8-159 BLACK FKM 90D BACK-UP RING

VBU90159 is an AS568-159 black Viton® (FKM) 90 Shore A Back-Up Ring measuring an inside diameter of 4.987 in (126.67 mm), a cross section of 0.103 in (2.62 mm), and an outside diameter of 5.193 in (131.9 mm). In service, this back-up ring bridges the extrusion gap so the primary seal holds its shape under load.

The material holds up against petroleum oils and fuels, engine and transmission fluids, and chlorinated solvents. That behavior comes from the compound itself: Viton® (FKM) is specified for long service life in hot, chemically aggressive environments and very low compression set at elevated temperature. Rated temperature range runs from -15°F (-26.1°C) to 400°F (204.4°C) in continuous service. Applications involving ketones and esters or low-molecular-weight organic acids call for a different compound.

You will find this material specified across high-temperature process equipment, aerospace, and oil and gas.

Stocked as VBU90159 and sold individually. Application requirements vary, so validate compatibility with your process conditions prior to installation. For a size or compound outside the standard catalog, APG can quote from a print or sample.