8-338 BLACK FKM 90D BACK-UP RING

APG stocks the VBU90338, an AS568-338 black Viton® (FKM) 90 Shore A Back-Up Ring built to an inside diameter of 3.1 in (78.74 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 3.52 in (89.41 mm). A back-up ring bridges the extrusion gap so the primary seal holds its shape under load.

As a material, Viton® (FKM) delivers very low compression set at elevated temperature and outstanding high-temperature capability. This material stands up to aggressive chemicals, engine and transmission fluids, and many acids. Continuous operating temperature is published at -15°F (-26.1°C) to 400°F (204.4°C). Applications involving hot water and steam or ketones and esters call for a different compound.

It sees regular use in chemical processing, high-temperature process equipment, and automotive fuel systems.

Order part number VBU90338, sold individually. Unit weight is approximately 3.6689 g and nominal inside diameter is listed as 3 1/8 inch. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing.