8-394 BLACK BUNA 90D BACK-UP RING

Part number HB90394 is an AS568-394 black Buna-N (Nitrile) 90 Shore A Back-Up Ring with an inside diameter of 24.94 in (633.48 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 25.36 in (644.14 mm). A back-up ring installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

The material holds up against petroleum-based oils, propane and butane, and many alcohols. That behavior comes from the compound itself: Buna-N (Nitrile) is specified for the most widely specified general-purpose sealing elastomer and an economical choice for high-volume maintenance programs. Service temperature is rated from -40°F (-40°C) through 250°F (121.1°C).

Common environments for this compound include general industrial maintenance, agricultural equipment, and hydraulic and pneumatic systems.

Reference part number HB90394 when ordering; the item is sold individually. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing.