Zamil MAC-240, Installation, Operation & Maintenance Manual

Page: 41 / 67

40
9.5 EVACUATING THE REFRIGERANT SYSTEM
Anytime the compressor or refrigerant system is exposed for long periods of time to atmospheric air, becomes contami-
nated, or requires removal of the refrigerant charge, evacuate the system using the procedures that follow.
CAUTION:
POTENTIAL FOR SERIOUS DAMAGE TO THE MOTOR WINDINGS IN THE COMPRESSOR. DO NOT START
THE COMPRESSOR OR ATTEMPT TO OPERATE THE UNIT WHILE THE SYSTEM IS UNDER HIGH VACUUM.
Use a small portable vacuum pump designed for R-22 refrigerant system evacuation. Do not use the refrigerant system
compressor as a vacuum pump. This could result in severe damage to the compressor.
It is possible to use the manifold gauges to connect the vacuum pump to the service valves on the refrigerant system. For
larger systems and larger vacuum pumps, copper tubing or vacuum hoses of 1/4" minimum inside diameter are recom-
mended for high vacuum work. The procedures that follow are for use with a small vacuum pump connected through
manifold gauges.
Triple evacuation is strongly recommended for all field installed systems.
(1) Attach the common connection on the manifold gauges to the suction connection on the vacuum pump.
(2) Connect the high and low pressure connections on the manifold gauges to the service valves on the high and low
sides of the system respectively.
(3) With the valves on the manifold gauges closed (front-seated), open the service valves and adjust to a point approxi-
mately midway between the front-seat and backseat position.
(4) Start the vacuum pump and gradually open the valves on the manifold gauges. It may be necessary to restrict the
vacuum pump suction pressure using the manifold gauges to avoid overloading the vacuum pump motor.
(5) Continue evacuation until obtaining the desired vacuum reading on both gauges.
(6) When evacuation is complete, close the valves on the manifold gauges tightly, remove the line from the vacuum
pump and connect it to an R-22 refrigerant cylinder.
(7) Loosen the common hose connection at the manifold gauges, crack the refrigerant cylinder valve to purge the hose
and retighten the hose connection.
(8) Crack the valves on the manifold gauges until the system pressure rises to 2 psig.
(9) Close the refrigerant cylinder valve and the valves on the manifold gauges.
For triple evacuation, perform the above procedure three times, evacuating twice to 500 microns and the last time for
eight hours to ensure complete system evacuation.
When triple evacuation is complete, the system is ready for recharging. If it is not to be charged immediately, seal the
system by back-setting the service access valves and plugging or capping all open gauge ports or connections.
9.6 REFRIGERANT LEAK TESTING
WARNING:
WHEN WORKING WITH REFRIGERANTS, ALWAYS WEAR GOGGLES. CONTACT WITH REFRIGERANT MAY CAUSE INJURY.
A leak-free system assures trouble-free system operation and performance. Loss of refrigerant reduces system effi-
ciency and capacity. It also causes repeated activation of system safety monitors, shutting down the unit. Perform leak
testing at scheduled intervals and after doing any work on the unit.
A leak may spread refrigerant throughout the interior of the unit, making locating the leak difficult. Air the interior of the
unit prior to testing. If a leak is detected but it is difficult to pinpoint the location, use compressed air to blow the area free
of vapor then immediately retest before the leaking vapor spreads.
Use a draft free area when leak testing to prevent the loss of vapor from small leaks. Ensure the testing area is free of
compressor oil, which may contain dissolved refrigerant, giving false test indications.