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New Industrial Products

New motorized actuator for linear valves

GEMÜ has developed a new motorized open/close actuator for globe and diaphragm valves. The 24 V DC actuator is an advanced alternative to current designs and also to solenoid valves.

Posted on September 6, 2010 - ( views)

by Constanze Schmitz

The valves using this actuator are ideally suited to applications without plant air. At the same time, the operating costs of the motorized actuator are lower than those of a comparable pneumatic actuator or even a solenoid valve. In a pneumatic actuator or a solenoid valve with control function normally closed, the valve must be supplied with compressed air or consumes power the entire time that it is open. The new motorized actuator, with a power consumption of approx. 24 W, is designed so that it only requires power to position the valve. When it has reached the closed or open end position, the integrated limit switch switches the actuator off automatically and holds the valve in position until the next control signal. A seal adjuster can be implemented using the adjustable limit switch of the CLOSED position. The electrical connection is made via M12 connectors.   The actuating speed is between 4-10 mm/sec., depending on the nominal size. The GEMÜ S680 diaphragm valve closes in approx. 0.5 sec. in nominal size DN 15, and for DN 25 in approx. 2 sec. The even closing process noticeably reduces water hammer in comparison to fast closing pneumatic and solenoid valves. The compact actuator is no wider than the valve body and is therefore ideally suited for use in space-saving valve batteries.   The diaphragm valve has two distinct advantages over the solenoid valve: firstly solenoid valves in the sizes up to DN 50 are either directly controlled or servo assisted. Directly controlled valves require very large solenoids for the equivalent operating pressure, and therefore consume a lot of power and generate a considerable amount of heat. Solenoid valves are preferably servo assisted to avoid this disadvantage however very small control apertures are therefore necessary which are susceptible to solids and particles in the medium. Blocked control apertures cause the valves to fail. Particle filters to protect the solenoid valves increase procurement and operating costs and must be taken into account from a TCO point of view. By contrast, the design of motorized diaphragm valves makes them insensitive to particles and solids in the medium. Even grains of sand and pieces of limescale in water pipes, for example, impair neither the function nor the tightness of the valves. The second advantage of the diaphragm valve is its design, which creates a hermetic separation between the actuator and the working medium without additional parts or gaskets. Of course, this is also possible in solenoid valves, but it increases their complexity and their cost.   The new motorized actuator is offered in two valve designs. The GEMÜ S680 diaphragm valve is available in PVC-U, reinforced PP and brass in sizes DN 10 and DN 15. Ratings are max. 6 bar, depending on nominal size and maximum permissible operating temperatures are 60°C. The operating time is between 0.5-1 sec., depending on size.   The GEMÜ S580 angle seat globe valve is also available in sizes DN 10 and DN 15. Reinforced PP and brass are available as valve body materials and the ratings as per the S680. The operating time is between 0.8-1 sec., depending on size.


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