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 TM 55-1905-219-14-8
4-28. AIR CONDITIONING SYSTEM - MAINTENANCE INSTRUCTIONS (Continued).
Never use oxygen to build up pressure. An explosion may result.
CAUTION
Do not use the compressor to build up pressure. If used to compress air,
overheating and damage may result.
(3) To pressurize the system and test for leaks proceed as follows:
(a) With all refrigerant piping connections completed, open all liquid and suction line stop valves.
(b) Disconnect refrigerant lines to condenser water regulating valve, high and low pressure control
switches, and suction pressure gauge. Close any stop valves in actuating lines to this equipment or close the
lines with flared fitting plugs or flared caps. This is done to prevent injury to belows by the high test pressure.
(c) Break the union in condenser overboard discharge line and plug line to prevent loss of pressure
through overboard discharge relief valve. The relief valve is left in the line for later testing.
NOTE
The safety head type bursting disc diaphragm or the throwaway type
rupture disc assembly, located between the union and the overboard
discharge relief valve, is not to be installed until after pressure tests and
dehydration of the system have been completed.
(d) Connect a refrigerant-12 (R-12) drum to charging valve in liquid line.
(e) Open valves between R-12 drum and liquid line and introduce enough refrigerant to raise system
pressure to 20 psig (137.9 kPa). Close valves and disconnect drum. Test for leaks with an electronic or an
halide leak detector. Repair any leaks.
(f) Connect a drum of dry nitrogen to charging valve and add gas until system pressure is 150 psig
(1034 kPa).
4-864
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