8-389 BLACK BUNA 90D BACK-UP RING

Ordered as HB90389, this is an AS568-389 black Buna-N (Nitrile) 90 Shore A Back-Up Ring supplied with an inside diameter of 19.953 in (506.81 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 20.373 in (517.47 mm). The back-up ring installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

Buna-N (Nitrile) delivers an economical choice for high-volume maintenance programs and the most widely specified general-purpose sealing elastomer. The material holds up against many alcohols, water, and petroleum-based oils. Published continuous service range is -40°F (-40°C) to 250°F (121.1°C). It is not the right choice where ketones or strong acids are present.

Typical settings include automotive, hydraulic and pneumatic systems, and general industrial maintenance.

HB90389 ships individually. Unit weight is approximately 16.627 g. Check the compound against your process media, pressure and temperature before committing to a design. APG can cross-reference from an existing part number, a drawing or a physical sample if this size is not an exact match.