8-245 BLACK BUNA 90D BACK-UP RING

APG stocks the HB90245, an AS568-245 black Buna-N (Nitrile) 90 Shore A Back-Up Ring with an inside diameter of 4.359 in (110.72 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 4.637 in (117.78 mm). A back-up ring bridges the extrusion gap so the primary seal holds its shape under load.

As a material, Buna-N (Nitrile) is known for strong abrasion and tear resistance, reliable performance in both static and dynamic service. Expect good resistance to greases and lubricants, many alcohols, and water. The material carries a published service range of -40°F (-40°C) to 250°F (121.1°C). Verify compatibility before use with ketones or polar solvents.

You will find this material specified across construction equipment, automotive, and general industrial maintenance.

Reference part number HB90245 when ordering; the item is sold individually. Unit weight is approximately 1.6186 g. Check the compound against your process media, pressure and temperature before committing to a design.