What does the turndown ratio measure?

The turndown ratio is a critical measure in instrumentation and control systems, specifically referring to the range of flow measurement capabilities of a system. It is defined as the ratio of the maximum controllable flow to the minimum controllable flow. This ratio illustrates the flexibility and effectiveness of a control system in handling varying flow rates. A high turndown ratio indicates that the system can operate efficiently across a wide range of conditions, making it suitable for applications where flow rates may fluctuate significantly. Understanding the turndown ratio is essential for engineers and operators when selecting instrumentation for processes that require precise flow control, as it directly impacts the performance and reliability of the control system.