8-425 BLACK BUNA 90D BACK-UP RING

Part number HB90425 is an AS568-425 black Buna-N (Nitrile) 90 Shore A Back-Up Ring built to an inside diameter of 4.475 in (113.67 mm), a cross section of 0.275 in (6.99 mm), and an outside diameter of 5.025 in (127.64 mm). A back-up ring allows a standard o-ring to operate at higher pressures than it could unsupported.

Buna-N (Nitrile) is specified here for most widely specified general-purpose sealing elastomer and low compression set under sustained load. The compound resists petroleum-based oils, many alcohols, and propane and butane. The material carries a published service range of -40°F (-40°C) to 250°F (121.1°C). Verify compatibility before use with ozone and direct sunlight or polar solvents.

Common environments for this compound include agricultural equipment, automotive, and fluid power.

HB90425 ships individually. Unit weight is approximately 7.95 g and nominal inside diameter is listed as 4 1/2 inch. Review your operating media and conditions against this specification before installation. APG can cross-reference from an existing part number, a drawing or a physical sample if this size is not an exact match.