Ball valve develops from cock. its starting and closing parts are balls. It is opened and closed by rotating the ball 90°along the stem axis. Ball valve is used to stop, distribute and change the moving direction of media. V-shaped ball valve has good function of flow adjustment. Characteristics of ball valve: simple structure, good seal small size within a certain inside nominal diameter, small installation size, small driving force, easy operation, quick to start and close, secure seal of both sides, small flow resistance.