8-438 BLACK BUNA 90D BACK-UP RING

This back-up ring is supplied in AS568-438 black Buna-N (Nitrile) 90 Shore A with an inside diameter of 6.225 in (158.12 mm), a cross section of 0.275 in (6.99 mm), and an outside diameter of 6.775 in (172.09 mm), catalogued under part number HB90438. It installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

Buna-N (Nitrile) is known for strong abrasion and tear resistance, low compression set under sustained load. Expect good resistance to many alcohols, greases and lubricants, and propane and butane. Rated temperature range runs from -40°F (-40°C) to 250°F (121.1°C) in continuous service. Exposure to polar solvents or ozone and direct sunlight will shorten service life.

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

This item is sold individually under part number HB90438. Unit weight is approximately 11.473 g and nominal inside diameter is listed as 6 1/4 inch. As always, verify media compatibility and operating conditions against the requirements of your specific application. APG supports cross-referencing from drawings, samples and competitor numbers when a listed size is not an exact fit.