A regulator valve includes a duct, a valve element, and an actuator. The duct has an inner surface defining a flow passage. The valve element is movably disposed within the flow passage between an open position, in which fluid is permitted to flow through the flow passage, and a closed position, in which fluid is restricted from flowing through the flow passage. The actuator is coupled to the valve element and at least facilitates movement thereof between the closed and open positions and locking of the valve element in an intermediate position therebetween. The actuator comprises a shaft and a locking system. The shaft is coupled to the valve element and moves therewith. The locking system is coupled to the shaft and is activated when the valve element is in the intermediate position, to thereby at least inhibit movement of the shaft and the valve element.