Detailed Introduction Of Lined Ball Valve

A. Lined Ball Valve have the following advantages:

1. Low fluid resistance; its resistance coefficient is equivalent to that of a pipe section of the same length.

2. Simple structure, compact size, and light weight.

3. Tight and reliable. Plastic is currently widely used as the sealing surface material for ball valves, providing excellent sealing properties and widely used in vacuum systems.

4. Easy operation and quick opening and closing. A 90° rotation from fully open to fully closed facilitates remote control.

5. Easy maintenance. Ball valves have a simple structure, and the sealing ring is generally removable, making removal and replacement relatively easy.

6. When fully open or fully closed, the sealing surface between the ball and the valve seat is isolated from the medium, preventing erosion of the valve sealing surface when the medium passes through.

7. Widely applicable, with diameters ranging from a few millimeters to several meters, and applications from high vacuum to high pressure. When the ball is rotated 90 degrees, the inlet and outlet surfaces should be completely spherical, thus shutting off the flow. B. The operating principle of a fixed ball valve is as follows:

I. Opening Process

1. In the closed position, the ball is mechanically pressed against the valve seat by the valve stem.

2. When the handwheel is turned counterclockwise, the valve stem moves in the opposite direction, and the angled flat surface on its bottom causes the ball to disengage from the valve seat.

3. The valve stem continues to rise and interacts with the guide pin in the spiral groove of the valve stem, causing the ball to begin frictionless rotation.

4. When the valve stem reaches the fully open position, it rises to its limit, and the ball rotates to the fully open position.

C. Closing Process of a Fixed Ball Valve

1. To close, turn the handwheel clockwise, and the valve stem begins to descend, causing the ball to separate from the valve seat and begin rotating.

2. Continuing to turn the handwheel, the valve stem is acted upon by the guide pin embedded in the spiral groove, causing the valve stem and ball to rotate simultaneously 90°.

3. When the valve is almost closed, the ball has already rotated 90° without contacting the valve seat. During the last few turns of the handwheel, the angled surface at the bottom of the valve stem mechanically wedges the ball, pressing it tightly against the valve seat and achieving a complete seal.

D. Structural Features of a Fixed Ball Valve:

1. Frictionless Opening and Closing. This feature completely eliminates the sealing issue of traditional valves, which is affected by friction between the sealing surfaces.

2. Top-Entry Structure. Valves installed on the pipeline can be inspected and repaired directly online, effectively reducing equipment downtime and lowering costs.

3. Single Seat Design. This eliminates the issue of abnormal pressure buildup in the valve chamber, which could affect operational safety.

4. Low-Torque Design. The specially designed valve stem allows for easy opening and closing with only a small handwheel.

5. Wedge Seal. The valve relies on mechanical force provided by the valve stem to wedge the ball against the valve seat, sealing it. This ensures the valve's sealing performance is unaffected by fluctuations in pipeline pressure differentials, ensuring reliable sealing performance under various operating conditions.

6. Self-Cleaning Sealing Surface. When the ball tilts away from the valve seat, the fluid in the pipeline flows evenly along the ball sealing surface at a 360-degree angle. This not only eliminates localized erosion of the valve seat by high-speed fluid but also removes accumulated debris on the sealing surface, achieving a self-cleaning effect.

Operation and Use of Fixed Ball Valves

1. Before operation, ensure that the pipeline and valve have been flushed.

2. Valve operation is achieved by rotating the valve stem according to the actuator input signal: A forward rotation of 1/4 turn (90°) closes the valve. A reverse rotation of 1/4 turn (90°) opens the valve.

3. When the actuator direction indicator arrow is parallel to the pipeline, the valve is open; when the indicator arrow is perpendicular to the pipeline, the valve is closed.