Description

How Does A Casting Trunnion Mounted Ball Valve Work?

Opening process

1. In the closed position, the ball is pressed against the seat by the mechanical of the stem.
2. When the handwheel is turned counterclockwise, the valve stem moves in the opposite direction, and its bottom angular flat makes the ball disengage from the valve seat.
3. The stem continues to lift and interacts with the guide pin in the stem’s helical groove, causing the ball to begin to rotate without friction.
4. Until it reaches the fully open position, the valve stem is lifted to the limit position, and the ball rotates to the fully open position.

Closing Process

1. When closed, turn the handwheel clockwise, the valve stem starts to descend and the ball leaves the valve seat and starts to rotate.
2. Continue to rotate the handwheel, the valve stem is acted by the guide pin embedded in the upper spiral groove, so that the valve stem and the ball rotate 90° at the same time.
3. Just before closing, the ball has rotated 90° without making contact with the seat.
4. During the last few turns of the handwheel, the angular plane at the bottom of the valve stem mechanically wedges the ball to press it tightly against the valve seat to achieve a complete seal.

Casting Trunnion Mounted Ball Valve Structural Features

1. Open and close without friction. This function completely solves the problem that the traditional valve affects the sealing due to the friction between the sealing surfaces.
2. Top-loading structure. The valve installed on the pipeline can be directly inspected and maintained online, which can effectively reduce the shutdown of the device and reduce the cost.
3. Single valve seat design. It eliminates the problem that the medium in the cavity of the valve affects the safety of use due to abnormal pressure increase.
4. Low torque design. The specially designed valve stem can be easily opened and closed with only a small handwheel valve.
5. Wedge-shaped sealing structure. The valve relies on the mechanical force provided by the valve stem to press the ball wedge onto the valve seat to seal, so that the sealing performance of the valve is not affected by the change of pipeline pressure difference, and the sealing performance is reliably guaranteed under various working conditions.
6. Self-cleaning structure of sealing surface. When the ball is tilted away from the valve seat, the fluid in the pipeline passes 360° evenly along the sealing surface of the ball, which not only eliminates the local scouring of the valve seat by the high-speed fluid, but also washes away the accumulation on the sealing surface to achieve the purpose of self-cleaning .