传统的球阀，无论是浮动式或固定式，球体与阀座始终接触，开关扭矩大，密封面容易损伤。V型半球控制阀启闭时，球体先偏转-δ角，然后转动，开关全过程中球体与阀座脱离，故阀座不会被擦伤，并且启闭扭矩小，用于调节及切断纤维类介质。

The ball and the seat ring is always contact with each other on the traditional ball valve. The torque is big from open to close and the seal face is easy to abrade. This kind of ball valve ,the ball first deflexed –δ，then turns. The ball and the seat ring break away from open to close. So the seat ring can not be abraded