8-278 BLACK BUNA 90D BACK-UP RING

The HB90278 is an AS568-278 black Buna-N (Nitrile) 90 Shore A Back-Up Ring measuring an inside diameter of 11.984 in (304.39 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 12.262 in (311.45 mm). This back-up ring allows a standard o-ring to operate at higher pressures than it could unsupported.

It resists petroleum-based oils, hydraulic fluids, and many alcohols. That behavior comes from the compound itself: Buna-N (Nitrile) delivers an economical choice for high-volume maintenance programs, reliable performance in both static and dynamic service. Published continuous service range is -40°F (-40°C) to 250°F (121.1°C). It should not be specified for service in ketones or ozone and direct sunlight.

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

This item is sold individually under part number HB90278. Unit weight is approximately 4.415 g and nominal inside diameter is listed as 12 inch. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing.