72 MANAGEMENT OF DAIRY PLANTS 



the heat it has removed from these rooms; here, in turn, this 

 heat is taken up by the vaporizing ammonia in the expansion 

 coils. Ice-cream freezers and cooHng tanks may be connected 

 with the brine circulation, thus saving the handling of ice for 

 cooling purposes and its consequent loss from meltage. It may 

 not be advisable, however, to connect the brine directly to the 

 cream ripeners as it is apt, in time, to cause the cooling coil of 

 the cream vat to leak. The more satisfactory way is to have a 

 separate cooling tank in which the water used for cooling the 

 cream is first cooled by the brine. 



3. Brine-Tables. — The brine may be made from either 

 sodium chloride or calcium chloride. The latter is most com- 

 monly used, owing chiefly to the fact that it does not cause the 

 iron pipes and pumps to deteriorate as does the former. The 

 brine should be kept at such a strength that it will not freeze; 

 therefore, if lower temperatures are desired, the brine should be 

 of higher specific gravity. For readily determining what 

 strength of solution will give a desired result under a given 

 temperature, tables have been published. 



The table on page 73 is that prepared by Van Schaack & 

 Sons of Chicago. 



4. Piping Required for Each Method. — The amount of 

 piping required for a refrigerator room depends primarily on the 

 temperature to be maintained in the room and the temperature 

 of the refrigerating medium. Siebel estimates that for direct 

 expansion one running foot of 2-inch pipe ' will take care of 10 

 cubic feet of space in rooms that are kept below freezing to a 

 temperature of 10° F. ; that one running foot of 2-inch pipe will 

 take care of 40 cubic feet of space in rooms to be kept at or above 

 32° F. or thereabout. .It is a general rule in practice to allow 

 from one and a haK to two times as much surface for brine 

 circulation as for direct expansion. 



Ammonia Compressor. — The ammonia compressor is a 

 machine which draws the ammonia gas from the expansion 

 coil into the compressor, whence it is forced into the condenser 



^The surface of one running foot of 2-inch pipe is equal to 1.44 feet of i^-inch 

 pipe, or to 1.8 feet of i-inch pipe. 



