MECHANICAL REFRIGERATION 115 



working properly. If too much air is present the 

 sound will be irregular. Remove air in the same 

 manner as when charging the system. The presence 

 of oil or water is detected by shocks occurring in the 

 compressor cyUnder. Oil is removed by an oil 

 separator placed in main pipe between compressor 

 and condenser." 



The compressor sucks the gaseous ammonia into 

 its cylinder, compresses it and sends it into the 

 condenser. The latter thus describes a continuous 

 circuit. The same ammonia is used continually. A 

 five-ton refrigerating machine requires about an 18 

 horse-power boiler. 



The compressor, the most essential part,' is a 

 pumping engine, used to pump the ammonia gas 

 from the cooling apparatus and compress it and 

 force it through the condenser at a pressure of from 

 150 to 185 pounds per square inch. See illustration. 



The machinery for pasteurizing and clarifying 2500 

 quarts of milk and for a refrigerating machine of 

 five tons, will cost about $2500. 



An ice plant which will make two and one-half 

 tons of ice will have a refrigerating capacity of five 

 tons; that is, it will cool as much as will five tons 

 of ice melting in twenty-four hours. 



For ice-making, pasteurizing, ice cream making 

 and running a separator, not less than a 30 horse- 

 power boiler should be used. 



The water used in the condenser is warm and can 

 be stored up for various purposes. 



About a half ton of coal is required daily to make 



