REFRIGERATION SYSTEM. - TM-5-4120-386-140175

TM 5-4120-386-14

5-9. REFRIGERATION SYSTEM.

a. Description

Whenever it is necessary to open the

refrigeration system for any reason,

discharge the refrigerant carefully. Avoid

contact with liquid refrigerant. Severe

freezing of body tissues can take place

with extreme rapidity. Avoid excessive

inhalation of refrigerant gas, and ventilate

the area in which it is released.

Refrigerant gas in contact with flame or

hot surfaces is converted to phosgene, a

highly toxic gas having an odor similar to

newly mown grass or hay.

(1) The refrigeration system, illustrated by the refrigerant flow diagram is a

mechanical, vapor-cycle circuit consisting of the evaporator, thermal expansion

valve, compressor, condenser, and the necessary valves and cutout devices for

automatic control during operation.

(2) The thermal expansion valve releases high-pressure liquid refrigerant into the

evaporator at reduced pressure.

(3) The liquid refrigerant begins to vaporize by absorbing heat from the air

passing over the outside surface of the evaporator coil.

(4) The heated vapor is sucked out of the evaporator section by the compressor,

and is forced into the condenser section under high pressure where it is cooled and

condensed back into a liquid.

(5) The heat released during condensation is carried off by the condensing

airstream.

(6) The liquid refrigerant flows from the condenser to a receiver, to a subcooler,

and then to the thermal expansion valve to repeat the cycle.

(7) If the temperature control switch (evaporator return-air thermostat)

becomes satisfied or the evaporator return-air temperature is lower than the point

at which you have set the control, the refrigeration system will switch to a by-pass

condition.

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