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TM 9-4120-389-14
h. Allow nitrogen to sweep through the system at the rate of less than 1 - 2 cfm (0.028-0.057 m3minute)
for a minimum of 5 minutes, before starting any brazing operation. Then allow it to continue to flow at the same
rate until all brazing operations are completed (See para. 5-5 for brazing/debrazing procedures).
i. After installation brazing operations are completed, allow nitrogen to flow for a minimum of 5 minutes.
j. Close nitrogen cylinder valve, nitrogen regulator and charging manifold valve.
k. Disconnect the hose from the nitrogen tank.
l. Replace filter dryer (See para. 5-10).
m. Leak test system (See para. 5-6).
5-5. BRAZING/DEBRAZING PROCEDURES
Supplies: Brazing alloy (silver) (items 5 and 6, Appendix E)
Nitrogen cylinder (item 4, Appendix E)
Brazing flux (item 7, Appendix E)
Abrasive cloth (item 8, Appendix E)
Rags (item 9, Appendix 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 those provided 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:
WARNING
All refrigerant -22 must be discharged from system and entire system must be purged with dry nitrogen before
beginning any debrazing operation.
5-7
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