8-257 BLACK FKM 90D BACK-UP RING

The VBU90257 is an AS568-257 black Viton® (FKM) 90 Shore A Back-Up Ring with an inside diameter of 5.859 in (148.82 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 6.137 in (155.88 mm). This back-up ring installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

The compound resists chlorinated solvents, engine and transmission fluids, and petroleum oils and fuels. Viton® (FKM) offers outstanding high-temperature capability and long service life in hot, chemically aggressive environments. Continuous operating temperature is published at -15°F (-26.1°C) to 400°F (204.4°C). It should not be specified for service in hot water and steam or low-molecular-weight organic acids.

Common environments for this compound include chemical processing, high-temperature process equipment, and automotive fuel systems.

Stocked as VBU90257 and sold individually. Review your operating media and conditions against this specification before installation. If you need a size, durometer or compound that is not listed, APG can cross-reference from a print, a sample or a competitor part number.