Valve position switch
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Help: I know that normal interlock cut-off valves are equipped with valve position switches in normal operation, but I’m not sure what their function is or where they are installed
A valve position switch refers to a switch that indicates the position of the valve. It typically provides two signals – one for when the valve is in the open position and another for when it is in the closed position – which are sent as DI signals to the controller or control system for use in logical calculations or to trigger subsequent actions； Small travel switches (microswitches) are commonly used; a cam is installed on the rotating shaft of the actuator. When the valve reaches its open or closed position, the cam comes into contact with the travel switch, causing the contacts to close and a signal to be generated.
Simply put, it tells the DCS whether the valve is closed or open
A typical valve position switch refers to a two-position signal, and there are mechanical types, proximity types, and others.
For the full-open and full-close switches of valves, there are mainly mechanical limit switches and proximity limit switches； For the feedback signals corresponding to various valve opening degrees, an intelligent valve positioner or a valve position feedback device is required to reflect the opening degree ranging from 0% to 100%.
Currently, proximity types are more commonly used on site
Used to detect the on/off status of the valve. The installation methods vary; it depends on the form of the product.
They can be divided into contact and non-contact limit switches. Originally, contact types were more common, but now they are mostly designed to be non-contact