "ammonia still/' "ammonia pressure generator." 
 
 The steam connection is not shown in the drawing. The am- 
 monia gas is driven off by heat and passes up through fhe^conjiec- 
 tion T into the dehydrating coil B. As the ammonia: gai passes 
 from the sjill,it carries with it a small quantity of wa^e^in^ 
 ing condition which is separated from the gas iri^lie 
 coil. This coil is enclosed in a tank and filled with water which is 
 maintained at a temperature of approximately 150 degrees Fahr. 
 At this temperature the water condenses, but allows the ammonia 
 to remain a gas. The pressure in the still corresponds to the tem- 
 perature being maintained in the condenser for liquefaction. Here 
 the same ratio is obtained as in the compression machines, usually 
 from 110 to 180 pounds per square inch. It is usually considered 
 necessary to maintain 150 pounds per square inch for liquefaction. 
 This requires condensing water at approximately 60 degrees. 
 
 From the dehydrating coil the gas and water pass to a sepa- 
 rate tank C, which is a plain cylinder. The action is to separate 
 the gas from the water, the gas passing from the top of the sepa- 
 rating tank C to the condenser coil D, while the water which has 
 been separated from the gas by the action of the dehydrating coil 
 drops by gravity through pipe L and valves 10 back to the still. 
 
 The law of gravity holds good in all cases and under all 
 circumstances where pressures are the same. Therefore, in all 
 parts of the ammonia generating plant this law of falling of liquids 
 'by gravity is made use of and care must be taken in designing 
 plants that liquids will come to their proper places by gravity. 
 
 The ammonia gas is now separated from water and passes 
 to the condenser for liquefying. 
 
 Ammonia Condensers. The condenser coils D may be en- 
 closed in a tank and surrounded with water, or they may be left 
 open to the atmosphere and the water allowed to drip over them. 
 In the ammonia condenser, the heat held latent by the ammonia 
 gas is given off and a liquefaction takes place, the liquid ammonia 
 having the appearance of clear water. The ammonia drops into 
 a liquid storage tank E, through connection P. 
 
 Freezing or Ice Making Tank. The ammonia is now 
 liquefied and ready for use under a pressure normally of 150 
 pounds per square inch. 
 
 Note: Do not confuse liquid ammonia with anhydrous ammonia. 
 
102 
 
 BEFKIGEKATIOK 
 
 Erom the liquid tank E, the liquid ammonia flows through 
 the connecting pipe Q, being held in check by the main liquid 
 valve 5. The object of this main liquid 
 i e * valve- is to simplify the working of the 
 <plant. v Ttie : nme valves 12, are the ex- 
 o "S ? ; padding: valves/ each connected to the 
 * v coir of pipe in the freezing tank. Each 
 coil has a separate return with a stop 
 valve, entering connection 13. The 
 tank is shown with insulation but the 
 coils are not shown. This freezing tank 
 is designed to hold 240 cans or ice 
 moulds, each having the capacity of 200 
 pounds of ice, when the freezing is com- 
 plete. The tank is eight cans wide and 
 thirty cans long, or a tank 9 feet wide 
 by 60 feet long and 36 inches deep, in- 
 side measure. These tanks may be 
 built either of iron or wood as the de- 
 signer wishes. The coils run the entire 
 length of the tank, between the cans and 
 outside of them. 
 
 Freezing* In operating, the main 
 liquid valve 5 is opened and the gas 
 flows to the nine expanding valves 12, 
 which are opened to permit a flow of 
 gas through an opening varying from 
 T^o" to J of a square inch. 
 
 Low Pressure Side of the Ap- 
 paratus. At this point the gas is al- 
 lowed to pass from the pressure under 
 which it is condensed to the vaporizing 
 pressure, usually from 150 to 15 
 pounds per square inch. 
 
 Note: In all cases where pressures 
 are referred to, the zero point is the at- 
 mosphere and not absolute zero. 
 
