8-470 BLACK BUNA 90D BACK-UP RING

The HB90470 is an AS568-470 black Buna-N (Nitrile) 90 Shore A Back-Up Ring with an inside diameter of 20.955 in (532.26 mm), a cross section of 0.275 in (6.99 mm), and an outside diameter of 21.505 in (546.23 mm). This back-up ring bridges the extrusion gap so the primary seal holds its shape under load.

Expect good resistance to greases and lubricants, propane and butane, and petroleum-based oils. That behavior comes from the compound itself: Buna-N (Nitrile) is widely chosen for an economical choice for high-volume maintenance programs, reliable performance in both static and dynamic service. Service temperature is rated from -40°F (-40°C) through 250°F (121.1°C).

You will find this material specified across general industrial maintenance, hydraulic and pneumatic systems, and construction equipment.

This item is sold individually under part number HB90470. Unit weight is approximately 36.441 g and nominal inside diameter is listed as 21 inch. Review your operating media and conditions against this specification before 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.