208 CREAMERY BUTTER MAKING 



ammonia, under pressure, is again liquified by running 

 cold water over the coils. From the condenser coils it 

 enters the liquid receiver, thence again on its journey 

 through the refrigerating coils. 



The intensity of refrigeration is regulated by an ex- 

 pansion valve, which is placed between the liquid receiver 

 and the refrigerating coils. This valve may be adjusted 

 so as to admit the desired quantity of liquid ammonia to 

 the coils. 



Systems of Refrigeration. There are two ways in 

 which the cooling may be accomplished by mechanical 

 refrigeration : ( i ) by evaporating the liquid ammonia 

 in a series of pipes placed in the room to be refrigerated ; 

 and (2) by evaporating the liquid ammonia in a series of 

 coils laid in a tank of brine and forcing the cold brine 

 into coils laid in the room to be refrigerated. The former 

 is known as the direct expansion system, the latter as the 

 indirect expansion or brine system. 



Brine System. In creameries where the machinery is 

 run only five or six hours a day the brine system is the 

 more satisfactory as it permits the storing of a large 

 amount of cold in the brine, which may be drawn upon 

 when the machinery is not running. 



The brine tank is preferably located near the ceiling in 

 the refrigerator where it will serve practically the same 

 purpose as an overhead ice box. In addition to this, the 

 refrigerator should contain a coil of direct expansion 

 pipes which may be used when extra cold is desired. 



Brine from the above tank may be used for cooling 

 cream by conducting it through coils which are movable 

 in the cream vat ; it may also be conducted through sta- 

 tionary pipes placed in the make room for the purpose. 



