An electric solenoid valve, methods for operating and/or actuating the solenoid valve, valve system diagnostics, and applications for use are described. The valve may be designed to actuate in a manner so as to control liquid flow into and/or through a device, such as a spray nozzle. By altering the characteristics of the electrical signal transmitted to the solenoid valve, the instantaneous pressure across the valve and duration of fluid flow through the valve can be controlled with a single actuator. Controlled cyclic durations of flow may be implemented to regulate the exact timing of flow through the valve. Alternatively, cyclic durations may occur with a pulse-width modulation technique in which the duty cycle regulates average flow rate through the valve.