^57 
 
 .56. 
 
opy 1 
 
 The Ohio State University Bulletin 
 
 Volume XXII MAY, 1918 Number 28 
 
 EFFECT OF GAS PRESSURE ON 
 
 Natural Gas Cooking 
 Operations in the Home 
 
 BASED ON / — .^ ^ A 
 
 TESTS MADE IN THE LABORATORY 
 
 OF THE 
 
 DEPARTMENT OF HOME ECONOMICS 
 
 THE OHIO STATE UNIVERSITY 
 
 Columbus. Ohio 
 
 Under the Direction of 
 
 EDNA NOBLE WHITE, Head of Department of Home Economics 
 
 GRACE LINDER, Instructor in Home Economics 
 
 AND 
 
 SAMUEL S. WYER, Consulting Engineer. Columbus. Ohio 
 
 PUBLISHED BY THE UNIVERSITY AT COLUMBUS 
 
 Entered as second-class matter November 17, 1905, at the postofBce at Columbus, Ohio 
 under Act of Congress, July 16, 1894 
 
INTRODUCTION 
 
 The determination of "what is usable natural gas pressure for 
 cooking service" has long been desirable. Since more than 36 per 
 cent of all of the natural gas consumers in the United States live 
 in Ohio, and 73 per cent of Ohio's population are dependent on 
 natural gas for their cooking service, it became evident that the 
 problem had a vital relation to the homes of the State, and that the 
 Home Economics Department should undertake to obtain accurate 
 data to answer this much discussed and little understood question. 
 
 The primary object of the tests was to duplicate household 
 operations rather than fancy laboratory conditions. Although a 
 water calorimeter, such as described in Vol, 1, page 699, of the Pro- 
 ceedings of the American Gas Institute for 1906, would give a 
 slightly higher efficiency for the burner, we thought it fairer to 
 measure the eflficiency with an ordinary cooking vessel rather than 
 with the more refined calorimeter, which would be of no interest to 
 the gas user. We believe that utility or usability may be of more 
 importance than mere efficiency; tests were therefore made to de- 
 termine exactly what results could be obtained with ordinary 
 kitchen utensils, from the very lowest to the highest pressures that 
 might be found in a natural gas distributing plant. 
 
 The experimental results obtained are given in Part 1, pages 
 3 to 17. The conclusions to be drawn from the tests are given on 
 pages 18 and 19. Some of the fundamental principles that must be 
 understood to secure a proper conception of the natural gas pres- 
 sure question are given in Part II, pages 20 to 27. 
 
 The routine work of the tests, under constant supervision, was 
 carried on by the Misses Biebricher, Erskine, Kirkpatrick, Nolan 
 and Steiger, members of the Department's senior class. 
 
 In conclusion we wish to emphasize that the tests were made 
 to determine what were usable natural gas pressures and not rel- 
 ative merits of particular stoves. 
 
 Columbus, Ohio 
 
 May 9, 1918. *•••* - ^^ ^ 
 
f^^^ TABLE OF CONTENTS 
 
 PART I 
 EXPERIMENTAL DATA TO DETERMINE EFFECT OF PRES- 
 SURE ON NATURAL GAS COOKING OPERATIONS 
 
 Section Page 
 
 1. Description of Apparatus 3 
 
 2. Importance of Vessel Position 3 
 
 3. Efficiencies at Various Pressures 6 
 
 4. Boiling Potatoes at Various Pressures , 12 
 
 5. Frying Potatoes at Various Pressures '. 12 
 
 6. Cooking Meat at Low Pressures 12 
 
 7. Baking Tests £|t Low Pressures 13 
 
 8. Accuracy of Meter Registration at Low and Various Gas Pressures 14 
 
 9. Conclusions 18 
 
 PART II 
 
 FUNDAMENTAL PRINCIPLES UNDERLYING NATURAL 
 GAS PRESSURE QUESTION 
 
 Section Page 
 
 10. Definition of "Natural Gas" 20 
 
 11. What Makes Gas Pressure 20 
 
 12. Gage Pressure 20 
 
 13. Atmospheric Pressure 21 
 
 14. Barometric Changes Make More Difference on Total Pressure Than 
 Gage Pressure Variation 21 
 
 15. Absolute Pressure .., 21 
 
 16. Differential Pressure 22 
 
 17. What Makes Gas Flqw? 23 
 
 18. Effect of Pressure on Gas Volume ^ 24 
 
 19. Effect of Temperature on Gas Volume 24 
 
 20. Standard Conditions 24 
 
 21. Heat Unit 24 
 
 22. Heating Value 25 
 
 23. Effect of Pressure or Temperature Changes on Heating Value of Gas.... 25 
 
 24. Combustion of Natural Gas 26 
 
 25. Action of Gas Mixer 26 
 
 26. Efficiency 27 
 
 27. Efficacy 27 
 
 28. Cooking and Heating Distinguished 27 
 
 LIST OF ILLUSTRATIONS 
 
 Fig. Page 
 
 1. Diagram of Apparatus Used in Cooking Tests 3 
 
 2. Photograph of Apparatus Used in Cooking Tests 4 
 
 3. Photograph of Drilled Burner 5 
 
 4. Photograph of Slotted Burner ^ 5 
 
 5. Curves Showing Gas Required to Boil Potatoes at Various Pressures.. 7 
 
 6. Curves Showing Gas Required to Fry Potatoes at Various Pressures.. 8 
 
 7. Curves Showing Variation in Time Required to Boil Potatoes at Vari- 
 ous Pressures 9 
 
 8. Curves Showing Variation in Time Required to Fry Potatoes at Vari- 
 ous Pressures 10 
 
 9. Curves Showing Efficiencies at Various Pressures 11 
 
 10. Diagram Showing Relation of Atmospheric and Gage Pressure 21 
 
 11. Curve Showing Effect of Pressure on Gas Volume 22 
 
 12. Curve Showing Mean Monthly Temperatures of Natural Gas 23 
 
 13. Diagram Showing Construction of Ordinary Gas Mixer 26 
 
 14. Diagram Showing Construction of Gas Mixer with Adjustable Spud.... 27 
 
PART I 
 
 EXPERIMENTAL DATA TO DETERMINE EFFECT OF PRES- 
 SURE ON NATURAL GAS COOKING OPERATIONS 
 §1. Description of Apparatus. 
 
