8-339 BLACK BUNA 90D BACK-UP RING

Ordered as HB90339, this is an AS568-339 black Buna-N (Nitrile) 90 Shore A Back-Up Ring supplied with an inside diameter of 3.225 in (81.92 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 3.645 in (92.58 mm). The back-up ring installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

Buna-N (Nitrile) is specified here for reliable performance in both static and dynamic service, strong abrasion and tear resistance. This material stands up to water, many alcohols, and propane and butane. Service temperature is rated from -40°F (-40°C) through 250°F (121.1°C). Exposure to strong acids or ozone and direct sunlight will shorten service life.

Common environments for this compound include fluid power, hydraulic and pneumatic systems, and agricultural equipment.

Reference part number HB90339 when ordering; the item is sold individually. Unit weight is approximately 2.8426 g and nominal inside diameter is listed as 3 1/4 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.