BRAZING/DEBRAZING PROCEDURES

TM9-4120-423-14&P

components are brass. All joints, except those provided with flare fittings, are made by brazing in

accordance with MIL-B-7883, except that radiographic examination is not required.

Filler Alloy. Grade IV or VI brazing alloy and type B flux, as specified in MIL-B-7883, must be used

for all copper to brass joints, Grade III brazing may be substituted for Grade IV or VI for copper to

copper joints; flux is not required for copper to copper joints.

Debrazing. Debraze joints for removal of refrigeration system components as follows:

WARNING

Be sure the refrigeration system is fully discharged and purged and that dry nitrogen is

flowing through the system at the rate of less than 1-2 cfm (0.028-0.057 m3/minute)

before all brazing or debrazing operations.

Determine which joints are to be debrazed. Due to the limited workspace inside the air

conditioner, it may be more convenient to remove a part of the interconnecting tubing with the

component rather than debrazing the joints on the component itself.

Before debrazing a joint on a valve, disassemble the valve to the extent possible, and then wrap

all but the joint with a wet rag to act as a heat sink.

WARNING

The burning of polyurethane foams is dangerous. Due to chemical composition of

polyurethane foam, toxic fumes are released when it is burned or heated. If it is burned

or heated indoors, such as during a welding operation nearby, you should take care to

ventilate the area thoroughly. An exhaust system like that of a paint spray booth should

be used. Air-supplied respirators, approved by the National Institute for Occupational

Safety and Health Administration or the United States Bureau of Mines, should be used

for all welding in confined spaces and in places where ventilation is inadequate. Persons

who have chronic or recurrent respiratory conditions, including allergies and asthma,

should not work in these areas.

Protect insulation, wiring harnesses, cabinet, and other surrounding components with appropriate

shields.

Be sure the work area is well ventilated and that dry nitrogen is flowing through the refrigeration

system at a rate of less than 1 - 2 cfm (0.028 - 0.057 cubic meters/minute).

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.

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