APPLICATION OF REFRIGERATION TO HANDLING OF MILK. 83 



to do the actual churning, and about 20 minutes more to work the 

 butter. During this time the cream ripen ers are washed. 



The arriving cream from the auxiliary creameries or farms is 

 weighed, sampled, and pasteurized. The pasteurizing may be done 

 either in the ripening vats or in a separate pasteurizing machine. 

 When the cream is pasteurized in the ripening vats it is cooled by 

 running cold water through the coils and the jacket surrounding the 

 vat. When a separate machine is used, the cream is run over a 

 cooler on its way to the ripening vats, where it is held at the proper 

 temperature for ripening from 18 to 20 hours. After the churning 

 is finished and the butter packed in tubs or boxes and stored in the 

 refrigerator, the churns and other apparatus are washed as well as 

 the floors of the building. The afternoons are usually given up to 

 office work, making repairs, etc. The machinery is, therefore, 

 operated only about eight hours a day; consequently, the refrigerating 

 machine should be of sufficient capacity to do the work in about eight 

 hours' time. 



The size of the room necessary to accommodate a creamery making 

 2,000 pounds of butter daily is about 10 by 10 by 10 feet, giving 

 600 square feet surface. Assuming that the walls, floors, and ceiling 

 are insulated for a heat transmission of 2 B. T. U. per square foot 

 per 24 hours for each degree of difference between the inside and 

 outside temperature, then with an average outside temperature 

 of 80° F. the refrigeration necessary is : 



B. T. TJ. 



Removing heat coming through walls, floors, and ceiling, 600X2(80°-32°). . . 57, 600 



Cooling cream, 5,500 X .90(75°-50°) 123, 750 



Cooling butter, 2,000 X .5494(58°-32°) 28, 568 



209, 918 



In view of the fact that the greater part of the refrigeration is 

 required for cooling the cream, an increase of 25 per cent to com- 

 pensate for losses of various kinds should be ample. Therefore, the 

 total amount of refrigeration necessary in 24 hours is 262,398 B. T. U. 

 But as the work is to be accomplished in 8 hours, the capacity of the 



,'. . 262,398X3 _ Q , _ , ,. 



machine necessary is: oqq onn = 2.73 tons, say, 3-ton machine. 



The cooling of the cream will take about one hour and the amount 

 of brine necessary, allowing a 10° rise in brine temperature, is 



-Aq — = 238 cubic feet, without the aid of the machine at the time. 



With the machine running during the time the cooling takes place, 



,, , . , , , , . . 123,750-36,000 1C _ ... 

 the cubic leet ol brine necessary is — ^^ — = 168. Alter 



the cream is cooled and run into the vats for ripening, the brine 

 is cooled down for holding over the room temperature during the 



