Actuator

A single process facility can have hundreds, if not thousands, of valves to control everything from turbine operation to ventilation, to systems that ensure the safety of personnel and equipment. The valves used can range in size from less than an inch to several feet in diameter. While some of these valves are designed to be operated manually, many of them require some form of automatic or remote operation.

A valve actuator is the mechanism for opening, closing or throttling of a valve remotely. Manually operated valves require someone in attendance to adjust them using a direct or geared mechanism attached to the valve stem. Power-operated actuators use gas pressure, hydraulic pressure or electricity and allow a valve to be adjusted remotely and rapidly. Power-operated valve actuators may be the final elements of an automatic control loop which automatically regulates any flow process. Actuators may be used to open and close the valve, or may allow intermediate positioning (throttling). Some valve actuators include switches or other ways to remotely indicate the position of the valve.

There are many applications that call for the use of actuators, such as:

• Automating a process
• Positioning valves that require large amounts of torque to operate
• Instantaneous operation of systems used to protect personnel and equipment from dangerous conditions
• Use in controlling areas where manual operation is impractical or impossible
• Continually adjusting systems that must maintain desired parameters

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