8-209 BLACK BUNA 90D BACK-UP RING

Part number HB90209 is an AS568-209 black Buna-N (Nitrile) 90 Shore A Back-Up Ring supplied with an inside diameter of 0.671 in (17.04 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 0.949 in (24.1 mm). A back-up ring bridges the extrusion gap so the primary seal holds its shape under load.

The compound resists many alcohols, water, and petroleum-based oils. Buna-N (Nitrile) is widely chosen for reliable performance in both static and dynamic service, strong abrasion and tear resistance. Rated temperature range runs from -40°F (-40°C) to 250°F (121.1°C) in continuous service. It is not the right choice where automotive brake fluid or ketones are present.

Typical settings include general industrial maintenance, agricultural equipment, and fluid power.

Stocked as HB90209 and sold individually. Unit weight is approximately 0.3 g. Application requirements vary, so validate compatibility with your process conditions prior to installation. 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.