8-356 BLACK BUNA 90D BACK-UP RING

This back-up ring is supplied in AS568-356 black Buna-N (Nitrile) 90 Shore A measuring an inside diameter of 5.35 in (135.89 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 5.77 in (146.56 mm), catalogued under part number HB90356. It installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

Expect good resistance to petroleum-based oils, greases and lubricants, and propane and butane. That behavior comes from the compound itself: Buna-N (Nitrile) delivers strong abrasion and tear resistance, the most widely specified general-purpose sealing elastomer. Rated temperature range runs from -40°F (-40°C) to 250°F (121.1°C) in continuous service. Verify compatibility before use with ketones or automotive brake fluid.

You will find this material specified across construction equipment, hydraulic and pneumatic systems, and agricultural equipment.

Stocked as HB90356 and sold individually. Unit weight is approximately 4.6941 g. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing. If you need a size, durometer or compound that is not listed, APG can cross-reference from a print, a sample or a competitor part number.