Gree GMVVQ224WM/C-X Owner's Manual page 40

When leaving the factory, low pressure gas pipe, high pressure gas pipe, liquid pipe and stop
valve of outdoor unit have been closed. Please confirm it during installation.
Before the test, a small amount of lubricant oil required by the corresponding system should be
smeared at the nut and the end of the pipe. Two wrenches should be used when fixing the nut.
It is not allowed to connect the pipeline of outdoor unit for test during the air tightness test.
The test pressure for R410A system is 4.15 MPa. The air tightness test must use nitrogen as the
medium and the nitrogen should be dried. Slowly increase the pressure in three steps:
Step 1: Slowly increase the pressure to 0.5MPa, stay for 5 minutes and conduct the leakage
inspection. You may find big leakage;
Step 2: Slowly increase the pressure to 1.5MPa, stay for 5 minutes, conduct the air tightness
inspection, and you may find small leakage;
Step 3: Slowly increase the pressure for R410A system to 4.15 MPa, stay for 5 minutes and
conduct the strength test. You may find small penetration or blisters. After increasing the pressure to
the test pressure, hold the pressure for 24 hours, and observe whether the pressure drops. If the
pressure does not drop, it is qualified.
3.6.2 Vacuum Drying
(1) Selection requirements for vacuum pumps.
1) Can't vacuumize different refrigerant systems with the same vacuum pump.
2) The ultimate vacuum of the vacuum pump should be -0.1MPa.
3) The air displacement of the vacuum pump should be above 4L/s.
4) The accuracy of the vacuum pump should be above 0.02mmHg.
5) The system vacuum pump must have a check valve.
(2) Operation procedures of vacuum drying
1) Before vacuuming, confirm that the stop valves of low pressure gas pipe, high pressure
gas pipe and liquid pipe are at closed status.
2) Connect the regulating valve and vacuum pump to the inspection joint of the gas pipe valve
and liquid pipe valve valves with a filling tube.
3) Vacuumize it for 4 hours, and check if the vacuum degree reaches -0.1 MPa or above. If
not, there may be a leak. It needs to conduct the leakage test once again. If there is no
leak, vacuumize it for another 2 hours.
4) If the vacuum degree cannot be maintained by two times of vacuums, you can confirm that
there is water inside the pipeline under the condition that there is no leakage. At this time,
the water should be removed by vacuum destruction. The specific method is: fill the pipeline
with 0.05MPa nitrogen gas, vacuumize it for 2 hours, and keep vacuum for 1 hour. If it still
can't reach the vacuum degree of -0.1 MPa, repeat this operation until the water is drained.
5) After vacuuming, close the valve of the regulating valve and stop vacuuming for 1 hour.
Confirm that the pressure of the regulating valve has not risen.
(3) Notices for vacuum drying
1) Vacuumize it from both the low pressure gas pipe, the high pressure gas pipe and the
liquid at the same time.
GMV Heat Recovery DC Inverter VRF
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