Permeation and Stress Relaxation Resistance of Elastomeric Fuel Seal Materials 2001-01-1127
Today's fuel systems place many demands on the seals containing liquid and vapor hydrocarbons. California Air Resource's LEV II and EPA's Tier 2 demands require fuel systems which are essentially hermetically sealed with a robust, long term (12-15 year), life. Two properties which are key to long-term seal life are the material's ability to retain it's sealing force, and the ability to resist fuel permeation.
To evaluate these two fuel seal properties, testing was conducted on a number of rubber compounds including HNBR, an HNBR-fluoroplastic alloy, FVMQ (fluorosilicone), an FKM-FVMQ blend, and FKM. To evaluate permeation through a seal, Thwing Albert cups were fitted with stainless steel lids and sealing gaskets prepared from the various test materials. Fuel losses through the gaskets were determined at elevated temperatures. Long term, >1000 hour, stress relaxation testing was conducted in “hot” 60°C fuel and “sour” fuel on these compounds. The results of the permeation though sealing materials and the stress relaxation in fuel will be presented in this paper.