TM 9-4120-407-14
4-14. BRAZING/DEBRAZE PROCEDURES. (Cont)
The polyurethane foam used as insulation in the air conditioner will
break down to form toxic gases if exposed to the flame of a torch or
brazing temperature. Work in well ventilated area.
(2) Protect insulation, wiring harnesses, and other components with appropriate heat shields.
Never use a heating torch on any part that contains refrigerant.
Heat causes the refrigerant to break down and form carbonyl chloride
(phosgene), a highly toxic and corrosive gas. All refrigerant must be
discharged from the system and the entire system must be purged
with dry nitrogen before beginning any brazing operation.
NOTE
It may be easier to access a component by cutting or debrazing the
copper lines in accessible areas and removing part of the
interconnecting tubing with the component.
(3) If debrazing a joint on a valve, disassemble the valve to the extent possible and wrap all but the
joint with a wet cloth to act as a heat sink.
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.
(4) Apply sufficient heat uniformly around the joint to quickly melt the filler alloy. Remove heat as
soon as the joint is separated.
b. Clean. All filler alloy must be cleaned from debrazed joints before reassembly. Heat each piece of
the joint until the filler is melted and then wipe it away with a wire brush. Be sure no filler alloy or
other debris is left inside any tubing, fitting, or component.
c. Braze.
The pressure in a nitrogen cylinder can exceed 2000 psi. A nitrogen
pressure regulator should be used at all times to avoid personal
injury.
Nitrogen is an inert gas that can cause suffocation and must be
discharged in a well ventilated area.
4-34