8-345 BLACK BUNA 90D BACK-UP RING

The HB90345 is an AS568-345 black Buna-N (Nitrile) 90 Shore A Back-Up Ring measuring an inside diameter of 3.975 in (100.97 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 4.395 in (111.63 mm). This back-up ring 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) is known for strong abrasion and tear resistance, the most widely specified general-purpose sealing elastomer. It resists petroleum-based oils, propane and butane, and greases and lubricants. Continuous operating temperature is published at -40°F (-40°C) to 250°F (121.1°C). It is not the right choice where automotive brake fluid or ketones are present.

Common environments for this compound include hydraulic and pneumatic systems, agricultural equipment, and construction equipment.

HB90345 ships individually. Unit weight is approximately 3.5313 g. Check the compound against your process media, pressure and temperature before committing to a design. 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.