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Polyurethane seal from Freudenberg-NOK Sealing Technologies replaces PTFE seals in hydraulic piston

SIMKO 300 seal ring proves impressive in wind power facilities

Hydratech Industries, a leading provider of solutions forwind power facilities and hydraulic systems, is relying on a polyurethanesealing solution from Freudenberg-NOK Sealing Technologies for its newhydraulic accumulator. Test comparisons with other products have shown thatFreudenberg-NOK’s SIMKO 300 seal ring offers distinct advantages overfrequently used polytetrafluorethylene (PTFE) seals with regard to operatinglife, form stability and sealing characteristics.

The durability of sealing rings in piston accumulators isa crucial parameter for operating life. For this reason, piston accumulatorsundergo accelerated load tests at the Hydratech test center in Sikeborg,Denmark that simulate 20 years of service life. During the testing process, thebehavior of the seals under pressures greater than 200 bar and temperaturesranging between -104 degrees to +140 degrees F is measured – conditions thatexceed actual stresses. 

Based on its form stability, extreme hardness and lowabrasion, Hydratech now uses the SIMKO 300 from Freudenberg-NOK. The sealingsolution “fully meets our expectations and is impressive due to its longservice life,” said Jimmi Wenderby, Hydratech research and developmentmanager.

Most sealing systems in piston accumulators work with twoseals, one for oil and another for gas. This leads to increased wear due to theextreme load, especially in PTFE seals. By contrast, the SIMKO 300 is a singleseal (consisting of a seal ring and a pressure ring) and is made ofpolyurethane. Polyurethane’s hardness grade of 98 Shore A corresponds to thatof PTFE but is much more robust. Its susceptibility to potential surface damageduring installation is also lower. The pressure ring creating the necessarypre-tension is made of an elastomer.  

The SIMKO 300 seal’s high form stability, its surfacefirmness and its long operating life make it especially appealing for use inhydraulic pitch controllers in wind power facilities. They are an importantcomponent of the security technology in wind power facilities, as the pistonaccumulator must not merely function reliably under extreme weather conditionsbut also withstand the high differential pressures that are also produced. Theaccumulator must be able to operate leak-free over very long periods of time.

The SIMKO 300 is a cost-effective and extremely reliablesolution for use in piston accumulators, and it provides a long service lifefor the wind power station due to its outstanding sealing qualities.

About Freudenberg-NOK Sealing Technologies

Freudenberg-NOK Sealing Technologies is the Americasjoint venture between Freudenberg and Co. in Germany and NOK Corp. in Japan.Freudenberg-NOK is a leading producer – through its Automotive, Merkel, ProcessSeals and Simrit sales channels – of advanced sealing technologies for avariety of markets including: aerospace; agriculture; appliance; automotive;construction; diesel engine; energy; food and beverage; heavy industry; andpharmaceutical.

Founded in 1989 under the legal name Freudenberg-NOKGeneral Partnership, Freudenberg-NOK is headquartered in Plymouth, Mich. andoperates more than 20 facilities across the Americas. For additionalinformation, please visit

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Wed. July 17th, 2024

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