What is the best type of valve to use for throttling, or when the valve must be opened and closed frequently?

The globe valve is the best choice for throttling and frequent operation due to its design, which allows for precise control of flow. Its internal structure features a movable disk that can vary the size of the flow passage, making it ideal for regulating the flow rate. This capability makes the globe valve effective in applications where fine adjustments to flow are necessary.

Moreover, globe valves are designed to withstand the physical stresses of constant operation and frequent opening and closing, which contributes to their durability in demanding environments. They can maintain a tighter seal compared to some other valve types when closed, which helps prevent leaks during operation.

In contrast, other valve types such as ball valves are designed primarily to be either fully open or fully closed, providing low resistance to flow but not offering the same level of control for throttling. Similarly, gate valves are not suitable for throttling because, when partially open, they can create turbulence and pressure drops, whereas butterfly valves, though capable of some throttling, are typically less precise than globe valves due to their design and the flow characteristics they produce.

With these factors in mind, the globe valve stands out as the optimal choice for applications requiring frequent adjustments and flow regulation.