ProControl designed a Carbon Steel epoxy coated declutchable mechanical blocking device which when engaged allows a pre-set valve / actuator partial stroke of approximate 20°.
The Pro Lock mechanical blocking device is located between the valve and the actuator and consists of a heavy duty steel self-contained unit, therefore it does not stress the valves shaft nor the actuators yoke. It is pad lockable and can also be fitted with a limit switch if required by the client to signal that it is engaged. During normal operation the device is passive and will allow the valve to ESD on demand.
When a partial stroke test is required, the device is “engaged” and the ESD valve will only travel to the specified percentage of stroke.