8-443 BLACK BUNA 90D BACK-UP RING

Ordered as HB90443, this is an AS568-443 black Buna-N (Nitrile) 90 Shore A Back-Up Ring with an inside diameter of 7.475 in (189.87 mm), a cross section of 0.275 in (6.99 mm), and an outside diameter of 8.025 in (203.84 mm). The 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) is specified here for most widely specified general-purpose sealing elastomer, strong abrasion and tear resistance. This material stands up to hydraulic fluids, water, and propane and butane. The material carries a published service range of -40°F (-40°C) to 250°F (121.1°C). It is not the right choice where automotive brake fluid or ketones are present.

Maintenance and OEM teams specify it across agricultural equipment, fluid power, and hydraulic and pneumatic systems.

Reference part number HB90443 when ordering; the item is sold individually. Unit weight is approximately 13.557 g and nominal inside diameter is listed as 7 1/2 inch. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing.