568-381 BUNA 70 SQUARE CUT RINGS

APG stocks the SH70381, an AS568-381 black Buna-N (Nitrile) 70 Shore A Square-Cut Ring measuring an inside diameter of 11.975 in (304.17 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 12.395 in (314.83 mm). A square-cut ring seals with a broad flat contact band instead of the line contact of a round-section ring.

As a material, Buna-N (Nitrile) delivers low compression set under sustained load, reliable performance in both static and dynamic service. The compound resists many alcohols, water, and petroleum-based oils. Rated temperature range runs from -40°F (-40°C) to 250°F (121.1°C) in continuous service. Applications involving automotive brake fluid or strong acids call for a different compound. The profile itself contributes a flat contact band that spreads sealing load across a wider area and greater resistance to extrusion than a round section of the same size. Note that a square section is less suited to high-speed rotary service, where the larger contact area raises friction and heat.

Typical settings include fluid power, hydraulic and pneumatic systems, and general industrial maintenance.

SH70381 ships individually. Nominal inside diameter is listed as 12 inch. Review your operating media and conditions against this specification before installation. Not finding the exact configuration you need? APG cross-references from prints, samples and competitor part numbers.