To give a fixed rule for packing house refrigeration, applicable to all conditions, would be impossible, as much depends upon conditions and surroundings, and the requirements would vary accordingly. For instance, atmospheric conditions, quantity of space to be cooled, temperature to be maintained, time for chilling, etc., these and many other factors affecting the general results must be taken into consideration and provided for, and as these vary, so will the refrigeration requirements vary. A few ideas will be set out to assist in the computation of the quantity of equipment to provide. The capacity or size of the refrigerating equipment required for any given plant is variable but can be reasonably closely computed by assuming certain conditions. =Space Per Ton Machine.=--Practice has demonstrated that one ton of mechanical refrigerating effect duty, as rated by manufacturer used continuously during a period of twenty-four hours will maintain at a temperature of 33° to 38° F. from 7,000 to 12,000 cubic feet of storage space. Conditions of exposure, insulation and outside temperature affect this. The minimum for beef storage coolers, the maximum for curing cellars. The area of room or quantity of space enters into each of these assumptions. If small rooms are used the unit to be assumed is smaller. Concrete buildings are easier to control due to the stored cold in the building mass of floors, columns and girders. =Machinery Per Head.=--It is customary to figure that in addition to that needed for cooling the space, one ton of refrigeration for twenty-four hours would be required for either one of the following items: From fifteen to twenty-two hogs, average weight, 225 pounds. From five to six head of cattle, average weight, 700 pounds. About forty-five calves, average weight, 80 pounds. From fifty to sixty-five sheep, average weight, 60 pounds. =For Cooled Meats.=--For cold storage rooms, where meats which have already been chilled or cooled are stored and held for a greater or lesser period, the refrigeration requirements are not so great as in chill and cooling rooms. The animal heat has been removed and the meats cooled down to a low temperature, consequently but little more refrigeration is required than that necessary to take care of the heat leakage through the insulation, and possibly the recooling of the meat through a range of a few degrees, when the meats may have gained a little in temperature by exposure. Therefore it is estimated that one ton of refrigerating duty will handle 12,000 cubic feet of curing or storage space for temperature of 33° to 35° F.