TM 9-4120-398-14
5-7. BRAZING/DEBRAZING PROCEDURES (cont)
(1) Determine which joints are to be debrazed.
(2) Before debrazing a joint on a valve, disassemble the valve to the extent possible, then apply a wet rag (Item 12
Polyurethane foam used as insulation in air conditioner will break down to form toxic gases if exposed
to flame of a torch at brazing temperature.
(3) Protect insulation, wiring harnesses, cabinet, and other 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 1 to 2 cfm (0.028-0.057 m3/minute).
(5) Apply sufficient heat uniformly around the joint to quickly melt the filler alloy. If heat is applied slowly or
only on one side, the entire component or length of tubing will be heated and filler alloy in adjacent joints may also be melted.
Remove heat as soon as the joint separates.
d. Cleaning debrazed joints. All filler alloy must be cleaned from debrazed joints before reassembly. Heat each piece of
the pint until the filler alloy is melted and then wipe it away with a damp cloth.
CAUTION
Be sure no filler alloy or other debris are left inside any tubing, fitting, or component.
e. Reassembly. If tubing sections or fittings were removed with a component, debraze them from the component, clean
the pints, and braze them to the new component before reinstallation.
f. Brazing. Braze joints within the air conditioner as follows
(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 apply a wet rag
(Item 12 Appendix E) to all but the joint.
(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 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.
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