MBCHAMCAL RBFRIGURATION 141 



Refrigerating Pipes. The refrigerating pipes vary 

 from one to two inches in diameter. With moderately 

 good insulation it is estimated that by the direct expansion 

 system one running foot of two-inch piping will keep a 

 room of forty cubic feet content at a temperature of 32° 

 F. With brine nearly twice this amount of piping would 

 be necessary. 



For cooling the brine in the brine tank, about 140 

 feet of 1 34 -inch pipes are required per ton of refrigera- 

 ting capacity. 



Expense of Operating. When a refrigerating plant 

 has once been installed and charged with the necessary 

 ammonia, the principal expense connected with it will 

 be the power required to operate the compressor. This 

 power is supplied by the engine that is used for the regu- 

 lar dairy work. The ammonia, being used over and over 

 again, will add but a trifle to the running expenses. 

 Nor can the water used for cooling the ammonia vapors 

 add much to the cost of operating. It is true, however, 

 that the refrigerating plant will require some of the dairy- 

 man's time and attention, but this is probably no more 

 than would be consumed in the handling of ice in the 

 dairy. 



Charging and Operating an Ammonia Plant. This 

 subject is so ably discussed in The Engineer by H. H. 

 Kelley that the author feels he can do no better than 

 present the following extracts from that article. 



"When about to start an ice or refrigerating plant, the 

 first thing necessary is to see that the system is charged 

 with the proper amount of ammonia. Before the ammonia 

 is put in, however, all air and moisture must be removed ; 

 otherwise the efficiency of the system will be seriously 

 interfered with. Special valves are usually provided for 



