The working principle of the three-piece ball valve is as follows:
I. opening process
In the closed position, the ball is pressed on the valve seat by the mechanical pressure of the valve rod. When the handwheel is turned anticlockwise, the valve rod moves in a reverse direction, and the angle plane at the bottom of the valve rod makes the ball free from the valve seat. The valve rod continues to lift and interacts with the guide pin in the screw groove of the valve rod so that the ball starts to rotate without friction. Until it reaches the fully open position, the valve rod is lifted to the limit position, and the ball rotates to the fully open position.
II. Closing process
When the valve is closed, rotate the handwheel clockwise, and the valve stem starts to lower and the ball starts to rotate when it leaves the valve seat. Continue to rotate the handwheel, and the valve rod is affected by the guide pin embedded in the spiral groove on it so that the valve rod and the ball can rotate 90 ° at the same time. Near closure, the ball has rotated 90 ° without contact with the seat. In the last few turns of the handwheel, the angle plane at the bottom of the valve stems mechanically wedges against the ball to press it tightly on the valve seat to achieve complete sealing.