Buna 70-343-Black-Pk25

Ordered as SB-H70343-25, this is an AS568-343 black Buna-N (Nitrile) 70 Shore A O-Ring measuring an inside diameter of 3.725 in (94.62 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 4.145 in (105.28 mm). The o-ring seats in a machined groove and forms a leak-tight barrier when compressed between two mating surfaces. Source specification: 4.125IDX3.75"ODX.1875"CS.

The compound resists petroleum-based oils, greases and lubricants, and hydraulic fluids. Buna-N (Nitrile) is valued for reliable performance in both static and dynamic service, low compression set under sustained load. The material carries a published service range of -40°F (-40°C) to 250°F (121.1°C). Exposure to ozone and direct sunlight or automotive brake fluid will shorten service life.

It sees regular use in fluid power, automotive, and general industrial maintenance.

SB-H70343-25 ships by the bag. Nominal inside diameter is listed as 3 3/4 inch. As always, verify media compatibility and operating conditions against the requirements of your specific application. 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.