568-389 FKM 75 SQUARE CUT RINGS

Part number SV70389 is an AS568-389 black Viton® (FKM) 70 Shore A Square-Cut Ring built to an inside diameter of 19.953 in (506.81 mm), a cross section of 0.21 in (5.33 mm), and an outside diameter of 20.373 in (517.47 mm). A square-cut ring resists the spiral failure that affects round rings on long reciprocating strokes.

This material stands up to chlorinated solvents, aromatic hydrocarbons, and engine and transmission fluids. That behavior comes from the compound itself: Viton® (FKM) is widely chosen for excellent resistance to compression set and permeation, outstanding high-temperature capability. Published continuous service range is -15°F (-26.1°C) to 400°F (204.4°C). Exposure to low-molecular-weight organic acids or amines will shorten service life. 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.

Common environments for this compound include oil and gas, chemical processing, and high-temperature process equipment.

Stocked as SV70389 and sold individually. Check the compound against your process media, pressure and temperature before committing to a design. APG can cross-reference from an existing part number, a drawing or a physical sample if this size is not an exact match.