568-039 BUNA 70 SQUARE CUT RINGS

APG stocks the SH70039, an AS568-039 black Buna-N (Nitrile) 70 Shore A Square-Cut Ring with an inside diameter of 2.739 in (69.57 mm), a cross section of 0.07 in (1.78 mm), and an outside diameter of 2.879 in (73.13 mm). A square-cut ring presents a flat rectangular section that cannot roll or twist in its groove, making it a dependable static seal.

Expect good resistance to hydraulic fluids, many alcohols, and greases and lubricants. That behavior comes from the compound itself: Buna-N (Nitrile) is valued for low compression set under sustained load and an economical choice for high-volume maintenance programs. The material carries a published service range of -40°F (-40°C) to 250°F (121.1°C). Exposure to polar solvents or automotive brake fluid will shorten service life. The profile itself contributes greater resistance to extrusion than a round section of the same size 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 hydraulic and pneumatic systems, agricultural equipment, and construction equipment.

This item is sold individually under part number SH70039. Unit weight is approximately 0.786 g and nominal inside diameter is listed as 2 3/4 inch. Review your operating media and conditions against this specification before installation.