 The apparatus used in the tests is shown in Figures 1 and 2. 
 A 10 cu. ft. meter prover is shown at the right. The pressures were 
 increased by placing weights on top of the meter prover, as shown. 
 The gas from a service line was passed into the meter prover bell 
 and the weights and counter weights were then adjusted to give the 
 desired pressure. 
 
 FIGURE I 
 
 DIAGRAM OF APPARATUS USED 
 
 COOKING 
 
 Bi/rner 
 
 
 The gas was measured in an ordinary domestic natural gas 
 mjeter. This had a differential pressure gage attached to the top, 
 as shown, to indicate the pressure drop over the meter, or, in other 
 words, the amouHt of gas pressure necessary to operate the meter, 
 this was found to be .1 inch of water pressure. The pressure at 
 the cooking fixtures was determined by the U-tube pressure gage, 
 and measured in ounces per square inch by means of a scale grad- 
 uated in ounces. 
 
 Referring to Fig. 2, the stove at the extreme left is a natural 
 gas range, with adjustable spud similar to the one shown in Fig. 14. 
 The stove in the middle is a range designed for manufactured gas, 
 with a non-adjustable spud, having a No. 47 orifice, similar to that 
 shown in Fig. 13. The hot plate at the right is simply an ordinary 
 natural gas hot plate with a non-adjustable spud, similar to that 
 shown in Fig. 13. 
 
 §2. Importance of Vessel Position. 
 
 For cooking operations it is only the tip of the flame that can 
 be used for effective service. If the flame is short and the vessel 
 
FIG. 2 
 PHOTOGRAPH OF APPARATUS USED IN COOKING TESTS 
 
FIG. 3 
 
 PHOTOGRAPH OF DRILLED BURNER WITH NAIL OR 
 
 WIRE INSERTS TO SUPPORT COOKING VESSEL 
 
 FOR LOW PRESSURE NATURAL GAS SERVICE. 
 
 FIG. 4 
 
 PHOTOGRAPH OF SLOTTED BURNER WITH THREE 
 PIECES OF SHEET IRON FOR SUPPORTING COOK- 
 ING VESSEL FOR LOW PRESSURE NATURAL 
 GAS SERVICE. 
 
is so far away that the hot point of the flame does not come close 
 to the vessel, satisfactory results cannot be obtained. If the flame 
 is very long in order to reach the high vessel, the stove will be 
 wasteful in the use of gas. 
 
 The following experiment brings out this feature in a rather 
 startling manner. This consisted merely in placing a standard 
 granite-ware vessel containing 7 lbs. of water on top of each of the 
 three stoves as shown, and with .8 oz. pressure, noting the length 
 of time required to bring the water to a vigorous boil, and the gas 
 consumption necessary to accomplish this. The results were as 
 follows : 
 
 Natural Manufactured Hot 
 
 Gas Range Gas Range flate 
 
 Vessel distance, inches 2.1 1.8 1.5 
 
 Length of flame, inches .6 .6 .3 
 
 Cu. ft. of gas _ 6.9 3.6 3.9 
 
 Time in minutes 47 16 49 
 
 In order to bring the vessel to the best operating position for 
 short flames all that is necessary is some device that will hold the 
 vessel the correct distance from the burner. With the drilled type 
 of burner this can be easily accomplished by removing the stove 
 top and inserting three nails or pieces of wire, as shown in Fig. 3, 
 and then placing the vessel on the top of these. With the slotted 
 type of burner, remove the stove top and simply insert three pieces 
 of sheet iron or heavy tin, as shown in Fig. 4, and then place the 
 vessel on the top of these. This is the only change necessary in 
 order to secure satisfactory cooking results with the ordinary 
 stove with low pressures and the resulting short flame lengths. 
 
 With low pressures, we found that no perceptible change could 
 be made in the combustion conditions by attempting to adjust the 
 air shutter. That is, entirely satisfactory results were obtained 
 with the air shutter wide open, without any adjustment whatsoever. 
 
 §3. Efficiencies at Various Pressures. 
 
 In order to determine the efl[iciencies of the three stoves at 
 various pressures, a granite-ware kettle — having a diameter of 8I/2 
 in. and height of 6 in., and of the form shown in Fig. 2 — containing 
 6 lbs. of water was heated, and the number of cu. ft. of gas required, 
 to raise this water to 200 degrees F. was noted. The heating value* 
 of the gas was determined in a gas calorimeter and the gas used m 
 these tests averaged 1,000 B. t. u. per cu. ft. 
 
 Since the B. t. u. is merely the amount of heat required to raise 
 one lb. of water one degree F., multiplying the number of pounds 
 of water by the total rise in temperature would give the number 
 of heat units actually delivered to the cooking vessel. This figure 
 in turn divided by the number of heat units in the gas used in heat- 
 ing the water will represent the efficiency, as defined in Sec. 26. 
 The efficiency tests of the three types of stoves, at the various 
 pressures, are tabulated in Table I, page 15 and shown in graphical 
 form in Fig. 9, page 11. 
 
FIGURE 5 
 
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 BOIL 2 LBS. OF OLD UNREELED POTATOES ON 
 
 THREE TYPES OF GAS STOVES 
 
 AT VARIOUS PRESSURES 
 
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 CURVES SHOWING VARIATION IN TIME REQUIRED TO 
 
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 CURVES SHOWING VARIATION IN TIME REQUIRED TO 
 
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12 
 
 §4. Boiling Potatoes at Vsurious Pressures. 
 
 In this test two pounds of old, unpeeled potatoes were cooked 
 in 6 lbs. of water, in an ordinary granite-ware kettle having a 
 diameter of 8V2 in. and height of 6 in., and of the form shown in 
 Fig. 2. 
 
 The data obtained on the three stoves at various pressures are 
 shown in tabulated form in Table III, page 17 and in graphical form 
 in Figs. 5 and 7, pages 7 and 9. 
 
