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TM 9-4110-257-14
5-8.PURGING THE REFRIGERANT SYSTEM
This task covers:
Purge
INITIAL SETUP
Tools:
Nitrogen Regulator
5, Section III, Appendix B
Materials/Parts:
Nitrogen
11, Appendix E
Equipment Conditions:
Refrigerant system discharged (para. 5-7).
General Safety Instructions:
WARNING
•
Never pressurize refrigerant lines with oxygen, mixture with oil could
cause an explosion.
•
The pressure in a nitrogen cylinder can exceed 2000 psi. A nitrogen
pressure regulator should be used at all times to avoid personal
injury.
•
Nitrogen is an inert gas that can cause suffocation and must be
discharged in a well ventilated area.
Purge. The refrigeration system must be purged with dry nitrogen before brazing is performed on any component. A
flow of dry nitrogen should be continued during all brazing operations to minimize internal oxidation and scaling.
(1) Disconnect charge hose from recovery unit and connect to nitrogen regulator and nitrogen tank.
(2) Disconnect the compound gage hose from the service manifold and place end in a suitable container to catch
any oil that may come out.
(3) Be sure the service manifold compound gage and vacuum valves are closed.
(4) Open the service manifold pressure gage and charge valves.
(5) Open the nitrogen tank valve and adjust the regulator so that approximately 1-2 cfm (0.028-0.057 m3/minute) of
nitrogen flows through the system.
(6) Check discharge from the hose attached to the suction service valve to be sure that no oil is being forced out of
the system.
(7) Perform any brazing/debrazing operations necessary (para. 5-9).
(8) When purging is completed, close nitrogen tank valve.
(9) Disconnect the charge hose from nitrogen regulator.
(10)Connect the compound gage hose to service manifold.
5-13
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