8-042 BLACK BUNA 90D BACK-UP RING

Part number HB90042 is an AS568-042 black Buna-N (Nitrile) 90 Shore A Back-Up Ring measuring an inside diameter of 3.239 in (82.27 mm), a cross section of 0.07 in (1.78 mm), and an outside diameter of 3.379 in (85.83 mm). A back-up ring allows a standard o-ring to operate at higher pressures than it could unsupported.

Buna-N (Nitrile) is specified here for strong abrasion and tear resistance, low compression set under sustained load. The material holds up against water, hydraulic fluids, and many alcohols. Rated temperature range runs from -40°F (-40°C) to 250°F (121.1°C) in continuous service. Verify compatibility before use with automotive brake fluid or strong acids.

Maintenance and OEM teams specify it across agricultural equipment, automotive, and general industrial maintenance.

Order part number HB90042, sold individually. Unit weight is approximately 0.572 g and nominal inside diameter is listed as 3 1/4 inch. As always, verify media compatibility and operating conditions against the requirements of your specific application.