 §5. Frying Potatoes at Various Pressures. 
 
 In this series of tests 2 lbs. of thin sliced, old, raw potatoes 
 were fried, with an ample supply of hot lard, in an ordinary pressed 
 steel skillet. 
 
 The data obtained on the three stoves at various pressures are 
 shown in tabulated form in Table II, page 16 and in graphical form 
 in Figs. 6 and 8, pages 8 and 10. 
 
 §6. Cooking Meat at Low Pressures. 
 
 In this test 2 lbs. of ground round beefsteak was fried in an 
 ordinary pressed steel skillet, with a gas pressure of .2 oz. The 
 data obtained for the three stoves were as follows : 
 
 Frying Beefsteak 
 
 Natural Manufactured 
 
 Ckis Oas Hot 
 
 Range Range Plate 
 
 Weight, ground Round Steak 2 lb. 2 lb. 2 lb. 
 
 Gas pressure in ounces per sq. in. .2 .2 .2 
 
 Cu. ft. of gas 1.85 1.675 1.225 
 
 Time in minutes 14 14 27 
 
 Flame length in inches 3 .3 .2 
 
 Skillet distance, inches 6 .6 .3 
 
 Barometric pressure in inches 
 
 mercury 29.37 29.37 29.37 
 
 In the following test 1 lb. of thick Porterhouse beefsteak was 
 pan-broiled in an ordinary pressed steel skillet, with a gas pressure 
 of .2 oz. The data obtained for the three stoves were as follows : 
 
 Pan-Broiled Beefsteak 
 
 Natural Manufactured 
 
 Gas Gas Hot 
 
 Range Range Plate 
 
 Weight, Porterhouse Steak 1 lb. 1 lb. 1 lb. 
 
 Gas pressure in ounces per sq. in. .2 .2 .2 
 
 Cu. ft. of gas 9 .6 .7 
 
 Time in minutes 7. 7. 16. 
 
 Flame length in inches 2 .3 .2 
 
 Skillet distance, inches 6 .6 .3 
 
 Barometric pressure in inches 
 
 mercury 29.18 29.18 29.18 
 
13 
 
 §7. Baking Tests at Low Pressures. 
 
 In baking 1 lb. loaves of white bread made up of two-thirds 
 wheat and one-third barley flour, at .5 oz. and 4 oz. pressures, the 
 following results were obtained in the bakers of the natural gas 
 and manufactured gas ranges: 
 
 Natural Oas Manufactured Qag 
 
 Range Range 
 
 Time Cu. ft. Time Cu. ft. 
 in min. Gas in min. Gas 
 .5 oz. Pressure — 
 
 Heating oven ready to receive bread 26 7.5 16 3.2 
 Baking bread 32 3.25 33 6 
 
 Totals 58 10.75 49 9.2 
 
 4 oz. Pressure 
 
 Heating oven ready to receive bread 14 6 7 2.2 
 
 Baking bread 32 4.2 32 7.2 
 
 Totals 46 10.2 39 9.4 
 
14 
 
 §8. Accuracy of Meter Registration at Low and Various Gas 
 Pressures. 
 
 The popular belief is that meters run faster when the pressure 
 is low than when the pressure is high. This is contrary to the facts. 
 Variation in pressure makes no appreciable difference in the regis- 
 tration of the meter, the meter merely registering — within a 
 reasonable limit of tolerance* — the amount of gas that passes, and 
 this is neither increased nor decreased by changes in pressure.** 
 
 A No. 1 Iron Clad, Pittsburg Meter Co., Dry Meter, No. 298598, 
 was used for measuring the gas in these tests. This was proved 
 for accuracy before the tests were started. The meter had been 
 in use for about two years prior to the tests and was in no way 
 specially prepared by adjustment or lubrication for this work, other 
 than merely to check its accuracy against a certified meter prover. 
 
 After the cooking tests were completed the meter prover used 
 for adjusting the pressures — shown in Fig 2 — was filled with nat- 
 ural gas which was then allowed to stand for several hours, until 
 it acquired the room temperature. The gas from this meter prover 
 was then passed through this meter at various pressures, through 
 the middle burner — having a No. 47 spud opening — of the Peerless 
 range, giving the following results : 
 
 Per cent. 
 Pressure in oz. No. minutes Cu. ft. gas Cu. ft. gas Error of 
 
 per sq. inch to pass 1 cu. ft. by meter by m^ter prover meter 
 
 .2 10.5 1 1.01 1% slow 
 
 .4 6.3 1 1.01 1% slow 
 
 .6 5.4 1 .99 1% fast 
 
 .8 5.0 1 .98 2% fast 
 
 1.0 4.0 1 1.01 1% slow 
 
 1.5 3.2 1 1.00 
 
 2.0 2.5 1 .99 1% fast 
 
 3.0 2.0 1 1.01 1% slow 
 
 4.0 1.8 1 1.00 
 
 5.0 1.5 1 1.01 1% slow 
 
 The above data show that low pressures do not make the meter 
 run faster. Incidentally, the number of minutes required to run 
 1 cu. ft. of gas becomes an index of the leakage tendencies ?t vari- 
 ous pressures. Since it takes about one-half the time to pass the 
 same amount of gas at 4 oz. as at 1 oz., it is evident that the rate of 
 leakage, on the consumer's premises and on the company's distribut- 
 ing plant, would be about twice as great at 4 oz. pressure as it 
 would be at 1 oz. pressure. 
 
 *The Ohio Laws fix the limit of tolerance at 3 per cent, fast or 3 per cent, slow for gas 
 meters. That is, a meter that is within not to exceed 3 per cent, fast or 3 per cent, slow is 
 regarded as commercially accurate. 
 
 **The same conclusion was reached in a report published by the Kansas Public Utilities 
 Commission, as Engineering Bulletin No. 2, of the University of Kansas, on "Natural Gas: 
 Its Properties, Its Domestic Use, and Its Measurement by Meters," under date of July 1, 1912. 
 
