Can anybody guide me over a following string of question? What is difference between positioner and solenoid valve? What i know positioner gets signal from loop controller then observe valve position.

SOV is also for fast opening or closing of the valve so as positioner do in opening and closing of the valve. actually i get confuse, need guidance

 

Basically, a solenoid valve is a 2 position device - either full open or full closed, based on whether the solenoid is energized or de-energized. Typically, de-energized is the "safe" state of the valve, which is usually (but not always) closed.

A positioner generally is driven by a 4-20 ma analog signal that can hold the valve at any position from full closed to full open. This type of valve is usually a modulating control valve.