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5-8.
TM5-4120-377-14
Supplies: Brazing alloy (silver) (items 5 and 6, Appendix E)
Nitrogen cylinder (item 4, Appendix
Brazing flux (item 7, Appendix E)
Abrasive cloth (item 8, Appendix E)
Rags (item 9, Appendix E)
E)
a. General. All tubing in the refrigeration system is seamless copper with a bright internal finish that
permits thorough cleaning and prevents entrapment of moisture or other impurities. Rigid grade copper is used
for straight sections and soft grade for sections that must be bent. All interconnecting fittings, such as elbows,
tees, etc., are also copper. The bodies of all valves and all connections on other components are brass. All
joints, except theme provide with flare fittings, are made by brazing in accordance with MIL-B-7883, except
that radiographic examination is not required.
b. 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 alloy may be substituted for Grade IV or VI for copper to copper joints;
flux is not required for copper to copper joints.
c. Debrazing. Debraze joints for removal of refrigeration system components as follows:
All refrigerant-22 must be discharged from system and entire system must be purged with
dry nitrogen before beginning any debrazing operation.
(1) Determine which joints are to be debrazed. Due to the limited work space 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.
(2) Before debrazing a joint on a valve, disassemble the valve to the extent possible, then wrap all but the
joint with a wet rag to act as a heat sink.
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 less than 1-2 cfm (0.028-0.057 m3/minute).
(5) Apply suficient 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 joint until the filler alloy is melted and then wipe it away with a damp cloth.
Be sure no filler alloy or other debris are left inside any tubing, fitting, or component.
5-11
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