8-328 BLACK BUNA 90D BACK-UP RING

Part number HB90328 is an AS568-328 black Buna-N (Nitrile) 90 Shore A Back-Up Ring measuring an inside diameter of 1.85 in (46.99 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 2.27 in (57.66 mm). A back-up ring allows a standard o-ring to operate at higher pressures than it could unsupported.

It resists many alcohols, propane and butane, and water. That behavior comes from the compound itself: Buna-N (Nitrile) is widely chosen for strong abrasion and tear resistance, the most widely specified general-purpose sealing elastomer. Published continuous service range is -40°F (-40°C) to 250°F (121.1°C). Applications involving strong acids or ozone and direct sunlight call for a different compound.

You will find this material specified across fluid power, general industrial maintenance, and agricultural equipment.

Stocked as HB90328 and sold individually. Unit weight is approximately 1.7418 g and nominal inside diameter is listed as 1 7/8 inch. As always, verify media compatibility and operating conditions against the requirements of your specific application.