8-248 BLACK FKM 90D BACK-UP RING

The VBU90248 is an AS568-248 black Viton® (FKM) 90 Shore A Back-Up Ring with an inside diameter of 4.734 in (120.24 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 5.012 in (127.3 mm). This back-up ring extends o-ring service life by supporting the seal against extrusion under high pressure.

The compound resists engine and transmission fluids, aromatic hydrocarbons, and chlorinated solvents. That behavior comes from the compound itself: Viton® (FKM) offers 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. It is not the right choice where amines or low-molecular-weight organic acids are present.

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

VBU90248 ships individually. Unit weight is approximately 2.285 g. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing. APG can cross-reference from an existing part number, a drawing or a physical sample if this size is not an exact match.