Structure and application: This kind of valve makes up of main valve, one-way valve, pin valve, ball valve and pressure meter etc. It applies to the water supply and drainage system directly operated by the water pump in the industrial and mine enterprises and high buildings. It has the function of controlling the speed of opening and closing and preventing the medium from flowing backwards when the pump starts or stops and making the pump adjust to the best running speed and reducing water hammering and water pounding.