8-028 BLACK FKM 90D BACK-UP RING

The VBU90028 is an AS568-028 black Viton® (FKM) 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). This back-up ring installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

Expect good resistance to many acids, aromatic hydrocarbons, and petroleum oils and fuels. That behavior comes from the compound itself: Viton® (FKM) is known for very low compression set at elevated temperature, excellent resistance to compression set and permeation. Service temperature is rated from -15°F (-26.1°C) through 400°F (204.4°C).

Maintenance and OEM teams specify it across semiconductor equipment, automotive fuel systems, and chemical processing.

Stocked as VBU90028 and sold individually. Unit weight is approximately 0.215 g and nominal inside diameter is listed as 1 3/8 inch. Check the compound against your process media, pressure and temperature before committing to a design. 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.