Air-Tightness Test; Thermal Insulation For Pipes - Mitsubishi Electric CITY MULTI PURY-HP-TNU-A Manuel D'installation

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 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 high- and low-pressure 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.
Ⓐ
Ⓓ

9-7. Thermal insulation for pipes

Insulate pipes to prevent condensation.
- Condensation may collect and drip from the unit onto the ceiling or floor.
Insulate the high- and low-pressure pipes, and liquid and gas pipes separately with polyethylene foam insulation materials. Inadequate insulation
may cause condensation to drip. Pipes in the ceiling are especially vulnerable to condensation and require adequate insulation.
9-7-1. Insulation material
・Check that the insulation materials meet the standards in the table below.
Between an outdoor unit and BC controller
Thickness [mm (in)]
Heat resistance
WT09112X02
Ⓑ
Ⓕ
Ⓑ
Ⓑ
Ⓒ
HI
LO
Ⓔ
High-pressure pipe
Min. 10 (7/16)
Example of closure materials (not supplied)
Ⓐ
Ⓑ Fill the openings
Ⓐ Nitrogen gas
Ⓑ To indoor unit
Ⓖ
Gauge manifold
Ⓒ
Low pressure knob
Ⓓ
Ⓗ
Ⓔ High pressure knob
Ⓕ Service valve
Ⓘ
Ⓖ Low-pressure pipe
Ⓙ
High-pressure pipe
Ⓗ
Outdoor unit
Ⓘ
Ⓙ Service port
Low-pressure pipe
Min. (13/16)
Min. 120°C (248°F)
GB-22