568-161 FKM 75 SQUARE CUT RINGS

This square-cut ring is supplied in AS568-161 black Viton® (FKM) 70 Shore A built to an inside diameter of 5.487 in (139.37 mm), a cross section of 0.103 in (2.62 mm), and an outside diameter of 5.693 in (144.6 mm), catalogued under part number SV70161. It resists the spiral failure that affects round rings on long reciprocating strokes.

This material stands up to many acids, petroleum oils and fuels, and engine and transmission fluids. Viton® (FKM) is widely chosen for excellent resistance to compression set and permeation, very low compression set at elevated temperature. Continuous operating temperature is published at -15°F (-26.1°C) to 400°F (204.4°C). It is not the right choice where ketones and esters or amines are present. The profile itself contributes greater resistance to extrusion than a round section of the same size and a rectangular section that will not roll in the groove. 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 high-temperature process equipment, semiconductor equipment, and automotive fuel systems.

Order part number SV70161, sold individually. Nominal inside diameter is listed as 5 1/2 inch. Confirm chemical compatibility, pressure and temperature against your own application requirements before installing. If you need a size, durometer or compound that is not listed, APG can cross-reference from a print, a sample or a competitor part number.