Air-Tightness Test - Mitsubishi Electric CITY MULTI PUHY-P-YKB-A1 Installation Manual

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.
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9-6. Air-tightness test

Do not use oxygen, flammable gas, or a refrigerant containing chlorine for air-tightness
testing.
- 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.
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KD79S703H01
Example of closure materials (not supplied)
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Fill the openings
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HI
LO
Ⓓ Ⓔ
Nitrogen gas
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To indoor unit
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Ⓖ
Gauge manifold
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Low pressure knob
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High pressure knob
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Service valve
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Liquid piping
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Gas piping
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Outdoor unit
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Service port
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GB-26