8-359 BLACK BUNA 90D BACK-UP RING

This back-up ring is supplied in AS568-359 black Buna-N (Nitrile) 90 Shore A measuring an inside diameter of 5.725 in (145.42 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 6.145 in (156.08 mm), catalogued under part number HB90359. 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 specified here for most widely specified general-purpose sealing elastomer and economical choice for high-volume maintenance programs. This material stands up to many alcohols, water, and greases and lubricants. Service temperature is rated from -40°F (-40°C) through 250°F (121.1°C). Applications involving strong acids or polar solvents call for a different compound.

Maintenance and OEM teams specify it across automotive, agricultural equipment, and construction equipment.

Reference part number HB90359 when ordering; the item is sold individually. Unit weight is approximately 4.626 g. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing.