Low Temperature Compression Set Resistant O-Ring Materials

Materials used in the construction of aircraft hydraulic and fuel system o-rings and seals must provide long-term performance in aggressive chemical environments over a wide range of temperatures and loads. Current materials, while chemically compatible with existing aircraft fuels and hydraulic fluids, are subject to both low temperature and high temperature performance deficiencies and failure. New o-ring materials are needed that exhibit good low temperature performance characteristics at -40 F (with a preference for -65 F performance) while maintaining durability and service life requirements at operating temperatures up to 225 deg F in fuels systems and 275 deg F in hydraulic fluid systems. Multiple materials representing eight different classes of rubber chemistries were evaluated under this program for high temperature resistance to aircraft hydraulic fluids and jet fuels, and low temperature sealing performance before and after 3- and 28-day high temperature fluid exposure. Performance criteria and program test methods were derived from MIL-P-83461 and MIL-P-53153. In situ compression stress relaxation testing was also performed to evaluate static sealing performance as a function of fluid exposure time at high and low temperatures. The results of the testing performed under this program demonstrate the deficiencies of conventional o-ring materials, and the availability of new classes of o-ring materials that provide exceptional high temperature chemical stability and low temperature performance.
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