outline: there are various specifications of caliber for your choice: dn40, dn50, dn80, dn100, dn150; one user is assembled with one meter and one card, to use water by card; the data in the card is transmitted to the water meter and then the meter opens the valve and begins water supply, after the money is used up, it will cut off water supply. this series have separate structures, and composed of water use controller, waterproof electric ball valve and transmitting water meter. main function: 1. 220v ac power supply and spare battery at the same time. if the ac is cut off, the spare battery can go into operation; when the spare battery is below capacity, valve is automatically closed. 2. it alarms automatically when being destroyed and valve is automatically closed 3. when the remaining water volume of the user is 20 tons; the controller automatically closes the valve and prompts the user to buy water. water supply is resumed by inserting the card again. 4. when water meter is attacked, it closes the valve instantly and water supply is resumed only after the water management department examines the water meter. 5. after the valve is closed, if the controller can still receive digital signals from transmitting water meter, the remaining water volume shown on the controller will be negative number, and the valve will be closed again 6. it has the function of timing control of the valve, which can effectively prevent the phenomenon of being locked with rust due to long time idle state.