8-367 BLACK FKM 90D BACK-UP RING

APG stocks the VBU90367, an AS568-367 black Viton® (FKM) 90 Shore A Back-Up Ring with an inside diameter of 7.475 in (189.87 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 7.895 in (200.53 mm). A back-up ring installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

This material stands up to engine and transmission fluids, aromatic hydrocarbons, and petroleum oils and fuels. That behavior comes from the compound itself: Viton® (FKM) offers very low compression set at elevated temperature 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). Applications involving amines or ketones and esters call for a different compound.

Typical settings include high-temperature process equipment, aerospace, and oil and gas.

Order part number VBU90367, sold individually. Nominal inside diameter is listed as 7 1/2 inch. 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.