I want to re-state what I said earlier: when working with DC solenoid, be sure to check if the solenoid is latching or non-latching. Some DC valves use latching solenoids, the coil resistence is typically very low (a few ohms). These valves must be ‘pulsed’ open or close, you should never apply constant voltage more than 50 to 200 milliseconds, as that will smoke the coil. Other DC valves that are non-latching, the coil resistance is typically higher (30 to 60 ohms), and you can apply constant voltage on it to open the valve, and release voltage to close the valve.