8-329 BLACK BUNA 90D BACK-UP RING

APG stocks the HB90329, an AS568-329 black Buna-N (Nitrile) 90 Shore A Back-Up Ring supplied with an inside diameter of 1.975 in (50.17 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 2.395 in (60.83 mm). A back-up ring bridges the extrusion gap so the primary seal holds its shape under load.

As a material, Buna-N (Nitrile) is valued for an economical choice for high-volume maintenance programs, strong abrasion and tear resistance. The material holds up against many alcohols, hydraulic fluids, and petroleum-based oils. Service temperature is rated from -40°F (-40°C) through 250°F (121.1°C). Verify compatibility before use with automotive brake fluid or polar solvents.

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

Reference part number HB90329 when ordering; the item is sold individually. Unit weight is approximately 1.8782 g. Review your operating media and conditions against this specification before installation.