8-240 BLACK BUNA 90D BACK-UP RING

APG stocks the HB90240, an AS568-240 black Buna-N (Nitrile) 90 Shore A Back-Up Ring supplied with an inside diameter of 3.734 in (94.84 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 4.012 in (101.9 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.

As a material, Buna-N (Nitrile) is specified for low compression set under sustained load, strong abrasion and tear resistance. The material holds up against many alcohols, greases and lubricants, and petroleum-based oils. Continuous operating temperature is published at -40°F (-40°C) to 250°F (121.1°C).

Typical settings include agricultural equipment, general industrial maintenance, and construction equipment.

Stocked as HB90240 and sold individually. Unit weight is approximately 1.3383 g and nominal inside diameter is listed as 3 3/4 inch. Application requirements vary, so validate compatibility with your process conditions prior to installation. If you need a size, durometer or compound that is not listed, APG can cross-reference from a print, a sample or a competitor part number.