200 DAIRY TECHNOLOGY 



system as when leaving the expansion valve, a low temper- 

 ature is produced and the cylinder and connections be- 

 come covered with frost. When this occurs the cylinder 

 must be slightly warmed in order to be able to get all the 

 ammonia out of it. The ammonia cylinders, when filled, 

 should never be subjected to rough handhng and are 

 preferably kept in a cool place free from any liability 

 to accident. The fact that ammonia is soluble in water 

 should be well understood by persons charging a refrigerat- 

 ing system, or working abotit the plant. One part of water 

 will absorb about 800 parts of ammonia gas and in case of 

 accident to the ammonia piping or machine, water should 

 be employed to absorb the escaping gas. Persons em- 

 ployed about a plant of this kind should be provided with 

 some style of respirator, the simplest form of which is a 

 wet cloth held over the mouth and nose. 



" After starting the compressor at the proper speed 

 and adjusting the regulating valve note the temperature of 

 the delivery pipe, and if there is a tendency to heat, open 

 it wider, and vice versa. This valve should be carefully 

 regulated until the temperature of the delivery pipe is 

 practically the same as the water discharged from the 

 ammonia condenser. With too light a charge of ammonia 

 the delivery pipe will become heated even when the regulat- 

 ing valve is wide open. As a general thing when the plant 

 is working properly the temperature of the refrigerator is 

 about 15° lower than the brine being used, the temperature 

 of the water discharged from the ammonia condenser will 

 be about 15° lower than that of the condenser, the pointers 

 on the gauges will vibrate the same distance at each stroke 

 of the compressor and the frost on the pipes entering and 

 leaving the refrigerator will be about the same. By placing 

 the ear close to the expansion valve the ammonia can be 

 heard passing through it, the sound being uniform and 

 continuous when everything is working properly. 



" When air is present the flow of ammonia will be more 

 or less intermittent, which irregularity is generally notice- 

 able through a change in the usual sound heard at the 

 expansion valve. The pressure in the condenser will also 



