8-432 BLACK BUNA 90D BACK-UP RING

The HB90432 is an AS568-432 black Buna-N (Nitrile) 90 Shore A Back-Up Ring built to an inside diameter of 5.35 in (135.89 mm), a cross section of 0.275 in (6.99 mm), and an outside diameter of 5.9 in (149.86 mm). This back-up ring extends o-ring service life by supporting the seal against extrusion under high pressure.

As a material, Buna-N (Nitrile) is known for an economical choice for high-volume maintenance programs and low compression set under sustained load. It resists many alcohols, propane and butane, and greases and lubricants. Service temperature is rated from -40°F (-40°C) through 250°F (121.1°C). It is not the right choice where polar solvents or strong acids are present.

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

Order part number HB90432, sold individually. Unit weight is approximately 9.6775 g. Application requirements vary, so validate compatibility with your process conditions prior to installation.