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TM5-4120-376-14
5-9.
a.
b.
REPLACING TUBING or REFRIGERANT COMPONENTS.
WARNING
Purge system with dry nitrogen prior to soldering. Refrigerant heated to
1200°F (649°C) creates phosgene gas.
WARNING
Dry nitrogen is always used to purge the refrigeration system during brazing or
debrazing of connections to prevent internal oxidation scaling.
NOTE
A careful analysis of any trouble should first be made to determine if
replacement is necessary. The cause of failure must be determined before
replacement is made.
System Discharge. Discharge system in accordance with paragraph 5-8, page 5-10.
Debrazing Joints.
(1) Connect a cylinder of dry nitrogen (Table D-1, Item 8) to the gauge port of the
suction service valve. Open the cylinder shutoff valve and the suction service valve slightly and
completely open the discharge service valve to purge the system of refrigerant gas. Use 1-2
cfm (0.1 to 1.02 M3/minute).
(2) Debraze those joints which must be removed in order to replace the tubing, fitting, or
refrigerant component that is defective.
c .
Hold
d.
e.
f.
5-17.
h. Pressure Test. Pressure test in accordance with paragraph 5-14, page 5-18 through 5-19.
Cutting Copper Tubing.
(1) Use a tubing cutter.
(2) Cut tubing square and remove all burrs from inside and outside with a sharp fine file.
tubing so filings will drop away from tube opening.
Brazing. Braze joints in accordance with paragraph 5-10, page 5-13.
Leak Check. Leak check in accordance with paragraph 5-11, page 5-13.
System Evacuation. Evacuate system in accordance with paragraph 5-12, page 5-14.
Charging System. Charge system in accordance with paragraph 5-13, page 5-15 through
5-11
g.
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