Frequently Asked Questions — AU O-Rings
What is AU polyurethane rubber?
AU (Polyester Polyurethane) is a cast polyurethane elastomer renowned for its outstanding mechanical properties: the highest tensile strength, tear resistance, and abrasion resistance of any common sealing material. AU is used when wear, extrusion, and mechanical loading are the primary failure modes rather than chemical attack.
What temperature range can AU o-rings handle?
AU o-rings operate from −40 °C to +100 °C in dry service. In hot water or steam environments, the ester linkages in AU are susceptible to hydrolysis above 60–80 °C; ether-based EU grades are preferred for continuous hot water applications. Avoid AU where continuous exposure to water above 60 °C is expected.
What chemicals is AU resistant to?
AU has good resistance to mineral oils, aliphatic hydrocarbons, fuels, non-polar solvents, and dilute acids. It is not suitable for hot water or steam (hydrolysis), concentrated acids or alkalis, aromatic solvents, chlorinated solvents, or ketones, which attack the urethane linkages.
What are typical applications for AU o-rings?
AU o-rings are used in high-pressure hydraulic cylinders, pneumatic actuators, mobile construction equipment, mining machinery, and any application where extrusion under high pressure, abrasion, and mechanical wear are the dominant concerns. AU o-rings outlast NBR or FKM dramatically in abrasive or high-pressure dynamic service.