8-266 BLACK BUNA 90D BACK-UP RING

APG stocks the HB90266, an AS568-266 black Buna-N (Nitrile) 90 Shore A Back-Up Ring measuring an inside diameter of 7.984 in (202.79 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 8.262 in (209.85 mm). A back-up ring bridges the extrusion gap so the primary seal holds its shape under load.

Buna-N (Nitrile) is specified here for reliable performance in both static and dynamic service, economical choice for high-volume maintenance programs. It resists petroleum-based oils, propane and butane, and water. Service temperature is rated from -40°F (-40°C) through 250°F (121.1°C). Verify compatibility before use with ozone and direct sunlight or strong acids.

Maintenance and OEM teams specify it across agricultural equipment, automotive, and fluid power.

Reference part number HB90266 when ordering; the item is sold individually. Unit weight is approximately 2.9458 g and nominal inside diameter is listed as 8 inch. Check the compound against your process media, pressure and temperature before committing to a design.