 TO STEAM 
 TRAP 
 
 Fig. 5(1. 
 
 The liquefied ammonia entering 
 the freezing coils under pressure of 15 
 pounds per square inch immediately begins to vaporize and in so 
 
REFRIGERATION 103 
 
 doing takes the specific heat from the water. The heat passes 
 through the iron pipes, is taken up and returned to the absorber G 
 through connection S. The boiling point of liquid ammonia at 15 
 pounds pressure approximates 26 degrees below zero Fahr. The 
 action of the ammonia in boiling is identical to water boiling at 
 212 degrees in the atmosphere, with which every one is familiar. 
 
 Absorber. The vaporized gas flows into the top of the ab- 
 sorber where it meets the water from which the gas has been 
 driven. 
 
 Circuit of Weak Water. Returning now to the ammonia 
 still ; during the period of distillation, the water, freed from the 
 gas by heat and called by different names such as "mother liquid," 
 "weak water," etc., is allowed to flow from the bottom of the still 
 through connection, M, and passing through "heat exchanger" or 
 "equalizer" J, flows on to weak water cooler V, entering the cooling 
 coil at the bottom. It is preferable to have this coil enclosed in a 
 tank so as to get the advantage of "Baudlett" system of cooling or 
 the bringing of the hot water to the hot gas and cold water to the 
 cold gas. From this cooler, the weak liquid returns to the ab- 
 sorber G, through valve 9. The water is carried to the top where 
 it falls down over a spiral coil of water pipes. The w r ater and 
 gas here intermingle and the water absorbing the gas is allowed to 
 flow into reservoir H. A strong solution of- aqua ammonia is taken 
 by the pump through connection 8 and returned to the still through 
 connection 7, there to be re-distilled and the cycle of operation 
 again to be performed. 
 
 Pressure Gages. There are two pressure gages : one being a 
 high-pressure and the other a low-pressure instrument. The high- 
 pressure gage reads from zero to 300 pounds or more, the low- 
 pressure being a combination gage reading from 30 inches vacuum 
 to 150 pounds pressure per square inch, the zero point being at 
 atmosphere and not absolute. These gages are connected as fol- 
 lows ; the high pressure gage to the head of the ammonia still A, 
 the low pressure gage to the head of the absorbing tank G. Stop 
 valves must be placed in the gage lines between absorber and still- 
 tank heads to permit the removal of the gages for cleaning or 
 repairs. In locating gages, a position about 12 inches higher than 
 the eyes should be chosen. At this point they are easily seen and 
 accessible for cleaning. 
 
104 REFKIGERATION 
 
 A steam gage is required on the steam line entering the still, 
 also a reducing valve on the steam line to control the pressure of 
 steam. The steam gage is- connected between the reducing valve 
 and the ammonia still steam coil. 
 
 A steam trap is placed on the discharge of the steam coil 
 coming from the still, and so connected as to keep the still coils 
 free from water at all times. 
 
 Glass Gages. It is common with many builders of refrig- 
 erating and ice-making plants to place on their systems glass gages, 
 in order to determine the amount of liquid in the different parts by 
 actual observation. Many accidents of a severe nature have been 
 the result of breaking these glass tubes. 
 
 Automatic Gage Cocks. There have been many devices to 
 close the gage cocks automatically in case of breaking the glass ; 
 one device being the placing of long lever handles on the plug 
 cocks and closing them by a rope over a pulley at a safe distance. 
 These glasses are often made 36 inches in length, and from that 
 down to a few inches. 
 
 Enclosed Glass Gages. It is often the practice to enclose 
 these glass tubes within a pipe split for a quarter of an inch on 
 opposite sides and the space between the glass and the tube filled 
 with plaster of paris ; or, to make the tubes quite thin and drill 
 holes through them, the drill passing straight from side to side and 
 at right angles to the pipe, the object being that when the glass 
 bursts the pipe covering keeps the glass from flying and injuring 
 the attendant. 
 
