Mitsubishi Electric CITY MULTI PUHY-P-YKB-A1 Manuel D'installation page 28

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9-5-3. Sealing the openings around the pipes

Seal all openings around pipes and wires to keep out small animals, rainwater, or snow.

- Failure to do so may result in current leakage, electric shock, or damage to the unit.

9-6. Air-tightness test

Do not use oxygen, flammable gas, or a refrigerant containing chlorine for air-tightness

- Doing so may result in an explosion. Chlorine will deteriorate the refrigerant oil.

After refrigerant pipe installation is completed, check the system for leaks by conducting an air-tightness test. If there

is a leak, the composition of the refrigerant will change and the performance will drop.

<Air-tightness test procedures>

① Make sure the service valves are closed.

② Add pressure to the refrigerant pipes through the service ports of the liquid and gas pipes.

* Pressurize to the design pressure (4.15 MPa) using nitrogen gas.

③ If the pressure holds for one day and does not decrease, the pipes have passed the test and there are no leaks.

If the pressure decreases, there is a leak. Look for the source of the leak by spraying a bubbling agent (e.g.,

Gupoflex) on the flared or brazed sections.

④ Wipe off the bubbling agent.

Example of closure materials (not supplied)

Fill the openings

Nitrogen gas

To indoor unit

Gauge manifold

Low pressure knob

High pressure knob

Service valve

Liquid piping

Outdoor unit

Service port