Tuesday, August 31, 2010

Q: What role do valve positioners play in valve actuation and control applications?

A: We very often describe the positioner as the brain and heart of the control valve, because its functions and capabilities are so comparable. Analog positioners are used to precisely convert the input signal from a controller or control system and control the valve position correspondingly, despite various actuator bench ranges and disturbance variables, such as varying supply air, dynamic forces affecting the valve plug, and valve stem friction. In addition, positioners are responsible for adapting the inherent characteristic of butterfly and ball valves to the required characteristic form.
At the present time, digital positioners are expected to perform additional tasks, such as automatic startup and self-diagnostics, as well as many asset management functions, which enable predictive, status-oriented maintenance of control valves.