8-240 BLACK FKM 90D BACK-UP RING

Part number VBU90240 is an AS568-240 black Viton® (FKM) 90 Shore A Back-Up Ring supplied with an inside diameter of 3.734 in (94.84 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 4.012 in (101.9 mm). A back-up ring installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

The compound resists chlorinated solvents, engine and transmission fluids, and petroleum oils and fuels. That behavior comes from the compound itself: Viton® (FKM) is valued for long service life in hot, chemically aggressive environments and very low compression set at elevated temperature. Continuous operating temperature is published at -15°F (-26.1°C) to 400°F (204.4°C).

Common environments for this compound include automotive fuel systems, semiconductor equipment, and chemical processing.

Reference part number VBU90240 when ordering; the item is sold individually. Unit weight is approximately 1.818 g and nominal inside diameter is listed as 3 3/4 inch. As always, verify media compatibility and operating conditions against the requirements of your specific application. APG supports cross-referencing from drawings, samples and competitor numbers when a listed size is not an exact fit.