Brine Outlet. covering the pressures and temperatures of vaporization is given in Fig. 1. Not only must the machine be built very heavy to withstand such a pressure, and unusually heavy fittings used on the pipe, but, besides this, leaks are almost impossible to avoid and the diameter of the gas cylinder must be kept much smaller than the steam cylinder. Leaks of carbonic anhydride gas are particularly dangerous as they are not noticeable by smell (as is the case with ammonia) and the gas being heavier than air sinks into cellars or other low spots, collecting at such points and rendering a person almost unconscious before its discovery is made. For this reason when this gas is used leaks are particularly dangerous and must be most carefully guarded against. Compressors for carbonic anhydride gas are almost invariably of small size and made of the single-acting type, owing to the difficulty of keeping stuffing boxes tight under the high pressures necessary; compressors of larger size are constructed, however, for liquefying this gas for special beverages and for use in charging the familiar soda fountain. For such purposes it is liquefied and transported in steel carboys which are delivered to the various fountains. The compressors are generally compounded, the low press Low Pressure Gauge. plant operated with this gas follows along lines similar to that of the ammonia compression plant; as indicated in Fig. 2, the gas after compression passes into an oil separator where it is freed from the oil from the compressor cylinder; from the cylinder the gas passes into the condenser where it is cooled and condensed, its latent heat being absorbed by the condensing water. The liquid then flows to a receiver and from there is carried to the cooling coil through an expansion valve which allows the pressure to drop to about 40 lbs. It is possible to use the gas directly in the cooling coils or to use the coils to cool brine which in turn is circulated to the brine refrigeration coils, thus securing better temperature control in the coils by controlling the brine temperature. Direct expansion coolers are also built for use with the system when it is desired to do air cooling, the cooler being placed in the air washer spray chamber. Such a cooler is shown in Fig. 3. COMPARISON OF CARBONIC ANHYDRIDE AND AMMONIA PLANTS According to the manufacturers of carbonic machines the following is a comparison of the advantages and disadvantages between carbonic anhydride and ammonia. High Pressure Gauge. FIG. 2.-CYCLE OF OPERATION FOR A REFRIGERATION PLANT OPERATED WITH CARBON ANHYDRIDE GAS. ure cylinders delivering the gas to a receiver at about 500 lbs. pressure; the gas is cooled in the receiver and is then compressed farther in the high-pressure cylinder up to a pressure of 1000 lbs. The cycle of operation for a refrigeration CARBONIC ANHYDRIDE 1. Is harmless and odorless. 2. Is a fire extinguisher; it does not unite with lubricants, cannot be disintegrated, and does not deteriorate. 3. Is neutral, does not attack metals nor food products, and is a preservative. 4. It is cheaper than ammonia. 5. The entire charge of CO2 in a refrigerating plant could be discharged into the engineroom without any evil results whatsoever. 6. CO2 is absolutely non-explosive and will not support combustion under any conditions, but on the contrary will retard it. 7. The actual horsepower required for CO, machines of capacities between 10 to 25 tons is 1.2 H. P. per ton for refrigeration with condensing water at 70° F. With larger capacities the economy in power requirements increases correspondingly. In this connection they refer to pratical tests made by themselves, by consulting engineers employed by them for this purpose, and by a commission of engineers appointed by the Danish Government. The results are as follows: No. 1-Twelve-ton plant at 1.2 H. P. per ton of refrigeration with water at 56° F. and brine at 6° F. No. 2-Fifty-ton plant at P. Barman Brewery, Kingston, N. Y., 1.01 H. P. per ton of refrigeration with water on condenser 53° F., off 81° F. 8. Carbonic acid machines are constructed very strong and compact without reaching the proportions of ammonia machines of the same capacity. A cylinder bore of 4% in. in these machines corresponds to a bore of 91⁄2 in. in an ammonia machine of same capacity. 9. The operation of CO, machines is very simple; for instance, if it is desired to inspect the inside of cylinder, it is only necessary to close the discharge and suction stop valves (both valves being mounted on the side of the cylinder) and open the machine where desired. 10. It is an acknowledged fact that the CO. refrigerating machine is the only one which may be installed anywhere with perfect safety. This is especially important for plants installed in hotels, stores, hospitals or any building where a number of people assemble. This also applies to ships of all kinds. This machine is provided with a safety valve which relieves the pressure, should it become excessive. The use of this valve is impossible with the NH, system on account of danger from the escaping gas. A substantial proof of the foregoing is the fact that with thousands of CO, machines in practical operation, there is not a record of a single accident in connection with same. 11. The CO2 machine possesses the maximum economy of any compressor. One of the most important factors of this machine is the low ratio of compression which is but one to three, and consequently the re-expansion of the gas in the clearance space amounts to very little. ANHYDROUS AMMONIA 1. Is a blood poison and possesses a very pungent, unbearable odor. 2. Is inflammable when mixed with oil. It disintegrates at a high temperature and becomes an explosive. 