568-390 BUNA 70 SQUARE CUT RINGS

Part number SH70390 is an AS568-390 black Buna-N (Nitrile) 70 Shore A Square-Cut Ring supplied with an inside diameter of 20.953 in (532.21 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 21.373 in (542.87 mm). A square-cut ring provides an economical lathe-cut alternative where a moulded o-ring is not required.

The material holds up against greases and lubricants, propane and butane, and hydraulic fluids. Buna-N (Nitrile) is valued for low compression set under sustained load and an economical choice for high-volume maintenance programs. Published continuous service range is -40°F (-40°C) to 250°F (121.1°C). Applications involving ozone and direct sunlight 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.

You will find this material specified across agricultural equipment, construction equipment, and fluid power.

Order part number SH70390, sold individually. Nominal inside diameter is listed as 21 inch. As always, verify media compatibility and operating conditions against the requirements of your specific application. APG can cross-reference from an existing part number, a drawing or a physical sample if this size is not an exact match.