8-206 BLACK BUNA 90D BACK-UP RING

APG stocks the HB90206, an AS568-206 black Buna-N (Nitrile) 90 Shore A Back-Up Ring with an inside diameter of 0.484 in (12.29 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 0.762 in (19.35 mm). A back-up ring extends o-ring service life by supporting the seal against extrusion under high pressure.

The material holds up against many alcohols, hydraulic fluids, and water. That behavior comes from the compound itself: Buna-N (Nitrile) delivers reliable performance in both static and dynamic service, an economical choice for high-volume maintenance programs. Rated temperature range runs from -40°F (-40°C) to 250°F (121.1°C) in continuous service. Exposure to automotive brake fluid or ozone and direct sunlight will shorten service life.

Maintenance and OEM teams specify it across agricultural equipment, fluid power, and general industrial maintenance.

This item is sold individually under part number HB90206. Unit weight is approximately 0.238 g and nominal inside diameter is listed as 1/2 inch. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing. Not finding the exact configuration you need? APG cross-references from prints, samples and competitor part numbers.