REFRIGERATION. 



95 



brine, and any moisture is deposited in the casing, the air in the chamber itself belli!, perfectly dry. 

 Tin: gases most commonly used as a refrigerant are carbon dioxide (CO-), ammonia, sulphurous 

 acid and ether. Much of these require- a special compressor to suit its special properties. The ( ( )- machine 

 is by far the most suitable for this class of work ; the gas used is the same as that which causes the aeration 

 in aerated waters and wines ; so that it is absolutely safe to use these machines whatever may happen, 

 whereas the occurrence of a serious leak in the other machines would cause danger to lite. I!e^ide&amp;gt; this 

 ad vantage., the CO- system is fully as efficient as any other and the compressor is very much smaller, so 

 that the machine occupies less space. 



Figure i-Jo shows a convenient plant where it is not possible to insulate a separate room. 

 On the left is seen the compressor of the machine, which can be driven by a small electric motor 

 or engine. The circular cast-iron casing on which this compressor is mounted contains the condenser 

 coils, the ends of which can be seen projecting; through this casing the cooling water is passed. I he two 

 gauges show the pressure of the gas under the full compression and the pressure when the gas evaporates 

 Irom the liquid to the gaseous state in what is called the evaporator coil. 1 he evaporator coil in this 

 case is contained in the ice tank itself, seen in the centre. This tank, it will be seen, is covered by boarding, 

 which contains the insulating material, so that no heat passes into the brine. There arc two moulds in 

 this tank, and the lugs for lifting them can be seen projecting. On the right of the illustration is an 

 insulated cabinet divided into three parts. The two partition:-, arc formed by Hat tanks extending 1mm 



I2(&amp;gt;. I l.ANT WI1HKK SPACE MUST UK KCON&amp;lt; &amp;gt;.MISKI&amp;gt;. 



top to bottom of the cupboard. The brine cooled by the evaporator coil in the ice tank is circulated through 

 these tanks and causes the temperature in the cabinet to fall. 



The particular cabinet illustrated was designed for hanging meat, poultry and game in the centre 

 compartment, dairy produce in the left-hand compartment, and wine and Innt in the two right-hand com 

 partments. The shelves are made of perforated zinc and are all removable. The pipes are not connected 

 up, as the plant was merely arranged for photographing. 



In the plan of the plant illustrated in Fig. 125 the engine-room is situated in the basement underneath 

 the front hall ; it will be noticed that the compressor is driven by a belt from an electric motor with the 

 condenser close by. The ice tank in the left-hand corner of the room is fitted with an apparatus for 

 producing clear ice ; the moulds are swung to and fro during the process of freezing. If this were not 

 done, cloudy, opaque ice would be produced unless distilled water were used. If it is required to make 

 clear ice from ordinary water, as in this instance, some such method as this must be adopted. Sometimes 

 paddles are used for agitating the water ; but rocking gear is preferable, as the paddles sometimes get 

 frozen into the ice. Near the motor driving the compressor are placed the two pumps driven by an 

 electric motor. One of these pumps circulates the cooling water through the condenser, and the other 

 circulates the brine cooled in the ice tank through the various cooling appliances. The brine drums are 

 clearly shown in the dairy produce room, the meat-room being cooled by a brine wall, while outside the 

 engine-room is placed the air cooler immediately underneath the ceiling. The air is led to the chamber 

 by wooden ducts. 



