8-394 BLACK FKM 90D BACK-UP RING

The VBU90394 is an AS568-394 black Viton® (FKM) 90 Shore A Back-Up Ring measuring an inside diameter of 24.94 in (633.48 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 25.36 in (644.14 mm). This back-up ring extends o-ring service life by supporting the seal against extrusion under high pressure.

Expect good resistance to aggressive chemicals, aromatic hydrocarbons, and petroleum oils and fuels. That behavior comes from the compound itself: Viton® (FKM) offers outstanding high-temperature capability and the industry benchmark where nitrile reaches its thermal limit. The material carries a published service range of -15°F (-26.1°C) to 400°F (204.4°C). Verify compatibility before use with amines or low-molecular-weight organic acids.

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

VBU90394 ships 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.