8-243 BLACK FKM 90D BACK-UP RING

The VBU90243 is an AS568-243 black Viton® (FKM) 90 Shore A Back-Up Ring built to an inside diameter of 4.109 in (104.37 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 4.387 in (111.43 mm). This back-up ring bridges the extrusion gap so the primary seal holds its shape under load.

Viton® (FKM) is specified here for long service life in hot, chemically aggressive environments and outstanding high-temperature capability. The material holds up against aromatic hydrocarbons, engine and transmission fluids, and aggressive chemicals. Published continuous service range is -15°F (-26.1°C) to 400°F (204.4°C). Applications involving low-molecular-weight organic acids or amines call for a different compound.

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

Reference part number VBU90243 when ordering; the item is sold individually. Unit weight is approximately 2.038 g and nominal inside diameter is listed as 4 1/8 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.