18
Power and signal cable routing of the third
indoor unit
Power and signal cable routing of the fourth
indoor unit
1. The stop valves for the gas pipe and liquid pipe on the indoor unit side are open, and those
on
the outdoor unit side are closed.
2. (Leakage test with nitrogen) Inject nitrogen until the pressure reaches 3.0 MPa. Verify that
the pressure does not decrease after 24 hours at a stable ambient temperature. If any leak is
found after pressure preservation, check the pipe for leaks, especially the welding points and
stop valves.
3. (Vacuumizing) Replace the reducing valve and nitrogen cylinder with a vacuum pump.
Perform vacuumizing for at least 80 minutes and ensure that the final absolute pressure is
not greater than 60 Pa. When the final pressure does not decrease any more, continue to
vacuumize for 10 minutes. After vacuumizing is complete, close the vacuum pump and all
valves, and preserve the pressure for 10 minutes. Ensure that the absolute pressure does not
exceed 90 Pa. If the minimum reading of the pressure gauge is greater than 60 Pa, ensure
that the pointer stays at the smallest scale of the pressure gauge and preserve the pressure
for 1 hour. Then check that the pressure does not rise.
4. Open the stop valves for the gas pipe and liquid pipe of the outdoor unit.
•
After the outdoor unit stop valve is opened, the refrigerant in the outdoor unit flows to the
engineering pipe and indoor unit pipe. When performing other operations, be careful to
prevent refrigerant from spraying out.
•
After the vacuumization and before removing the rubber hose, ensure that there is positive
pressure inside the refrigerant pipe of the indoor unit. For detailed operations, see steps 1–4
in section "Commissioning Procedure".
9
Leakage Test with Nitrogen and Vacuumizing
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