TM 9-4120-370-14
TO 35E9-229-1
BRAZING/DEBRAZING PROCEDURES - Continued.
5-9.
(1) Position the component to be installed.
(2) To prepare a joint on a valve for brazing, disassemble the valve to the extent possible. Then wrap all but
the joint with a wet rag to act as a heat sink.
(3) Protect insulation, wiring harnesses, and surrounding components with appropriate shields.
(4) Be sure the work area is well ventilated and that dry nitrogen is flowing through the refrigeration system
at a rate of less than 12 cfm (0.0280.057 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.
Supplies:
Refrigerant22 (item 10, Appendix E)
The entire repaired area should be thoroughly leak tested after repair or replacement of any component, before
a.
it is recharged with refrigerant22. 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 min-
ute 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 af-
ter testing is completed. A residual soap film will attract and accumulate an ex-
cessive 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
c.
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.
(b) Connect the hoses from a charging manifold to the service valves.
NOTE
If it is possible that the problem may not be a leak and that you may not have to replace
a refrigeration system component, refrigerant22 may be substituted for the nitrogen in
the following test. If nitrogen is used, you will have to discharge, evacuate, and recharge
the system after this test is completed.
(c) Connect a nitrogen pressure regulator and nitrogen bottle to the center hose connection of the charg-
ing manifold.
(d) Open the unit service valves and the charging manifold valves.
(e) Open the nitrogen tank valve and pressurize the system to 350 psi (24.7 kg/cm).
