8-278 BLACK FKM 90D BACK-UP RING

VBU90278 is an AS568-278 black Viton® (FKM) 90 Shore A Back-Up Ring built to an inside diameter of 11.984 in (304.39 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 12.262 in (311.45 mm). In service, this back-up ring installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

Viton® (FKM) offers excellent resistance to compression set and permeation, very low compression set at elevated temperature. It resists petroleum oils and fuels, aggressive chemicals, and many acids. Service temperature is rated from -15°F (-26.1°C) through 400°F (204.4°C). Exposure to ketones and esters or low-molecular-weight organic acids will shorten service life.

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

Order part number VBU90278, sold individually. 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.