8-393 BLACK FKM 90D BACK-UP RING

This back-up ring is supplied in AS568-393 black Viton® (FKM) 90 Shore A built to an inside diameter of 23.94 in (608.08 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 24.36 in (618.74 mm), catalogued under part number VBU90393. It installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

It resists petroleum oils and fuels, chlorinated solvents, and many acids. That behavior comes from the compound itself: Viton® (FKM) is known for very low compression set at elevated temperature and outstanding high-temperature capability. 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, semiconductor equipment, and oil and gas.

Reference part number VBU90393 when ordering; the item is sold individually. Nominal inside diameter is listed as 24 inch. As always, verify media compatibility and operating conditions against the requirements of your specific application.