A valve Positioner is a device used to increase or decrease the air load pressure driving the actuator.
valve's stem reaches a POSITION balanced to the output SIGNAL from the process variable instrument controller.
Valve positioners are used on controlling valves where accurate and rapid control is required without error or hysterises.
Positioners are generally mounted on the side-yoke or top casing of the pneumatic actuator for linear sliding stem control valves.
