64 BULLETIN" 98, U. S. DEPARTMENT OF AGRICULTURE. 



ery and properly arranged and proportioned accessories the cost of 

 repairs and operation is reduced to a minimum. 



In the summer months the refrigerating plant is often required to 

 operate continuously in order to handle the increased amount of 

 milk during the flush season, and, furthermore, there is a greater 

 amount of refrigeration required on account of the higher summer 

 temperature. A breakdown at this time would result in the prob- 

 able loss of the stored products; besides, the daily supply of milk 

 and cream which arrives in the plant at a temperature that will 

 cause the rapid development of bacteria if held even for a short 

 period. During the summer months the temperature of the con- 

 densing water will be higher, and consequently a greater quantity 

 will be required for satisfactory operation. 



With properly proportioned pipe coils, brine tanks or congealing 

 tanks, and good air circulation within the cold-storage room, cool and 

 dry air will be obtained and a lower temperature and purer atmos- 

 phere than is possible with ice. The temperature obtained in the 

 average refrigerator cooled with ice is seldom below 45° or 40° F., 

 and the air always contains more moisture than it should for the best 

 results. 



When employing a properly designed mechanical refrigerating 

 plant the temperatures are under perfect control of the operator, 

 regardless of weather conditions; consequently the result is a higher 

 grade and more uniform product. It is absolutely necessary in 

 manufacturing the highest grade dairy products to be able to control 

 the temperatures at will. 



As the refrigerating plant is generally operated by persons unskilled 

 in the management of machinery of this type, it should be as simple 

 as possible in its construction and operation, especially in the smaller 

 plants. In the larger plants, however, where an experienced attend- 

 ant is employed, the equipment may be more elaborate. The appa- 

 ratus should be designed to occupy as small a space as possible con- 

 sistent with strength and efficiency, and as it is to be operated by 

 unskilled persons, nothing but the very best material and workman- 

 ship should be used in its construction. 



In order to keep the size of the refrigerating plant as small as pos- 

 sible, it is advisable to provide storage tanks of ample capacity. 

 The brine should be cooled and a large quantity held for quick action 

 when needed, as when a supply of warm milk is received into the 

 plant and it is necessary that it should be cooled in the shortest 

 possible time. And, further, the cold brine in the storage room can 

 be depended upon to hold the temperatures in case of a temporary 

 shutdown of the refrigerating machine. 



In view of the fact that the quantity of milk or cream is liable to 

 vary greatly from day to day, depending upon the supply from the 



