KACTICAmHANDBOOKSi LIBRARY OF THE UNIVERSITY OF CALIFORNIA. GIFT OF THE STATE VITICULTURAL COMMISSION. Deceived, January, i8g6. Accession No.b/t/2-tf .. Class No. THEORETICAL AND PRACTICAL AMMONIA REFRIGERATION. A WORK OF REFERENCE FOR ENGINEERS And others Employed in the Management of Ice and Refrigeration Machinery. BY ILTYD I. REDWOOD, ASSOC. M. AM. SOC. OF M. E. : M. SOC CHEMICAL INDUSTRY, ENGLAND. WITH 25 PAGES OF TABLES. UHI\ NEW YOKE: SPON & CHAMBERLAIN, 12 CORTLANDT STREET. LONDON : E. & F. N. SPON, 125 STRAND. 1895. Copyrighted, 1894. Copyrighted, 1895. Printed by Henry I. Cain, 35 and 37 Vesey Street, New York, U.S.A. PREFACE. THERE are many engineers and others interested in refrigerating machinery who have felt the want of a book of reference that will enable them to determine, with sufficient accuracy for all practical pur- poses, what work their machines are doing without resorting to laborious calculations ; therefore a number of tables have been pre- pared to meet this want, and a short treatise on the Theory and Practice of Refrigeration incorporated therewith. The tables, which have been calculated as accurately as possible, and have been checked by a gentleman of considerable "expert" experience, cover a sufficiently wide range of temperatures and pressures to meet all ordinary, and a good many extraordinary, requirements. ILTYD I. REDWOOD, BROOKLYN, February, 1895. CO PAGE INTRODUCTORY REMARKS i CHArTER I. BRITISH THERMAL UNIT . . . . . 3 MECHANICAL EQUIVALENT OF A UNIT OF HEAT . 4 SPECIFIC HEAT ....... 4 EFFECT OF TEMPERATURE AND PRESSURE ON SPE- CIFIC HEAT 6 EFFECT OF PRESSURE ON SPECIFIC HEAT OF AM- MONIA GAS 7 SPECIFIC HEAT OF AIR \vrni CONSTANT PRESSURE 7 SPECIFIC HEAT OF AIR WITH CONSTANT VOLUME . 9 LATENT HEAT 10 LATENT HEAT OF LIQUEFACTION . . . .10 LATENT HEAT OF VAPORIZATION . . . . 11 LATENT HEAT OF WATER 12 ABSOLUTE PRESSURE 13 ABSOLUTE TEMPERATURE 13 ABSOLUTE ZERO 16 EFFECT OF PRESSURES ON VOLUME OF GASES. 16 ii. Contents. CHAPTER II. TAGE THEORY OF REFRIGERATION ..... 18 FREEZING BY COMPRESSED AIR . . ... .19 FREEZING BY AMMONIA 21 CHARACTERISTICS OF AMMONIA .22 EXPLOSIVENESS 23 TENDENCY OF THE GAS TO RISE . . . . 24 SOLUBILITY IN WATER ...... 24 ACTION ON COPPER ....... 25 26 BEAUME AMMONIA 25 ANHYDROUS AMMONIA 25 CHAPTER ITT. GENERAL ARRANGEMENT ..... 26 DESCRIPTION OF THE PLANT . . . . .27 CONSTRUCTION DETAILS THE COMPRESSOR . 30 STUFFING-BOXES. . . . . . . .32 SPECIAL LUBRICATION 34 OIL FOR LUBRICATION 35 CLEARANCE SPACE, ETC. ..... 35 SUCTION AND DISCHARGE VALVES ... . 36 EFFECT OF EXCESSIVE VALVE-LIFT . . .' 37 REGULATION OF VALVE-LIFT - .... 37 CHAPTER IV. THE SEPARATOR . . 3'! THE CONDENSER 42 CONDENSER-WORM 42 RECEIVER " . . 43 PAGE REFRIGERATOR OR BRINE TANK .... 44 SIZE OF PIPE AND AREA OF COOLING SURFACE . 45 EXPANSION VALVES 46 WORKING DETAILS. CHARGING THE PLANT WITH AMMONIA . 47 CHAPTER V. AMMONIA TO BE GRADUALLY CHARGED . . 49 JACKET-WATER FOR COMPRESSOR . . . .52 JACKET-WATER FOR SEPARATOR .... 53 CONDENSING WATER 53 LESSENING THE COST FOR CONDENSING WATER . 54 QUANTITY OF CONDENSING WATER NECESSARY . 56 Loss DUE TO HEATING OF CONDENSED AMMONIA, 56 Loss DUE 58 SUPERHEATING AMMONIA GAS ..... 58 CHAPTER VI. EXCESS CONDENSING PRESSURE .... 59 CAUSE OF VARIATION IN EXCESS PRESSURES . . 60 OTHER CONDITIONS THAT AFFECT EXCESS PRESSURE, 62 USE OF CONDENSING PRESSURE IN DETERMINING Loss OF AMMONIA BY LEAKAGE . . ,63 COOLING DIRECTLY BY AMMONIA . . . .65 BRINE 66 FREEZING POINT OF BRINE 68 EFFECT OF COMPOSITION ON FREEZING POINT . 68 EFFECT OF STRENGTH ON FREEZING POINT . . 69 SUITABLENESS OF THE BRINE . . . . . 70 MAKING BRINE . . . . . . , .71 iv. Contents. CHAPTER VII. PAGE SPECIFIC HEAT OF BRINE 73 REGULATION OF BRINE TEMPERATURE . . -73 INDIRECT EFFECT OF CONDENSING WATER ON BRINE TEMPERATURE 77 CHAPTER VIII. DIRECTIONS FOR DETERMINING REFRIGERATING EF- FICIENCY 78 EQUIVALENT OF A TON OF ICE .... 79 COMPRESSOR MEASUREMENT OF AMMONIA CIRCU- LATED 79 Loss IN WELL-JACKETED COMPRESSORS . . 80 Loss IN DOUBLE-ACTING COMPRESSORS . . .80 DISTRIBUTION OF MERCURY WELLS . . . 81 EXAMINATION OF WORKING PARTS . . . .86 NUMBER OF READINGS TO BE TAKEN ... 86 CHAPTER IX. DURATION OF TEST 87 INDICATOR DIAGRAMS 87 AMMONIA FIGURES. EFFECTUAL DISPLACEMENT . 97 VOLUME OF GAS 97 AMMONIA CIRCULATED PER TWENTY-FOUR HOURS, 98 REFRIGERATING EFFICIENCY 98 BRINE FIGURES. GALLONS CIRCULATED . . 99 POUNDS CIRCULATED 100 DEGREES COOLED 100 TOTAL DEGREES EXTRACTED . 100 Contents. v. CHAPTER X. PAGE Loss DUE TO HEATING OF LIQUID AMMONIA . 102 Loss DUE TO HEATING OF AMMONIA GAS . . 103 CHAPTER XL CALCULATION OF THE MAXIMUM CAPACITY OF A MACHINE 106 PREPARATION OF ANHYDROUS AMMONIA . . 107 CONSTRUCTION OF APPARATUS . . . . . 108 CONDENSER-WORM IOQ WHY STILL is WORKED UNDER PRESSURE . .no BEST TEST FOR AMMONIA in WATER FROM SEPARATORS 101 LIME FOR DEHYDRATOR in YIELD OF ANHYDROUS FROM 26 AMMONIA . 112 INDEX 139 LIST OF ILLUSTRATIONS. j F.g. Page I. Specific Heat with Constant P ressure Determi- nation .... . 8 2. Absolute Zero Determination . 14 3- Ammonia Plant . . 28 4- < 29 5- Discharge Valve . . . . . 36 6. Suction " 36 7- Separator .... . 40 8. Expansion Valve . 46, 47 9- Mercury Well . 82 10. f . . . .. . . . 84 11. Indicator Diagram . 88 12. " " . . . 89 13- " " . . 90 14. " " 91 '5- Anhydrous Ammonia Distilling Apparatus . -US TABLES. Table Page I. Volume of Ammonia Gas at High Temperatures, 51 II. Yield, etc., of Anhydrous Ammonia from Am- monia Solutions 113 III. Boiling Point, Latent Heat, etc., of Anhydrous Ammonia , 116, 117 IV. Temperature to which Ammonia Gas is raised by Compression .... n8toi22 V. Volume of One Pound of Ammonia Gas at Various Pressures and Temperatures, 122 to 130 VI. Volume of One Pound of Ammonia Gas at Various Pressures and Temperatures, 131 to 138 UHI7BRSITY AMMONIA REFRIGERATION INTRODUCTORY REMARKS. THE ammonia "compression" types of freezing machines are now coming so gener- ally into use in large factories and manufac- turing establishments where natural ice was formerly employed, that they are of necessity placed directly or indirectly under the super- vision of men who, owing to the comparative newness of the subject of ammonia refrigera- tion in relation to the manufactures, can not be expected to be thoroughly conversant with their theoretical and practical working. In a great many instances engineers who have charge of these machines only run them by rule-of-thumb methods, and know- 2 Introductory Remarks. ing nothing about the why and the wherefore are, in the event of the conditions being changed, unable to reason out what will re- sult from the changed conditions, and what other changes ought to be made to counter- balance them. It is therefore with a view to giving those connected with the running of ammonia re- frigerating plants a more intelligent idea of what they are doing thereby tending to make their work interesting instead of labo- rious that this Book has been written. BEFORE dealing with ammonia refrigera- tion it is necessary that the different heat terms, etc., that are used in regard to this subject should be thoroughly understood, and they will therefore be explained forth- with. The terms with which we have principally to deal are : (1) British Thermal Unit. (2) Mechanical Equivalent of a Unit of Heat. (3) Specific Heat. (4) Latent Heat. (5) Absolute Pressure. (6) Absolute Temperature. BRITISH THERMAL UNIT. A British thermal unit is the standard unit of heat in this country, and represents the amount of heat necessary to raise the tem- perature of one pound weight of water one 4 Theoretical and Practical degree Fahrenheit the temperature of the water being 32; on the other hand, it is the amount of heat given up by one pound of water in cooling one degree Fahrenheit (i. e., from 33 down to 32). MECHANICAL EQUIVALENT OF A UNIT OF HEAT. Joule found, by means of a suitably con- structed agitator placed in water and actuated by a falling weight, that the amount of fric- tion caused by a weight of I Ib. falling a dis- tance of 772 feet, or a weight of 772 Ibs. falling a distance of i foot, was sufficient to heat i Ib. of water i Fahr. Therefore, the production of one British thermal unit of heat is equivalent to raising a weight of i Ib. 772 feet, or 772 Ibs. I foot, and consequently the mechanical equivalent of a unit of heat is 772 foot-pounds. SPECIFIC HEA-T. Specific heat is the number of British ther- mal units required to raise the temperature Ammonia Refrigeration. 5 of one pound weight of any particular sub- stance i Fahr., or it may be expressed as the capacity of different substances for heat. Scientists have proved that a pound of water has a greater capacity for heat than a pound of any other known substance, and therefore water is taken as the standard of comparison, and its specific heat at 32 Fahr. is unity. Turpentine has a specific heat of 0.472 and the specific heat of mercury is 0.033 ; from these figures it is understood that to raise the temperature of i Ib. of turpentine i Fahr. 0.472 B. T. U.* will be required, while the same weight of mercury will require only 0.033 B. T. U. to raise its temperature one degree. If 2 Ibs. of water at 32 Fahr. are heated to 42 Fahr., or through 10, they will absorb (2 Ibs. x 10 x i. ooo Sp. Ht. =) 20 B. T. U's, but if 2 Ibs. of turpentine are heated through the same number of degrees they * British Thermal Units. 6 Uieoretical and Practical will absorb only (2 Ibs. X 10 X 0.472 Sp. Ht. =) 9.44 B. T. U's. EFFECT OF TEMPERATURE AND PRESSURE ON SPECIFIC HEAT. The specific heat of substances varies with varying conditions of temperature and pres- sure, and invariably increases with increase of temperature or pressure. The variation in the specific heat of water at different temper- atures is so small that it may be passed un- noticed, but in the cases of certain oils and gases it is considerable : for instance, a min- eral oil that has a specific heat of 0.4503 at 85 Fahr. will have a specific heat of 0.4843 at 120 Fahr. Another point in regard to the specific heat of mineral oils is the fact that as the weight (specific gravity) of the oil "increases" the specific heat "decreases." Also, in the case of paraffin waxes, the higher the melting point the lower the spe- cific heat. Ammonia Refrigeration. 7 EFFECT OF PRESSURE ON SPECIFIC HEAT OF AMMONIA GAS. The effect of pressure on the specific heat of ammonia gas is very marked, for whereas the specific heat is only 0.508 when the gas is under a pressure of 28 Ibs. or less on the square inch, it is raised to 0.532 when the pressure reaches 80 Ibs. or upwards. The specific heat of a gas when expansion is allowed and when mechanical work is per- formed is greater than the specific heat of a gas that is not allowed to expand ; in other words, specific heat of a gas with constant pressure is greater than the specific heat of a gas with constant volume. In order to un- derstand this more clearly, the following explanation must be given : SPECIFIC HEAT OF AIR WITH CONSTANT PRESSURE. Let Figure I represent a cylinder with a cross sectional area of 144 square inches (one 8 Theoretical and Practical square foot) tightly closed at both ends and fitted with a piston, B, that will move without friction, and let the piston weigh 2, 1 1 6. 2 Ibs. Now, if a perfect vacuum is maintained in the space A, and if C contains I Ib. of air (= 12.387 cubic feet) at a temperature of 32 Fahr., the air will be under a pressure of 14.696 Ibs. per square inch, and will maintain the piston at a height of 12.387 feet. If this air is now heated to 33 Fahr. thus raising its tem- perature i Fahr. its volume will be increased, but the pressure will be exactly the same as before, because the piston has risen to make room for the increased volume of the air. According to Regnault's determina- tions, the amount of heat that would be necessary to raise the temperature of the air i Fahr. under the above conditions, would be 0.2379 B. T. U. Therefore the specific heat of air with Fig. 1 constant pressure is 0.2379 Ammonia Refrigeration. 9 SPECIFIC HEAT OF AIR WITH CONSTANT VOLUME. In the experiment just cited, not only was the temperature of the air raised i Fahr., but, owing to its expansion, a certain amount of mechanical work was performed when the piston was raised. Now, by heating the air i Fahr., its volume was increased (see page 4SS.4 + 33 16) to (12.387 X B-fg.-) I2 . 4I226 cubic feet, therefore the piston was raised from 12.387 feet up to 12.41226 feet, or through 0.02526 of a foot. As already men- tioned, the piston weighed 2,1 16.2 Ibs., there- fore the amount of work done by the expan- sion of the air was 2,116.2 Ibs. X 0.02546, height raised = 53.4552 foot-pounds. As it is known that the mechanical equivalent of a unit of heat is 772 foot-pounds, it is seen that the amount of heat that was required to perform the mechanical work of raising the piston was 53.4552 -r- 772 = 0.06924 B. T. U. Therefore, if the air had been heated from 32 up to 33 Fahr. without being allowed IO Theoretical and Practical to expand and perform mechanical work, the amount of heat that would have been neces- sary would have been (0.2379 0.06924=) 0.16866 B. T. U. ; hence the specific heat of air with constant volume is 0.16866. LATENT HEAT. Latent heat is heat that is hidden or is ab- sorbed (without making itself apparent to the thermometer) when a solid passes to the liquid state, or a liquid to the gaseous state. There are, therefore, two kinds of latent heat, one being the latent heat of liquefac- tion and the other the latent heat of vapor- ization. LATENT HEAT OF LIQUEFACTION. If I lb. of ice at 32 Fahr. and I Ib. of water at 33 Fahr. are placed in separate vessels of exactly the same size and shape, and these vessels are put in a place that is perfectly free from draughts and where the temperature is stationary at, say, 50 Fahr., Ammonia Refrigeration. 