=Freezer Space.=--As will be explained in the chapter relating to refrigerating machine capacity, the capacity of a compressor very rapidly decreases when operating under conditions necessary to produce low freezer temperatures, and owing to the severe conditions imposed it seems necessary to compute that one ton of refrigerating duty will handle about 3,000 feet of freezer space. =Ice Computations.=--Before the application of mechanical refrigeration to packing house purposes, all artificial refrigeration was accomplished by means of ice melting alone, and at that time the packers computed ice melting requirements on a basis of cooling three pounds of meat from 80° F. to as low as it could be cooled by ice melting, for each pound of ice melted. While this rule undoubtedly was the result of practical experience with well constructed coolers, and was in no wise based upon theoretical or heat unit formulas, yet it is interesting to note how close this old rule compares with modern formulas of computing refrigeration. For example, the cooling of 100 head of hogs, averaging 250 pounds dressed, by the packer’s rule, would require-- 100 × 250 --------- = 8,333 pounds, or 4.16 tons ice melting. 3 And on a heat unit basis, cooling the same number and weight of hogs from 80° to 32° F. would require-- 100 × 250 × (80 - 32) --------------------- = 4.166 tons refrigeration. 288,000 The above comparison shows that theory and practice approach very closely to a common line, although in the calculation the factor of specific heat of the meat is ignored, and in practice this may well be left out, as specific heat of meats at various temperatures has by no means been accurately established. =Chilling Lard.=--The chilling of lard is a severe task on refrigerating equipment owing to the very heavy duty imposed in a short time. For example, with an eight-foot lard roll turning off 4,000 pounds per hour and changing the temperatures of the lard from 90° to 50° F. requires a very large compressor capacity per hour. =Summary--Computations.=--Assuming the killing of 100 cattle and 250 hogs per day; making 10,000 pounds of lard, fifteen tons ice; maintaining a freezer of 100,000 cubic feet and the small work connected with the establishment: For 100 cattle killed daily, and storage of 400 hanging, about 6,500 square feet area of cooler would be required; the height of this with the lofts would be about twenty-two feet or a capacity of 143,000 cubic feet. For 250 hogs daily or 750 total hanging, there would be required 3,000 square feet of floor area and a height of 18 feet or 54,000 cu. ft. The above number of hogs daily would also require a storage or cellar capacity based upon one hundred pounds meat sent to cellar for a turn over in sixty days equal to storing 1,500,000 pounds of product, or 15,000 to 20,000 square feet of floor area, requiring 200,000 cubic feet of building space.