The DC7 dribble control valve actuator consists of two solenoid valves attached to a fail-safe valve actuator to enable precise fluid dosage. The two stage design refers to partially closing the valve at a high speed and finishing closure at a slower speed to significantly reduce the water hammer effect, a form of hydraulic shock that damages valves and other pipeline components.
When the dual solenoids are not energized the valve will automatically be in the closed position due to the spring return style "fail safe" actuator design.
When solenoid #1 is energized the valve can actuate fully open. When only solenoid #2 is energized the actuator begins turning back to the closed position and during its return travel "trips" (actuates) the second solenoid, stopping the actuator. The trip position is set to half-way by default and can be adjusted otherwise by the operator. This status is referred to as the "reduced flow position".
Reducing the flow rate at a given point in the dosing operation increases the accuracy of the filling operation, enabling a quick-to-slow operation with the valve only and not requiring the pump speed to be controlled.
The reduced flow position will essentially dictate the timing for complete closure and thus easily settable by the user.