94 



THE HOUSE AND ITS EQUIPMENT. 



Practically all the machines of this size work on what is called the compression system ; that is 

 to say, by alternately compressing and allowing to expand some gas which can be easily liquefied. Tin- 

 system of operation is as follows : The gas is first compressed in the compressor ; it then passes, still 

 under a high pressure, through a coil of piping known as the condenser, where the heat, generated by 

 compression, is removed by means of water flowing over the coils. When the temperature of the gas 

 is reduced to somewhere near that of the water, being both cool and at the same time under pressure, it 

 becomes a liquid. This liquid is passed through a valve and allowed to evaporate into a gas, which causes 

 it to become intensely cold. In this state it is passed through another coil called the evaporator, which 

 is surrounded by brine, which, in its turn, is made cold, but by its nature cannot freeze. The gas is then 



drawn back to the com 

 pressor and the operation 

 begins afresh, the same 

 charge of gas being used 

 over and over again. The 

 brine which is cooled in 

 this way can be used for 

 making ice and for 

 reducing the temperature 

 ;&amp;gt;f the cold store, being 

 pumped to the point where 

 the cold is required by 

 means of a small pump in 

 the engine-room. 



For making ice the 

 brine is contained in a 

 tank in which galvanised 

 steel moulds are suspended. 

 These moulds are filled 

 with water, which is frozen 

 by the cold brine surround 

 ing them. The length of 

 time that it takes to freeze 

 a block solid depends on 

 the size of the block ; the 

 most convenient form for 

 the size of plant under 

 consideration is a b o u t 

 twenty - eight pounds in 

 weight, which would freeze 

 soli d i n approximately 

 eight hours. 



The cold chamber is 

 formed by insulating some 

 room or larder, as described 

 later. The cooling appli 

 ances are fixed in the 

 chamber and vary slightly 

 in their design. T h e s e 

 sometimes take the form 

 of piping bent into grid 

 shape, the grids being 

 suspended on the ceiling 

 and sides of the chamber. When it is desired to maintain an even temperature, it is usual 

 to place what are termed brine drums in the chamber. These are practically large pipes, 

 about nine inches in diameter, and as they contain a large volume of brine, the cooling 

 effect is continued for some time after the machine itself has stopped working. In a small 

 chamber a brine wall is sometimes used to produce the same effect ; this is a flat steel tank 

 containing brine, which is placed at one side of the chamber. When it is desired to keep the atmosphere 

 in the chamber sweet and fresh, an air cooler is used. This is usually formed of grid piping similar 

 to the grids already described ; but they are closely nested together and are put in an insulated casing, 

 which is often placed outside the chamber itself. A fan blows air over these grids, which contain cold 



125. PLAN OF REFRIGERATING PLANT. 



