8-428 BLACK FKM 90D BACK-UP RING

APG stocks the VBU90428, an AS568-428 black Viton® (FKM) 90 Shore A Back-Up Ring with an inside diameter of 4.85 in (123.19 mm), a cross section of 0.275 in (6.99 mm), and an outside diameter of 5.4 in (137.16 mm). A back-up ring installs on the low-pressure side of an o-ring to prevent extrusion into the clearance gap at elevated pressure.

Viton® (FKM) is specified here for outstanding high-temperature capability, excellent resistance to compression set and permeation. The compound resists petroleum oils and fuels, engine and transmission fluids, and aromatic hydrocarbons. Service temperature is rated from -15°F (-26.1°C) through 400°F (204.4°C). Exposure to amines or low-molecular-weight organic acids will shorten service life.

You will find this material specified across semiconductor equipment, aerospace, and chemical processing.

This item is sold individually under part number VBU90428. Unit weight is approximately 11.613 g. Check the compound against your process media, pressure and temperature before committing to a design. Not finding the exact configuration you need? APG cross-references from prints, samples and competitor part numbers.