148 MANAGEMENT OF DAIRY PLANTS 



cooler and the temperature of the same water as it leaves the 

 cooler. The amount of water required for cooling may differ 

 greatly in proportion to the amount of water admitted through 

 the cooler. If more water is admitted the cooling will be done 

 more rapidly but at a greater expense than when the water 

 flows through the cooler more slowly. It is evident that the 

 temperature of the cooling water greatly influences the cost as 

 well as the rapidity of cooling. 



1. Efficiency of Coolers. The tubular cooler may be consid- 

 ered to be of high efficiency. The author found that the cool- 

 ing water when a certain type of tubular cooler was used took 

 up 41.59 B. T. U. of heat per pound as against 12.58 B. T. U. 

 when cooling with the vat, or it required 3.3 times as much 

 water for cooling with the vat as with the tubular cooler, when 

 cooling with water of 54 F. It was also observed that the 

 evaporation was slightly greater when using the tubular cooler; 

 however, that shall be left out of consideration in the follow- 

 ing. 



2. Cost of Cooling-Water. From experiments referred to, 

 the cost of cooling was figured on the basis of the cream con- 

 taining 30 per cent of butter fat. About 2,000 pounds of cream 

 were pasteurized at a time. The cost of the water was figured at 

 ten cents per thousand gallons. The cost per pound of butter 

 fat for cooling when using a tubular cooler was found to be 

 0.009 cen t as against 0.021 cent when cooling in the vat. 



3. The Regenerator. The regenerator may be considered 

 as a saving device for the pasteurizing and cooling equipment. 

 It is an apparatus over which the cool and hot milk pass simul- 

 taneously, the cool milk taking up heat from the hot milk, thus 

 saving both in steam and cooling water. Bowen 1 reduced the 

 cost of coal about 50 per cent and the cost of refrigeration ap- 

 proximately 60 per cent by installing a regenerator. 



III. Cost of Labor and Equipment. The cost of labor 

 varies somewhat with the different type of pasteurizer employed. 

 Thus a continuous pasteurizer requires more of a person's 

 attention than is required when the cream ripener is used as a 



i Bui. 85, U. S. Dept. of Agriculture, 1914. 



