8-284 BLACK FKM 90D BACK-UP RING

Part number VBU90284 is an AS568-284 black Viton® (FKM) 90 Shore A Back-Up Ring measuring an inside diameter of 17.955 in (456.06 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 18.233 in (463.12 mm). A back-up ring installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

It resists chlorinated solvents, engine and transmission fluids, and aggressive chemicals. That behavior comes from the compound itself: Viton® (FKM) is valued for excellent resistance to compression set and permeation, outstanding high-temperature capability. Continuous operating temperature is published at -15°F (-26.1°C) to 400°F (204.4°C). Exposure to hot water and steam or low-molecular-weight organic acids will shorten service life.

Maintenance and OEM teams specify it across aerospace, semiconductor equipment, and chemical processing.

VBU90284 ships individually. Nominal inside diameter is listed as 18 inch. As always, verify media compatibility and operating conditions against the requirements of your specific application.