8-444 BLACK BUNA 90D BACK-UP RING

The HB90444 is an AS568-444 black Buna-N (Nitrile) 90 Shore A Back-Up Ring measuring an inside diameter of 7.725 in (196.22 mm), a cross section of 0.275 in (6.99 mm), and an outside diameter of 8.275 in (210.19 mm). This back-up ring extends o-ring service life by supporting the seal against extrusion under high pressure.

Buna-N (Nitrile) is specified here for economical choice for high-volume maintenance programs and most widely specified general-purpose sealing elastomer. Expect good resistance to water, greases and lubricants, and hydraulic fluids. Service temperature is rated from -40°F (-40°C) through 250°F (121.1°C). Exposure to ketones or polar solvents will shorten service life.

Maintenance and OEM teams specify it across general industrial maintenance, construction equipment, and agricultural equipment.

Order part number HB90444, sold individually. Unit weight is approximately 13.725 g and nominal inside diameter is listed as 7 3/4 inch. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing. Not finding the exact configuration you need? APG cross-references from prints, samples and competitor part numbers.