1 1 it will be found that the ice will take about 2 1 times as long to melt and heat up to, say, 40 Fahr. as the water will take to heat up to the same temperature. Now it is quite plain that if both vessels are exposed to exactly the same temperature, their contents must each be absorbing heat at the same rate, and as the temperature of the water in rising from 33 to 40, or through seven degrees, only required i-2ist of the time that the ice took, the ice must have absorbed (7X21) = 147 Fahr., but only 8 (32 to 40) of this had been registered by the thermometer, and therefore 139 Fhr. had become latent or hid- den. Of course this is but a crude method of determining latent heat, and accurate de- terminations have fixed 142.4 as the latent heat of ice. LATENT HEAT OF VAPORIZATION. If water is heated in an open vessel it will be found that the temperature can not be raised above 212 Fahr. No matter how long the heat may be applied the tempera- 12 Theoretical and Practical ture will remain stationary, although the water is constantly receiving additional heat. The heat thus hidden in the water is called the latent heat of vaporization, and if I Ib. of steam at 212 Fahr. were passed through a condenser and converted into I Ib. of water at 212 Fahr. it would be found that, although the condensation of the steam to water had not affected the temperature suffi- ciently to be noticeable by the thermometer, the condenser would have absorbed 966 B. T. U's, or sufficient heat to have raised the temperature of over 6^ Ibs. of water from 60 Fahr. up to 212 Fahr. The latent heat of vaporization of water is therefore 966. LATENT HEAT OF WATER. It is thus seen that to convert I Ib. of ice at 32 Fahr. into I Ib. of steam at 212 Fahr. requires : Ice at 32 to water at 32 (latent) . . 142.4 Water at 32 to water at 212 . . . 180.0 Water at 212 to steam at 212 (latent) 966.0 1,288.4 B. T. U's; A mmonia or the amount of heat that would reduce about 2^/2 Ibs. of cast-iron or about 9 Ibs. of silver to the molten state. In making a great many calculations in regard to heat it is necessary to make use of absolute pressures and temperatures. ABSOLUTE PRESSURE. Absolute pressure is pounds per square inch above a vacuum, and, as steam gauges are adjusted so that the O, or zero mark, represents the atmospheric pressure, it is necessary to add 14.7 Ibs. to the guage pres- sure, in order to convert it into absolute pressure. ABSOLUTE TEMPERATURE. In regard to absolute temperature experi- ments have proved that all pure, dry gases expand very nearly to the same extent for equal increments of heat, and it therefore matters little what gas is taken for the pur- pose of explaining the principle on which the basis for absolute temperatures has been determined. Theoretical and Practical Let Fig. 2 be a cylinder closed at both ends, and having a cross sectional area of 144 square inches (i square foot), a depth of about 1 8 inches, and a piston, B, capable Fig. 2 of moving without friction. It must now be supposed that the space C contains I cubic foot of air at a temperature of 32 Fahr., and that the piston, B, is weighted so as to exert Ammonia Refrigeration. i$ a pressure of 14.7 Ibs. on the square inch, while a perfect vacuum is maintained in A. Regnault's experiments have proved that if the contents of C are now heated to 212 Fahr., or through 180 Fahr. (i. e., 212 32), the piston and its load will be raised 0.367 foot, or to D, and the cubic foot of air will be increased in volume to 1.367 cubic feet. If we start again with the temperature at 32 Fahr. and the piston at E, and extract in- stead of add 1 80 Fahr. of heat (i. e., cool down the contents of C to 148 Fahr.), the piston will descend the same distance that it rose when the air was heated, namely, 0.367 foot, or to F. The extraction of another 180 Fahr. by cooling down the contents of C to 328 Fahr., would cause the piston to again descend another 0.367 foot, or to G, and to cause the piston to descend to H (and thus contract the air in C to, theoretically speak- ing, nothing), would necessitate the air being 1 80 cooled down - = 490.4 Fahr. below 32 Fahr. or to 458.4 Fahr. below zero. 1 6 Theoretical and Practical ABSOLUTE ZERO. Absolute zero is 458.4 Fahr., and an absolute temperature is the absolute zero temperature, plus the ordinary thermometer reading. The absolute temperature of a gas at 32 Fahr. is 490.4 (458.4 + 32), and if the temperature were o Fahr. the absolute tem- perature would be 458.4, while if the temper- ature were 32 the absolute temperature would be 426.4 (= 458.4 32). With the aid of this knowledge it is now easy to understand how the volume of gases at different temperatures is computed by the 458.4 + t formula v = V X - T^F* in which 458.4+ 1 V = Volume of the gas at the original temperature, T. v = volume of the gas at the new tem- perature, t. EFFECT OF PRESSURES ON VOLUME OF GASES. The volume of gases is also altered by pressure, and, according to Marriotte, the Ammonia Refrigeration 17 volume of any gas varies inversely as the pressure the temperature remaining con- stant. Thus: one cubic foot of air at 10 Ibs. absolute pressure on .the square inch, if sub- jected to an absolute pressure of 100 Ibs., will be reduced in volume to (i cubic foot X 10 Ibs. -^ 100 Ibs. =) o.i cubic foot, provided the work of compressing is done without gener- ating heat. But it is known that when work is done, heat is necessarily generated, and if the cubic foot of air at 10 Ibs. absolute pressure is compressed to i-ioth its volume by being subjected to an absolute pressure of 100 Ibs., its temperature will be raised to about 810 Fahr. Therefore, in calculating the volume of a gas that has been subjected to pressure, it is necessary to take into con- sideration the changes in volume caused by both temperature and pressure together, and the general formula becomes : P. X 458._4! P 458.4 +T in which V, P and T, and v, p and t, are the respective volumes, pressures and tempera- 1 8 Theoretical and Practical tures of the gas before and after compres- sion. Thus, if I cubic foot of air = V at 20 Ibs. Absolute Pressure = P and 60 Fahr. temperature = T is heated to 600 Fahr. temperature = t by being subjected to 200 Ibs. Absolute Pressure = p it will be reduced in volume to : Pres. Temp. 2O 458.4 -f- 6OO i cubic foot x x -- = - 2 cubic ft ---- v CHAPTER II. THEORY OF REFRIGERATION. A CAREFUL study of the foregoing pages ought to have made the two following facts quite plain : I. In order to effect the expansion of a Ammonia Refrigeration. 19 gas it is necessary that the gas should absorb heat. 2. The act of compressing a gas generates heat. FREEZING BY COMPRESSED AIR. If a compressed gas is re-expanded it practically absorbs the same amount of heat that was generated by compression, and the re-expanded gas will therefore be cooled down to its original (i. e., before compression) temperature. The gas in this case will sim- ply absorb the heat necessary for its re-ex- pansion from itself; but if, on the other hand, the compressed gas is cooled down before it is allowed to re-expand, it is very evident that it will not contain sufficient heat in itself to effect its own expansion, and therefore it will have to extract the necessary heat from its surroundings, and by so doing it will pro- duce the sensation of cold, although, strictly speaking, cold can not be produced, as it is a negative condition. 2O . Theoretical and Practical The following example will make the fore- going explanation plainer: i lb. of air at 14. 7 Ibs. Abs. Pres. and 60 Fahr. if compressed to no Ibs. Abs. Pres. will have its temperature raised to.. 475 Fahr. This compressed air is now cooled 10.65 Fahr. or through (475 65) 410 Fahr. As the specific heat of air is 0.238, the number of thermal units that have been extracted from the com- pressed air are... (410 X 0.238) 97. 58. If this cool compressed air is now re-ex- panded to its original absolute pressure of 14.7 Ibs., it will have to absorb 97.58 B. T. U's. As the extraction of 170 thermal units from i lb. of water whose temperature is 60 Fahr. will convert the pound of water into a pound of ice, it is evident that if the i lb. of above compressed air at a temperature of 65 Fahr. is expanded in a suitable appa- ratus surrounded by (97.584- 170=) 0.574 lb. of water at 60 Fahr. temperature, the water will be converted into 0.574 lb. of ice of 32 Fahr. temperature. The above figures are only approximately Ammonia Refrigeration. 21 correct, and are simply given as an illustra- tion of the theory of freezing by compressing and re-expanding a gas (such as air) that is not liquefied by compression. FREEZING BY AMMONIA. In considering the theory of refrigeration by means of the liquefiable gas ammonia it will be seen that the great advantage of am- monia over air lies almost entirely in the latent heat of vaporization. Suppose i Ib. of ammonia gas at 20 Ibs. absolute pressure and 32 Fahr. is compressed to 110 Ibs. absolute pressure, its temperature will thereby be raised to 268.6 Fahr. If the compressed gas is cooled to 65 Fahr. its temperature will be lowered 203.6, and this number of degrees multiplied by the specific heat of ammonia gas (which in this case is 0.532) shows that 108.31 thermal units have been extracted from the gas. But if instead of cooling the compressed gas to only 65 Fahr. it is cooled to 60 Fahr., it will be converted into a liquid, and as the 22 Theoretical and Practical latent heat of vaporization of ammonia at nolbs. absolute pressure is 517.23, the fol- lowing will now be the number of thermal units extracted. Temperature of compressed gas was 268.6 Fahr., and if cooled to 60 Fahr. its temperature will be lowered 208.6. Degrees cooled X specific heat = 110.97 T. U's. Latent heat of vaporization = 517.23 " Therefore total thermal units extracted = 628.20 These figures show how the advantage de- rived by the use of ammonia in the place of air lies in the comparative ease with which ammonia gas can be liquefied, thereby allow- ing of use being made of its latent heat of vaporization. CHARACTERISTICS OF AMMONIA. Ammonia is a colorless, irrespirable gas, with the odor of hartshorn. It is feebly combustible if mixed with a large propor- tion of air, and burns with a greenish-yellow flame ; if mixed with about twice its volume of air it explodes with some violence. It Ammonia Refrigeration. 23 is only a little more than half the weight oi air, is exceedingly soluble in water, and has a very strong action on copper and its alloys. The characteristics of ammonia ren- der it necessary that the following precau- tions should be observed in regard to the handling of it and in constructing an am- n onia refrigerating plant. EXPLOSIVENESS. Owing to the explosiveness of the gas it i important that any part of an apparatus ? hould be thoroughly aired before a naked l.ght is brought near it. This precaution is sometimes ridiculed by those who, through good luck rather than good management, have never exploded any large volume of the gas ; but the author has personal knowl- edge of a case where a man was thrown from a scaffold by the violence of an explosion which took place when the man lowered a lighted candle into a tall cylinder used in connection with ammonia refrigeration by the absorption process. 24 Theoretical and Practical TENDENCY OF THE GAS TO RISE. When a pipe that conveys ammonia bursts, anybody who happens to be near it should keep his head as low as possible while effect- ing his escape, because the gas being only half as heavy as air naturally rises as soon as it is liberated into the air ; if a man stood erect he might possibly be overcome by the gas, while if he stooped he would, in a great many cases, escape without experiencing any bad effects. SOLUBILITY IN WATER. As ammonia is exceedingly soluble in water (so much so that i part of water will at 60 Fahr. absorb about 800 parts o f the gas) the latter should be used to " kill" the gas in the event of any considerable quan- tity of strong ammonia solution being spilt. Also, in the case of a man going to the res- cue of anybody who is overcome by the gas, he should first take the precaution of placing a piece of waste or rag soaked with water Ammonia Refrigeration. 25 over his nose and mouth before entering the atmosphere that is impregnated with am- monia. ACTION ON COPPER. No part of an ammonia apparatus with which the ammonia is liable to come directly in contact must be constructed of copper or any of its alloys, such as brass, bronze, etc., as the parts containing that metal will be rapidly eaten away. 26 AMMONIA. Commercial liquid ammonia, commonly known as " spirits of hartshorn," is a solution of ammonia gas in water. In the wholesale trade it is sold in large iron drums, and as its usual strength is 26 Beaume, it is known as " 26 ammonia." ANHYDROUS AMMONIA. The other commercial preparation of am- monia is liquid anhydrous ammonia, and it 26 Theoretical and Practical must not be confounded with the ordinary liquid 26 ammonia. The difference between the two is that the liquid anhydrous (from the Greek vdor meaning without water) ammonia is the pure, dry, ammonia gas compressed to a liquid, while the 26 am- monia, as we have already seen, is a solution of the gas in water. CHAPTER III. GENERAL ARRANGEMENT. USERS of ammonia refrigerating machines arrange their plant in a manner that best suits their special requirements or accommo- dations; but wherever it is practicable the whole of the plant should be as compact as possible, so that the possibility of loss of refrigerating effect due to the absorption of heat by long connections from the sur- rounding atmosphere may be reduced to a minimum. Ammonia Refrigeration. 27 Figs. 3 and 4 show the principal parts of an ammonia plant, arranged so that the fol- lowing explanation can be easily followed and understood : DESCRIPTION OF THE PLANT. When the plant is in working order the liquid anhydrous ammonia is contained in the receiver, E, and the bottom two or three coi4s of the condenser; and being under a gauge pressure of, say, 120 Ibs., it flows through the pipe F and the manifold G to the expan- sion valves, H. Passing through the expan- sion valves, the ammonia traverses a series of pipes or coils which are surrounded by brine in the refrigerator, I, and terminate in the manifold K, that leads to the suction of the compressor, A. The suction of the com- pressor maintains a gauge pressure of, say, 28 Ibs. in these series of pipes, and thereby relieves the ammonia of its high pressure as soon as it passes the expansion valves. Directly the liquid anhydrous ammonia ex- periences this relief of pressure it commences 28 Theoretical and Practical Ammonia Refrigeration. 29 30 Theoretical and Practical to boil, or vaporize, and in so doing it ex- tracts heat from the brine, which latter could be cooled down to the boiling point of the ammonia due to a suction pressure of 28 Ibs., namely, to 14 Fahr. By the time the am- monia reaches the manifold K it has been entirely vaporized, and therefore passes off in the gaseous state, and entering the com- pressor by the pipe L it is compressed and then discharged through the pipe B into the separator, C, where any of the oil (used for lubricating the compressor) or other foreign matters that are mechanically carried for- ward by the gas are separated, and the gas then enters the condenser, D, where it is again liquefied and, running down into the receiver, E, recommences the above -de- scribed movements. CONSTRUCTION DETAILS THE COMPRESSOR. Owing to the heat that is generated during the compression of ammonia gas it is neces- sary that the compressor shall be surrounded, Ammonia Refrigeration. 31 or jacketed, with water, so as to prevent the overheating of the cylinder, etc., and undue abrasion of the rubbing surfaces. The hori- zontal type of compressor is usually jacketed from end to end, but the heads are not arti- ficially cooled. A, Fig. 3, is a half-sectional end view of a horizontal compressor. The cylinder, a, and jacket, b, together with the gas passages, f and g, in Fig. 4, are cast in one piece, which is bolted to the engine frame, G. The pas- sage g supplies the two suction valves, d and k, while the discharge valves, e and /, connect with the passage f. The jacket is supplied with water by the pipe /, the water filling up the space h and overflowing through r. The cylinder heads, i i, which contain the valves, ports and passages leading to / and g, are held in place by the bolts, s. In the vertical type of compressor the water-jacket is built so that the water not only surrounds the compressor cylinder but also entirely submerges the cylinder head and its valves. The relative efficiency of the two types of compressors will be com- 32 Theoretical and Practical pared under the heading " Indicator Dia- grams." STUFFING-BOXES. One of the principal sources of loss of ammonia in a refrigerating plant is in the stuffing-boxes of the compressor. The stuf- fing-boxes in some of the vertical types of compressors are packed with lead or babbitt- metal rings cut with a bevel, so that when they are subjected to pressure every alter- nate one hugs the piste n-rod, while the others are pressed tightly against the inner surface of the stuffing-box, thus forming a tight yet smooth working packing. In the vertical compressor, which is only single-act- ing, the pressure on the packing dc3s not exceed 28 Ibs. on the square inch, while with the horizontal compressor, which is double- acting, the pressure may reach and even exceed 165 Ibs., according to the tempera- ture of the condensing water. For this reason it is necessary that the packing for stuffing-boxes in a horizontal compressor Ammonia Refrigeration. 33 stuffing-box shall be deep. The depth is usually 12 inches, and the annular space be- tween the piston-rod and the inside of the box is about % of an inch. It requires a considerable amount of attention which is more or less proportional to the condensing pressure, but more especially to the kind of packing that is used, and it is with a sense of the benefit that the user will derive that "Common Sense," "Oarlock's," and " Sel- den's " packings are recommended as being specially suitable (if used conjointly) for hori- zontal compressor stuffing-boxes. The most satisfactory way to employ this combination packing is to, first of all, pack the stuffing- box to a depth of 5 to 5 ^ inches with Com- mon Sense packing ; then, having placed the perforated ring in position, half fill the rest of the box with Garlock's packing and finish off with Selden's packing. The packing should be driven tightly home, piece by piece, and then the gland should be screwed on only hand-tight, so as to allow the packing room to expand and fill the spaces without undue pressure. If the 34 Theoretical and Practical packing is forced into the stuffing-box by means of the gland, and is not allowed room to expand, it will last but a very short time, and give trouble as long as it does last SPECIAL LUBRICATION. The hot ammonia gas under high pressure will cut through the best, packing in a very short time if a liberal supply of oil is not forced into the stuffing-box at intervals of an hour or so. To effect the thorough lubrica- tion of the packing it is necessary that a hole shall be tapped in the centre (longitudinally) of the stuffing-box, which is then connected by a i^-inch pipe with a small hand forcr- pump. The packing is divided into two portions by a perforated iron ring, which ring is directly opposite the above-men- tioned hole, so that when the oil is deliv- ered by the pump it is distributed through the perforations to the packing on either side of the ring. Ammonia Refrigeration. 35 OIL FOR LUBRICATION. On no account must any animal or vege- table oils be used for lubricating the com- pressor, because as soon as any of these oils come in contact with the ammonia they will form soaps that will give endless trouble and annoyance. Nothing but a mineral oil of high viscosity and guaranteed purity should be used. CLEARANCE SPACE, ETC. It is very essential that there shall be no unnecessary spaces, such as screw-slots, deep ports, etc., on the inside of the compressor cylinder, and the clearance space between the piston and cylinder head should not exceed i-3?d to 3-64ths of an inch. If attention is not paid to these particulars too much gas will remain in the cylinder after the piston has completed its stroke, and the re-expan- sion of this clearance-space gas as the piston recedes will greatly diminish the working capacity of* the cylinder. 36 Theoretical and Practical SUCTION AND DISCHARGE VALVES. The suction and discharge ports are closed by poppet valves. The discharge valve, Fig. 5, screws into the outside of the cylinder head, and the spring, a, presses the valve Fig. 5 Fig. 6 against the seat on the inside of the head. The suction-valve, Fig. 6, screws into both the outside and inside of the cylinder head, and the gas in G, Figs. 3 and 4, passes in Ammonia Refrigeration. 37 through the holes, a, in its passage to the cylinder. The spring, b, is held in its place by the nut, c. EFFECT OF EXCESSIVE VALVE-LIFT. The lift of the valves is of very great im- portance, as it materially affects the refriger- ating effect of a machine. If the lift is too great the valve will not act with sufficient quickness, and especially is this so in the case of high-speed compressors, in which an additional valve-lift of y& of an inch will cause a diminution of one ton refrigerating effect in 24 hours. REGULATION OF VALVE-LIFT. The lift of the discharge valve is regulated by the plug, b, against which the valve-stem strikes, the distance between the striking surfaces being regulated by the thickness of gasket, c. In the case of the suction-valve, 38 Theoretical and Practical the lift is regulated by means of an iron sleeve around the valve-stem against which the nut, c, strikes when the valve opens. CHAPTER IV. THE SEPARATOR. OWING to the large volume of oil that is, or should be, used for lubricating the stuf- fing-box of the compressor, it is evident that a considerable quantity of it must pass into the cylinder and be carried through the dis- charge valves by the ammonia gas. If this oil were allowed to pass into the condenser it would soon find its way into the rest of the apparatus, and would cause trouble by chok- ing up the expansion valves, etc. ; therefore, with a view to obviating this annoyance, a separator is interposed between the com- pressor and condenser. The usual form of separator is an iron cylinder about 18 inches Ammonia Refrigeration. 39 in diameter and from 18 to 36 inches high. The ammonia gas enters by a connection on one side and leaves by a connection on the opposite side. The connections are usually 3 or 4 inches from the top, and the gas com- ing in contact with the side of the cylinder is freed of the most of its oil and passes on to the condenser, while the oil falls to the bot- tom of the separator. This and most other forms of separators are very imperfect, for the reason that they are not supplied with sufficient contact-surface and are not kept sufficiently cool. The gas when it passes through the separator is at a high temper- ature, say 200 Fahr., and consequently the oil held in suspension is exceedingly limped and light in weight, and has not any great tendency to separate from the gas. The author w 7 ould, therefore, advise the construc- tion of a separator on the principle shown in Fig. 7. The cast-iron cylinder, A, with its inlet, E, and outlet, F, opposite one an- other, has its cover, B, and contact plates, C, cast in one piece, and these are arranged so that when the gas impinges on them it is Theoretical and Practical Fig. VI 1 ,H .v 1 1 1 s\ c 1 I \ >Ws^^^^ .ML SECTION THRO, X. Y. Ammonia Refrigeration. 