 Glass Gages in Operation. It is a fact that most gages 
 after they have been in use about six months become filled with a 
 dirty substance, and become inoperative, their reading being mis- 
 leading to the attendant. To the successful operation of any re- 
 frigerating plant, either compression or absorption, the presence 
 of glass gages is an unnecessary adjunct, and the attendant soon 
 becomes so familiar with his plant that he can operate it without 
 reference to glass gages. 
 
 In installing and first charging a plant, these gages are a 
 convenience but not a necessity. In order to charge a plant with- 
 out gages, the engineer must know positively the amount of liquid 
 necessary to fill the different parts of his apparatus. Often ther- 
 mometers are inserted to determine the temperatures of the liquids 
 
KEFKIGEKATION 105 
 
 at the different parts. This may be very important to determine 
 the positive condition where a test is made for laboratory purposes. 
 In the parts of the apparatus shown in Fig. 55, glass gages 
 could be located on ammonia still A about 30 inches from the bot- 
 tom of the tank ; a glass about 24 inches long should be used. The 
 water collecting at this point should fill the tank to a height of 
 about 45 inches from the bottom, which would bring it to the 
 center of the glass. A thermometer could also be inserted in the 
 still 6 inches from the bottom, this to be an angle thermome- 
 ter and a "thimble" inserted to come in contact with the liquid. 
 In this thimble the bulb of the thermometer should be p^ced. 
 This thermometer should read from 80 to 300 degrees Fahrenheit. 
 
 Absorbing Tank Glass Gages and Thermometer. Glass 
 gages and thermometer may be placed on this tank in the same 
 way as those described for the distilling tank A. On liquid re- 
 ceiving tank E glass gages may be placed, the connection being 
 made in the head or from the upper and lower sides of the tank. 
 This glass is to indicate the quantity of liquefied ammonia in the 
 tank. 
 
 Operating Without Glass Gages. The object of a refrig- 
 erating or ice-making plant is to do the work for which it is 
 designed, and when an absorption plant is operating and the 
 output is not equal to the amount that it has turned out when 
 operating at its best, either it is short in some requirements neces- 
 sary to make it work successfully, or there is present a condition 
 that is foreign to the best working condition. No glass gages can 
 determine these conditions for the attendant. Only familiarity 
 with his plant will instruct him what to do. Passing his hand on 
 the weak water pipe as it leaves the still and also on the return for 
 the water entering the absorber, will tell him the conditions neces- 
 sary for successful operation. 
 
 Gas Foreign to Ammonia. One of the most serious ob- 
 stacles to the successful operation of absorption ice-making ma- 
 chinery is the generating with the ammonia still of a super- 
 abundance of free hydrogen gas, ammonia gas being composed of 
 three parts nitrogen gas. 
 
 There is present in the still, water which forms the method of 
 transit of the ammonia for part of its journey. This water is 
 formed of two parts of hydrogen to one part of oxygen. The iron 
 
106 REFRIGERATION 
 
 piping forming the heating coils has a large capacity for taking 
 oxygen and holding it in the shape of iron scales or rust. The 
 action of the ammonia tends to free this rust or oxygen scale from 
 the piping on which it has formed and as a result a large deposit of 
 scale forms in the ammonia still. The worst feature is that the 
 affiliation of the oxygen and iron has liberated a large amount of 
 free hydrogen gas which finally rises to the highest point in the 
 system, usually in the condensers, and remains there where the 
 conditions are not right for it to liquefy, because there is not 
 enough nitrogen gas to combine with it and form new ammonia. 
 It is necessary to get this hydrogen gas out of the system. This is 
 done by having a valve at a convenient place and occasionally 
 blowing it off. In a refrigerating plant in operation in 1904, 
 which was built to do refrigeration equal to the melting of 12 
 tons of ice for every twenty-four hours of operation, the actual re- 
 sult upon a careful observation, where the conditions permitted 
 a knowledge of the facts, was 2.6 tons. Part of the defect prob- 
 ably might have been due to a depreciated charge of ammonia gas. 
 
