Buna 70-159-Black-Pk25

APG stocks the SB-H70159-25, an AS568-159 black Buna-N (Nitrile) 70 Shore A O-Ring measuring an inside diameter of 4.987 in (126.67 mm), a cross section of 0.103 in (2.62 mm), and an outside diameter of 5.193 in (131.9 mm). An o-ring creates a positive seal at flange, piston and rod interfaces without added hardware. The catalog record notes: 5.1875IDX5"ODX.0938"CS.

The material holds up against water, hydraulic fluids, and greases and lubricants. That behavior comes from the compound itself: Buna-N (Nitrile) offers low compression set under sustained load, strong abrasion and tear resistance. Service temperature is rated from -40°F (-40°C) through 250°F (121.1°C). It should not be specified for service in ozone and direct sunlight or ketones.

It sees regular use in fluid power, automotive, and hydraulic and pneumatic systems.

Stocked as SB-H70159-25 and sold by the bag. Review your operating media and conditions against this specification before installation. For a size or compound outside the standard catalog, APG can quote from a print or sample.