41 distributed over a large surface and is forced against the side of the cylinder in its zigzag passage from E to F. The oil in striking against these division plates will separate from the gas far more readily than if it meets with no obstruction, but even with the aid of the contact plates the separator will not effect a perfect separation unless the oil is rendered more viscous so as to increase its tendency to adhere to the plates, etc. This can be easily accomplished by making use of the water-jacket, D, which will keep the separator cold enough to make the oil separate and fall to the bottom. The bot- tom of the separator may be connected with the compressor so that the separated oil may be used over again ; but this connection is of little or no use with double-acting com- pressors, because pieces of packing, etc., that find their way from the stuffing-box into the compressor and thence into the separator will soon choke it up. The separator should be periodically cleaned, the cover, B, and plates, C, being raised by the ring, G, after the water has been run off from the jacket 42 Theoretical and Practical by the cock, I. On no account must the inlet to the separator look down, because the gas will then impinge on the oil lying in the bottom, and will be likely to become more contaminated with, rather than freed of, the oil. THE CONDENSER. The shape of the condenser tank affects the efficiency of the condenser to some ex- tent : it should be deep and narrow rather than long and shallow, so that there may be as great a distance as possible between the more or less warm water on the surface and the cold water that is admitted at the bot- tom. Another important point is to see that the water is properly distributed when it enters the bottom of the condenser, and not allowed to all run in at one point, as in the case of a discharge through an open-end pipe. CONDENSER- WORM. The condenser- worm or piping through which the ammonia passes should consist of Of TH3J 'UNIVERSITY; Ammonia Refriger&tt8g~z.S2^%$ about one-third of 2-inch, one-third of I Y^- inch, and one-third of i-inch pipe. This gradual decrease in the size of the pipe will give far less " excessive" condensing pressure than when the gas passes from a manifold into a series of three or four separate one- inch worms. The friction of the gas in pass- ing through a 2-inch pipe is less than when the gas passes through a number of pipes whose aggregate areas are equal to a 2-inch pipe. Another point is, it is quite unneces- sary to have the same cross-sectional area for the exit as for the inlet pipe, because the volume of the liquid anhydrous ammonia passing through the exit is only about I -75th of the volume of the gas that passes through the inlet pipe. RECEIVER. The receiver should be capable of holding 4 Ibs. of liquid anhydrous ammonia for every 24-hour-ton maximum capacity of the ma- chine. That is to say, if the machine has a maximum capacity of 65 tons of ice in 24 44 Theoretical and Practical hours, the receiver should be capable of holding 65 X 4 = 260 Ibs. of liquid anhy- drous ammonia. REFRIGERATOR OR BRINE TANK. The arrangement of the piping in the re- frigerator is different from that in the con- denser. By referring to Fig. 3 it will be seen that the liquid ammonia entering the series of piping at the manifold G descends by the vertical pipes, T, and then passes upward through the coils, U, before it is taken into the suction manifold K. The object of arranging the piping in this way is to insure the thorough vaporization of the liquid ammonia when the brine has become cooled down to a point near to the ooiling point of the ammonia due to any given suc- tion pressure, and the vaporization is thor- oughly effected because any liquid ammonia that does not vaporize will not pass upwards, and therefore the gaseous or vaporized am- monia has to bubble through it, and the liquid thereby absorbs sufficient heat from Ammonia Refrigeration. 45 the gaseous ammonia to effect the vaporiza- tion of the whole. If the liquid ammonia passed in at the higher and out at the lower extremity, as in the case of an ordinary con- denser-worm, a large quantity of the am- monia would pass through in the liquid form, as the warmer, or gaseous portion, would not be brought so intimately in contact with it. The refrigerator should be thoroughly insu- lated, and for this purpose it should be sur- rounded by a wooden jacket so that there is a space of about 3 to 6 inches between the refrigerator and the inside of the jacket, and this space should be filled with mineral-wool, charcoal, sawdust, or any other good non- conductor. SIZE OF PIPE AND AREA OF COOLING SURFACE. The size of pipe and total cooling surface exposed to the brine very materially affect the economical running of a refrigerating plant, and practical results have demon- strated without doubt that coils, or worms, made of 2-inch pipe are far more econom- 4 6 Theoretical and Practical ical in regard to the use of steam, etc., than i -inch pipe. The total length of piping in contact with the brine should be sufficient to give a mean cooling surface of 50 to 55 square feet per 24-hour-ton maximum ca- pacity. EXPANSION VALVES. The expansion valves are of the spindle type as shown in Fig. 8, and should be made of the best quality of cast-iron. Fig. VIII Ammonia Refrigeration. 47 A Manifold when number of valves are connected by flanges, B, B. C and D = Inlet and Outlet Passages. E = Flange connecting valve with coil in refrigerator. F = Needle-Valve. G = Plug to simplify cleaning passages in case of stoppage. WORKING DETAILS. CHARGING THE PLANT WITH AMMONIA. In order to charge a new or at any rate an empty plant with ammonia it is first of all necessary to expel the air. This is done 48 Theoretical and Practical by opening all the valves and cocks with the exception of O, P, and S, which latter are tightly closed, and allowing the compressor to exhaust the air from D, E, F, G, I, K, and L, and discharge it through the open cock N, until the combination vacuum-pressure gauge connected to the suction, of the com- pressor shows that the engine is not capable of exhausting the apparatus any further ; the cock N and valve H are then closed and the valve O opened. The drum of anhy- drous ammonia (if an anhydrous ammonia generating apparatus is not included in the plant) is now connected with the cock S, which latter is then opened to allow the compressor to transfer the ammonia from the drum. When the plant is charged the cock S is closed and the valves H ars then opened sufficiently to allow the compressor to maintain the suction pressure correspond- ing to the required brine temperature, which will be alluded to later. Ammonia Refrigeration. 49 CHAPTER V. AMMONIA TO BE GRADUALLY CHARGED. THE plant should not be charged with more than 60 per cent, of its full comple- ment of ammonia at its first charging be- cause it is impossible to exhaust the whole of the air from the plant by means of the compressor, and the only way to get entirely rid of the air is by displacement. This is effected by very cautiously opening the cock P once or twice a day and allowing the air to escape, at the same time taking every pre- caution to prevent undue loss of ammonia. After the air has been displaced a fresh quantity of ammonia is pumped into the plant in the manner above described, and the next day the same operation is gone through again, until at the end of, say, six days, the full complement of ammonia has been charged. In this manner the whole of the air is effectually expelled with but a slight loss of ammonia. An experienced man can easily tell from the general condi- 5O Theoretical and Practical tions and working of the plant when suffi- cient ammonia has been charged ; but as the uninitiated might experience some difficulty in ascertaining whether the plant was suffi- ciently charged, the following method has been formulated for calculating the quantity of ammonia that constitutes a full charge. Suppose the maximum capacity of plant is 65 tons of ice per 24 hours, and that the sizes of the different parts are as follows : Connection from ^ Compressor to Sepa- ( B 2 in. rator. ) Separator C 24 " LENGTH. 10 ft. - 2 " CAPAC- ITY. CUBIC ) FT " k 4.1. 1 Containing \ Ammonia \ D 1 ..i^ " Condenser- as gas. ) Worm. j Containing \ Ammonia > D 2 ..i> " - as liquid. ) Receiver -E 24 *' 2800 " 7 00 " 3 " 1 Connection from Receiver ^ to Refrigerator ^ 18-3 Manifold for Expansion ) p 2 6 " Valves \ Refrigerating Piping T & U 1)4 " Connection from \ Refrigerator to C K&L...2 " Compressor ) 6000 " o 1 J >I00.3 Ammonia Refrigeration. 5 I The parts B, C, and D 1 will contain am- monia in the gaseous state at a gauge pres- sure of, say, 1 20 Ibs. and average temperature of 80 Fahr. The parts D 2 , E, F, and G will contain liquid anhydrous ammonia. The parts T, U, K, and L will contain gas- eous ammonia at a gauge pressure of 28 Ibs. and an average temperature of 1 5 Fahr. TABLE I. GAUGE PRES- SURE. TEMPERATURE OF GAS. 66 740 80 84 9< D o 95 o ir^i,. ~r TU _r r* _ : r< 1_- T7._^ 80 3-470 85 3.292 90 3-!3i 95 3-35 100 2.900 , 105 2.785 IIO 2.695 115 2.590 120 2.490 125 2.418 130 2-333 135 2.252 140 2.204 145 2.134 ISO 2.088 !55 2.037 52 Theoretical and Practical From Tables I. and V. it will be seen that the volumes of the ammonia gases at the above pressures and temperatures of 120 Ibs. and 80 Fahr. and 28 Ibs. and 15 Fahr. are respectively 2.490 and 10.763 cubic fee*- per pound of ammonia ; therefore the amount of ammonia required to charge the plant is : B, C, and D 1 = (41. 1 2.49) 16^ Ibs. D 2 , E, F, andG =(18.3x38-66*) 707^ " T, U, K, and L = (100.310.763) 9^ " Total, 733^ Ibs. JACKET-WATER FOR COMPRESSOR. The amount of jacket-water necessary for the compressor varies according to the con- densing pressure. With a low condensing pressure say 90 to 105 Ibs. gauge pressure 10 to 15 gallons of water per hour per 24- hour ton refrigerating effect will usually be found ample, but when the condensing pres- sure reaches, say, 140 to 150 Ibs., the amount of water will have to be increased to about * Weight of a cubic foot of liquid anhydrous ammonia, Ammonia Refrigeration. 53 45 to 50 gallons per hour per 24-hour ton refrigerating effect. JACKET- WATER FOR SEPARATOR. The amount of water used in the separa- tor jacket should be as large as possible, and so that the water may not be wasted or be- come expensive, the overflow-pipe, H, should be continued down midway into the con- denser, where the water should be distributed and used along with the condensing water that is admitted at the bottom of the con- denser. CONDENSING WATER. As the pressure against which the com- pressor has to work is regulated almost en- tirely by the temperature of the condensed ammonia, it is obvious that the lower the temperature of the condensed ammonia, the greater the saving in the wear and tear of the engine, in the use of steam and con- sequently the consumption of coal, will be. The quantity and the temperature of the 54 Theoretical and Practical condensing water are, therefore, points that need careful consideration. The manufac- turer who has to use the city water-supply for condensing purposes can not, under or- dinary circumstances, economically cool the ammonia to a lower temperature than 55 to 60 Fahr. during the winter months, and 65 to 75 Fahr. during the summer months, because, should he increase his supply of water sufficiently to reduce the temperature of the ammonia, say 10 below the above figures, he would at once incur an extra ex- pense that would not be warranted by the resulting increase in the refrigerating effi- ciency of the plant. This increased expen- diture can, however, be overcome if the following plan is adopted : LESSENING THE COST FOR CONDENSING WATER. Instead of supplying the steam-boilers in the establishment with the whole of their water direct from the main, the author ad- vises arrangements being made to draw the Ammonia Refrigeration. 55 boiler water-supply from the overflow of the ammonia condenser, then making up the deficiency from that source by drawing from the main. This method of working would be beneficial in every respect, because in the first place, the water in passing through the condenser will receive a certain amount of heat which is distinctly an advantage, as boiler-water is, or should be, heated before entering the boiler. Secondly, if the whole or a part of the water required for the boilers is taken from the ammonia-condenser over- flow, the cost of condensing the ammonia is practically reduced to //, because the boilers have to be supplied with water, and the fact that that necessary supply has been pre- viously used for condensing purposes in no way increases the cost after the first cost of putting up the system of piping for convey- ing the water has been paid for. Thirdly, the effect of the use of a superabundance of condensing water will be a reduction of, at least, 30 to 40 Ibs. per square inch in the condensing pressure and a corresponding saving in steam. 56 Theoretical and Practical QUANTITY OF CONDENSING WAVER NECESSARY. If the temperature of the water supplied to the condenser is 5 5 to 60 Fahn, and the temperature of the overflow or outlet water is 85 to 90 Fahr., the quantity of water that will be required will be about 0.9 gallons per minute per 24-hour ton of ice ; but if the temperature of the overflow were oily 70 to 75 Fahr. (the inlet temperature being 5 5 to 60), the quantity of water that would be necessary would be about 2^ gallons per minute per 24-hour ton of ice. This reduc- tion of fifteen degrees in the temperature of the overflow means a reduction of 30 to 40 Ibs. in the condensing pressure, and if the ammonia leaves the condenser at the tem- perature of the inlet water, a minimum con- densing pressure and large saving in steam will result. Loss DUE TO HEATING OF CONDENSED AMMONIA. One very weak point and very surprising oversight in the management of a great num- Ammonia Refrigeration. 