The change from chlorofluorocarbon (CFC) refrigerants to hydrofluorocarbon (HFC) refrigerants has resulted in the extensive use of polyol ester-based lubricants. The use of esters has necessitated changes in manufacture and assembly of refrigerating and air-conditioning systems. The different reactivity and solubility profile that esters exhibit compared to traditional mineral oil lubricants were the drivers for these changes. This paper outlines some of the issues resulting from the use of ester lubricants and the steps required to minimize the impact on system life and performance. Issues covered include hydrolytic stability, copper plating, and compatibility with metals, elastomers, and process fluids.

Units: SI