The valve consists of a main valve and an external guide valve. It is beneficial for the floating ball to move the guide valve in water because of the change of the page, so that the water supply and closure of the main valve can be controlled within a certain range to prevent overflow and low water level. The valve is suitable for the automatic water supply system of various pools (tanks) water towers in industrial and mining enterprises and civil buildings. It is also commonly used in water supply systems of various pools (tanks) water towers. Pressure boilers follow no water supply system, main valves open and close slowly, without water hammer, tightly sealed, no risk of flooding.