57 her of refrigerating plants is the fact that, although manufacturers often go to a deal of expense in order to condense and cool the ammonia to the lowest possible tempera- ture, they entirely ignore the importance of making arrangements to maintain that low temperature until the ammonia reaches the refrigerator. The receiver, and a consider- able length, if not the whole, of the piping through which the anhydrous ammonia has to pass on its way to the refrigerator are, as a rule, situated in the engine-room which is not usually the coolest of places and the temperature of the ammonia is consequently often raised 5, 10, 15, or even 20 degrees (above the temperature at which it left the condenser) before it reaches the refrigerator ; and as these 5 to 20 degrees gain in tem- perature mean a loss of from J^ to I J^ ton refrigerating effect per 24 hours, on a 65 -ton machine, it seems as though it would be ad- vantageous to have the receiver and piping covered with a cheap non-conducting mate- rial, so as to take full advantage of the bene- fits resulting from a liberal water-supply to 58 Theoretical and Practical the condenser, and thus prevent an unneces- sary waste. Loss DUE. It might be advisable to here refer to an- other source of needless loss which has even a greater effect on the refrigerating efficiency of a machine than the case just considered. SUPERHEATING AMMONIA GAS. It is the loss incurred by the ammonia gas absorbing heat in the transit from the re- frigerator to the compressor. Some people argue that it is absurd to go to any expense for the purpose of preventing that gas from absorbing heat, as it is heated up, any way, as soon as it enters the compressor. Others, again, consider that any heat absorbed by the gas simply means that a few more ther- mal units will have to be extracted from the gas when it passes into the condenser. If these people would just take time to think, they would at once see that the higher the temperature of the gas is before it enters Ammonia Refrigeration. 59 the compressor the greater the volume of a given weight must be, and therefore the compressor, although circulating or pumping the same volume, will not circulate so great a weight ; and as the refrigerating efficiency of a machine is proportional to the weight of ammonia circulated, it is obvious that the higher the temperature of the gas before it enters the compressor, the smaller the re- frigerating efficiency of the machine will be, the suction pressure being the same in both cases. The effect of covering the ammonia pipes is more particularly dealt with under the heading " Directions for Determining Refrigerating Efficiency." CHAPTER VI. EXCESS CONDENSING PRESSURE. THE condensing pressure, when the appa- ratus is working, is always greater than the theoretical. This "excess" pressure is due almost entirely to the confining of 60 Theoretical and Practical heated gaseous ammonia in the more or less limited space of the coils of the condenser, and varies greatly according to circum- stances. When running at a low suction pressure, say atmospheric pressure, the ex- cess condensing pressure should not be over 5 to 10 Ibs., but when running with a suction- gauge pressure of 20 to 28 Ibs. the excess pressure will vary from 40 to 60 Ibs. CAUSE OF VARIATION IN EXCESS PRESSURES. The reason why there is such a large vari- ation in the excess pressure is obvious : with 28 Ibs. suction-gauge pressure, the com- pressor is pumping a three times greater weight of gas than it would pump if the gas were under only an atmospheric pressure, and therefore the condenser is crowded to a greater extent in the former than in the latter case. It may be argued that if the compressor is forcing into the condenser a three times greater weight of ammonia in Ammonia Refrigeration. 61 one case than in another, the condenser at th^ same time will be relieved by the ex- pansion valves of a three times greater weight of liquid ammonia, and one will thus counterbalance the other. It is, of course, true that the weight of liquid ammonia pass- ing the expansion valves will be the same as the weight of ammonia gas entering the condenser from the compressor; but as the volume of a given weight of the gas at con- densing temperature and pressure is about 75 times greater than the volume of the same weight of liquid ammonia, it is plain that if instead of pumping in 75 volumes of gas into the condenser we increase the amount three times, or to 225 volumes, the increased delivery from the condenser (by means of the expansion valves) of only two volumes is insignificant in comparison with the increased receipt from the compressor, and therefore the increase of excess con- densing pressure is what might naturally be expected to accompany increased suction pressure, 62 Theoretical and Practical OTHER CONDITIONS THAT AFFECT EXCESS PRESSURE. No table of the excess condensing pres- sures for various suction pressures would be of any practical use, because different makes of refrigerating plants give different results. The high speed (140 revolutions per min- ute) horizontal compressor invariably gives a greater excess pressure than the vertical compressor, which only has a speed of from 40 to 60 revolutions per minute. The method of connecting the condenser piping also affects the excess pressure considera- bly, and if four separate one-inch pipes, or worms, connected by manifolds are used, the excess pressure will be greater than if one continuous worm (starting at the top with two-inch piping and reducing to one-inch, as recommended in previous pages) is used. Also, the higher the condensing pressure due to the temperature of the condensing water the greater the excess pressure will be. Ammonia Refrigeration. 63 USE OF CONDENSING PRESSURE IN DE- TERMINING Loss OF AMMONIA BY LEAKAGE. As the condensing pressure is one of the principal means by which the engineer can tell when the loss of ammonia by leakage has amounted to such a quantity as to render the replenishing of the plant advisable, it is very necessary that the man in charge, if inexpe- rienced, should record in a book the temper- ature of the condensed ammonia at its point of exit from the condenser, and the suction and condensing pressures, every two or three hours. If these figures are thoroughly mem- orized and the engineer started with a plant that was fully charged with ammonia he ought to be able, at the end of a month or two, to tell by looking at the suction-pres- sure gauge, and the temperature of the con- densed ammonia whether the condensing pressure was what it should be. For ex- ample, suppose the plant has been running for two or three months with an average condensing temperature of 60 Fahr., con- 64 Theoretical and Practical densing pressure of 120 Ibs. and suction pressure of 25 Ibs., and that during the next three months the condensing pressure gradually fell to 1 1 5 Ibs., while the condens- ing temperature and suction pressure were still 60 Fahr. and 25 Ibs. respectively; it would be plain that neither the condensing temperature nor the suction pressure could account for this falling off in the condensing pressure because they have not altered, and therefore it is obvious that the quantity of ammonia can alone account for this altera- tion. The diminution in the condensing pressure caused by loss or leakage of am- monia is due to the increased condenser space resulting from the leakage, thereby allowing the gas a greater length of worm in which to condense and assume the liquid form, thus lessening the "crowding" of the hot compressed gas. When the condensing pressure falls off 5 or 10 Ibs. the plant should be re-charged with sufficient ammonia to restore the nor- mal condensing pressure. Ammonia Refrigeration. 65 COOLING DIRECTLY BY AMMONIA. It is very seldom that ammonia can be used directly for freezing purposes, and in nearly all cases it is used indirectly with brine as a medium. The greatest drawback to using ammonia directly is the liability of ammonia to leak through the fittings, joints, etc., and as meats or other provisions would be rendered valueless as far as the market is concerned by such a leakage, it would be exceedingly risky and injudicious to cool a warehouse directly by ammonia if the only object for so doing was to save the cost of the brine portion of the plant. But in build- ings where a slight smell of ammonia would not result in any pecuniary loss other than the value of the escaping ammonia, which latter if properly looked after will be ex- ceedingly small it would certainly be advis- able to cool directly by ammonia. In this case the expansion valves would be in the building to be cooled, and the ammonia would be expanded in a system of piping hung up on the walls or otherwise conve- 66 Theoretical and Practical niently arranged. This method of working is decidedly the most economical, as it does away with the necessity of a refrigerator and its long series of piping, the brine pumps and the steam required to run them, the brine piping (4 to 5 inches in diameter) conveying the brine between the pumps, building to be cooled, and the refrigerator, and all the numerous fittings and valves in connection therewith. BRINE. Brine is a solution of either common salt (chloride of sodium), chloride of calcium, or chloride of magnesium in water. Brine made of chloride of magnesium is undesirable, as it is liable to contain free acid, which above all other things is most objectionable, owing to its action on metals ; whereas common salt, or the "commercial fused" chloride of cal- cium, are both free from acid. Salt is usually sold by the bag, each bag containing about 200 Ibs. and costing about 74 2 Ibs. in the weight of ammonia cir- culated is almost entirely due to the fact that the water-jacket on the compressor head of the vertical compressor causes a 96 Theoretical and Practical complete collapse of the clearance space gas, and thereby allows the suction- valves to open immediately the piston commences its return stroke. Having ascertained the circulating capacity of our compressor we will now see what the freezing capacity of the plant is and how it could be improved. We will suppose that the mean results of a 24-hour test were as follows : Gauge Pressure 5 SuCti n IO lbs - ( Discharge (Condensing) .... 140 lbs. r Suction ... 8 Fahr. at Compressor < -p.- , -r-, , Ammonia < ( -Discharge . 251 rahr. Temperature ^ at Discharge from Condenser, 62 Fahr. !at Refrig'ator Supply Manifold, 69 Fahr. " " Discharge " o Fdhr. C Leaving Refrigerator i6l4 Fahr. 1 emperaturcs > -,, , T , . t Return to 31^0 j, anr Revolutions of Pump per Minute 40 Strength 22 Beaume. Revolutions of Compressor Engine per Minute 120 Diagram 1 3 represented the working of the compressor while the test was being made. The compressor piston displacement was 1.30 cubic feet per revolution. The displacement of the brine pump piston was 0.802 1 gallon per revolution. Ammonia Refrigeration. 97 AMMONIA FIGURES. EFFECTUAL DIS- PLACEMENT. Compressor: 120 revolutions per minute X 1.3 = 156 cubic feet per minute = 224,640 cubic feet per 24 hours. This amount less 27.5 per cent. = 162,864 cubic feet, and 30 per cent, deducted from that leaves 114,005 cubic feet effectual displacement per 24 hours. VOLUME OF GAS. The gas as it entered the compressor was at a temperature of 8 Fahr. and under a gauge pressure of 10 Ibs. (= 24.7 Ibs. abso- lute pressure). By referring to Table VI. we see that I Ib. of ammonia gas at 24^ (24.75) Ibs. absolute pressure and 8 Fahr. = 12.013 cubic feet and at 24.5 Ibs. pressure and 8 Fahr. = 12.137 cubic feet. Our pressure was 24.7 Ibs., or 0.05 Ibs. less than 24^, so, as there are 5, 5-100 difference between 24^ and 24^, we divide the difference in the volume of the gas at those two pressures by 98 Theoretical and Practical 5 and add the quotient to the figures due to the pressure 24.75 Ibs. Thus : 12.137 12.013 = 0.124; 0.124-^5 = 0.0248. 12.013-}- 0.0248 = 12.0378 cubic feet = the volume of I Ib. of am- monia gas at 8 Fahr. and 24.7 Ibs. absolute pressure. AMMONIA CIRCULATED PER TWENTY- FOUR HOURS. The effectual displacement of the com- pressor was 162,864 cubic feet, and as the volume of one pound of the gas was 12.0378 cubic feet, the amount of ammonia circu- lated per 24 hours was (114,005 -r- 12.0378) 9,470 Ibs. REFRIGERATING EFFICIENCY. We see by referring to Table III. (page 1 1 6) that the latent heat of ammonia at 9.86* Ibs. gauge pressure is 561, therefore (9,470 X 561 =) 5,312,670 thermal units were absorbed by the ammonia in passing from the liquid to the gaseous state (/. e. t in ex- * For all F ract i c:i l purposes these figures are near enough to 10 Ibs. Ammonia Refrigeration. 