3. Ruins everything with which it comes in contact, either through its penetrating, suffocating odor, or its corrosive action which attacks all metals. 4. Costs more. 5. One-half per cent of ammonia in the atmosphere renders life unendurable. 6. Ammonia becomes a high explosive in case of fire, as it disintegrates at high temperature into its constituents, nitrogen and hydrogen, the latter being a combustible gas. 7. Requires 1.3 H. P. per ton of refrigeration with condensing water at 70° F. and machine capacities between ten and twenty-five tons is the best economy ordinarily reached with ammonia machines in practice. It is claimed that the theoretical efficiency of ammonia machines is greater than that of the carbonic acid machines when using condensing water of high temperature. This assertion, however, is not substantiated by practical experience. On the contrary, marine refrigerating engineers and plant owners in tropical climates who have both systems in operation, contend that the economy of the ammonia machines falls short of the economy of carbonic acid machines when using condensing water at 90° F. and above. 8. Ammonia machines of even capacities considerably exceed the carbonic acid machines in bulk; they have longer frames and require a compressor volume six times as large as the compressor volume of CO, machines. 9. Ammonia machines possess numerous bypass connections and arrangements for evacuating the different parts of the system, which are controlled by a great many valves, etc., and before the machine can be opened for the inspection of stuffingbox, piston packing or the valves, it is absolutely necessary to discharge all the ammonia into the condenser, confining it there by closing all the valves leading from same to the part to be inspected. 10. Ammonia explosions occur frequently, and while it is doubtful from a strict chemical point of view that such explosions can take place at the ordinary temperatures, the fact remains and the causes have been attributed to the presence of hydrocarbons, resulting from the decomposition of the lubricating oil. Most of the ammonia accidents may have been caused purely by bursts, giving evidence of excess of pressure which may have been caused by water. 11. The efficiency of ammonia machines is very readily impaired by clearance space, leaky valves, etc., for the reason that the ratio of compression in the ammonia machine is high, being ordinarily one to ten and sometimes one to fifteen, and such clearance space will allow the re-expansion of the gas, and reduce the capacity of the machine. not need to be reminded that the perversion of these plants for such purposes is not only pernicious but will not be endured under present conditions. Patriotic owners can assist the government and the country by personally preventing the use of their plants to aid such purposes. A new helmet to protect the operators of ammonia plants when ammonia leaks cause dangerous fumes to form has been put on the market by the Protecto Safety Appliance Co., Newark, N. J. The helmet somewhat resembles the well-known smoke helmet and can be adjusted on the wearer in one-half minute. After entering a gas-filled room this helmet will protect the wearer for a period of two hours. Notes It is claimed that electric wiring in conduits is not suitable for cold storage rooms or refrigerators owing to short-circuiting which is almost positive to occur within the compartment. It is recommended that all such wiring be made of waterproof wire, run exposed. Kroeschell Bros. Ice Machine Co., of 472 West Erie St., Chicago, makes a specialty of carbonic anhydride plants for air cooling It has been agreed that clear artificial ice costs more than gray ice and, as the cooling effect is the same and the cost less, that clear ice is a useless and expensive requirement. Possibly this is true, yet we challenge any one to produce the effect of apparent purity and the appetitizing delight contained in a piece of clear sparkling ice. Ice for purposes where it is used visibly will be clear for a long time to come and we believe that ice so opaque as to prevent seeing through a comparatively thin piece will never enjoy the popularity of the clear and transparent production. Refrigeration enjoys a place in the sun and for the preservation and conserving of the food supply the cold storage warehouse is a most valuable adjunct-but as a means for the speculator to corner the market it is indeed abhorrent. There has been considerable agitation against the cold storage warehouses from time to time as evinced by the more or less frequent enactment of laws of increasing stringency relation to the length of time products may be held. The far-sighted cold storage owners will FIG. 1.