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TM 9-4120-389-14
(4) Be sure the work area is well ventilated and that dry nitrogen is flowing through the refrigeration
system at a rate of 1 to 2 cfm (0.028-0.057 m3/minute).
(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.
5-6. 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 sensitive 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 possible leakage while closely watching for the formation of bubbles.
CAUTION
If the soap solution testing method is 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.
5-9
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