8-244 BLACK FKM 90D BACK-UP RING

Ordered as VBU90244, this is an AS568-244 black Viton® (FKM) 90 Shore A Back-Up Ring built to an inside diameter of 4.234 in (107.54 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 4.512 in (114.6 mm). The back-up ring installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

This material stands up to aromatic hydrocarbons, chlorinated solvents, and engine and transmission fluids. That behavior comes from the compound itself: Viton® (FKM) is known for the industry benchmark where nitrile reaches its thermal limit and outstanding high-temperature capability. Continuous operating temperature is published at -15°F (-26.1°C) to 400°F (204.4°C).

You will find this material specified across automotive fuel systems, high-temperature process equipment, and aerospace.

Reference part number VBU90244 when ordering; the item is sold individually. Unit weight is approximately 2.112 g. 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.