568-178 BUNA 70 SQUARE CUT RINGS

The SH70178 is an AS568-178 black Buna-N (Nitrile) 70 Shore A Square-Cut Ring built to an inside diameter of 9.737 in (247.32 mm), a cross section of 0.103 in (2.62 mm), and an outside diameter of 9.943 in (252.55 mm). This square-cut ring resists the spiral failure that affects round rings on long reciprocating strokes.

The material holds up against propane and butane, greases and lubricants, and petroleum-based oils. That behavior comes from the compound itself: Buna-N (Nitrile) delivers 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 should not be specified for service in automotive brake fluid or strong acids. The profile itself contributes a rectangular section that will not roll in the groove 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.

Maintenance and OEM teams specify it across hydraulic and pneumatic systems, general industrial maintenance, and construction equipment.

Stocked as SH70178 and sold individually. Nominal inside diameter is listed as 9 3/4 inch. Check the compound against your process media, pressure and temperature before committing to a design. For a size or compound outside the standard catalog, APG can quote from a print or sample.