It's important to understand that all polyol ester (POE) lubricants are not the same.
Important areas where POEs can differ include lubricity, miscibility with refrigerant, viscosity, viscosity index, additive packages, pour point, and moisture content.
The advantages of POEs include miscibility with HFCs, CFCs and HCFCs and backwards compatibility with mineral oil. Furthermore, the lubricity of POEs can be designed to be at least as good or even better than those of mineral oils.
POE is far more hygroscopic than mineral oil, which means it will absorb moisture. As a result POE must be handled more carefully and compressor and system processing procedures must be more rigorous to avoid absorbing moisture.
Also, POEs are better solvents, which means that they will dislodge and carry debris through a system to a far greater extent tan do mineral oils. It's important to pay particular attention to adequate use of filters and dryers in the design and service of equipment with POEs.
Reprinted from Copeland Corp.'s the HFC Report, Refrigerant Alternatives for the Air Conditioning Industry
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