8-473 BLACK FKM 90D BACK-UP RING

Part number VBU90473 is an AS568-473 black Viton® (FKM) 90 Shore A Back-Up Ring built to an inside diameter of 23.94 in (608.08 mm), a cross section of 0.275 in (6.99 mm), and an outside diameter of 24.49 in (622.05 mm). A back-up ring bridges the extrusion gap so the primary seal holds its shape under load.

Expect good resistance to engine and transmission fluids, aggressive chemicals, and many acids. That behavior comes from the compound itself: Viton® (FKM) is valued for very low compression set at elevated temperature and the industry benchmark where nitrile reaches its thermal limit. Continuous operating temperature is published at -15°F (-26.1°C) to 400°F (204.4°C). It is not the right choice where low-molecular-weight organic acids or ketones and esters are present.

It sees regular use in aerospace, automotive fuel systems, and chemical processing.

Order part number VBU90473, 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. APG can cross-reference from an existing part number, a drawing or a physical sample if this size is not an exact match.