99 panding), but the average results of the test show that the ammonia entered the refriger- ator at a temperature of 69 Fahr. and that the gas left at a temperature of o Fahr. , it was therefore cooled down from 69 to o, or through 69 degrees, and as the specific heat of ammonia at suction pressures is 0.508, as already shown, it is evident (9,470 X 69 X .508) = 331,942 thermal units were thus util- ized in cooling down the ammonia itself, and therefore, not being available for cool- ing down the brine, they must be deducted from the 5,312,670 thermal units credited to the ammonia, thus leaving (5,312,670 331,- 942 =) 4,980,728 effective thermal units, or (4,980,728 -T- 284,800 =) 17.49 tons of ice pei 24 hours. BRINE FIGURES. GALLONS CIRCULATED. The capacity of the brine pumps per revo- lution was 0.8021 gallon, and as it made 40 revolutions per minute, the volume of brine circulated w r as 0.8021 X 40 X 1440 = 46,200 rallons* per 24 hours. American gallons (= 8.3^ Ibs. of water). loo Theoretical and Practical POUNDS CIRCULATED. The gravity of the brine was 22 Beaume, and as brine at that strength weighs 9.84 Ibs. per gallon, the number of pounds of brine circulated in the 24 hours was (46,200 X 9.84 =) 454,608. DEGREES COOLED. The average temperatures of the brine were : Return 31^ Fahr. Outgoing 16^ Fahr. Therefore the brine was cooled I Fahr. TOTAL DEGREES EXTRACTED. The total number of degrees Fahrenheit that were extracted from the brine were (454,608 X 15.25 =) 6,932,772. Ammonia Refrigeration. IOI CHAPTER X. WE have shown previously that the spe- cific heat of 22 Beaume brine is 0.765, therefore the number of thermal units ex- tracted were (6,932,772 X 0.705 =) 4,887,604, or (4,887,604-1-284,800) 17.16 tons of ice per 24 hours. These figures give 0.33 ton of ice per 24 hours less than we obtained from the ammonia figures. This is a result that must always be looked for, as no insula- tion is perfectly non-conducting, and the air surrounding the refrigerator, etc., is always cooled more or less according to circum- stances. The heat imparted to the refrig- erator, etc., in this way is a varying amount and can not, under ordinary circumstances, be accurately estimated. It will have been noticed in the average ammonia tempera- tures that the liquid anhydrous ammonia was heated from 62 Fahr. up to 69 Fahr. in its passage from the condenser to the refriger- ator supply manifold. We will now see what IO2 Theoretical akd Practical effect this rise in temperature had on the capacity of the plant. Loss DUE TO HEATING OF LIQUID AMMONIA. We have just figured that 5,312,670 ther- mal units were absorbed by the ammonia in passing from the liquid to the gaseous state, and that 331,942 thermal units of that amount had to be deducted for loss due to cooling the ammonia itself from 69 Fahr. to Fahr. .Let it now be assumed that the tempera- ture of the liquid ammonia remained at its condensing temperature of 62 Fahr. and our figures will be : 9,470 (Ibs. of ammonia) X 62 X. 0.508 = 298,267 thermal units required to cool the ammonia itself from 62 Fahr. to oFahr., and therefore the number of ther- mal units available for cooling the brine would be (5,312,670 298,267 =) 5,014,403, or 17.61 tons of ice per 24 hours. These figures show that the seven degrees Fahren- Ammonia Refrigeration. 103 heit that the ammonia was heated in its pas- sage from the condenser to the refrigerator represented a loss in the refrigerating effi- ciency of the plant of (17.61 17.49 =) 0.12, or one-eighth of a ton of ice per 24 hours. Loss DUE TO HEATING OF AMMONIA GAS. A glance at the average figures again will also show that the ammonia gas in its pas- sage from the refrigerator to the compressor was heated eight degrees Fahrenheit the gas entering the compressor at a tempera- ture of 8 instead of o. To determine what was the lost refrigerating effect in this case it will be necessary to calculate how many pounds of ammonia would have been circu- lated by the compressor had the temperature of the ammonia gas remained at o until it entered the compressor. Reference to Table V. (page 127) shows that I Ib. of ammonia gas at 24.5 Ibs. absolute pressure and o Fahr. has a volume of 11.917 cubic feet, and at 24.75 Ibs. and o Fahr. 11.794 cubic feet; IO4 Theoretical and Practical therefore, at the absolute pressure of 24.7 Ibs., the. volume of I Ib. of ammonia gas would be 1 1. 8 1 86 cubic feet. The effectual displacement of the compressor was 114,005 cubic feet per 24 hours, so the number of Ibs. of ammonia circulated would be (i 14,005 4- 1 1. 8 1 86 = ) 9,646 per 24 hours. The latent heat of vaporization we have already seen was 561, therefore (9,646 X 561 =) 5,411,406 thermal units would be absorbed by the ammonia. But the temperatures of the ammonia at the supply and discharge manifolds of the refrigerator were respec- tively 69 and o Fahr., and, consequently, as the ammonia itself had to be cooled sixty-nine degrees, the available number of thermal units would be reduced to (5,411,^ 406 (9,646 X 69 X 0.508) =) 5,073,244, or (5,073,244-^-284,800=) 17.81 tons of ice per 24 hours, showing that the loss due to the superheating of the gas only eight degrees in its passage from the refrigerator to the compressor amounted to (17.81 17.49=) 0.32 ton, or about one-third of a ton of ice per 24 hours. If the liquid anhydrous ammonia piping between the condenser and the refrigerator and the ammonia gas piping between the re- frigerator and compressor had been covered with a thoroughly non-conducting material, the refrigerating efficiency of the plant would have been : Gas entering Compressor at ) 9,646 Ibs. o Fahr $ 5,411,406 Thermal units. Ammonia cooled from 62 to o Fahr. (9,646 X 62 X 0.508) 303,810 " " Effective Thermal Units = 5,107,596 or (5, 107,596 -f- 284,800 =) 17.93 tons f ice being an increase of (17.93 * 7-49=0 -44> or nearly half a ton of ice per 24 hours. As the question of condensing water has been fully discussed previously, it is consid- ered unnecessary to go further into figures in relation to this part of the subject. 106 Theoretical and Practical CHAPTER XI. CALCULATION OF THE MAXIMUM CAPACITY OF A MACHINE. As the capacity of a machine is propor- tional to the quantity of anhydrous ammonia circulated, it is evident that if the ammonia valves are regulated so as to give a brine temperature of o Fahr., the refrigerating efficiency expressed in tons of ice will not be nearly so great as when the valves are ad- justed for a 28 Fahr. brine temperature. The amount of anhydrous ammonia circu- lated at the former temperature would only be one-half the weight circulated at the iat- ter temperature. If the brine temperature were above 28 Fahr. it would be incapable of doing prac- tical refrigerating work that is, the tem- perature would be too high to freeze water sufficiently quick to be of any practical value. Ammonia Refrigeration. 107 Twenty- eight degrees Fahrenheit is there- fore the highest practical brine temperature, and in order to maintain that the ammonia must boil at 14 Fahr., which latter tempera- ture is obtained by regulating the ammonia valves so that a suction-gauge pressure of 28^ Ibs. is maintained. Therefore, in calculating the maximum ca- pacity of a machine we must figure upon the suction-gauge pressure being 28 J^ Ibs. and the suction temperature, say, 20 Fahr. at the point where the gas enters the compressor. PREPARATION OF ANHYDROUS AMMONIA. The principal parts of the apparatus neces- sary for the production of anhydrous ammo- nia from 26 ammonia are : (1) An iron cylinder (still) about 2 feet in diameter by 3 feet deep. (2) An iron cylinder (column) about 10 inches in diameter by 2 feet high. (3) A tank (condenser) about 3 feet in di- ameter by 4*4 feet deep. Io8 Theoretical and Practical (4) Two iron cylinders (separators) about 10 inches in diameter by 5^ feet high. (5) An iron vessel (dehydrator) about 3^ feet long by 2 feet broad and 2 feet deep. CONSTRUCTION OF APPARATUS. The apparatus should be of sufficient strength to withstand a pressure of 60 Ibs. on the square inch. Its general arrange- ment is shown in section in Fig. 15, in which A is the still, the contents of which is heated by the steam coil, a. The ammonia gas, to- gether with a little water vapor, pass off through b into the column B, and coming in contact with the plates c, the larger portion of the water separates and flows back into A by the pipe d, while the ammonia gas passes upwards through the holes e, and over to the condenser, C, After leaving the condenser the gas passes through the two separators D, D (where the water condensed in C sepa- rates) into the dryer, E, where, coming in contact with lime placed on the perforated plates f, it is rid of its last traces of moisture. Ammonia Refrigeration. 109 It is then drawn through the pipe / into the suction of the ammonia engine. The plates in B are -separated by, and rest on, the iron rings /'. The head of the still and bottom end-plate of B, together with the connections b and d, may be conveniently cast in one piece. CONDENSER- WORM. An efficient worm for the condenser, C, may be cheaply and easily made of heavy lead pipe. It is advisable to place a cock or valve on the connection between B and C, so that when the spent water is drawn from the still, the gas contained in the rest of the apparatus will not escape. However, it is not abso- lutely necessary to have a cock or valve at that point, because if the water is carefully run off no gas will escape. After the still, A, has been charged it is slowly heated by the coil, a, to a tempera- ture of about 2 1 2 Fahr. When the gauge, k, registers 25 to 30 Ibs. pressure the valve 1 1 o Theoretical and Practical connecting / with the suction of the c m- pressor (of the ammonia engine) is opened and the engine run so as to maintain the pressure of 25 to 30 Ibs. WHY STILL is WORKED UNDER PRESSURE. The reason for running the still under a pressure is to enable the contents of the still being heated up to, or slightly above, the normal boiling-point of water without al- lowing the water to boil thus driving off the whole of the ammonia, while only a minimum quantity of the water is vapor- ized. After the still has been heated for about an hour, a small quantity (about a teaspoon- ful) should be drawn off and tested with acid litmus paper, and as soon as it ceases to turn the paper blue it may be understood that the contents of the still have been ex- hausted of ammonia and that the charge is *' spent." Ammonia Refrigeration. 1 1 1 BEST TEST FOR AMMONIA. A better method for telling when the charge is spent, is to have a small cock in the head of the still, and, opening it slightly, test the escaping vapors with a piece of tur- meric paper. If the paper is turned brown, the whole of the ammonia has not been driven off, but if it still retains its yellow color the charge is thoroughly exhausted. The spent water is run off from the still by the cock g, and after the still has cooled down it is ready for re-charging. WATER FROM SEPARATORS. Very little water accumulates in the sepa- rators D, D, if the pressure in the still is carefully watched, but the cocks /i, h should be cautiously opened (care being taken that no gas escapes) after about the fifth or sixth distillation, and if any water runs out it should be saved, as it will be saturated with ammonia gas, and therefore ought not to be thrown away, but should be placed in the drum containing the 26 ammonia. 1 1 2 Theoretical and Practical LIME FOR DEHYDRATOR. The lime in E should be examined occa- sionally by removing the hand-hole plate, F, and if it has slaked to any great extent the cover on E should be removed and the plates /taken out and replenished with newly burnt lime broken in pieces about the size of a hen's egg. The lime should not be laid more than one layer deep on each plate. The amount of 26 ammonia that has to be distilled in order to obtain a given quantity of anhydrous ammonia can be determined by the use of Table II. YIELD OF ANHYDROUS FROM 26 AMMONIA. Let it be supposed that 50 gallons of an- hydrous ammonia are required. By referring to the table it is seen, under the heading " Per Cent, by Volume," that 26 ammonia contains 38.5 per cent, of anhydrous ammo- nia, therefore, as 50 gallons of anhydrous ammonia are required it will be necessary to Ammonia Refrigeration. distill (38.5 : 50 : : 100) 130 gallons of 26 ammonia. It is, of course, always advisable to try the strength of the 26 ammonia, as it is liable TABLE II. SOLUTION. ANHYDROUS AMMONIA, Weight of In. ^ f a c "" Tl fl C G j^ ^ . 'o Illlj .S c '| it c "Si [1 -ri 3 o r o > - 4 'S u -2 tA "3 V J3 u .9 u 11 * s, "o PQ S rt -C c Jfe a o^ > ^l^l o -5 ^ 1 34-7 7.09 26 494 3-77 59-5 43-4 32.8 7.17 38 4^6 2.841 54-9 39-6 31.0 7-25 50 419 2.610 50-7 36.0 29.0 7-34 62 382 2-379 46.0 3 2 -5 27.2 26.0 25.6 7.42 7-48 7-50 74 83 86 346 320 2.156 1-993 1-937 41.7 38-5 37-5 29.1 26.6 25.8 237 7-59 98 277 1.726 33-4 22.8 22.2 7.67 110 244 1.520 29.4 19.7 to vary somewhat ; and should it be found stronger or weaker (/. c., lighter or heavier in gravity) than the supposed strength, an al- lowance can be made, by means of Table II., 1 1 4 Theoretical and Practical when calculating the quantity necessary to be distilled to yield a given quantity of an- hydrous ammonia. The cost of preparing anhydrous ammo- nia from 26 ammonia is very small, and the difference in the price between the " home prepared" and the "commercial" anhydrous will very soon pay for the cost of the ap- paratus. In most works were freezing plants are in use there are ample large-sized pipmg, small tanks or odd pieces of apparatus lying in disuse which could be easily fitted together on the principle of Fig. 15, and at a total cost of, say, $150. The price of commercial anhydrous am- monia is 44.88c. per lb., and the price of commercial 26 ammonia is 6c. per lb. Twenty-six degree ammonia contains 26.6 per cent, by weight of anhydrous ammonia, therefore 3.76 Ibs. of 26 ammonia g ; ve I lb. of anhydrous at a cost (irrespective of labor) of 22.56c. Ammonia Refrigeration. 5 116 Theoretical and Practical TABLE III. PRESSURE. I. yZ rz o o M J rt B i 5 PRESSURE. 1 W C 1 1 c i rt ,j Absolute. V H 3 rt O 1 Absolute. i o IO.C9 4.01 40 579-7 58.00 43-3 28.9 537-6 11.00 3.70 39 579-1 59-41 44.71 3O.O 536.9 12.31 2.39 35 576-7 6O.OO 45-30 3-6 536.5 13.00 1.70 32-7 575-3 61.50 46.80 32-0 535-7 14-13 0-57 30 573-7 62.OO 47-3 32.3 535-5 14.70 ^o.oo 28.5 S72-3 63.00 48.30 33-o 535-o 15.00 4-0.30 27.8 571-7 64.00 49-3 33-7 534-6 16.17 1.47 -25 570.7 65-93 51-23 35-o 533-8 16.71 2.OI 22 568.9 67.00 52-30 35-8 533-3 17.00 2.30 21.8 568.7 69.00 54-3 37-2 532-4 18.45 3'75 20 567-7 7I.OO 56-30 38.6 531-5 19.00 4-3 18.9 567-0 73.00 58-30 40.0 530-6 20.99 6.29 -15 564.6 74.07 59-37 41.0 53. 