8-426 BLACK BUNA 90D BACK-UP RING

The HB90426 is an AS568-426 black Buna-N (Nitrile) 90 Shore A Back-Up Ring supplied with an inside diameter of 4.6 in (116.84 mm), a cross section of 0.275 in (6.99 mm), and an outside diameter of 5.15 in (130.81 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.

Buna-N (Nitrile) is widely chosen for strong abrasion and tear resistance, reliable performance in both static and dynamic service. The compound resists petroleum-based oils, propane and butane, and greases and lubricants. Published continuous service range is -40°F (-40°C) to 250°F (121.1°C). Verify compatibility before use with ozone and direct sunlight or polar solvents.

You will find this material specified across agricultural equipment, general industrial maintenance, and construction equipment.

HB90426 ships individually. Unit weight is approximately 8.533 g and nominal inside diameter is listed as 4 5/8 inch. 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.