Ordered as VBU90252, this is an AS568-252 black Viton® (FKM) 90 Shore A Back-Up Ring with an inside diameter of 5.234 in (132.94 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 5.512 in (140 mm). The back-up ring bridges the extrusion gap so the primary seal holds its shape under load.
As a material, Viton® (FKM) is specified for excellent resistance to compression set and permeation, long service life in hot, chemically aggressive environments. Expect good resistance to aggressive chemicals, engine and transmission fluids, and petroleum oils and fuels. Continuous operating temperature is published at -15°F (-26.1°C) to 400°F (204.4°C).
You will find this material specified across aerospace, high-temperature process equipment, and chemical processing.
Order part number VBU90252, sold individually. Review your operating media and conditions against this specification before installation.
Description 8-252 BLACK FKM 90D BACK-UP RING
Actual Cross Section 0.139 inch (3.53 mm)
Actual Inside Diameter 5.234 inch (132.94 mm)
Actual Outside Diameter 5.512 inch (140 mm)
Measurement System Imperial
Product Category O-Rings - Backup Rings