Closing the inner loop

An actuator driven only by an air signal can stick, hysterise and drift with supply pressure. A positioner measures actual stem position and corrects the actuator until the position matches the controller output.

Diagnostics

A smart positioner records friction, travel and air consumption. Trending those signals shows a valve degrading months before it fails.

Safety functions

A partial-stroke test moves a shutdown valve a few percent to prove it is free, without interrupting the process.