Ordered as HB90005, this is an AS568-005 black Buna-N (Nitrile) 90 Shore A Back-Up Ring measuring an inside diameter of 0.101 in (2.57 mm), a cross section of 0.07 in (1.78 mm), and an outside diameter of 0.241 in (6.12 mm). The back-up ring allows a standard o-ring to operate at higher pressures than it could unsupported.
The material holds up against water, hydraulic fluids, and propane and butane. That behavior comes from the compound itself: Buna-N (Nitrile) is widely chosen for reliable performance in both static and dynamic service, strong abrasion and tear resistance. The material carries a published service range of -40°F (-40°C) to 250°F (121.1°C). It should not be specified for service in ozone and direct sunlight or automotive brake fluid.
It sees regular use in fluid power, construction equipment, and general industrial maintenance.
This item is sold individually under part number HB90005. Unit weight is approximately 0.0341 g and nominal inside diameter is listed as 3/32 inch. Review your operating media and conditions against this specification before 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.
description 8-005 BLACK BUNA 90D BACK-UP RING
Actual_CS 0.07 inch (1.78 mm)
Actual_ID 0.101 inch (2.57 mm)
Actual_OD 0.241 inch (6.12 mm)
ProductCode Description O-Rings - Backup Rings