8-277 BLACK FKM 90D BACK-UP RING

VBU90277 is an AS568-277 black Viton® (FKM) 90 Shore A Back-Up Ring built to an inside diameter of 11.484 in (291.69 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 11.762 in (298.75 mm). In service, this back-up ring bridges the extrusion gap so the primary seal holds its shape under load.

It resists aggressive chemicals, engine and transmission fluids, and many acids. That behavior comes from the compound itself: Viton® (FKM) is valued for the industry benchmark where nitrile reaches its thermal limit and outstanding high-temperature capability. The material carries a published service range of -15°F (-26.1°C) to 400°F (204.4°C).

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

This item is sold individually under part number VBU90277. Nominal inside diameter is listed as 11 1/2 inch. Check the compound against your process media, pressure and temperature before committing to a design. For a size or compound outside the standard catalog, APG can quote from a print or sample.