In process interlocking applications, sequential operating control is dependent on the interlock function of trapping and releasing the appropriate keys relative to the position of the host valve (i.e. open and/or closed positions). Typically speaking, Smith Flow Control provides mechanical interlocks with one key free and one key trapped.
SFC’s valve interlocks have two aperture points, designed to receive the interlocking keys, which change the state of the valve (open or closed). When the key is trapped in the left side, (looking directly at the key aperture points), the interlock is in the locked closed position (i.e. the valve is closed). When the key is trapped in the right aperture point, the valve is locked open. Insertion of the keys enables rotation/movements of the valve operating handwheel or lever.