8-158 BLACK FKM 90D BACK-UP RING

Part number VBU90158 is an AS568-158 black Viton® (FKM) 90 Shore A Back-Up Ring supplied with an inside diameter of 4.737 in (120.32 mm), a cross section of 0.103 in (2.62 mm), and an outside diameter of 4.943 in (125.55 mm). A back-up ring bridges the extrusion gap so the primary seal holds its shape under load.

The material holds up against engine and transmission fluids, many acids, and aggressive chemicals. That behavior comes from the compound itself: Viton® (FKM) is specified for very low compression set at elevated temperature, excellent resistance to compression set and permeation. The material carries a published service range of -15°F (-26.1°C) to 400°F (204.4°C).

Common environments for this compound include aerospace, semiconductor equipment, and automotive fuel systems.

VBU90158 ships individually. Nominal inside diameter is listed as 4 3/4 inch. As always, verify media compatibility and operating conditions against the requirements of your specific application.