Gree GMV-224WM/B-X, Service Manual

Page: 77 / 375

GMV5 DC INVERTER VRF UNITS SERVICE MANUAL
74
II. Vacuumization and Desiccation for the
System
1. Requirements on the Vacuum Pump
The vacuum pump for different refrigerant systems cannot be the same.
The ultimate vacuum degree of the vacuum pump should reach -0.1 MPa.
The air discharge capacity of the vacuum pump must be greater than 4 L/S.
The precision of the vacuum pump must be greater than 0.02 mmHg.
The system vacuum pump must be equipped with a check valve.
2. Procedure and Precautions for Vacuumization and Desiccation
2.1 Procedure
a. Before vacuumization, ensure that the stop valves of the gas and liquid pipes are turned off.
b. Use the perfusing duct to connect the regulator valve and vacuum pump to detection connectors of
the gas pipe and liquid pipe.
c. Vacuumize for 4 hours and check whether the vacuum degree reaches -0.1 MPa or more. If not,
leakage may exist. Perform leakage check again. If no leakage exists, continue to vacuumize for 2
hours.
f. If the vacuum degree cannot be kept after vacuumization is performed for twice, there may be water
in the pipe when it is confirmed that no leakage exists. In this case, discharge water by means of
vacuum breaking. Perfuse nitrogen at 0.05 MPa to the pipe. Vacuumize for 2 hours and keep
vacuuming for 1 hour. If the vacuum degree of -0.1 MPa cannot be reached, repeat this operation till
water is discharged.
g. After vacuumization, turn off the regulator valve and keep for 1 hour. Ensure that the pressure of the
regulator valve does not increase.
2.2. Precautions:
a. The gas pipe and liquid pipe must be vacuumized at the same time.
b. Turn off the valve before powering off the vacuum pump.
c. Keep vacuuming for 2 hours. The vacuum meets the requirement if the pressure displayed by the
vacuum gauge does not increase.
d. The units parallel connected to the module and oil-equalizing pipe also need to be vacuumized.