8-339 BLACK FKM 90D BACK-UP RING

Part number VBU90339 is an AS568-339 black Viton® (FKM) 90 Shore A Back-Up Ring measuring an inside diameter of 3.225 in (81.92 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 3.645 in (92.58 mm). A back-up ring bridges the extrusion gap so the primary seal holds its shape under load.

Viton® (FKM) is specified here for very low compression set at elevated temperature and outstanding high-temperature capability. The material holds up against engine and transmission fluids, many acids, and aromatic hydrocarbons. Continuous operating temperature is published at -15°F (-26.1°C) to 400°F (204.4°C). Verify compatibility before use with hot water and steam or amines.

It sees regular use in oil and gas, automotive fuel systems, and aerospace.

Reference part number VBU90339 when ordering; the item is sold individually. Unit weight is approximately 3.804 g. Review your operating media and conditions against this specification before installation. If you need a size, durometer or compound that is not listed, APG can cross-reference from a print, a sample or a competitor part number.