112 DAIRY LABORATORY GUIDE 



orated and liquified so that its use is continuous. 

 The cycle of its operation starts from the liquid 

 receiver and enters the refrigerating coils in which it 

 evaporates, absorbing a large amount of heat. By 

 means of a compression pump operated by an engine 

 the ammonia vapors are forced in the condenser coils 

 where the ammonia under pressure is again liquified 

 by running cold water over the coils. Here it again 

 enters the liquid receiver and repeats the cycle. The 

 amount of refrigeration is regulated by an expansion 

 valve placed between the liquid receiver and the 

 refrigerating coils. This valve may be adjusted so 

 as to admit the condensed quantity of liquid ammonia 

 to the coils. Note difference between brine system 

 and direct refrigeration. Take temperatures of brine. 

 At different regulations of the expansion valve, take 

 temperature of the room surrounding the brine tank. 

 If the direct refrigeration system is used entirely, take 

 temperatures similarly as above directed. Note size 

 of compressor refrigerating pipes, power required, 

 expense of operating, etc. After careful examination 

 of the machine, charge it and operate under direction 

 of the operating engineer as described by H. H. 

 Kelley: 



" Discharge air with special valves by starting the 

 compressor and pumping it out by reversing the 

 operation of the gas cylinder to that of its working 

 order. Charge with proper amount of anhydrous 

 ammonia through the charging valve by connecting 

 the ammonia cylinder with suitable pipe, and open 

 the valve. Run compressor slowly with the suction 



