8-238 BLACK FKM 90D BACK-UP RING

Ordered as VBU90238, this is an AS568-238 black Viton® (FKM) 90 Shore A Back-Up Ring built to an inside diameter of 3.484 in (88.49 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 3.762 in (95.55 mm). The back-up ring allows a standard o-ring to operate at higher pressures than it could unsupported.

Viton® (FKM) is specified here for excellent resistance to compression set and permeation, very low compression set at elevated temperature. The compound resists many acids, aggressive chemicals, and petroleum oils and fuels. Continuous operating temperature is published at -15°F (-26.1°C) to 400°F (204.4°C). Exposure to hot water and steam or ketones and esters will shorten service life.

Maintenance and OEM teams specify it across automotive fuel systems, chemical processing, and semiconductor equipment.

This item is sold individually under part number VBU90238. Unit weight is approximately 1.74 g and nominal inside diameter is listed as 3 1/2 inch. As always, verify media compatibility and operating conditions against the requirements of your specific application.