4-7. BRAZING/DEBRAZING PROCEDURES. - Continued
REFRIGERANT UNDER PRESSURE
is used in the operation of this equipment.
or severe injury may result if you fail to observe safety precautions. Never use a
heating torch on any part that contains refrigerant 22. Do not let liquid refrigerant
touch you, and do not inhale refrigerant gas.
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
b. Filler Alloy
. Use brazing alloy, silver and flux, for all copper
to brass joints. Use brazing alloy, copper for
all copper to copper joints without flux.
c. Debrazing. Debraze joints for removal of refrigeration system components as follows:
All refrigerant 22 must be recovered 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 apply heat sink to all
nearby surfaces but the joint. (If heat sink is not available a wet rag may be used).
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 1 to 2 psi.