MECHANICAL REFRIGERATION 143 



der without first applying heat. The process of cooling 

 being the same when the ammonia expands from the cylin- 

 der into the system as when leaving the expansion valve, 

 a low temperature is produced and the cylinder and con- 

 nections become 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 handling 

 and are preferably kept in a cool place free from any lia- 

 bility to accident. The fact that ammonia is soluble in 

 water should be well understood by persons charging 

 a refrigerating system, or working about 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 employed 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 care- 

 fully 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 am- 

 monia the delivery pipe will become heated even when 

 the regulating 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 