-TYPE OF SELF-CONTAINED REFRIGERATING UNIT. purposes, and also of small and compact refrigeration plants. Fig. 1 shows a self-contained refrigerating unit, the condenser and machine being mounted on a combined brine and ice tank. For refrigeration plants of small capacity the Remington Machine Co., Wilmington, Delaware, has specially suited machinery arranged for electric drive. Automatic Control For Boiler Feed Pumps Having selected the boiler-feed pumps and determined their size, (see October issue) the piping and method of control should next be decided upon. The piping is separated into two distinct parts, these consisting of the connections for the steam end and the arrangement of suction and discharge piping on the water end. The water connections depend a good deal on just what the pump is required to do besides strictly boiler-feed work. If used for feeding alone the common practice is to run two headers along back of the water cylinder -one being a suction header and the other a discharge header. From these headers branches are run to each pump, the suction branch being valved and usually provided with a strainer between the valve and the pump. The discharge branch is also valved, is usually provided with a check between the valve and the pump and should have a relief valve between the check and the pump. Strainers, as the reader is aware, are for the purpose of preventing any obstructions entering the pump and getting into the valves or cylinder; they are manufactured in a variety of forms, some of the most common of which are illustrated in Fig. 1. Relief valves should be of the hydraulic type and should be capable of taking the entire delivery of the pump, assuming that the discharge valve has accidently been left closed when the pump is started. If the pump is to serve as an emergency pump for other lines, or if other pumps are to be cross-connected so as to serve as emergency boiler-feed pumps, an arrangement somewhat as shown in Fig. 2 can be used with advantage. In this scheme all the suction headers are run along the wall close to the floor back of the pumps and the discharge headers are carried along the same wall immediately above. Branches from each suction and discharge header are taken off at each pump and connected together, entering and leaving the pump through a common valved line. The way this piping would be arranged in plan view is shown in the sketch, Fig. 3, but for the sake of clearness the strainers and relief valves have not been shown in either drawing; these, of course, would come on the branch into the pump and not on the separate branches from the mains. With three pumps so connected any one pump can be used for any given service by properly manipulating the valves to handle such service. FIG. 1.-COMMON FORMS OF STRAINERS On the steam end more diversity with fewer pipes is practiced. This is because, while there is never anything to consider on the steam end except steam and exhaust pipes. the matter of pump control results in several methods of piping being used. The simplest form of steam and exhaust connections is shown in Fig. 4 where a steam line is carried down to the pump and the pump controlled by a globe valve. This line, however, when the pump is closed down-will fill up with water; before starting the pump the drip valve should be opened on the blow-off line and this water allowed to empty out. The exhaust is dripped, generally through a trap, FIG. 2. TYPICAL ARRANGEMENT OF PIPING WHERE PUMPS ARE CROSS-CONNECTED FOR EMERGENCY SERVICE. although this, too, can be allowed to go to the blow-off tank or sewer by cracking the drip valve slightly. Such piping is entirely nonautomatic and is only used where the work installed must be of the cheapest or the operation of the plant placed in charge of inferior help. The fact should not be lost sight of that the reciprocating steam pump, to a great extent, duplicates the common steam engine as far as the steam cylinder is concerned. While the steam is not used expansively in the cylinder still cylinder drips are advisable and an endeavor to keep the steam cylinder free from water and to provide it with dry steam is quite necessary for satisfactory operation. MAKING BOILER-FEED PUMPS AUTOMATIC The first step in making the boiler-feed pump an automatic proposition consists of placing a trap on the high-pressure steam line so as to keep the drop free from water at all times. This is so simple that the reader is already prepared to take the next step which consists of controlling the pump from the discharge pipe pressure by a pump regulator placed in the steam line supplying the pump. Most of such regulators are constructed on the principal of having a small pipe (connected to the discharge line of the pump) carried up and connected to a chamber located on one side of a diaphragm. On the other side of the diaphragm is placed another Pump Discharge Discharge FIG. 3.-PLAN OF PIPING SHOWN IN FIG 2 chamber connected by a pipe to the steam supply. Thus the diaphragm is separating two opposing forces and, as the steam pressure is |