Evaluation of Non-Asbestos Sheet Gasket for Mobile Refrigeration Compressors

Maintaining a high level of gasket performance with current non-asbestos materials can be difficult. The replacement of previous asbestos containing sheet gaskets with other types of fiber reinforced sheet gaskets required a thorough evaluation using a simulated service testing procedure. In this paper we will discuss the details of the fabrication of a test fixture which simulates the temperature, refrigerant pressure and load bearing conditions often observed in mobile refrigeration compressors and evaluation of the load changes and refrigerant leakage over a large number of temperature and pressure cycles. Highlights of the results obtained in this study will be presented. INTRODUCTION Due to the health hazards in the use of asbestos, both the manufacturing and availability of asbestos gaskets became difficult a few years ago. The refrigeration industry has successfully used asbestos reinforced nitrile-butadiene rubber gaskets in sealing various component in the compressor. The replacement of these sheet gaskets with other types of fiber reinforced sheet gaskets required a thorough evaluation. Traditional screening tests, such as tensile strength, elongation, compression set under various loads, permanent set and stress-relaxation are good tools for screening. But for actual performance of the gasket under service conditions required fabrication of a special simulated service test equipment which was capable of temperature and refrigerant pressure cycling the gasket and simultaneously determining the refrigerant leak rate and gasket load changes. Screening test results and simulated service test results obtained in this study are presented.