(8) In direct expansion plants the cooling effect is stopped immediately when the compressor is stopped. It is required to operate incessantly, or if speed be reduced the current is chiefly wasted in resistance grids if electrically driven. Whereas in a brine plant the compressors can be stopped several hours, the brine being circulated rises in temperature but not sufficiently to vary room temperatures. This is a great advantage, permitting keeping “off peaks” on commercial electric lines and consequently earning lower rates. (9) With an electrically driven compressor, speed control is fixed within quite limited bounds and if direct expansion system is used more power is purchased than needed for reasons already mentioned. (10) The total cost for operating pumps and calcium taken collectively will be far less than the uncontrollable ammonia leakage. The coil attendants can be less skilled. (11) Brine temperature 25 degrees below zero, Fahr., can be carried, sufficiently low for all purposes. Rooms can not be controlled at as exact temperatures with direct expansion as with brine, owing to its sensitiveness. (12) Lastly and very important, the complicated piping system to carry several back pressures to produce varying temperatures and the necessity of operating several compressor “ends” makes a complicated installation of small units as against a simple system carrying one temperature brine. Plants of the character described usually operate on direct expansion, require three sets of temperatures, three sets of suction pressures and three sets of suction mains with various cross connections and intricate pump-out arrangements. This necessitates multiplicity of machines and connections to various cylinder ends. Progressive authorities recognize the necessity of freezer storage in meat plants. In combination pork and beef or pork plants, newer installations will be made with far less curing space for sweet pickled meats and far greater space for storing meats frozen either before or after curing to the end of producing palatable meats, not salt soaked and of inferior quality. There are slaughtering plants for export where beef is shipped chilled or frozen, and mutton frozen. Some have exclusive freezer buildings, others parts set aside for freezers. One temperature brine is circulated, the temperature in the rooms being governed by the quantity of pipe in service. In all instances, sharp freezers, storage rooms and curing rooms are equipped with pipes therein--and the chilling rooms for beef and pork closed coils or spray, optional. Shell and tube coolers have proven so fitting that no hesitancy need be made about using them, and the possibility of freezing is negligible with reasonable prudence. Tanks with submerged coils can be used, but it prevents the saving made by using balanced brine pumping, on high buildings, a quite material one. CHAPTER VI POWER PLANT REQUIREMENT.