8-255 BLACK FKM 90D BACK-UP RING

Ordered as VBU90255, this is an AS568-255 black Viton® (FKM) 90 Shore A Back-Up Ring with an inside diameter of 5.609 in (142.47 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 5.887 in (149.53 mm). The back-up ring extends o-ring service life by supporting the seal against extrusion under high pressure.

Viton® (FKM) offers very low compression set at elevated temperature, excellent resistance to compression set and permeation. This material stands up to engine and transmission fluids, petroleum oils and fuels, and aggressive chemicals. 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.

Maintenance and OEM teams specify it across chemical processing, oil and gas, and semiconductor equipment.

Order part number VBU90255, sold individually. As always, verify media compatibility and operating conditions against the requirements of your specific application. APG can cross-reference from an existing part number, a drawing or a physical sample if this size is not an exact match.