MODEL PCA090480WH
CHAPTER 2
SERVICE
Section 3: Refrigeration Basics and Service
March 2013
2-3
Proprietary/Confidential
Page 47
© 2013 Twist, Inc.
Start the vacuum pump and gradually open the gauge manifold valves.
It may be necessary to restrict the vacuum pump suction pressure by
means of the gauge manifold valves to avoid overloading the pump
motor. Continue evacuation until the desired vacuum reading on “Low
Pressure” gauge is reached.
When evacuation is complete, close the gauge manifold valves tightly,
remove the line from the vacuum pump, and connect it to the refrigerant
cylinder. Loosen the common hose connection at the gauge manifold,
crack the refrigerant drum valve to purge the hose, and retighten the
hose connection. Crack the valves on the gauge manifold until the
system pressure rises to 2 psig. Close the refrigerant drum valve and
the gauge manifold valves.
For triple evacuation, repeat the above procedure three times,
evacuating twice to 1500 microns and the last time to 500 microns.
When the procedure is complete, the system is ready for charging.
J.
Charging
With the gauge manifold connected to the service valves of the system,
connect the common hose to the refrigeration cylinder. Loosen the
common hose connection at the gauge manifold, crack the refrigerant
drum valve to purge the hose, and retighten the hose connection.
Weigh the refrigerant cylinder prior to charging. Open the refrigerant
cylinder vapor valve, open the suction valve allowing pressure to build
up in the system, and start the compressor. Modulate the rate of
charging with the gauge manifold valve.
The refrigerant cylinder must remain upright with refrigerant withdrawn
only through the vapor valve to insure that only vapor reaches the
compressor. The vaporizing of the liquid refrigerant in the cylinder will
chill the liquid remaining and reduce the cylinder’s pressure. To
maintain cylinder pressure and expedite charging, warm the cylinder by
placing it in warm water or by using a heat lamp.
Do not
apply heat
with a torch.
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