Mitsubishi Electric PURY-M200YNW-A1 Service Handbook page 28

[1-3 Working with Refrigerant Piping ]
6. Special vacuum drying
When 5Torr(650Pa) or lower degree of vacuum cannot be attained after 3 hours of evacuation, it is likely that water has pen-
etrated the system or that there is a leak.
If water infiltrates the system, break the vacuum with nitrogen. Pressurize the system with nitrogen gas to
2
0.5kgf/cm G(0.05MPa) and evacuate again. Repeat this cycle of pressurizing and evacuation either until the degree of vac-
uum below 5Torr(650Pa) is attained or until the pressure stops rising.
Only use nitrogen gas for vacuum breaking. (The use of oxygen may result in an explosion.)
7. Notes
To evacuate air from the entire system
Applying a vacuum through the check joints at the refrigerant service valve on the high and low pressure sides (BV1
and 2) is not enough to attain the desired vacuum pressure.
Be sure to apply a vacuum through the check joints at the refrigerant service valve on the high and low pressure
sides (BV1 and 2) and also through the check joints on the high and low pressure sides (CJ1 and 2).
To evacuate air only from the outdoor units
Apply a vacuum through the check joints on the high and low pressure sides (CJ1, and 2).
To evacuate air from the HBC and extension pipes
Apply a vacuum through the check joints at the refrigerant service valve on the high and low pressure sides (BV1
and 2).
When performing the maintenance work, such as vacuum drying, pumping down, or refrigerant recovery, on the out-
door unit or the heat-source unit, set SW001-1 first and then SW002-5 on the HBC board to ON to operate the water
circuit pump and circulate the water to prevent the water side of the heat exchanger within the HBC from freezing.
* When vacuum drying, pumping down or refrigerant recovery has been completed, set SW002-5 first and then
SW001-1 to OFF.
BS_01_L
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