15 
 
 TABLE I 
 
 Efficiencies obtained with three different types of gas stoves 
 in heating 6 lbs. of water from the faucet temperature to 200 
 degrees F., at various pressures, using natural gas having a heating 
 value of 1,000 B. t. u. per cubic foot. The vessel distances were 
 the same as those given on page 17 for the various pressures. 
 
 Pressures in ounces 
 
 per square inch 2 .4 .6 .8 1. 1.5 2. 3. 4. 5. 
 
 NATURAL Gas Range. 
 
 Final temperature of 
 
 water 200 200 200 200 200 200 200 200 200 200 
 
 Initial temperature of 
 
 water 76 78 74 78 78 76 76 76 79 77 
 
 Rise of water 124 122 126 122 122 124 124 124 121 123 
 
 B. t. u. in water 744 732 756 732 732 744 744 744 726 738 
 
 Cu. ft. of gas 1.97 2.3 2.1 2.55 2.6 2.5' 3.7 5.5 5.6 5.1 
 
 B. t. u. in gas 1970 2300 2100 2550 2600 2500 3700 5500 5600 5100 
 
 Efficiency*% 37 32 36 29 28 30 20 14 13 14 
 
 MANUFACTURED Gas Range. 
 
 Final temperature of 
 
 water 200 200 200 200 200 200 200 200 200 200 
 
 Initial temperature of 
 
 water 76 78 78 77 78 75 75 78 73 77 
 
 Rise of water 124 122 122 123 122 125 125 122 127 123 
 
 B. t. u. in water 744 732 732 738 732 750 750 732 762 738 
 
 Cu. ft. of gas 1.71 1.87 1.9 2.2 3.1 2.7 2.55 2.1 2.6 2.45 
 
 B. t. u. in gas 1710 1870 1900 2200 3125 2700 2550 2100 2600 2450 
 
 Efficiency*% 43 40 35 33 23 27 29 35 29 30 
 
 HOT PLATE. 
 
 Final temperature of 
 
 water 200 200 200 200 200 200 200 200 200 200 
 
 Initial temperature of 
 
 water 78 72 78 76 75 72 76 76 75 78 
 
 Rise in water 122 128 122 124 125 128 124 124 125 122 
 
 B. t. u. in water 732 768 732 744 750 768 744 744 750 732 
 
 Cu. ft. of gas 2.45 1.825 1.65 1.65 2.125 2.05 1.9 2.95 2.08 2. 
 
 B. t. u. in gas 2450 1825 1650 1650 2125 2300 1900 2950 2080 2000 
 
 Efficiency* % 21 42 44 45 36 33 39 26 35 36 
 
 *For definition of term "Efficiency" and method of calculation see Sections 3 and 26. 
 
16 
 
 4. 
 
 4.3 
 
 3.45 
 
 3.72 
 
 4.8 
 
 4.6 
 
 5.65 
 
 5.5 
 
 5.9 
 
 21 
 
 21 
 
 16 
 
 16 
 
 16 
 
 18 
 
 17 
 
 20 
 
 24 
 
 .7 
 
 .7 
 
 .7 
 
 .8 
 
 .8 
 
 .9 
 
 1. 
 
 1. 
 
 1.1 
 
 1. 
 
 1. 
 
 1.2 
 
 1.2 
 
 1.2 
 
 2.1 
 
 2.1 
 
 2.1 
 
 2.1 
 
 TABLE II 
 
 Data obtained in frying 2 lbs. of thin sliced, old, raw potatoes 
 in an ordinary pressed steel skillet, with an ample supply of hot 
 lard, on three different types of stoves, with natural gas at various 
 pressures and having a heating value of 1,000 B, t. u. per cubic foot. 
 
 Pressures in ounces 
 
 per square inch 2 .4 .6 .8 1. 1.5 
 
 NATURAL Gas Range. 
 
 Cu. ft. of gas 3.1 
 
 Time in minutes 23 
 
 Flame length in inches .6 
 
 Skillet distance, inches .6 
 Barometric pressure in 
 
 inches mercury 29.44 28.85 29.32 29.06 29.21 29.34 29.4 29.34 29.34 29.69 
 
 MANUFACTURED Gas Range. 
 
 Cu. ft. of gas 2.44 
 
 Time in minutes 22 
 
 Flame length in inches .3 
 Skillet distance, inches 1.1 
 Barometric pressure in 
 
 inches mercury 29.42 29.21 29.34 29.16 29.24 29.34 29.26 29.41 29.33 29.21 
 
 HOT PLATE. 
 
 Cu. ft. of gas 1.45 1.975 
 
 Time in minutes 30 28 
 
 Flame leng-th in inches .3 .3 
 
 Skillet distance, inches .3 .7 
 Barometric pressure in 
 
 inches mercury 29.225 29.2 
 
 3.6 
 
 3.75 
 
 4.675 
 
 3.76 
 
 4.175 
 
 3.2 
 
 4.1 
 
 4.2 
 
 3.8 
 
 20 
 
 19 
 
 18 
 
 21 
 
 21 
 
 22 
 
 15 
 
 19 
 
 17 
 
 .5 
 
 .6 
 
 .7 
 
 .7 
 
 .7 
 
 .7 
 
 .7 
 
 .8 
 
 .9 
 
 1.1 
 
 1.5 
 
 1.6 
 
 1.7 
 
 1.7 
 
 1.7 
 
 1.7 
 
 1.7 
 
 1.7 
 
 1.7 
 
 2.65 
 
 2.9 
 
 2.125 
 
 2.3 
 
 2.8 
 
 2.71 
 
 2.5 
 
 30 
 
 25 
 
 19 
 
 21 
 
 21 
 
 22 
 
 19 
 
 18 
 
 .3 
 
 .5 
 
 .6 
 
 .6 
 
 .6 
 
 .6 
 
 .6 
 
 .7 
 
 .7 
 
 .7 
 
 1.7 
 
 1.7 
 
 1.7 
 
 1.7 
 
 1.7 
 
 1.7 
 
 '.56 
 
 29.18 
 
 29.07 
 
 29.15 
 
 29.28 
 
 29.41 
 
 28,98 
 
 29.21 
 
17 
 
 TABLE ill 
 
 Data obtained in boiling 2 lbs. of old, unpeeled potatoes in 
 6 lbs. of water, in an ordinary granite ware kettle, on three dif- 
 ferent types of stoves, with natural gas at various pressures and 
 having a heating value of 1,000 B. t. u. per cubic foot. 
 
