Introduction of Manual Ball Valve

Manual ball valve is a new type of ball valve. It has some unique advantages of its own structure. For example, the switch has no friction. It’s sealed and it does not wear easily. The opening and closing moment is small. This reduces the size of the actuator. With multi-rotating electric actuator, the medium can be regulated and severely interrupted. Manual ball valve with limit switch is also a common type. Manual ball valves are widely used in petroleum, chemical industry, urban water supply and drainage and other strict cut-off conditions. Manual ball valve is mainly used to cut off, distribute and change the flow direction of medium in pipeline. Ball valve is a new type of valve widely used in recent years.

It has the following advantages:

• 1. It has simple structure, small volume and light weight.
• 2. Its fluid resistance is small, and its resistance coefficient is equal to that of the same length pipe section.
• 3. It is easy to operate and quick to open and close. From full-open to full-close, it only needs to rotate 90 degrees, which is convenient for long-distance control.
• 4. It is compact and reliable. At present, the sealing surface materials of ball valves are widely used in plastics and have good sealing performance. It has also been widely used in vacuum systems.
• 5. It is easy to maintain. The ball valve has simple structure. Seal rings are generally movable and it is easy to disassemble and replace.
• 6. When it is fully open or closed, the sealing surface of the sphere and seat is isolated from the medium. When the medium passes through, it will not cause the erosion of the sealing surface of the valve.
• 7. It can be used in a wide range of applications, ranging from small to several millimeters in diameter and from high vacuum to high pressure. When the sphere rotates 90 degrees, it should present all spherical surfaces at the inlet and outlet so as to cut off the flow.

The working principle of manual ball valve is divided into opening and closing process.            

I. Opening Process

• 1. In the closed position, the ball is pressed on the seat by the mechanical pressure of the stem.            
• 2. When the handwheel is rotated counter-clockwise, the stem moves in reverse, and the bottom angular plane of the stem causes the sphere to detach from the seat.
• 3. The valve stem continues to rise and interact with the guide pin in the spiral groove of the valve stem, which causes the ball to begin to rotate without friction.
• 4. It reaches the full open position, the stem rises to the limit position, and the sphere rotates to the full open position.

II. Closing process

• 1. When it closes, turn the handwheel clockwise, the stem begins to drop and the ball starts to rotate away from the seat.
• 2. As you continue to rotate the handwheel, the stem is guided by the pin embedded in the upper spiral groove, so that the stem and sphere rotate 90 degrees simultaneously.
• 3. When it is about to close, the sphere has rotated 90 degrees without contact with the seat.
• 4. In the last laps of handwheel rotation, the angular plane at the bottom of the stem mechanically wedges the sphere so that it is pressed tightly on the seat to achieve complete sealing.

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