8-448 BLACK BUNA 90D BACK-UP RING

APG stocks the HB90448, an AS568-448 black Buna-N (Nitrile) 90 Shore A Back-Up Ring with an inside diameter of 9.475 in (240.67 mm), a cross section of 0.275 in (6.99 mm), and an outside diameter of 10.025 in (254.64 mm). A back-up ring installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

Expect good resistance to greases and lubricants, many alcohols, and propane and butane. That behavior comes from the compound itself: Buna-N (Nitrile) is widely chosen for reliable performance in both static and dynamic service, strong abrasion and tear resistance. Published continuous service range is -40°F (-40°C) to 250°F (121.1°C). It is not the right choice where ketones or strong acids are present.

Maintenance and OEM teams specify it across hydraulic and pneumatic systems, automotive, and construction equipment.

This item is sold individually under part number HB90448. Unit weight is approximately 16.983 g and nominal inside diameter is listed as 9 1/2 inch. Review your operating media and conditions against this specification before installation. Not finding the exact configuration you need? APG cross-references from prints, samples and competitor part numbers.