8-309 BLACK FKM 90D BACK-UP RING

VBU90309 is an AS568-309 black Viton® (FKM) 90 Shore A Back-Up Ring with an inside diameter of 0.412 in (10.46 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 0.832 in (21.13 mm). In service, this back-up ring allows a standard o-ring to operate at higher pressures than it could unsupported.

The compound resists aggressive chemicals, aromatic hydrocarbons, and chlorinated solvents. That behavior comes from the compound itself: Viton® (FKM) offers outstanding high-temperature capability and very low compression set at elevated temperature. The material carries a published service range of -15°F (-26.1°C) to 400°F (204.4°C).

Typical settings include automotive fuel systems, high-temperature process equipment, and oil and gas.

Reference part number VBU90309 when ordering; the item is sold individually. Nominal inside diameter is listed as 7/16 inch. Review your operating media and conditions against this specification before installation.