8-358 BLACK FKM 90D BACK-UP RING

APG stocks the VBU90358, an AS568-358 black Viton® (FKM) 90 Shore A Back-Up Ring measuring an inside diameter of 5.6 in (142.24 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 6.02 in (152.91 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.

This material stands up to many acids, chlorinated solvents, and aromatic hydrocarbons. That behavior comes from the compound itself: Viton® (FKM) delivers excellent resistance to compression set and permeation, outstanding high-temperature capability. The material carries a published service range of -15°F (-26.1°C) to 400°F (204.4°C). Exposure to hot water and steam or low-molecular-weight organic acids will shorten service life.

It sees regular use in semiconductor equipment, chemical processing, and automotive fuel systems.

Stocked as VBU90358 and sold individually. Unit weight is approximately 6.6225 g. Review your operating media and conditions against this specification before installation. APG supports cross-referencing from drawings, samples and competitor numbers when a listed size is not an exact fit.