8-125 BLACK BUNA 90D BACK-UP RING

The HB90125 is an AS568-125 black Buna-N (Nitrile) 90 Shore A Back-Up Ring with an inside diameter of 1.299 in (32.99 mm), a cross section of 0.103 in (2.62 mm), and an outside diameter of 1.505 in (38.23 mm). This back-up ring bridges the extrusion gap so the primary seal holds its shape under load.

The material holds up against hydraulic fluids, propane and butane, and water. That behavior comes from the compound itself: Buna-N (Nitrile) is specified for low compression set under sustained load, strong abrasion and tear resistance. Service temperature is rated from -40°F (-40°C) through 250°F (121.1°C). Applications involving polar solvents or ozone and direct sunlight call for a different compound.

It sees regular use in hydraulic and pneumatic systems, general industrial maintenance, and fluid power.

This item is sold individually under part number HB90125. Unit weight is approximately 0.3957 g. 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.