 Pressures in ounces 
 per square inch 
 
 .4 
 
 .6 
 
 1.5 
 
 3. 
 
 4. 
 
 NATURAL Gas Range. 
 
 Cu. ft. of gas 5. 
 
 Time in minutes 47 
 
 Flame length in inches .6 
 Vessel distance, inches .6 
 Barometric pressure in 
 inches mercury 29.42 
 
 5.5 
 
 6.62 
 
 6. 
 
 7.15 
 
 7.15 
 
 8.27 
 
 9.35 
 
 9.35 
 
 10. 
 
 33 
 
 32 
 
 29 
 
 30 
 
 24 
 
 34 
 
 35 
 
 38 
 
 37 
 
 .7 
 
 .7 
 
 .7 
 
 .8 
 
 .8 
 
 .9 
 
 1. 
 
 1. 
 
 1.1 
 
 1. 
 
 1. 
 
 1.2 
 
 1.2 
 
 1.2 
 
 2.1 
 
 2.1 
 
 2.1 
 
 2.1 
 
 29.20 29.33 29.04 29.22 29.34 29.40 29.34 29.34 29.68 
 
 MANUFACTURED Gas Range* 
 
 Cu. ft. of gas 4.83 5.4 5.9 6.45 6.55 
 
 Time in minutes 45 33 30 27 26 
 
 Flame length in inches .3 .5 .6 .7 .7 
 
 Vessel distance, inches .5 .9 1.3 1.6 1.7 
 Barometric pressure in 
 
 inches mercury... 29.425 29.215 29.18 29.16 29.22 
 
 6.4 
 31 
 
 .7 
 1.7 
 
 5.19 
 40 
 
 .7 
 1.7 
 
 5.3 
 23 
 
 .7 
 1.7 
 
 5.7 
 
 27 
 
 .8 
 
 1.7 
 
 6.1 
 
 25 
 
 .9 
 
 1.7 
 
 29.36 29.29 29.34 29.23 29.21 
 
 HOT PLATE. 
 
 Cu. ft. of gas 4.29 
 
 Time in minutes 85 
 
 Flame length in inches .3 
 Vessel distance, inches .3 
 Barometric pressure in 
 inches mercury 29.32 
 
 4.05 
 
 4. 
 
 4. 
 
 4.75 
 
 4.85 
 
 3.9 
 
 4.45 
 
 4.9 
 
 4.4 
 
 61 
 
 47 
 
 40 
 
 41 
 
 37 
 
 39 
 
 34 
 
 35 
 
 32 
 
 .3 
 
 .3 
 
 .5 
 
 .6 
 
 .6 
 
 .6 
 
 .6 
 
 .6 
 
 .7 
 
 .7 
 
 .7 
 
 .7 
 
 1.7 
 
 1.7 
 
 1.7 
 
 1.7 
 
 1.7 
 
 1.7 
 
 29.20 29.56 29.29 29.06 29.34 29.28 29.41 28.98 29.21 
 
 •This stove was designed for manufactured gas and gave these results with natural gas without any 
 change in stove construction, or adjustment. 
 
§9. Conclusions. 
 
 1. — Satisfactory cooking operations in frying potatoes, boiling 
 potatoes, frying beefsteak, and pan-broiling beefsteak can be car- 
 ried on with .2 oz. natural gas pressure. 
 
 2. — The changes in vessel position necessary to permit satis- 
 factory operation at pressures as low as .2 oz. are easy to make 
 and require no special changes in existing stoves. 
 
 3. — Bread can be satisfactorily baked with .5 oz. natural gas 
 pressure. 
 
 4 — Natural gas stoves are not properly constructed to use 
 natural gas efficiently at high pressures, nor satisfactorily at low 
 pressures. 
 
 5 — At high pressures natural gas stoves are inefficient and 
 therefore wasteful in their use of gas. 
 
 6 — The burners on natural gas stoves are too low. 
 
 7 — The holes in the spuds of natural gas stoves are too small. 
 
 8 — Long flames for cooking operations are wasteful. 
 
 9 — The maximum results are obtained with many short flames 
 rather than a few long flames. 
 
 10 — A strong draft of air may deflect the flame away from 
 cooking vessel so as to seriously interfere with and in many cases 
 stop cooking. 
 
 11 — Where two flames strike each other, due to the fact that 
 openings are too close in burner, poor combustion will result. This 
 will produce a luminous flame which will in turn result in a smok- 
 ing burner. Neither air nor gas adjustment can overcome this. 
 
 12 — Drilled burners are better than slotted burners, because 
 there is less hkelihood of two adjacent flames striking against each 
 other, therefore producing imperfect combustion conditions. 
 
 13 — Natural gas cook stoves should not be furnished with solid 
 stove tops since this suggests the carrying on of cooking operations 
 on top of the stove, rather than with the vessel in the proper posi- 
 tion. 
 
 14 — At low pressures no perceptible change can be made in the 
 combustion conditions by adjusting the air shutter. The best con- 
 ditions obtained were with the shutter wide open. 
 
19 
 
 15 — Too much heat is used in most cooking operations, correct 
 application is more important than mere intensity. 
 
 16 — ^The natural gas pressures carried in most natural gas dis- 
 tributing plants are too high for efficient operation. 
 
 17 — Meter registration is approximately correct regardless as 
 to variation in pressure. That is, meters do not run faster when 
 the pressure is low. 
 
 18 — Lowering the temperature of natural gas increases its 
 heating value per cubic foot. Natural gas has a temperature about 
 25 degrees lower in the coldest month in winter than in the hottest 
 month in summer, and the heating value per cubic foot due to 
 change in temperature is therefore about 5 per cent higher in the 
 coldest month in winter than in the warmest month in summer. 
 