INDEX 
 
 A 
 
 Page 
 
 Absorption system of refrigeration 97 
 
 absorber 103 
 
 ammonia condensers '. 101 
 
 automatic gauge cocks 104 
 
 circuit of weak water. . .' 103 
 
 freezing ,. 102 
 
 freezing tank 101 
 
 gas foreign to ammonia , 105 
 
 glass gauges 104 
 
 pressure gauges 103 
 
 reabsorbing 99 
 
 Agents of refrigeration 5 
 
 Ammonia , 5 
 
 loss of " '. 73 
 
 Ammonia condenser 35 
 
 * atmospheric 39 
 
 double-pipe 45 
 
 submerged " 37 
 
 Ammonia receiver 49 
 
 Atmospheric condenser 39 
 
 B 
 
 Beaume scale . . 57 
 
 Brine 56 
 
 Brine cooler 14 
 
 Brine systems 58 
 
 Brine tank : 9 
 
 C 
 
 Carbonic acid 5 
 
 Carbonic anhydride gas refrigeration 81 
 
 -Carre's first ice plant 98 
 
 Centigrade scale 4 
 
 Compressed air 5 
 
 Compressed air refrigeration ; 87 
 
 air compressor "B" 91 
 
 expansion of air 89 
 
 ice making tank " 94 
 
 oil and water traps 94 
 
 refrigerator box 95 
 
108 INDEX 
 
 Compressed air refrigeration 
 
 relief of valves 93 
 
 unbalanced valve pressure 93 
 
 water butt or cooler 95 
 
 Compressor 18 
 
 erection of . . 26 
 
 losses 32 
 
 lubrication _". 30 
 
 piston '../...."..:.: 25 
 
 stuffing box 20 
 
 valves 22 
 
 water jacket 29 
 
 D 
 
 Direct expansion refrigeration GO 
 
 purging and pumping out connection 63 
 
 Double-pipe condenser 45 
 
 E 
 
 Evaporators 8 
 
 F 
 
 Fahrenheit scale 4 
 
 L 
 
 Latent heat, definition of 3 
 
 Loss of ammonia 73 
 
 O 
 
 Oil separator or interceptor 49 
 
 R 
 
 Reaumer scale 4 
 
 Refrigeration 
 
 absorption system 97 
 
 by ammonia 5 
 
 by carbonic anhydride gas 81 
 
 by compressed air 87 
 
 compression system 5 
 
 unit of "- 3 
 
 Refrigeration agents 5 
 
 Refrigerating plant 
 
 ammonia condenser 35 
 
 ammonia receiver " 49 
 
 compressors 18 
 
 direct expansion '. 60 
 
 evaporators 8 
 
 oil separator or interceptor .'.- 49 
 
 operation and management of 70 
 
 pipes 50 
 
INDEX 109 
 
 Pape 
 Refrigerating plant 
 
 pressure gauges 53 
 
 proportion between parts of 74 
 
 testing and charging 67 
 
 valves 53 
 
 - . S 
 
 Slotted water pipe , 44 
 
 Specific heat, definition of 3 
 
 Submerged condenser 37 
 
 Sulphur dioxide 5 
 
 T 
 
 Tables 
 
 calcium brine solution 79 
 
 chloride or sodium brine 80 
 
 gas liquefied, temperature of 81 
 
 saturated ammonia, properties of 78 
 
 thermometer scales 77 
 
 Thermometers 3 
 
 Centigrade 4 
 
 Fahrenheit . . . : 4 
 
 Reaumer 4 
 
 U 
 
 Units of machines or plants 3 
 
i 
 
14 DAY USE 
 
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 books are subject to immediate recall 
 
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 University of Californis 
 
 Berkeley 
 
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