8-442 BLACK BUNA 90D BACK-UP RING

This back-up ring is supplied in AS568-442 black Buna-N (Nitrile) 90 Shore A measuring an inside diameter of 7.225 in (183.52 mm), a cross section of 0.275 in (6.99 mm), and an outside diameter of 7.775 in (197.49 mm), catalogued under part number HB90442. It bridges the extrusion gap so the primary seal holds its shape under load.

Buna-N (Nitrile) is specified here for most widely specified general-purpose sealing elastomer and low compression set under sustained load. Expect good resistance to water, many alcohols, and greases and lubricants. Published continuous service range is -40°F (-40°C) to 250°F (121.1°C). It is not the right choice where polar solvents or strong acids are present.

You will find this material specified across agricultural equipment, fluid power, and general industrial maintenance.

Reference part number HB90442 when ordering; the item is sold individually. Unit weight is approximately 13.202 g and nominal inside diameter is listed as 7 1/4 inch. Application requirements vary, so validate compatibility with your process conditions prior to installation.