21.27 6-57 13 563-4 75.00 60.30 41-5 529-7 22.10 7.40 12 562.8 70.00 61.30 42.2 529.2 22.93 8.2 3 II 562.2 78.00 63-30 43-4 528.5 23-77 9.07 10 561.6 80.66 65.96 45-o 527-5 24.56 9.86 9 561.0 88.96 74.26 50.0 524-3 25.32 10.62 8 j 560.4 92.OO 77-30 5!-4 523-4 20.08 11.38 7 559-8 95.00 80.30 53- 2 522.3 26.84 12.14 6 559-2 97.93 83-23 55-o 521.1 27-57 12.87 - 5 558.5 100.00 85.30 56.1 520.4 28.09 !3-39 4 557-9 104.84 90.14 59-o 518.6 28.64 I3.94 3 557-3 107.60 92.90 60.0 5!7-9 29.17 14.47 2 556.7 IIO.OO 95-30 61.1 517.2 29.76 15.06 I 556.1 115.00 100.30 63-5 515.7 30.37 15-67 ^(zero) 555-5 118.03 103-33 65.0 515.3 31.00 16.30 + L4 554-6 119.70 105.00 66.0 514.1 32.00 17.30 3-5 553-4 123.59 108.89 68.0 512.8 33-66 18.96 5 552.4 125.20 112.50 69.0 512.2 35-00 20.30 5-9 551-9 127.21 114.51 70.0 5II-5 36.00 21.30 7 551-2 138.70 124.00 74-5 508.6 37-00 22.30 8.2 550.5 141.25 I2 7-55 75-o 508.3 38.55 23-85 10 549-3 144.67 129.97 77-o 507.0 39.00 24.30 10.6 549-0 149.70 135-0 78.5 506.0 4O.OO 42.2O 25-30 27/50 12 14 548.1 546.8 154.11 161.70 I39-4I 147.00 80.0 82.5 504.7 53-5 Ammonia Refrigeration. TABLE III. Continued. II/ PRESSURE. PRESSURE. a e c | 8 J3 . * | 1 & 04 bfl I ^ ^ o il 3 1 3 I ' J * rt O 'o 3 42.93 44-00. 28.23 29.30 15 546.3 i 6 545-6 165.70 166.70 I5I.OO 152.00 84.5 84.9 502.1 501.8 45.00 30.30 17 545-o 167.86 I53-I6 85.4 501.6 46.00 47.00 47-95 3I-30 32-30 33-25 18.1 19.1 20 544-3 543-7 543-1 , 168.30 168.70 I75-70 154.00 161.00 86!o 88.5 501.2 500.8 499-5 49.00 34-3 21. 1 542.5 182.80 168.10 90.0 498.1 50.00 35-30 22-3 541-7 194.80 180.10 95.0 495-3 50-67 35-97 2 3 541-3 204. 70 190.00 98.0 493-3 51.00 36-3 23-3 54I-I 215.14 200.44 IOO.O 491-5 52.00 37-3 2 4 540.7 224.40 209.70 104.0 489.4 53-43 38-73 25 540.0 257.20 242.50 113.0 483-4 54-oo 39-3 25-5 539-7 293.20 278.50 I22.O 476.4 55-oo 40.30 26.3 539-3 318.40 I3I.O 471.4 56.00 41.30 27.1 538.7 377-20 352.50 140.0 465.4 57-oo 42.30 28 538.2 Theoretical and Practical TABLE IV. M s.s c TEMPERATURE OF SUCTION = FAIIR. 111 Absolute Suction Pressure. CJ 20 22 25 27 | 30 | 32 35 37 40 24 45 90 199 I8 4 I6 5 153 138 129 116 109 98 92 83 95 208 193 173 161 146 137 124 118 105 99 90 100 216 2O I 181 169 I S3 144 Hi 123 113 io5 97 105 224 208 1 88 177 161 137 130 119 113 103 no 232 215 196 183 1 66 ISS 126 119 109 115 239 22 3 203 191 174 164 151 143 132 I2S "5 1 20 245 230 211 197 181 171 I|8 149 138 121 125 253 237 216 204 187 177 164 IS6 144 137 127 130 261 244 222 2IO 193 169 161 ISO 142 132 135 266 250 229 216 199 189 175 167 iSS I 4 8 138 140 273 256 23 S 222 20S 194 181 172 161 ISS 141 145 279 262 240 228 2IO 197 186 178 166 158 15 285 268 246 233 216 206 191 183 I7i 164 i S3 155 291 273 2S2 239 221 211 197 1 88 176 169 iS8 1 60 165 296 302 279 285 257 262 244 249 226 232 216 221 202 206 $ 181 185 173 178 163 167 bo JJ S 4J 3 ^ M TEMPERATURE OF SUCTION = 5 FAHR. III Absolute Suction Pressure. CJ 20 22 25 27 30 32 35 37 40 42 | 45 90 206 191 172 1 60 145 13.5 123 US 104 98 89 95 215 2OO 1 80 1 68 IS3 143 130 122 III 96 IOO 223 208 186 176 160 138 130 119 112 103 105 231 216 195 183 I6 7 I 5 8 145 137 125 119 109 no 239 223 203 190 174 165 151 H3 132 125 "5 us 247 231 210 198 181 171 159 ISO 139 132 122 120 254 238 218 204 188 I 7 8 163 ij6 145 137 127 125 261 245 222 211 194 184 170 163 ISO H3 133 HO 268 2SI 230 217 200 190 176 1 68 156 149 139 135 273 258 236 223 206 196 182 174 162 155 145 140 281 264 242 229 212 202 1 88 179 I6 7 1 60 ISO 145 150 287 293 270 276 248 254 235 241 218 223 207 213 $ 185 190 172 I 7 8 I6 5 170 155 1 60 ISS 299 282 2S9 246 229 218 204 195 183 175 165 1 60 35 287 265 2.S2 234 223 209 200 1 88 1 80 170 165 3H 293 270 257 239 229 214 205 192 185 173 Ammonia Refrigeration. TABLE IV. Continued. 119 Absolute Condensing Pressure. 1 EMPERATURE OF SUCTI >N T = - 10 FAHR. Absolute Suction Pressure. 20 22 25 27 30 | 32 | 35 37 40 42 45 90 213 IQS I 7 8 I6 7 I 5 I 141 129 121 IIO 104 9 6 95 ! 222 207 I8 7 159 ISO 136 I2 9 118 III I O2 ioo : 231 i 215 183 167 157 144 136 j 125 118 109 105 , 239 223 2O2 190 174 164 151 H3 132 125 "5 no 247 229 2IO 197 181 172 158 I 5 139 132 122 "5 254 | 238 217 20S 188 178 164 156 H5 138 128 120 26l 245 226 211 : 95 185 171 163 151 144 134 125 269 252 231 218 201 191 177 169 1.57 150 140 130 27S 259 237 22 4 207 197 183 175 103 155 145 I3S 282 266 i 244 231 214 203 189 181 168 161 151 I4O 289 I 272 2SO 237 219 209 195 1 86 174 167 156 H5 295 278 2 S 6 244 22 S 211 200 192 179 172 l62 150 301 284 262 248 231 22O 20S 197 IS 177 167 155 307 2 9 266 254 236 225 211 202 190 182 172 1 60 3n 29 S 273 2 59 2 4 I 231 216 207 195 187 176 105 319 301 2 7 8 26 5 247 2 3 6 221 212 199 192 181 bd TEMPERATURE OF SUCTION = 15 FAHR. !U Absolute Suction Pressure. CJ 20 22 '25 i 27 30 32 35 37 40 42 i 45 90 221 205 185 ; 173 I 5 8 148 135 127 117 IIO IOI 95 2 3 214 194 i 182 166 IS 6 J 43 135 I2 4 117 1 08 IOO 238 222 202 i 189 173 164 151 142 131 124 US I0 5 246 230 209 i 197 181 171 I 5 8 150 138 131 121 IIO 254 2 3 8 2 1 7 204 1 88 178 I6 4 I 5 6 145 138 128 115 262 246 224 212 195 182 171 163 152 144 134 120 269 253 233 218 202 192 I 7 8 I6 9 158 '5 I4O 125 276 260 238 225 208 198 I8 4 176 163 146 I 3 283 267 245 i 232 2I 4 204 191 181 170 162 152 135 290 273 251 ! 238 221 210 196 187 175 1 68 I 5 8 140 297 279 257 ' 244 226 216 202 193 181 173 163 145 ; 303 286 263 I 250 2 3 2 221 207 199 i 86 179 1 68 150 ; 309 292 269 i 256 238 227 213 204 192 1 184 173 155 3*5 2 9 8 275 261 244 232 j 218 209 197 189 178 1 60 3 2I 34 281 1 267 249 238 ; 223 i 214 2O2 194 i 183 165 327 309 286 272 ' 254 243 : 228 219 206 199 188 120 TJicoretical and Practical TABLE IV.Contimtai. S.SB TEMPERATURE OF SUCTION = 20 FAHR. ||| Absolute Suction Pressure. 'u 20 22 25 27 30 32 35 37 40 42 45 90 228 212 192 180 164 154 141 133 123 116 106 95 237 221 2O I 189 j 172 I6 3 149 141 I 3 123 114 IOO 245 230 20 9 196 1 80 171 157 149 137 131 121 105 2 53 237 217 203 1 88 178 164 I 5 6 I 44 138 128 IIO 262 245 22 4 211 195 185 171 162 15 144 134 115 269 253 2 3 I 2I 9 202 192 178 I6 9 I 5 8 151 140 120 277 260 240 | 226 209 198 185 176 164 157 I4-.3 125 284 267 j 245 233 215 205 191 183 170 163 I 3 291 : 274 252 239 222 211 197 1 88 176 i 169 158 135 298 ! 281 260 245 228 219 203 194 182 174 ; 1 6l 140 305 28 7 265 251 234 223 20 9 200 i 88 181 ' 169 145 311 294 271 ; 258 240 j 226 214 205 193 185 ! '75 150 317 3 00 277 263 245 235 220 211 198 j 191 ; 1 80 155 323 3 06 283 | 269 251 240 225 216 203 196 185 1 60 329 3 I2 288 275 256 245 230 221 209 201 190 I 6 5 335 317 294 280 262 2 5 I 235 226 213 206 195 tat TEMPERATURE OF SUCTION = -- 25 FAHR. a'7 " o % 3| Absolute Suction Pressure. U 20 22 ! 25 27 30 ! 32 35 37 ! 40 1 42 | 976 13.819 13.665 2 9 14.858 14.680 I4-5 7 I4-338 14.174 14.012 I3-854 13.700 30 14.887 14.709 H-535 14-366 14.201 14.039 13.881 13.726 31 32 I4-9I5 14-953 14-737 14-775 14-5^3 14.600 14.389 14.430 14.229 14.265 14.066 14.102 13.908 13-943 I3-752 13.788 33 14.982 14.803 14.628 14.458 14.292 14.129 13.970 13.814 34 15.010 14.831 14.656 14.485 i4-3 ! 9 14.156 13.996 13.840 35 15.049 14.869 14.693 14.522 I4-356 14.192 14.032 13.876 36 i5- 77 14.897 14.721 14.548 14-383 14.219 14.059 13-902 37 15.106 14-925 14.749 14-577 14.410 14.246 14.085 13-928 3 i5-!44 14.963 14.786 14.614 14.447 14.282 14.121 13-963 39 15.172 14.991 14.814 14.642 14.474 14-309 14.148 13.990 40 | 15.201 15.015 1-4.842 14.669 14.501 14.336 14.174 14.016 Ammonia Refrigeration. 127 TABLE V. Continued. g 3 . POUNDS PER SQUARE INCH ABSOLUTE PRESSURE. -^ $ 23 23 % 23 K 23^ || 24 24^ 1 24 y 3 24 K So 1 ! 1 ^y Volume in Cubic Feet of One Pound Weight of Gas. 12.706 12.567 12.421 12.299 12.169 12.041 11.917 11.794 j 12.732 12.588 12-457 12.324 12.194 12.066 11.941 11.819 2 12.767 12.627 12.491 12-357 12.227 12.098 11.974 11.851 3 12-793 12.653 12.516 12.383 12.252 12.123 11.998 11.875 4 12.819 12.674 12.542 12.412 12.277 12.148 12.023 11.899 12.854 12.713 12.576 12.442 12.310 12.181 12.055 11.932 7 12.880 12.906 12.739 12.765 12.601 12.627 12.467 12.492 12-335 12.360 12.206 12.230 12.080 12.104 11.956 11.981 8 12.941 12.799 12.661 12.526 12.394 12.263 12.137 12.013 9 12.967 12.825 12.686 12.551 12.419 12.288 12.162 12.037 10 12-993 12.840 12.712 12.576 12.444 12.313 12.186 12.061 ii 13.028 2.885 12.746 12.610 12.477 12.343 12.219 12.094 12 I3-054 2.911 12.771 12.635 12.502 12.371 12.243 12.118 J3 13.080 2.932 12.797 12.661 12.527 I2 -395 12.268 12.142 H I3.H5 2.971 12.831 12.694 12.560 12.428 12.300 12.174 15 13.141 2-997 12.857 12.720 12.585 12-453 12.325 12.199 16 13.167 13-023 12.882 12-745 12.610 12.478 12.349 12.223 17 13.201 3-57 12.916 12.778 12.644 12.511 12.382 12.255 18 13.228 3-083 12.942 12.804 12.669 12.540 12.406 12.279 19 13-254 3.109 12.967 12.829. 12.694 12.560 12.431 12.304 20 13.288 3-H3 13.001 12.863 12.727 12-593 12.464 12.336 21 13-315 3.169 13.027 12.888 12.752 12.618 12.488 12.360 22 i3-34i 3- J 95 13-052 12.913 12.777 12.643 12.512 12.385 23 I3-376 13.229 13.086 12.947 12.810 12.676 12.545 12.417 2 4 13.402 I3-255 13.112 12.972 12.835 12.701 12.570 12.441 25 13.428 13.281 I3-I37 12.997 12.861 12.725 12.594 12.465 26 13.462 I3-3I5 13.171 13-031 12.893 12.758 12.627 12.498 27 13.488 I 3-34i i3-!97 13.056 12.919 12.783 12-651 12.522 28 I3-5I5 I3-367 13.223 13.082 12.944 12.808 12.675 12.546 2 9 13-549 13.401 13-257 i3."7 12.977 12.841 12.709 12.579 30 I3-576 I3-427 13.286 13.141 13.004 12.868 12.733 12.603 31 13.602 J 3-453 13-308 13.166 13.027 12.890 12.758 12.627 3 2 I3-637 13-487 J 3-342 13.200 13.060 12.923 12.790 12.659 33 13-663 !3-5i3 I3-367 13-225 13-085 12.948 12.815 12.684 34 13.689 13-539 !3-393 13.250 13.110 12.974 12.839 12.708 35 13-723 13-573 13-427 13-284 I3- I 44 13.006 12.872 12.740 36 13-749 13-599 13-452 13-309 13.167 13.030 12.896 12.764 37 13.776 13.629 I3-478 J 3-334 i3- I 94 !3.o55 12.921 12.789 38 13.802 r 3- 6 59 I3-5 12 13-368 13.227 13.088 I2 -953 12.821 39 13-837 13.685 J3-537 13-393 13-252 i3."3 12.978 12.845 40 13.863 I 3-7 I i 13-563 13-419 I3-277 13-138 13.002 12.869 28 Theoretical and Practical TABLE V '.Continued. 3 . I -a i) r rt 0.^ E o H POUNDS PER SQUARE INCH ABSOLUTE PRESSURE. 25 25 y 4 25 K 25% | 26 ae y 4 26 X 25 % Volume in Cubic Feet of One Pound Weight of Gas. O 11.675 ".558 11.440 "330 11.219 II. Ill 11.005 10.900 I 11.699 11.581 41.466 "353 11.242 11.134 11.027 10.923 2 "73 1 11.613 11.498 11.384 11.273 11.164 11.057 10.952 3 "755 11.637 11.521 11.408 11.296 11.187 II.oSo 10-975 4 11.779 11.661 "545 11.431 11.319 II. 210 11.103 10.997 5 11.811 11.692 11.570 11.462 "350 1 1 . 240 "-I33 11.027 6 "835 11.716 "599 11.486 "373 11.252 "-I55 II.O50 7 11.859 11.740 11.623 11.509 11.396 11.286 11.178 11.072 8 11.891 11.771 11.655 11.540 11.427 "-3I7 11.208 1 1. 102 9 11.915 n-795 11.678 11.563 11.450 "-339 11.231 11.124 10 i 1-939 11.819 11.702 11.586 "473 11.362 11.254 11.147 ii 11.971 11.851 "733 11.617 11.504 "-393 11.284 11.177 12 n-995 11.874 "753 11.641 11.527 11.415 11.306 11.199 J 3 12.019 11.898 11.780 11.664 "-55 11.438 11.329 11.222 14 15 12.038 12.075 11.930 n-954 11.811 11.835 11.695 11.718 11.581 11.604 11.469 11.359 11.492 11.382 11.252 11.274 1 6 12.099 11.977 11.858 11.742 H 11.627 11.515; 11.405 11.296 17 12.131 12.009 11.890 11.773 !! "- 6 5 8 11.545 11.435 11.326 18 12.155 12.033 11.913 11.796 11.681 11.568 11-457 "-349 19 2.179 12.057 "937 11.819 11.704 11.591 11.480 11.371 20 2. 211 12.088 11.964 11.850 i 11.735 11.621 ii-Sio 1 11.401 21 2-235 12.112 11.992 11.874 1 11.758 11.644 "533 11.423 22 2.259 12.136 12.015 11.897 11.781 11.667 "555 11.446 23 24 2.291 2-3I5 I2.I6S 12.192 12.047 12.070 11.928 "-95 1 ; 11.811 "835 11.697 1 1 . 720 11.586 1 1. 608 11.476 11.498 2 5 2-339 12.215 12.094 "975 11.857 "743 11.631 11.521 25 2-371 12.247 12.125 12.006 11.888 11.774 11.661 "-55I 27 2-395 12.270 12.149 12.029 11.911 11.797 11.684 ,"573 2*3 2.419 12.294 12.172 12.052 "935 11.819 1 1 . 706 "595 29 3 2-451 2-473 12.326 12.350 12.204 12.227 12.083 12.107 11.965 11.988 11.850 11.873 "737 "755 11.625 11.648 31 12.499 12-373 12.251 12.130 12. on 11.895 11.782 11.670 3 2 I2 -53i 12.405 12.282 12.161 12.042 11.926 11.812 11.700 33 12-555 12.429 12.305 12.184 12.065 "945 11.834 11.723 34 12.579 12-453 12.329 12.208 12.088 11.972 11.857 "745 35 12.611 12.484 12.360 12.239 12.119 12.002 n.888 "775 36 12.636 12.508 12.384 12.262 12.142 12.025 11.910 11.797 11 39 12.659 12.691 12.716 12-53 12.564 12.587 12.407 12.439 12.462 12.285 12.316 12.340 12.165 12.196 12.219 12.048 12.078 12.101 "933 11.963 11.986 11.820 11.850 11.872 4^ 12.739 12.611 12.486 12.363 || 12.242 12.124 12.008 11.894 Ammonia Refrigeration. TABLE V. Continued. 129 8.453 8.530 8-470 20 8.938 8.871 8.806 8.741 j 8-677 8.615 8.553 8.492 21 8-955 8.888 8.823 8.758 8.694 8.632 8.570 8.509 22 2 3 8-973 8.996 8.906 8.929 8.840 8.863 8-776 i 8.798 8.712 8-735 8.649 8.672 - 8.587 8.609 - 8.526 2 4 ' 9.014 8-947 8. 88 1 8.816 8.752 8.689 8.626 g 565 ' 25 9.032 26 9.055 8.964 8.990 8.899 8.922 8-833 8.856 ! 8.769 8.792 8.706 8-729 .8.643 8.674 8.582 8.604^. 27 9-073 9.005 8.940 8.873 8.809 &74S .8.682 8.621 28 9.090 9.022 8.956 8,891 i 8.826 8.762 8.6 99 8.638; 2 9 9.114 9.046 8.980 ! 8.914 || 8.849 8.788 - 8.722 8.660 30 9.132 9.063 8.997 8.931 i 8.866 8.802 8-739 8.677 31 9.149 9.081 9.014 8.948 , 8.883 8.819 8.756 8.693 3 2 9. I 70 9.104 1 9.037 8.971 8.906 8.842 8-778 8.716 33 9.190 : 9.122 0.055 8.988 ^.923 8.859 8.795 8 -733 34 9.209 9.139 9.072 9.006 8.940 8.876 8.812 8-749 35 ' 9.232 9.163 9.095 ; 9.029 l 8.962 8.899 8.834 8.772 36:9.249 9.177 9.113 9.046 8.980 8.916 8.85! 8.789 37 9-267 9.198 9.130 9.063 8.997 8-933 8.868 8.805 , 38 9.290 9.221 9.153 9.086 || 9.020. 8^955 8.891 8.828 " 39 9.308 9.239 9.171 ! 9.104 9.037 8-972 8.908 8.845 40 9.326 9.262 9.188 9.124 9.055 8.989 8.925 8.861 134 Theoretical and Practical TABLE VI. Continued. rt J; POUNDS PER SQUARE INCH ABSOLUTE PRESSURE. c6 -) 36% 36^ 36K || 37 37 X 37 X 37 < 4 Volume in Cubic Feet of One Pound Weight of Gas. o 8-.o6i ; '8.003 7.948 7.893 7.839 7.785 7-732 7.680 I 8.077 i 8.020 7-909 , 7-855 7.801 7.748 7.6 9 6 2 8.099 8.042 7^986 7-931 7-877 7.823 7.769 7.717 3 8. 116 \ 8.059 8.005 7-947 7-893 7.839 7.785 7-733 4 8.133 8.075 8.019 7-963 7.909 7.855 7.801 7-749 5 ! 8.155 8.097 8.041 7-985 ' 7-93 1 7.871 7.823 7.770 6 8.172 8.114 8.057 8.001 ! 7-947 7.892 7.839 7.786 7 8.188 8.130 8.074 8.018 I 7-963 7.908 7.855 7.801 8 8.2ii 8.152 8.096 8.040 7.985 7-93 7.876 7-823 9 8.227 8.169 8. 1 12 8.056 8.001 7.946 7.892 7-839 10 8.244 8.185 8.129 8.072 | 8.017 7.962 7.908 7-855 ii 8.266 8.208 8.150 8.094 8.039 7.984 7.929 7.876 12 8.283 8.227 8.167 8. 1 10 1 8.055 8.000 7-945 7.892 13 H 8.299 8.322 8-243 8.263 8.183 8.205 8.127 8.148 8.071 8.093 8.016 8.037 7.961 7-983 7.908 7.929 15 8.338 8.279 8.222 8.165 8.109 8-053 7-999 7-945 1 6 8-355 8.296 8.238 8.181 8.125 8.070 8.017 7.961 17 8-377 8.318 8.260 8.207 8.147 8.091 8.036 7.982 18 8.394 8-334 8.276 8.219 8.163 8.107 8.049 7.998 19 8.410 8-351 8.293 8.235 ! 8-179 8-123 8.068 8.014 20 8-433 8-373 8.315 8.251 8.201 8.145 8.089 8.035 21 8-449 8.390 8.331 ! 8.274 : 8.217 8.161 8.105 8.051 22 8.466 8.406 8.348 8.290 8.234 8.177 8.I2I 8.067 2 3 8.488 8.428 8.370 8.312 8-255 8.198 8-139 8.088 24 8-505 8-445 8.386 8.328 8.271 8.215 8.159 8.104 2 5 8.521 8.461 8.403 8.344 1 8.288 8.231 8.172 8. 12O 26 8-544 8.483 8.424 8.366 : 8.309 8.252 8.196 8.141 27 8.561 8.500 8.441 8.383 i 8.325 8.268 8.212 8.157 28 8-573 8.516 8-457 8.399 8.342 8.286 8.228 8.173 29 8-599 8-539 8.479 8.420 8.363 8.306 8.249 8.194 30 8.616 8-555 8.496 8-437 8.379 8-322 8.265 8.210 8-633 8-572 8.512 8.453 8.407 8.338 8.281 8.226 3 2 8-655 8-594 8-534 8-475 8.417 8.360 8.303 8.247 33 8.672 8.610 8-550 8.491 | 8.434 8.376 8.319 8.263 34 8.688 8.626 8-567 8.508 8.449 8.392 8-337 8.279 35 8.711 8.649 8.589 8.529 8.471 8.413 8-356 8.300 36 8-727 8.638 8.605 8.546 8.488 8.429 8.372 8.316 % 8-744 8.766 8.654 8.704 8.622 8.644 8.562 8.584 8.504 8.525 8-445 8.467 8.388 8.409 8.332 8-353 39 8.783 8.721 8.660 8.600 8.542 8.483 3.422 8.369 o S. 7QQ 8-737 8.676 8.616 8.558 8.499 8.441 8-385 Ammonia Refrigeration. TABLE VI. Continued. 135 g 3 . | POUNDS PER SQUARE IXCH ABSOLUTE PRESSURE. 38 38 % ss y 2 38% || 39 39 # 29 K | 39 ^ Volume in Cubic Feet of One Pound Weight of G-as. O 7.629 7.578 7.528 7.478 7-43 7-38I 7-334 7-287 I 7.645 7-593 7-543 7-494 7-446 7-397 7-349 7.302 2 7.666 7.614 7-564 7-5I5 7.466 | 7.417 7-369 7.322 3 7.682 7.630 7-580 7-53 7.482 7-432 7-385 7-337 4 7.698 7.646 7-595 7-546 7-497 7.448 7.400 7-35 2 5 7.719 7-667 7.616 7-566 ; 7-5 l6 7.468 7-421 7-375 7-734 7.682 7.632 7-582 | 7-533 7-483 7-435 7-388 7 7-75 7-698 7.647 7-597 1 7-548 ; 7.499 7-45 7-403 8 9 7.771 7-787 7.719 7-735 7.668 7.684 7.618 7.628 i 7-569 i 7.519 7-584 i 7-534 7-47 1 7.486 7-423 7.438 10 7.803 7-75 7-699 7-649 | 7-599 ; 7-55 7-501 7-453 1 1 7.824 7.771 7.720 7.669 7.620 7.570 7-521 7-473 12 7-839 7.787 7-685 i 7-635 7.585 7.536 7.488 13 7-85 7-803 7-751 7.700 ! 7.651 7.601 7.552 7-53 14 7.877 7-824 7.772 7.721 7.671 7.621 7-572 7-524 15 7.892 7-839 7-788 7-737 7.686 7.636 7.587 7-539 16 7.908 7.855 7.803 7-752 7.702 7.657 7.602 7-554 7 7.929 7.875 7.824 7-723 7.672 7-623 7-574 18 7-945 7.892 7.840 7.788 7-738 7-687 7-638 7-589 19 7.961 7-907 7.855 7.804 7-753 7.702 7-655 7.604 20 7.982 7.928 7-876 7.824 7-774 7.723 7-673 7.624 21 7.998 7-944 7.891 7.840 7.789 7.738 7.688 7-639 22 8.013 7.960 7.907 7.855 7-805 7-753 7.704 7-654 23 8.034 7.980 7.928 7.876 7.825 7-774 7-724 7-674 24 8.050 7.996 7-943 7.891 7.841 7.789 7-739 7.690 2 5 8.066 8.012 7-959 7.907 7.856 7.804 7-754 7.702 26 8.087 8.033 7-98o 7.928 7.876 7-825 7-774 7.7 2 5 27 , 8.103 8.048 7-995 7-943 i 7.892 7.840 7.790 7.740 28 8. 1 19 ' 8.064 8.0H 7-956 7.907 7.855 7-805 7-755 29 8.139 8.085 8.032 7.979 jj 7.928 7.876 7.825 7-775 3 i 8.101 8.047 7-995 7-943 ! 7-89 1 7.840 7.790 3 1 8. i 71 8. in 8.063 ' 8.010 7-958 7.906 7.855 7.805 3 2 8.192 1 8.137 8.084 8.031 7.979 ! 7.927 7.876 7.826 33 8.208 i 8.153 8.099 8.046 7.994 7.942 7.891 7.841 34 8.224 j 8.169 8.115 8.062 8.009 i 7-955 7-9o6 7.856 35 8.245 8.190 8.136 8.082 8.030 7.978 7.926 7.876 36 8.261 8.205 8.151 8.097 8.046 ! 7.993 7.942 7.891 37 8.277 8.221 8.167 8.113 8.061 i 8.008 7.957 7.906 38 8.298 8.242 8.188 8.134 8.082 : 8.029 7.977 7.926 39 , 8.313 8.258 8.203 8.149 8.097 8.044 7.992 7.941 40 I 8.329 8.273 8.219 8.165 8.113 8.059 8.007 7-956 136 Theoretical and Practical TABLE VI. Continued. i Ij3 SI POUNDS PER SQUARE INCH ABSOLUTE PRESSURE. 40 40# | 40K 40 X || 41 41 X 41 M 41% Volume in Cubic Feet of One Pound Weight of Gas. o 7.241 ' 7.193 7.125 7.105 ! 7.061 ! 7.017 6.974 6.932 I 7.256 7.201 7.164 7-I2O 7.076 7.032 6.989 6.946 2 7.276 7.230 7.184 7.139 j 7.096 7.051 7.008 6.966 3 7.291 7.245 7.199 7.154 7.IIO 7.066 7.023 6.980 4 7.306 7.260 7.214 7- *69 7-125 7.080 7.037 6-995 5 7.326 7.280 7-234 7.188 7.144 7-IOO 7.056 7-013 6 7-341 7.294 7-243 7.203 7.159 7.II4 7.071 7.028 7 7-356 7-3 c 9 7-263 7.218 7-174 7.129 7.085 7.042 8 7-376 7-329 7-283 7.238 7.193 7.148 7.105 7.061 9 7-391 7-344 7.298 7.252 7.208 7.163 7.119 7.076 10 7.406 7-359 7-313 7.267 7.222 7.177 7.134 7.090 ii 7.426 7-379 7-33 2 7.287 7.242 7.197 7.153 7.109 12 7.441 7-394 7-347 7.301 i 7.257 7.211 7.167 7.124 '3 7-45 6 7.409 7.362 7.316 7.271 7.226 7.182 7-138 14 7.476 7-429 7-382 7-336 7.291 7.245 7.201 7-157 15 7.491 7-443 7-397 7-350 7.305 7.260 7.215 7.172 16 7.506 7.458 7.411 7-365 7.320 7.274 7.230 7.186 '7 7.526 7.478 7-43 1 7-385 7-339 7.294 7.249 7.205 18 7-541 7-493 7-446 7.400 7-354 7.308 7.264 7.219 19 7.556 ! 7.508 7.461 7.414 7.369 7.323 7.278 7-234 20 7.576 7.528 7.480 7-434 , 7-388 7.342 7.297 7-253 21 7-590 7-543 7-495 7-449 ! 7-403 7-357 7.312 7.267 22 7.558 7-5 10 7.463 7.418 7-37 1 7.326 7.282 2 3 24 7.620 7.641 7-578 7-593 7-53 7-541 7-483 7.498 7-437 7-39 1 7.452 7.405 7.346 7-3 7-3 01 7-3!5 7.656 7.607 7.560 7-512 7.466 7.420 7-374 7-33 26 7.676 7.627 7-579 7.532 7.486 7.439 7-394 7-349 27 7.691 7.642 7-594 7-547 7-5o 7.454 7.408 7-363 28 7.710 7.657 7.561 7.515 7.468 7-423 7-377 29 7.726 7.677 7.629 7.581 7-535 7.488 7.442 7-397 30 7-741 7.692 7-643 7.596 7-549 7-502 7-456 7-4H 3i 7.756 7.707 7.658 7.611 7.564 , 7.514 7-47 1 7-425 32 7.776 7-727 7-678 7.630 7.583 7.536 7.490 7-445 33 7.791 7.742 7-693 7.645 7.598 . 7.551 7-505 7-459 34 7.806 7-757 7.708 7.660 7.613 7.565 7-5 T 9 7-473 35 7.826 7.776 7.727 \ 7.679 7.632 7.585 7.538 7.492 36 7.841 7.791 7-742 \ 7.694 7.647 7.599 7-553 7.507 37 7.856 7.806 7-759 7-709 7-66i j 7.614 7.567 7-521 38 7.876 7.826 7-777 7.728 7.681 7.633 7.587 7-54 39 7:891 7.841 7.792 7.743 7.696 7.648 7.601 7-555 40 7.906 7.856 7.806 7.758 7.710 7.662 7.615 7o69 Ammonia Refrigeration. 137- TABLE VI Continued. E 3 . POUNDS PER SQUARE INCH ABSOLUTE PRESSURE. ? -- U. re P.* 42 42 Y 4 42 K 42 # II 43 43 y 4 43 % 43^-; H Volume in Cubic Feet of One Pound Weight of Gas. o 6.88 55 51 water . . . . 5 Horizontal compressor . . . . 31 ICE, equivalent of a ton of . . 79 Indicator diagrams . . . . -87 55 5 used in calculating capacity of plant . . . 92 to 95 JACKET-WATER for compressor . . 52, 53 ,, ,, separator . . 53 144 Index. PAGE Joule's law ...... 4 LATENT heat ..... 10 ,, heat of ammonia, table of . . , . 116, 117 ,, liquefaction . . . 10 vaporization . . . .11 ,, water . . . . 12 Lime for dehydrator . . . . .112 Loss due to heating condensed ammonia . 102, 105 ,, ,, superheating ammonia gas . 103, 105 MAGNESIUM chloride brine . . . 66 Making brine . . . . . .71 Maximum capacity of plant . . . 106 Measurement of ammonia circulated . . -79 Mechanical equivalent of a unit of heat * 4 Mercury, specific heat of . . .5 ,, . wells, distribution of . . . 81 ,, ,, how made . . . 82 to 85 OIL for lubrication . . . . 35 PACKING for stuffing-boxes ..... 33 Piping (or worm) for condenser . . 42 ,, for refrigerator . . . -45 Preparation of anhydrous ammonia . . 107 ,, ,, ',, cost of . .114 Pressure, absolute . . . . .13 ,,. effect of, On specific heat . . 6, 7, 16 RECEIVER . . . . . . 43 Refrigerating efficiency of a plant, t"> determine . 78 . . 98 Index. 145 PAGE Refrigerating efficiency, maximum . . . 106 Refrigerator . . . . . - 44 ,, piping, size and area . . -45 Regnault's determinations of specific heat . 8 Regulation of brine temperature . . -73 ,, suction and discharge valve-lift . 37 SALT, and brine from . . . . 66 to 71 Separator . . . . . . 38 to 40 ,, for anhydrous ammonia distilling apparatus, 112 ,, jacket-water for ... 53 Specific heat ... . . 4 ,, ' ,, ' of air ..... 7 ,, ,, ,, ammonia . . .7 55 11 11 brine .... 73 .-.,, ,, effect of temperature and pressure on, 6 ,, ,, of turpentine, mercury, and water . 5 Still for anhydrous ammonia . . . 108 ,, ,, ,, worked under pressure, no Strength of brine . . . . .69 Stuffing-boxes . . . \ . 32 . packing for . . . 33 ,, lubrication of ... .... - 34 Suction and discharge valves . , - - . . . 36 Superheating ammonia gas, loss due to . . . 58 TEMPERATURE, absolute . . 13* 16 Tests, calculation results of 24 hours . . 96 ,, for ammonia . .-. . . . ni- Testing an ammonia plant (preliminaries) . 81 to 86 ,, ,, ,, (duration of test) : . -8^7 Theory of refrigeration .... 18 ,, ,, by compressed air . . 19 146 Tndex. PAGE Theory of refrigeration by ammonia . . 21 Turpentine, specific heat of . . . j UNIT, British thermal .... 3 ,, of heat, mechanical equivalent of -4 VALVES, expansion .... 46 ,, j, regulation of . . 73 to 75 lift 37 ,, suction and discharge . '. -36 Vertical compressor . . . . 31 Volume of ammonia gas calculated by compressor displacement . . 97 ,, ,, ,, tables of . 51, 122 to 138 ,, gases, formulae for calculating . 16 WATER for compressor jacket . . 52 ,, condenser .... 53 ,, ,, lessening cost of -54 ,, ,, quantity necessary . 56 ,, ,, effect of, on brine temperature, 77 ,, separator . . . . -53 Water from separator of anhydrous ammonia distil- ling apparatus . . . m ,, latent heat of . . . . .12 ,, specific heat of .... 6 W'orking details of ammonia plant . . -47 Worm for condenser . . . . 42 YIELD of anhydrous ammonia . . 112, 113 ZERO, absolute . . . 16 .* TH {TJIUVBRSIT SELDEN'S PATENT PACKING Either with Rubber Core or Canvas Core. Guaranteed for Air, Ammonia, Steam and Water, if used in stuff- ing boxes. "BRANDT'S TRIPLE EXPANSION GASKETS" For Hand and Man- hole plates of boilers are the best, and used on the highest steam pressures, RANDOLPH BRANDT, 38 Cortlandt Street, New York:. B. P. GiAPP AMMONIA COMPANY, MANUFACTURERS OF AQUA AND ANHYEEOOS AMMONIA OP THE BEST QUALITY. For Refrigerating Purposes and the Trade. OFFICE : BROADWAY, NEW YORK. GUILD & GARRISON, Kent Avenue, corner South loth Street, BROOKLYN, N. Y. AMMONIAPUMPS, Brine Pumps, Boiler Feeders. Practical Handbooks. Cromwell, J. H. A System of Easy Lettering SOcts. Dahlstrom, K. P. The Fireman's Guide. A handbook on the care of boilers. 28 pages, cloth, SOcts. Dubelle, G. Formulas for the Soda Fountain. 493 receipts for making natural and artificial fruit syrups, extracts, essences, punches, flavorings, colorings, &c., &c. 157 pages, 12mo., cloth, . 2.50 Eldridge, J. The Pump Fitters Guide, paper, 40cts, The Gas Fitters Guide, paper, 40cts. 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NATURAL AND ARTIFICIAL FRUIT SYRUPS, ARTIFICIAL FRUIT ESSENCES, NEW MALT PHOSPHATES, FRUIT MEADS, FRUIT JUICE SHAKES, FRUIT CHAMPAGNES, PUNCHES, NEW ITALIAN LEMONADES, CREAM FRUIT LACTARTS, SOLUBLE FLAVORING EXTRACTS, SOLUBLE WINE BITTERS EXTRACTS, NEW FANCY EGG PHOSPHATES, EXQUISITE ICE CREAM SODAS, NON-POISONOUS COLORS, FOAM PREPARATIONS, LATEST NOVELTIES IN SODA FOUNTAIN MIXTURES, &c., &c. SPON & CHAMBERLAIN, Publishers, 12 Cortlandt Street, New York. -.AMERICAN-. ENGINEER /^r-jo ** RAILROAD JOURNAL AN ILLUSTRATED MONTHLY PUBLICATION. Devoted to MECHANICAL ENGINEERING, RAILROAD TOPICS AND INTERESTS. Due attention is given to such topics as Shop Practice, Tools, Machinery, Stationary and Marine Engineering, Naval Progress, New Inventions, Ordnance, New Publications, Pro- ceedings of Engineering Societies, Condensed Notes and News, &c. 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