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TM5-4120-387-14
j.
Allow nitrogen to sweep through the system at the rate of less than
1 - 2 cfm (0.028-0.057 m3/minute) 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 paragraph 5-8 for brazing/debrazing
procedures.)
k.
After installation brazing operations are completed, allow nitrogen to flow
for a minimum of 5 minutes.
1.
Close nitrogen cylinder valve, nitrogen regulator, charging manifold valve,
and both high and low pressure service valves on the unit.
m.
Disconnect the hose from the nitrogen tank.
n.
Assuming that all repairs are completed,
5-8. BRAZING/DEBRAZING PROCEDURES
Supplies:
Brazing alloy (silver) (items 5 and
Nitrogen cylinder (item 4, Appendix
Brazing flux (item 7, Appendix E)
Abrasive cloth (item 8, Appendix E)
Rags (item 9, Appendix E)
go to paragraph 5-9.
6, 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 connec-
tions 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 radio-
graphic 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
requ
foll
be substituted for Grade IV or VI for copper to copper joints; flux is not
ired for
Debrazi
ows:
copper to copper joints.
ng.
Debraze joints for removal of refrigeration system components as
All refrigerant -22 must be discharged from system and entire
system must be purged with dry nitrogen before beginning any
debrazing operation.
5-11
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