POE vs Mineral Oil
R-22 systems use mineral oil, which is stable and does not absorb moisture easily. R-410A and most HFC systems require polyol ester (POE) oil, which is highly hygroscopic, meaning it absorbs moisture rapidly from the atmosphere. POE oil containers must be kept tightly sealed and exposure time minimized when adding oil. When retrofitting an R-22 system to R-407C or another HFC blend, you must also change the oil from mineral to POE for proper miscibility and lubrication.
POE oil (used with R-410A) is hygroscopic and absorbs moisture rapidly. Keep containers sealed and minimize exposure.
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