Why is the fluid resistance of Ball Valve so small?

Ball valve is a common and widely used fluid control equipment in industrial and civil fields. It has the advantages of simple structure, convenient operation, good sealing and low fluid resistance. It occupies an important position in petroleum, chemical industry, water supply and other industries. Location. A distinctive feature of the ball valve is that the fluid resistance is very small, which makes it perform well in many applications that require reducing energy consumption and maintaining efficient flow. The following is an analysis of the reasons for the small fluid resistance of the ball valve, and discusses its structural design and operation. How the principle affects fluid resistance.

1. Effect of structural design of ball valve on fluid resistance
The core component of a ball valve is a ball with a through hole, which is connected to an external handle or actuator through a valve stem. When the through holes on the sphere are parallel to the direction of the pipe, the fluid can pass directly through the through holes on the sphere without going through complicated paths or flow obstacles. This structural design is one of the main reasons for the low fluid resistance of the ball valve.
Compared with other types of valves (such as globe valves or gate valves), the fluid passage of a ball valve is relatively simple, and the fluid is rarely affected by the valve's internal components. The flow path of the fluid is almost linear, reducing bends and reflections, thus maintaining a high flow rate and reducing friction losses between the fluid and the valve body surface.

2. Full-bore design reduces fluid resistance
The ball valve's low fluid resistance is also due to its full-bore design. The hole diameter of a full-bore ball valve is consistent with the diameter of the pipe, which means that the fluid does not experience significant changes in cross-sectional area when passing through the ball valve, thus maintaining smooth flow of the fluid. This design significantly reduces fluid resistance, because when the fluid flows in the pipeline, the sudden contraction and expansion of the fluid cross-sectional area will cause changes in the flow rate, which in turn will produce larger pressure losses and fluid resistance.
In contrast, non-full-bore valves, such as partial stop valves or throttle valves, have relatively low fluid resistance due to their valve core, valve stem and other structures that require fluid to bypass obstacles or pass through a narrow area when passing through the valve. big. The full-bore ball valve allows fluid to pass smoothly with almost no obstruction, maintaining low energy loss.

3. Spherical shape reduces fluid interference
The ball shape of the ball valve also plays a key role in reducing fluid resistance. The ball has a smooth and rounded surface, which helps reduce friction between the fluid and the inner wall of the valve. When the fluid passes through the sphere, the turbulence of the fluid will be greatly reduced due to the smooth surface of the sphere. The reduction in turbulence means the fluid can remain laminar, thus reducing fluid resistance.
In addition, the symmetry of the spherical shape prevents the fluid from being significantly blocked and disturbed when passing through the ball valve, and the flow path is relatively smooth. This is different from other types of valves, where the shape and arrangement of internal parts in valves like globe valves tend to bend and complicate the fluid path, thereby increasing fluid resistance.

4. Full flow-through design in open state
When the ball valve is in the open state, the through hole of the ball is completely aligned with the pipe, which is equivalent to a straight pipe section. When the fluid passes through, there is no obvious contraction or expansion, the streamlines remain smooth, and no significant turbulence or vortex is formed. Since there are no complex flow channels and throttling devices inside the ball valve like other valves, there is almost no additional obstruction when the fluid passes through the ball valve, so the fluid resistance is quite small.
This is different from throttle valves or butterfly valves, which usually have throttling elements or rotating devices in the fluid channel, causing the fluid to flow around or be subject to friction, thereby increasing resistance. The complete flow design of the ball valve avoids these problems and gives it low fluid resistance characteristics.

5. Short-stroke operation reduces resistance changes
The ball valve requires a short stroke during the opening and closing process. It only needs to be rotated 90 degrees to change from fully open to fully closed. This short stroke operation reduces the resistance change of the fluid during the opening and closing process. In other types of valves, which require a longer stroke to open and close, the fluid may experience a gradually decreasing cross-sectional area or bypass flow as it passes, resulting in increased fluid resistance. The short stroke of the ball valve allows fluid to pass quickly, which greatly reduces the fluctuation of fluid resistance during the opening and closing process of the valve.