Which cage design provides a sharp increase in flow capacity at low plug travel while showing slower increases as it reaches maximum travel?

The quick opening cage design is engineered to deliver a significant increase in flow capacity with minimal movement or travel of the plug. This characteristic is particularly advantageous in applications where rapid response is needed for small changes in valve position, allowing for fine control at the beginning of the range.

As the plug continues to travel towards its maximum position, the rate of increase in flow becomes less steep, leading to a more gradual approach to the maximum flow capacity. This design balances sensitivity and control at low plug positions with stability and predictability as it nears full open, which can be beneficial in many process control scenarios.

In contrast, other designs may provide different flow characteristics. A linear opening cage tends to have a consistent flow increase throughout its travel, while an equal percentage cage offers a gradual and proportional increase across the entire range, which is distinct from the quick response of the quick opening cage. Low-noise trim usually focuses on reducing turbulence and noise rather than optimizing flow characteristics, which is not the primary aspect addressed in this question.