MODEL PCA090480WH
CHAPTER 2
SERVICE
Section 3: Refrigeration Basics and Service
2-3
March 2013
Page 46
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© 2013 Twist, Inc.
use a pressure-regulating valve in the line connecting the nitrogen
cylinder to the system.
Apply heat evenly to the tube and fitting until the flux begins to melt.
The way heat is applied can either draw flux into the joint or prevent its
entry. Apply heat around the circumference of the fitting to draw the
brazing alloy into the joint, making a mechanically strong and tight joint.
Never apply heat to a line under refrigerant pressure. The line may
rupture, and the escaping refrigerant pressure may throw blazing oil or
molten solder through the air. Refrigerants exposed to an open flame
may break down into irritating or poisonous gases.
Immediately
after
the
brazing alloy has set, apply a wet brush or cloth to
the joint to wash off the flux. All flux must be removed for inspection
and pressure testing.
H.
Pressure Testing
After repairs are made on a system, refer to sub-section “F” above to
review pressure-testing options. Ensure that no leaks exist before
proceeding forward. If leaks are noted, remove pressure from system
and re-solder joint(s) per sub-section “G.”
I.
Evacuation
Any time the compressor or system is exposed to atmospheric air or if
the system becomes contaminated and removal of the refrigerant
charge is necessary, evacuate the system. Use a portable vacuum
pump specifically built for refrigeration evacuation purposes. The gauge
manifold provides a convenient means of connecting the vacuum pump
to service valves on the compressor.
Triple evacuation is strongly recommended if possible. To evacuate a
system, attach the common connection on the gauge manifold to the
suction connection on the vacuum pump. Connect the “High” and “Low”
pressure connections on the gauge manifold securely to the service
valves on the “High” and “Low” pressure sides of the system
respectively and close the valves on the gauge manifold.
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