AN-92-05-4 -- Compatibilities of Nonmetallic Materials with R-134a and Alternative Lubricants in Refrigeration Systems PDF

Over the course of the past several years, the refrigerating and air conditioning industries have made significant progress in the transition from CFC-based systems to those based on alternative refrigerants and associated lubricants. For most applicants, R134a is seen as the replacement refrigerant of choice for use in applications that previously used R12. In the studies that have been done to allow for the use of R134a, a very large body of data has been developed, related to the compatibility of materials of construction with the new systems. These data have been important, both in knowing which materials to use and in actually defining the appropriate lubricants. For example, in the case of hermetic compressors, compatibility with PET films has been important in moving the home appliance industry from polyalkylene-glycol-based to polyol-ester-based lubricants. This issue of material compatibility is so important that at least two industry groups have established programmes to address it. Reviews much of the data generated in studies of nonmetallic materials compatibilities with R134a and associated lubricants. The work encompasses both sealed-tube testing and analytical investigations of compressor life tests and field unit evaluations. The presentation includes a review of the test and analytical methods used in these studies. Data have been derived from a range of both PAG- and ester-based lubricants in an effort to correlate structural parameters with performance for a range of elastomers and plastics. In some cases, these data are compared with those data already in the open literature. Specific attention has been paid to PET- and ester-based lubricants, and the results of an expanded series of tests are presented.

KEYWORDS: lubricants, compatibility, refrigerants, R134a, refrigeration, compressors, air conditioning, R12, testing, service life, calculating, performance, plastics, comparing, materials