8-354 BLACK FKM 90D BACK-UP RING

The VBU90354 is an AS568-354 black Viton® (FKM) 90 Shore A Back-Up Ring built to an inside diameter of 5.1 in (129.54 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 5.52 in (140.21 mm). This back-up ring bridges the extrusion gap so the primary seal holds its shape under load.

Expect good resistance to chlorinated solvents, engine and transmission fluids, and aromatic hydrocarbons. That behavior comes from the compound itself: Viton® (FKM) offers excellent resistance to compression set and permeation, long service life in hot, chemically aggressive environments. The material carries a published service range of -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.

You will find this material specified across semiconductor equipment, chemical processing, and automotive fuel systems.

Reference part number VBU90354 when ordering; the item is sold individually. Unit weight is approximately 6.391 g. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing. APG supports cross-referencing from drawings, samples and competitor numbers when a listed size is not an exact fit.