8-389 BLACK FKM 90D BACK-UP RING

APG stocks the VBU90389, an AS568-389 black Viton® (FKM) 90 Shore A Back-Up Ring measuring an inside diameter of 19.953 in (506.81 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 20.373 in (517.47 mm). A back-up ring extends o-ring service life by supporting the seal against extrusion under high pressure.

Viton® (FKM) is known for long service life in hot, chemically aggressive environments and very low compression set at elevated temperature. The compound resists chlorinated solvents, many acids, and aromatic hydrocarbons. Service temperature is rated from -15°F (-26.1°C) through 400°F (204.4°C). It should not be specified for service in amines or hot water and steam.

Typical settings include oil and gas, semiconductor equipment, and chemical processing.

VBU90389 ships individually. Check the compound against your process media, pressure and temperature before committing to a design.