Quantifying Water Vapor Diffusion across Elastomer Pressure Sensor Seals
Water vapor diffusion across elastomer seals causes reference cavity pressurization and dielectric drift, requiring coulometric ISO 15105-2 verification.
Fluoroelastomer
Polymer Material
Fluorine-containing synthetic rubbers exhibit extreme resistance to chemical degradation, high temperatures and aggressive hydrocarbon solvents. Material engineers specify fluoroelastomer compounds for sealing rings and diaphragms operating in hostile chemical environments. Fluorine content determines structural stability when elastomer seals encounter synthetic lubricants or fuels.
Operational limits for these synthetic elastomers restrict use below their specific glass transition temperatures where material embrittlement occurs.
Thermal Stability
Cross-linking density determines ultimate tensile strength and compression set resistance under prolonged thermal exposure. Curing agents in fluoroelastomer formulations govern mechanical elasticity when exposed to engine oils or fuels at elevated temperatures. Polymer backbones saturated with fluorine atoms resist oxidative degradation that causes cracking in standard nitriles.
Polymer synthesis blending bisphenol or peroxide vulcanization systems alters seal flexibility at low operating temperatures. Extended high-temperature exposure induces gradual cross-link cleavage, reducing effective seal force in flanged joints. Material qualification protocols subject test specimens to thermal aging prior to mechanical stress testing.
Compression Set
Permanent mechanical deformation occurs when static seals remain compressed under high thermal load. Standard testing of fluoroelastomer gaskets measures residual thickness after twenty-two hours of continuous heat exposure. Seal failure occurs when thermal degradation reduces elastic recovery below fluid pressure limits.
Chemical Compatibility
Volatile fluid contact causes minimal volume swelling in high-fluorine grades. High-fluorine fluoroelastomer grades retain dimensional integrity during direct contact with harsh chemical reagents.