Types of Actuation
As shutdown valves form part of a SIS it is necessary to operate the valve by means of an actuator. These actuators are normally fail safe fluid power type. Typical examples of these are:
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- Pneumatic cylinder
- Hydraulic cylinder
- Electro-hydraulic actuator
In addition to the fluid type, actuators also vary in the manner in which the energy is stored to operate the valve on demand as follows:
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- single-acting cylinder - Or spring return where the energy is stored by means of a compressed spring
- double-acting cylinder - Energy is stored using a volume of compressed fluid
The type of actuation required depends upon the application, site facilities and also the physical space available although the majority of actuators used for shutdown valves are of the spring return type due to the fail safe nature of spring return systems
Read more about this topic: Shut Down Valve
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