COLD STORAGE 



1170 



COLD STORAGE 



tensing ammonia gas, which is easily converted 

 into a liquid at 32 above zero F. or Centi- 

 grade (the freezing point), under a pressure of 

 :d>out sixty-one pound* to the square inch. 

 This liquid contains no water and is generally 

 knc.uu as anhydrous ammonia. 



Tin- iHriK'-iating apparatus consists of a force 

 pump for condensing the ammonia gas to a 

 liquid; a tank for holding the liquid ammonia; 

 roil- of pipe or an expansion chamber in which 

 i he .11111110111:1 changes to a gas; and pipes for 

 returning this gas to the pump to be again 

 condensed to a liquid. In its change to gas 

 the ammonia rapidly reduces the temperature 

 of surrounding objects. 



The plants are in charge of workmen who 

 thoroughly understand the system, and they 

 maintain any temperature desired. Rooms for 

 preserving beef, mutton and pork for a short 

 time are kept at just below the freezing point ; 

 for long storage, 20 colder. Those for the 

 I'M M i vation of poultry and fish must be several 

 degrees below freezing, because these articles 

 must be kept frozen. Eggs and fruits require 

 a temperature of about 36 F., but it is claimed 

 that butter retains its flavor better if kept at 

 a temperature below the freezing point. Milk. 

 however, should not be frozen. The rooms in 

 which butter, eggs and milk are stored must 

 be scrupulously clean, and the air free from 



DIAGRAM OF A COLD STORAGE SYSTEM 



The illustration shows a compression system for a cold storage machine, o is the compressing 

 cylinder, which is driven by the engine b. The gas on being compressed in a passes up through the 

 pipe to the condenser c, and then to the liquid ammonia reservoir d. Thence the liquid ammonia 

 at a temperature of about F. flows in coils of pipe in the brine cooling tank e, and abstracts heat 

 from the brine by being evaporated. The brine cooled by the evaporation of the ammonia pusses 

 into the coils /. 



odors, or these articles may become tainted and 

 unfit for use. See Cold Storage Temperatures, 

 below. 



Uses of Cold Storage. What the housewife 

 does on a small scale with her refrigerator, the 

 operators of cold storage plants do on a large 

 scale. Sometimes as many as a hundred mil- 

 lion cases of eggs (3,600 million dozen eggs) 

 are in storage at one time. Nearly all fruits, 

 vegetables, meats, milk, butter and eggs placed 

 on the market in large cities come from cold 

 storage warehouses. Every local meat market, 

 hotel, grocery and modern apartment house 

 has its cold storage room, in which are kept all 

 articles of food that would perish at ordinary 

 temperatures. 



Refrigerator cars transport fruit, milk, but- 

 ter and meat long distances and deliver them 

 in a condition of perfect preservation. The 



In large plants the evaporation takes place in 

 a closed chamber containing coils of pipe filled 

 with strong brine, which freezes at a much 

 lower temperature than water. The cold brine 

 is conducted through pipes to all parts of the 

 storage room, and in this way an even tempera- 

 ture is maintained. After completing the cir- 

 cuit of the pipes the brine returns to the 

 refrigerating coils and is used over and over 

 again. 



The storage rooms usually have double walls. 

 with an air space between to protect them from 

 the temperature of the outside air. The ceiling 

 is low, seldom exceeding eight or nine feet, 

 and the pipes are so distributed as to maintain 

 a uniform temperature In all parts of the room. 

 There must -be enough ventilation to keep the 

 air pure, but too much interferes with the 

 temperature. 