 19 — The maximum possible variation of heating value due to 
 variation in gage pressure would make the heating value during 
 the low pressure periods in winter less than 3 per cent lower than 
 during the high pressure period in summer, 
 
 20 — Since the heating value increase due to low temperature of 
 gas in winter more than offsets the possible decrease in heating 
 value due to low pressure, the practical effect of the two is that 
 the heating value per cubic foot of natural gas as served in the 
 winter under low pressures and low temperature is higher than that 
 served in the summer under higher pressures and higher temper- 
 ature. 
 
 21 — Variation in barometer from day to day may make more 
 of a change in the heating value of gas than any possible variation 
 in gage pressure. 
 
 22 — Better and more efficient service could be rendered if nat- 
 ural gas pressures were generally lowered to probably 2 oz. rather 
 than increased to 4 oz, or above. 
 
 23 — The lowering of natural gas distributing pressures to ap- 
 proximately 2 oz. would produce more efficient and satisfactory 
 operating conditions for the consumer, would greatly curtail the 
 leakage on the consumer's premises, which is paid for by the con- 
 sumer, and would also substantially lower the leakage in the gas 
 company's distributing plant. 
 
20 
 
 PART II 
 
 FUNDAMENTAL PRINCIPLES UNDERLYING NATURAL GAS 
 PRESSURE QUESTION 
 
 §10. Definition of "Natural Gas." 
 
 Natural gas is a highly combustible gas made by a secret pro- 
 cess of nature. It is not a chemical compound— as popularly sup- 
 posed — but a mechanical mixture of several combustible and diluent 
 gases and vapors thoroughly diffused— that is, thoroughly mter- 
 
 mixed through each other, the number and exact proportion of the 
 
 various crude natural constituents varying for the different locali- 
 ties and somewhat during the working lives of individual wells. 
 
 §11. What Makes Gas Pressure. 
 
 Natural gas is a fluid composed of a large number of molecules 
 which are vehicles of energy continually in motion and having an 
 inherent tendency to get farther and farther apart. The range of 
 motion of the molecules is limited only by the volume of the closed 
 containing vessel in which they constantly move to and fro. That 
 is the molecules are in a state of constant bombardment against 
 each other and against the sides of the containing vessel. 
 
 Natural gas pressure is the result of the combined efforts of all 
 the moving molecules in the gas trying to get farther and farther 
 apart ; that is, a mass of gas enclosed in a vessel expands and fills 
 it and being restrained from further expansion, it exercises a pres- 
 sure against the walls of the vessel. This pressure is the same m 
 all directions on equal areas of surface. Contracting the volume of 
 gas increases the intensity of its internal molecular motion and 
 therefore increases its pressure. 
 
 With a given mass of gas any increase in volume of containing 
 vessel will give the molecules more range of motion and thereby 
 lower the pressure. 
 
 Thus, if a part of a given mass of gas is removed from a closed 
 vessel or reservoir the remaining mass of gas will expand instanter 
 and keep the vessel or reservoir filled, but at a lower pressure. 
 
 §12. Gage Pressure. 
 
 This is simply the pressure indicated by a pressure gage. Two 
 o-eneral classes of gages are used for measuring gas pressure : 
 
 a— Spring Gages— Where the effect of the pressure ex- 
 erted against some form of spring is made to move a pointer 
 over a graduated dial or scale. 
 
 b— Fluid Gages— Where the effect of the pressure is indi- 
 cated by the height of the column of fluid in a "U" shaped 
 tube One side of the "U" shaped tube is open to the atmos- 
 phere and the other is attached to the pipe where the pres- 
 sure is to be measured. The gas pressure in this pipe then 
 lowers the fluid in one side of the tube and raises it m the other. 
 The total difference in the heights of the fluid on the two sides 
 
21 
 
 FIGURE 10 
 
 represents the total fluid pressures as shown in Fig. d'agram show- 
 1, page 3. When no pressure is applied to such a '^atmospheric '^ 
 "U" tube gage other than the prevaihng atmospheric cAcfl preIsure 
 pressure, the hquid will stand at the same level in 
 bothtubes. _ rp£ss^/Ff 
 
 The pressures m natural gas distributing plants i ^oz=J^0 -^ 
 are almost universally measured in ounces per square ""- 
 inch, while the pressures in manufactured gas dis- 
 tributing plants are measured in inches of water, 1 
 oz. equalling 1.73 inches of water. 
 
 Where the word pressure occurs in ordinances 
 or rules it invariably means gage pressure. 
 
 §13. Atmospheric Pressure. 
 
 Atmospheric pressure is measured by a bar- 
 ometer — usually in inches of mercury, one inch of 
 mercury equalling .49 lb. per square inch pressure — 
 and is synonymous with barometric pressure. 
 
 Sea level is the datum from which atmospheric 
 pressures are reckoned. At that point dry air at 
 82 degrees Fahrenheit exerts a pressure of 14.7 lbs. 
 per square inch. 
 
 This pressure varies with altitude and temper- 
 ature, the pressure decreasing with an increase in 
 altitude or temperature. 14.4 lbs. represents a fair 
 average barometric pressure for most natural gas 
 using communities. 
 
 §14. Barometric Changes Make More Di£Ference On 
 Total Pressure Than Gage Pressure Variation. 
 
 On account of the changing atmospheric condi- 
 tions the barometric pressure of gas varies from day 
 to day, and from hour to hour on the same day, thus, 
 during these tests the barometric pressure varied 
 from 29.69 to 28.85 inches of mercury, the equiva- 
 lent of .41 lbs. — 6 oz. — or considerably more than 
 the entire range in gage pressure. 
 
 §15. Absolute Pressure. 
 
 This is the sum of the gage pressure and the baro- 
 metric pressure. Thus, if the gage pressure is 4 oz. 
 — equalling 25 lbs. — and the atmospheric pressure 
 14.4 lbs. per square inch, the absolute pressure will 
 be 14.65 lbs. per square inch, as shown in Fig. 
 10. This must be used in all gas calculations dealing 
 with change of volume due to effect of pressure. 
 
 Failure to appreciate that the absolute pressure, 
 rather than merely the gage pressure, must be used 
 when computing the effect of pressure on gas vol- 
 ume, or heating value content, has been responsible 
 for most of the misunderstanding regarding the ef- 
 fect of variation in gage pressure on gas quality and 
 gas service. 
 
 14- 
 
 /3- 
 
 12- 
 
 //• 
 
 6- 
 
 6- 
 
 /- 
 
 •Lt—O- 
 
22 
 
 FIGURE 11 
 
 CURVE SHOWING EFFECT OF PRESSURE ON GAS VOLUME 
 AND GAS HEATING VALUE 
 
 §16. Differential Pressure. 
 
 This is the difference between the pressure at the inlet and out- 
 let point of a gas line. Thus, if the inlet pressure is 6 oz. and the 
 
 //oo 
 
 ^ 
 
 r 
 
 I 2 3 -^ - 
 
 &/75 P/?£5Siy/^£ //^ OZ. P£ff 5(?. /M 
 
23 
 
 outlet pressure is 4 oz., the differential head, or pressure, is 2 oz. 
 In gas transmission it is the differential pressure that constitutes 
 the effective force for pushing the gas through the line. 
 
 §17. What Makes Gas Flow? 
 
 The inherent tendency of gas to expand is the basic cause of 
 gas flow. Gas flow in pipes cannot take place except t)etween open- 
 ings of higher to openings of lower pressure. That is, flow can be 
 
 FIGURE 12 
 
 CURVE SHOWING MEAN MONTHLY TEMPERATURES OF 
 NATURAL GAS IN GAS MAINS AT COLUMBUS, OHIO 
 
 60 
 56 
 52 
 4S 
 44 
 
 
 
 
 
 
 
 y 
 
 s. 
 
 
 
 
 
 
 
 
 
 / 
 
 / 
 
 s 
 
 \ 
 
 
 
 
 
 
 
 
 / 
 
 
 
 > 
 
 s, 
 
 
 
 
 
 
 / 
 
 
 
 
 
 \ 
 
 
 
 
 
 > 
 
 / 
 
 
 
 
 
 \ 
 
 V 
 
 Sfc^ 
 
 
 
 / 
 
 
 
 
 
 
 
 N 
 
 4cP 
 36 
 52 
 28 
 24 
 20 
 /S 
 /2 
 
 ^V 
 
 \ 
 
 / 
 
 f 
 
 
 
 
 
 
 
 
 
 X 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 < ^ "^ ^ 
 
 /9/7 
 
 obtained only by sacrificing pressure. For this reason, it is a physi- 
 cal impossibility to maintain uniform pressure conditions and at 
 the same time have gas flow through the lines. 
 
24 
 
 §18. El£Fect of Pressure on Gas Volume. 
 
 For practical purposes, at a given constant temperature the 
 volume of natural gas is inversely proportional to the absolute 
 pressure — see Sec. 15 — to which the gas is subjected. That is, 
 with a given mass of gas, if you double the absolute pressure you 
 reduce the volume one-half, or if you double the space in which a 
 given mass can expand you reduce the absolute pressure one-half. 
 This is known as Boyle's Law. The small change in volume due to 
 variation in gage pressure is shown in Fig. 11, and the table in 
 Sec. 23. 
 
 §19. EfiFect of Temperature on Gas Volume. 
 
 Natural gas expands approximately 1 per cent in volume for 
 each 5 degrees Fahrenheit increase in temperature, and contracts 
 1 per cent in volume for each 5 degrees Fahrenheit decrease in 
 temperature. The variation in mean monthly temperature of nat- 
 ural gas at Columbus, Ohio, is shown in Fig. 12. 
 
 The variation in temperature of natural gas in the underground 
 mains makes more difference in the heating value than the varia- 
 tion in gage pressure. The maximum fluctuation in temperature 
 producing a difference in heating value of about 5 per cent, while 
 the maximum fluctuation in pressure produces a difference in heat- 
 ing value of less than 4 per cent. Furthermore, these variations 
 work in opposite directions. That is, in winter time when the pres- 
 sure is low, therefore tending to decrease the heating value, the 
 temperature is low, tending to increase the heating value. This 
 increase due to low temperature will always be more than the de- 
 crease due to low pressure. 
 
 §20. Standard Conditions. 
 
 Since the volume of a gas varies with the temperature and 
 pressure, in order to secure comparable results in gas calculations, 
 and the establishment of standards, a standard condition is neces- 
 sary. This is usually taken at 32 degrees Fahrenheit and a pres- 
 sure of 29.90 inches of mercury. 
 
 §21. Heat Unit. 
 
 The unit quantity of heat, or the heat unit, is the quantity 
 of heat required to raise the temperature of a unit weight of water 
 one degree. Different kinds of units in use are as follows: The 
 British Thermal Unit — B.t.u. — is universally used in America in 
 engineering work. The calorie is universally used in food problems ; 
 where used elsewhere it has been customary to use the expression 
 "large calorie" to distinguish it from the small calorie. The 
 gramme calorie, or small calorie, is universally used in scientific 
 work. 
 
 British Thermal Unit 
 
 Abbreviated B.t.u., is the heat required to raise one pound 
 of water one degree Fahrenheit. 
 
25 
 
 Calorie 
 
 This is the amount of heat required to raise one kilogram of 
 water one degree Centigrade. 
 
 Gramme Calorie 
 
 This is the amount of heat required to raise one gramme of 
 water from zero Centigrade to 1 degree Centigi'ade. 
 
 The arithmetical relation of these three units is as follows : 
 
 B. t. u. 
 1. 
 
 3.9682 
 0.003968 
 
 Large 
 Calorie 
 
 0.252 
 
 1 
 
 0.001 
 
 Gramme 
 
 Calorie 
 
 252 
 
 1 000 
 1 
 
 §22. Heating Value. 
 
 This is the number of heat units that are evolved by the com- 
 bustion of a unit weight or volume of fuel. The tei*ms "calorific 
 value," "calorific power," "heating power," "thermal value," and 
 "heat of combustion" are frequently applied to the same 
 phenomenon. 
 
