Mitsubishi Electric PUHY-200YMF-B Service Handbook page 5

[2] Piping Machining
Use ester oil, ether oil or alkylbenzene (small amount) as the refrigerator oil to coat flares and flange connections.
Reason :
1. The refrigerator oil used for the equipment is highly hygroscopic and may introduce water inside.
Notes :
• Introducing a great quantity of mineral oil into the refrigerant circuit may also cause a compressor failure.
• Do not use oils other than ester oil, ether oil or alkylbenzene.
Use only the necessary minimum quantity of oil !
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