Section VII. REFRIGERANT TUBING AND FITTINGS
Refrigerant tubing is seamless copper which has a bright internal finish to permit thorough cleaning and to prevent
entrapment of moisture or other impurities. Both rigid and soft grades are used, depending upon whether the tubing is to
be bent or is to remain straight. Sharp changes of direction are accomplished by the use of fittings, such as elbows, tees
and creases. Connections are made by silver soldering or brazing, and by flare fittings.
Inspect tubing and fittings visually for nicks, cuts, cracks or kinks. If damage appears to be minor, test for leaks. (Refer to
a. General. There refrigeration system must
be completely discharged (paragraph 5.22.a) before removing any
part of the system. If debrazing is required for removal a flow of oil pumped dry nitrogen must be introduced through the
system before the joint is heated to brazing temerature. Any refrigerant gas. air or moisture in the system would cause
serious corrosion at brazing or debrazing temperature
b. Heating. Sufficient heat should be applied uniformly around the joint to reach the melting point of the filler
metal quickly. Slow or non-uniform heating permits heat to be conducted away from the joint, sometimes melting an
adjacent joint at the same time as the one intended.
c. Cleaning. Residual filler metal can be removed from a debrazed tube in the folIowing manner.
Wear welders gloves or other thermal protective gloves when performing the following operation.
(1) Fold apiece of fiber-glass cloth about 6x6 inches and wrap it loosely around the tubing, a few inches
away from the tubing end to be cleaned.
(2) Heat the tubing at the end to recleaned, until the braze filler metal is throughly melted.
(3) Grasp the fiber-glass wrapping firmly, and pull it over the tubing end with a twisting motion.
d. Protection from heat.
Polyurethane foam insulation breaks down to form toxic gases when heated to brazing temperature.
(1) When brazing/debrazing refrigerant tubing or fitting near an insulated wall of the air condition, fabri-
cate a sheet metal shield to deflect the flame of the torch away from the insulation. Perform the operation a well venti-
brazing/debrazing to bing from expansion valves, solenoid valves
or other component
a that could
be warped or damaged by brazing temperature, the component should be disassembled to the extent possible, and &
body alone brazed/debrazed. If disassembly is impractical or impossible. the entire compontent except for the joints to be
heated. should be wrapped in wet cloth to act as a heat sink.