The paper follows the evolution of seals for water hydraulic actuators in the sanitary valve industry, which was part of a 5-year program 'Hydract' sponsored under the EU FP-7 initiative. Seals are critical to the performance of the actuator and were seen as a major obstacle to the development of the actuator which had to provide a low-energy alternative to present pneumatic installations. The paper discusses the factors and candidates for the choice of materials and seal types for the various applications within the actuator. Laboratory and site trials with early prototypes are described, concentrating on the seal performance and practical issues that were encountered. Later actuator designs called for considerable cost engineering, and a significant part of this was achievable through improved sealing solutions for the main actuator. The paper describes qualification testing of the new seals and their integration into a complete valve installation at a leading brewery in Denmark.
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