The ball valves in domestic are produced as standards; they can divide into many types.
 1.Ball valves with floating ball. The sphere of ball valves is floated. Under the function of medium's pressure, the ball will have displacement and press tightly on the sealing side of exit end. The structure of these ball valves is simple and the sealing performance is good.
2.Ball valves with fixed ball. The ball is fixed, while the valve seat is floated. With the pressure of medium, the valve seat will moved and the seal rings press tightly with the ball to ensure the sealing.
3. Ball valves with elastic ball (tract ball valves). The ball is elastic. The ball and seal ring of valve seat are made by metal material. The sealing specific pressure is very big, it can not meet the needs of sealing with the own pressure of medium.