The low temperature properties of fluorohydrocarbon elastomers (FKM) have been well documented using traditional rubber laboratory tests such as brittle point, temperature retraction, glass transition, and stiffness by Clash-berg and Gehman methods. Although these tests are considered good indicators of low temperature behavior, these techniques have not proven to be entirely accurate in predicting the low temperature sealing capability of fluoroelastomer molded products such as O-rings.
The purpose of this paper is to present an overview of the low temperature properties of standard fluoroelastomers and the newer improved low temperature types, by both traditional test methods and a recently developed static O-ring testing device. Through use of this static testing apparatus, the influence of several variables are investigated, which include polymer type, compound design, seal interference, temperature, and fuel plasticization of the FKM compounds.
In gaining a better understanding of the factors that influence and control the low temperature sealing ability of fluoroelastomer O-rings, the automotive engineer may design a more robust sealing system. Static sealing devices such as the O-rings used in today's automotive fuel injection and fuel handling systems are expected to benefit from the newer fluoroelastomer types offering improved low temperature sealing performance.