568-139 BUNA 70 SQUARE CUT RINGS

APG stocks the SH70139, an AS568-139 black Buna-N (Nitrile) 70 Shore A Square-Cut Ring built to an inside diameter of 2.175 in (55.25 mm), a cross section of 0.103 in (2.62 mm), and an outside diameter of 2.381 in (60.48 mm). A square-cut ring seals with a broad flat contact band instead of the line contact of a round-section ring.

Expect good resistance to petroleum-based oils, hydraulic fluids, and greases and lubricants. Buna-N (Nitrile) is specified for the most widely specified general-purpose sealing elastomer and low compression set under sustained load. 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 ketones or polar solvents are present. The profile itself contributes a flat contact band that spreads sealing load across a wider area and simple lathe-cut manufacture at low tooling cost. Note that a square section is less suited to high-speed rotary service, where the larger contact area raises friction and heat.

It sees regular use in agricultural equipment, automotive, and general industrial maintenance.

Order part number SH70139, sold individually. Unit weight is approximately 1.3587 g and nominal inside diameter is listed as 2 3/16 inch. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing. Not finding the exact configuration you need? APG cross-references from prints, samples and competitor part numbers.