TM 9-4110-258-13
5.9 PURGING THE REFRIGERANT SYSTEM.
This task covers:
Purge
INITIAL SETUP
Tools:
General Safety Instructions:
Nitrogen Regulator
WARNING
6, Section III, Appendix B
Never pressurize refrigerant lines with
Materials/Parts:
oxygen, mixture with oil could cause an
explosion.
Nitrogen
11, Appendix E
The pressure in a nitrogen cylinder can
Equipment Conditions:
exceed 2000 psi. A nitrogen pressure
regulator should be used at all times to
Refrigeration system discharged (para 5.8).
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 gauge 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 gauge and vacuum valves are closed.
(4) Open the service manifold pressure gauge 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 5.10).
(9) Disconnect the charge hose from nitrogen regulator.
(10) Connect the compound gauge hose to service manifold.
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