8-429 BLACK FKM 90D BACK-UP RING

APG stocks the VBU90429, an AS568-429 black Viton® (FKM) 90 Shore A Back-Up Ring supplied with an inside diameter of 4.975 in (126.37 mm), a cross section of 0.275 in (6.99 mm), and an outside diameter of 5.525 in (140.34 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.

It resists engine and transmission fluids, many acids, and aromatic hydrocarbons. Viton® (FKM) offers very low compression set at elevated temperature and long service life in hot, chemically aggressive environments. Rated temperature range runs from -15°F (-26.1°C) to 400°F (204.4°C) in continuous service. Verify compatibility before use with hot water and steam or amines.

You will find this material specified across aerospace, high-temperature process equipment, and chemical processing.

Reference part number VBU90429 when ordering; the item is sold individually. Unit weight is approximately 12.041 g and nominal inside diameter is listed as 5 inch. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing.