8-028 BLACK BUNA 90D BACK-UP RING

APG stocks the HB90028, an AS568-028 black Buna-N (Nitrile) 90 Shore A Back-Up Ring with an inside diameter of 1.364 in (34.65 mm), a cross section of 0.07 in (1.78 mm), and an outside diameter of 1.504 in (38.2 mm). A back-up ring extends o-ring service life by supporting the seal against extrusion under high pressure.

This material stands up to many alcohols, water, and petroleum-based oils. That behavior comes from the compound itself: Buna-N (Nitrile) delivers the most widely specified general-purpose sealing elastomer, strong abrasion and tear resistance. Published continuous service range is -40°F (-40°C) to 250°F (121.1°C). It should not be specified for service in polar solvents or ozone and direct sunlight.

Typical settings include general industrial maintenance, agricultural equipment, and construction equipment.

Reference part number HB90028 when ordering; the item is sold individually. Unit weight is approximately 0.247 g. Application requirements vary, so validate compatibility with your process conditions prior to installation. If you need a size, durometer or compound that is not listed, APG can cross-reference from a print, a sample or a competitor part number.