ductile iron remote control Float valve

The upper cavity of the main valve is connected with the controling floating ball valve ,the floating ball valve is fixed on the liquid level of the water tank and will be opened ,when the liquid level lowers,then the main valve is opened to supply water to the floating ball valve stays at,the said valve is closed and so is the main valve ,stopping the water supply. Principle: The pilot valve comes as a solenoid valve and then the solenoid valve is opened,the upper cavity