8-318 BLACK BUNA 90D BACK-UP RING

HB90318 is an AS568-318 black Buna-N (Nitrile) 90 Shore A Back-Up Ring built to an inside diameter of 0.975 in (24.77 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 1.395 in (35.43 mm). In service, this back-up ring bridges the extrusion gap so the primary seal holds its shape under load.

The compound resists many alcohols, hydraulic fluids, and petroleum-based oils. Buna-N (Nitrile) is valued for the most widely specified general-purpose sealing elastomer, strong abrasion and tear resistance. Continuous operating temperature is published at -40°F (-40°C) to 250°F (121.1°C). It should not be specified for service in ketones or automotive brake fluid.

It sees regular use in agricultural equipment, fluid power, and construction equipment.

Reference part number HB90318 when ordering; the item is sold individually. Unit weight is approximately 1.007 g and nominal inside diameter is listed as 1 inch. As always, verify media compatibility and operating conditions against the requirements of your specific application. If you need a size, durometer or compound that is not listed, APG can cross-reference from a print, a sample or a competitor part number.