Part number VBU90040 is an AS568-040 black Viton® (FKM) 90 Shore A Back-Up Ring measuring an inside diameter of 2.864 in (72.75 mm), a cross section of 0.07 in (1.78 mm), and an outside diameter of 3.004 in (76.3 mm). A back-up ring allows a standard o-ring to operate at higher pressures than it could unsupported.
As a material, Viton® (FKM) is specified for very low compression set at elevated temperature and long service life in hot, chemically aggressive environments. Expect good resistance to many acids, engine and transmission fluids, and aggressive chemicals. Rated temperature range runs from -15°F (-26.1°C) to 400°F (204.4°C) in continuous service. Applications involving hot water and steam or ketones and esters call for a different compound.
You will find this material specified across semiconductor equipment, high-temperature process equipment, and chemical processing.
Order part number VBU90040, sold individually. Nominal inside diameter is listed as 2 7/8 inch. Application requirements vary, so validate compatibility with your process conditions prior to installation.
Description 8-040 BLACK FKM 90D BACK-UP RING
Actual Cross Section 0.07 inch (1.78 mm)
Actual Inside Diameter 2.864 inch (72.75 mm)
Actual Outside Diameter 3.004 inch (76.3 mm)
Measurement System Imperial
Product Category O-Rings - Backup Rings