 §23. Effect of Pressure or Temperature Changes on Heating Value 
 of Gas. 
 
 These will produce changes in volume, but will neither destroy 
 nor create any heat units, and hence will neither increase nor de- 
 crease the total number of heat units contained in the gas. How- 
 ever, the volumetric changes will always alter the distribution of the 
 total number of heat units, as follows: 
 
 Gage 
 Pressure 
 
 Above 
 Atmosphere 
 
 8 oz. 
 
 7 
 
 6 
 
 5 
 
 4 
 
 3 
 
 2 
 
 1 
 
 
 
 Gas 
 Temperature 
 Fahrenheit 
 
 65 
 60 
 55 
 50 
 45 
 40 
 35 
 
 Relative 
 B. t. u. 
 
 1034 
 1030 
 1026 
 1022 
 1017 
 1013 
 1009 
 1005 
 1000 
 
 Relative 
 B. t.u. 
 
 970 
 
 980 
 
 990 
 1000 
 1010 
 1020 
 1030 
 
 Relative 
 Per cent. 
 
 103.4% 
 
 103. 
 
 102.6 
 
 102.2 
 
 101.7 
 
 101.3 
 
 100.9 
 
 100.5 
 
 100. 
 
 Relative 
 Per cent. 
 
 97 % 
 
 98 
 
 99 
 100 
 101 
 102 
 103 
 
26 
 
 §24. Combustion of NatursJ Gas. 
 
 The combustible constituents of natural gas are made up of 
 combinations of the elements carbon and hydrogen. When natural 
 gas is burned so as to secure perfect combustion only carbon dioxide 
 and water vapor are formed. That is, the carbon of the gas unites 
 with the oxygen of the air forming carbon dioxide and the hydro- 
 gen of the gas unites with the oxygen of the air forming water 
 vapor. The water vapor, of course, will condense when cooled. 
 This water vapor does not come from the gas, but is created and 
 formed by the chemical action of the hydrogen in the gas and the 
 oxygen in the air. 
 
 Each cubic foot of natural gas burned requires approximately 
 91/2 cu. ft. of air, forming 10 V2 cu. ft. of combustion products, 
 which are made up of 2 cu. ft. of steam, 1 cu. ft. of carbon dioxide, 
 and 71/2 cu. ft. of nitrogen, all thoroughly diffused through each 
 other. 
 
 FIGURE 13 
 
 DIAGRAM SHOWING CONSTRUCTION OF 
 ORDINARY GAS MIXER 
 
 ^ - • -\ (345 
 
 The combustion of 1,000 cu. ft. of natural gas will form 2,000 
 cu. ft. of water vapor or steam, and this when condensed will make 
 approximately 10 1/2 gallons of water. This is not peculiar to 
 natural gas, but is true of all gases containing hydrocarbon com- 
 pounds. 1,000 cu. ft. of manufactured gas will form about one- 
 half the water vapor produced by the combustion of 1,000 cu. ft. 
 of natural gas. It is this water vapor that causes the bakers and 
 broilers of stoves to rust, and where gas is used in open fires with- 
 out flues, or for lighting, makes the walls and windows sweat and 
 glued furniture open up. 
 
 If the combustion is not perfect, then carbon monoxide, which 
 is a deadly poison, may be formed. The toxic action of this is 
 so marked that 1/10 of one per cent, is enough to produce fatal 
 results. This is especially likely to be formed when a flame is 
 suddenly impinged on a cold surface, as for instance the first few 
 seconds operation of an instantaneous hot water heater. 
 
 §25. Action of Gas Mixer. 
 
 As stated in the preceding section, about 9I/2 cu. ft. of air 
 must be mixed with each cu. ft. of natural gas in order to secure 
 perfect combustion. In order to accomplish this the gas at a 
 
27 
 
 FIGURE 14 
 
 DIAGRAM SHOWING CONSTRUCTION OF GAS MIXER 
 
 WITH ADJUSTABLE SPUD 
 
 •VM-'/////M 
 
 
 pressure above atmospheric air is forced through a small orifice 
 by the gage pressure in the gas pipe, and thus acquires a relatively 
 high velocity in passing through the small opening, as shown in 
 Figures 13 and 14. In this way an aspirating action is produced 
 around the orifice and this draws atmospheric air from the room 
 in so that it will mingle with the gas. A gas mixer is therefore 
 in effect merely a small air injector. The mixer shown in Fig. 13 
 is the one most generally used, and has no adjustment for the gas. 
 The mixer shown in Fig. 14 has a stationary cone and by turning 
 the spud, with a wrench on the hexagonal head of the spud, the 
 effective area of the orifice may be made larger or smaller, thus 
 changing the velocity of the gas, and, therefore, its aspirating 
 action. We did not run any tests to determine the relative merits 
 of the two types of mixers. 
 
 §26. Efficiency. 
 
 The term "efficiency" which has become a hackneyed one on 
 accounl; of its misuse, means the ratio between input and output. 
 In other words, the percentage of input energy that can be ac- 
 counted for on the output side of the device. 
 
 §27. Efficacy. 
 
 This is the power to produce an intended effect, and is en- 
 tirely separate and distinct from the efficiency of the process. For 
 instance, a gas burner may be efficient and yet not be effective. 
 On the other hand it may be able to produce results, that is secure 
 efficacy, with very low efficiency. 
 
 §28. Cooking emd Heating Distinguished. 
 
 In a heating operation it is merely necessary to secure perfect 
 combustion in the heating device, because in so doing all of the 
 available heat in the gas can be utilized. In cooking it is not only 
 desirable to secure perfect combustion, but absolutely necessary to 
 direct the heat to a particular place and sometimes at a particular 
 time. It is for this reason that gas cooking operations are more 
 susceptible to changed pressure conditions than heating operations. 
 
 It may not be amiss to emphasize that the time element in 
 many cooking operations is of much more importance than in- 
 tensity. 
 
\ 
 
LIBRARY OF CONGRESS 
 
 0C14 486 559 5 
 
LIBRARY OF CONGRESS 
 
 014 486 559 5