Which design feature is characteristic of control valve plugs?

The characteristic design feature of control valve plugs is a linear opening cage. This feature allows the valve plug to move linearly to control the flow of fluid through the valve. As the plug lifts off the seat, the flow area increases, which facilitates precise control over the flow rate. This is particularly essential for applications requiring accurate adjustments to flow in response to varying process conditions.

Linear opening cages provide a predictable flow characteristic, making them suitable for processes that demand a stable and consistent response to changes in control signals. The ability to achieve a linear relationship between valve position and flow rate is crucial in many applications, ensuring that operators can maintain desired process conditions effectively.

In contrast, other designs such as variable opening cages may introduce complexities in flow characteristics, while rotational opening cages are typically found in different types of valves, such as ball or butterfly valves. Fixed opening cages do not allow for adjustment of flow, which is not suitable for control applications where fluid flow needs to be modulated.