568-138 BUNA 70 SQUARE CUT RINGS

Ordered as SH70138, this is an AS568-138 black Buna-N (Nitrile) 70 Shore A Square-Cut Ring with an inside diameter of 2.112 in (53.64 mm), a cross section of 0.103 in (2.62 mm), and an outside diameter of 2.318 in (58.88 mm). The square-cut ring seals with a broad flat contact band instead of the line contact of a round-section ring.

Buna-N (Nitrile) is widely chosen for the most widely specified general-purpose sealing elastomer, reliable performance in both static and dynamic service. Expect good resistance to propane and butane, water, and hydraulic fluids. The material carries a published service range of -40°F (-40°C) to 250°F (121.1°C). Exposure to automotive brake fluid or ketones will shorten service life. The profile itself contributes greater resistance to extrusion than a round section of the same size and a flat contact band that spreads sealing load across a wider area. 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 construction equipment, general industrial maintenance, and automotive.

SH70138 ships individually. Unit weight is approximately 1.385 g and nominal inside diameter is listed as 2 1/8 inch. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing. APG supports cross-referencing from drawings, samples and competitor numbers when a listed size is not an exact fit.