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TM5-4120-387-14
(5) Apply sufficient heat uniformly around the joint to quickly raise it to
a temperature that will melt the filler alloy.
Remove heat as soon as brazing is
completed.
5-9. LEAK TESTING THE REFRIGERANT SYSTEM
Supplies:
Nitrogen cylinder (item 4, Appendix E)
Refrigerant -22 (item 10, Appendix E)
a.
The entire repaired area should be thoroughly leak tested after repair or
replacement of any component, before it is recharged with refrigerant -22. Leak
testing is also the method for troubleshooting when a system has lost all or part
of Its refrigerant charge through an undetermined cause.
b.
Testing Method.
There are two acceptable methods for leak testing the
refrigeration system.
(1) Refrigerant gas leak detector.
If an electronic refrigerant gas leak
detector is available it should be used in accordance with the procedures
contained in TM 9-4940-435-14, “Leak Detector, Refrigerant Gas”.
NOTE
The electronic refrigerant gas leak detector is highly sensi-
tive to the presence of a minute quantity of gas in the air,
and due to this factor is quite effective in the detection of
small leaks.
However, due to the rapid dispersion of
refrigerant gas into the surrounding air, difficulty may be
encountered in pinpointing large leaks.
The detector must be
used in a well ventilated but draft-free area.
(2) Soap solutions.
In this method, a strong solution of a liquid
detergent and water is brushed onto all points of
watching for the formation of bubbles.
If the soap solution testing method is
possible leakage while closely
used, thoroughly rinse
with fresh water after testing is completed:
A residual soap
film will attract and accumulate an excessive amount of dust
and dirt during operation.
Testing procedures.
To perform leak testing by use of the electronic
detector, it is necessary that the system be pressurized with a proportion of
refrigerant gas.
To perform leak testing by use of the soap solution method, the
system may be pressurized with dry nitrogen alone.
(1) To pressurize a system that has some refrigerant charge, for either
leak testing method:
(a) Remove the hose connection protective caps from the high and low
pressure service valves.
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