—The chilling of the meat immediately after killing is perhaps the most important function in the whole refrigerating process and one that cannot have too much attention. In the matter of beef it is the practice of the best operators to see to it that immediately after the hide is removed the beef is placed in the coolers. At most it should not be allowed to stand out in the open air to exceed half an hour. Sheep and veal should be treated in the same manner. As for hogs in some climates, such as latitude equal to Chicago or north thereof, if space is available an open air hanging room is a valuable adjunct where the animal can be air dried, depending upon seasons, from one hour to over night. This feature also permits of increased slaughtering during the winter season. It is a custom that can be abused, however, by careless handling—resulting in sour meats.
Quantity of Refrigeration to Provide.
—There are so many factors which enter into the question of packing house refrigeration, and so many details of construction and application of refrigerating apparatus, that it is almost impossible to cover this subject practically and intelligibly without devoting a volume to refrigeration alone.
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: