8-370 BLACK BUNA 90D BACK-UP RING

This back-up ring is supplied in AS568-370 black Buna-N (Nitrile) 90 Shore A with an inside diameter of 8.225 in (208.92 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 8.645 in (219.58 mm), catalogued under part number HB90370. It installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

As a material, Buna-N (Nitrile) offers low compression set under sustained load, strong abrasion and tear resistance. It resists petroleum-based oils, water, and greases and lubricants. Published continuous service range is -40°F (-40°C) to 250°F (121.1°C). Exposure to ketones or polar solvents will shorten service life.

Typical settings include general industrial maintenance, agricultural equipment, and automotive.

Order part number HB90370, sold individually. Unit weight is approximately 7.07 g. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing. APG can cross-reference from an existing part number, a drawing or a physical sample if this size is not an exact match.