8-213 BLACK BUNA 90D BACK-UP RING

APG stocks the HB90213, an AS568-213 black Buna-N (Nitrile) 90 Shore A Back-Up Ring with an inside diameter of 0.921 in (23.39 mm), a cross section of 0.139 in (3.53 mm), and an outside diameter of 1.199 in (30.45 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.

Buna-N (Nitrile) delivers low compression set under sustained load and an economical choice for high-volume maintenance programs. It resists greases and lubricants, petroleum-based oils, and many alcohols. Continuous operating temperature is published at -40°F (-40°C) to 250°F (121.1°C). Exposure to ketones or automotive brake fluid will shorten service life.

You will find this material specified across fluid power, hydraulic and pneumatic systems, and agricultural equipment.

Order part number HB90213, sold individually. Unit weight is approximately 0.396 g. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing. 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.