Opening procedure
1. In the closed position, the ball is pressed against the seat by the mechanical pressure of the valve stem.
2. When the handwheel is turned counterclockwise, the valve stem moves in reverse, and its bottom angular plane makes the ball free from the seat.
3. The valve stem continues to lift and interact with the guide pin in the spiral groove of the valve stem so that the ball begins to rotate without friction.
4. Until it reaches the full open position, the valve stem is raised to the limit position, and the ball is rotated to the full open position.

Closing procedure
1. When closing, turn the handwheel clockwise, the stem begins to drop and the ball starts to rotate away from the seat.
2. Continue to rotate the handwheel, the valve stem is subjected to the action of the guide pin embedded in its upper spiral groove, so that the valve stem and the ball rotate 90° at the same time.
3. When close, the ball has rotated 90° without contact with the seat.
4. In the last few turns of the hand wheel rotation, the angular plane at the bottom of the valve stem is mechanically wedged to compress the ball, so that it is tightly pressed against the seat to achieve complete seal.