The tribological characteristics of various lubricant/refrigerant mixtures for refrigerant compressors have been experimentally investigated by means of a unique high-pressure tribometer (HPT). In order to identify more effective bench testers for screening lubricants for compressors, a comparison is made between data obtained from a pin and block specimen tester and those obtained from the HPT. The data obtained from a pin and block tester are supplied by three compressor manufacturers. These data were obtained by "bubbling" refrigerants through the lubricant, whereas the data from the HPT are obtained in environments (temperature and pressure) which approximate those found in specific contacts in compressors. The same contact geometries and materials are used for both the pin and block and the HPT tests. The main purpose of this comparison is to see if the controlled environment and the lower loads used with the HPT produce different lubricant rankings than those obtained from the pin and block tests. In general, the results obtained from the HPT do not always correlate to those obtained from the pin and block tester.

KEYWORDS: year 1995, lubricants, compressors, refrigeration, comparing, testing, refrigerants, replacing, mixtures