8-428 BLACK BUNA 90D BACK-UP RING

This back-up ring is supplied in AS568-428 black Buna-N (Nitrile) 90 Shore A measuring an inside diameter of 4.85 in (123.19 mm), a cross section of 0.275 in (6.99 mm), and an outside diameter of 5.4 in (137.16 mm), catalogued under part number HB90428. It allows a standard o-ring to operate at higher pressures than it could unsupported.

As a material, Buna-N (Nitrile) is specified for low compression set under sustained load and an economical choice for high-volume maintenance programs. The material holds up against petroleum-based oils, propane and butane, and greases and lubricants. Published continuous service range is -40°F (-40°C) to 250°F (121.1°C). Exposure to strong acids or automotive brake fluid will shorten service life.

Common environments for this compound include general industrial maintenance, hydraulic and pneumatic systems, and construction equipment.

Order part number HB90428, sold individually. Unit weight is approximately 25.0548 g and nominal inside diameter is listed as 4 7/8 inch. Check the compound against your process media, pressure and temperature before committing to a design. For a size or compound outside the standard catalog, APG can quote from a print or sample.