8-157 BLACK BUNA 90D BACK-UP RING

The HB90157 is an AS568-157 black Buna-N (Nitrile) 90 Shore A Back-Up Ring measuring an inside diameter of 4.487 in (113.97 mm), a cross section of 0.103 in (2.62 mm), and an outside diameter of 4.693 in (119.2 mm). This back-up ring extends o-ring service life by supporting the seal against extrusion under high pressure.

This material stands up to propane and butane, hydraulic fluids, and water. That behavior comes from the compound itself: Buna-N (Nitrile) is widely chosen for an economical choice for high-volume maintenance programs and low compression set under sustained load. Rated temperature range runs from -40°F (-40°C) to 250°F (121.1°C) in continuous service. Applications involving polar solvents or ozone and direct sunlight call for a different compound.

Maintenance and OEM teams specify it across hydraulic and pneumatic systems, automotive, and construction equipment.

Stocked as HB90157 and sold individually. Unit weight is approximately 1.3261 g. Review your operating media and conditions against this specification before installation.