Huawei FusionModule 500 Quick Manual page 10

Nitrogen Injection, Pressure Preservation, and
8
Vacuumization
1. Open the stop valve for the gas pipe of the indoor unit.
2. Connect the pressure gauge, rubber hose, and nitrogen cylinder. Ensure that the outlet
pressure of the reducing valve is less than or equal to 3.5 MPa.
3. Inject 3.5 MPa nitrogen and preserve the pressure for 24 hours. The system pressure should
stay constant under unchanging ambient temperature conditions. If there is a considerable
temperature change and the pressure changes, perform the test again.
4. If welding defects exist, locate and repair the leak point. If the pressure does not change,
exhaust the nitrogen through the injection needle valve.
5. Connect a pressure gauge to the gas pipe needle
valve and liquid pipe needle valve of the indoor
unit, and connect a vacuum pump.
6. Check that all pressure gauge valves are open.
7. Check that the time for vacuumization is 80
minutes or longer after ensuring that the cooling
system does not leak, and that the pressure
displayed on the vacuum pump is less than or
equal to 60 Pa (absolute pressure). When the
pressure stops dropping, pump for another 10
minutes.
8. After vacuumization, close all valves of the
pressure gauge and the vacuum pump without
disconnecting the pump. Preserve the pressure
for 10 minutes, and verify that the absolute
pressure of the cooling system is not greater
than 90 Pa (absolute pressure).
9. After ensuring that the pressure gauge has no
obvious increase, open the stop valves for the
gas pipe and liquid pipe of the outdoor unit.
10.Add refrigerant oil.
11.Fill refrigerant.
(1) Reducing
•
valve
(2) Nitrogen
cylinder
(3) Low
•
pressure gauge
(4) High
pressure gauge
•
(5) Gas pipe
needle valve
•
(6) Liquid pipe
needle valve
(1) Vacuum
pump
(3) Gas pipe
needle valve
10
The measuring range of the
pressure gauge must be greater
than or equal to 4.0 MPa, and the
rubber hose must withstand a
pressure of at least 4.5 MPa.
During pressure preservation, do not
remove the rubber hose and
pressure gauge; otherwise, nitrogen
may leak.
Do not use compressed air because
water and impurities in the air
affect the system operation.
Do not use oxygen or acetylene for
a leakage test.
(2) Pressure gauge
(4) Liquid pipe
needle valve