What does response time in tank level monitoring represent, and how is it commonly measured?

• A. Response time indicates the sensor's accuracy; measured by calibration.
• B. Response time indicates how quickly the sensor reflects level changes; measured as t90 or rise time from 10% to 90% of final value.
• C. Response time indicates mean time to repair; measured in hours.
• D. Response time indicates temperature drift; measured by long-term test.

Answer: (B)

Response time in tank level monitoring refers to how quickly the sensor’s output reflects a real change in liquid level. It’s about dynamic performance, not accuracy. The common way to quantify it is to look at the rise time, often called t90: the time it takes for the signal to move from 10% to 90% of the final value after a step change in level. This matters because a fast response lets the control system react promptly to level changes, reducing lag and improving stability and alarm timing. Calibration and accuracy concern how close readings are to the true level, not how fast they change. Mean time to repair is a maintenance metric, and temperature drift describes slow, long-term shifts with temperature, not immediate sensor response. Therefore, the correct concept is that response time shows how quickly the sensor reflects level changes, measured as t90 or rise time from 10% to 90% of the final value.