What are the performance indicators of flow meters?

The quality of a measuring instrument can be reflected by its accuracy, reproducibility, sensitivity, response time, zero drift and range drift.
(1) Accuracy: Also known as precision, it refers to the degree of accuracy of the instrument's measurement results close to the actual value. It can be expressed as absolute error or relative error:

① Absolute error = measured value - true value
② Relative error = absolute error / true value

No instrument can measure the true value of the measured parameter with absolute accuracy, and can only strive to make the measured value close to the true value. In practical applications, only the indication value of a standard instrument with higher accuracy can be used as the true value of the measured parameter, and the difference between the indication value of the measuring instrument and the indication value of the standard instrument is the measurement error. The smaller the error value, the higher the reliability of the measuring instrument.

(2) Reproducibility: It refers to the percentage of the difference between each measured value and the average value relative to the maximum scale range when a parameter is repeatedly measured with the same instrument under unchanged measurement conditions. This is an important indicator of the stability of instruments and meters, and generally needs to be tested at the time of commissioning and daily calibration.

(3) Sensitivity: It refers to the sensitivity of the instrument measurement. It is usually expressed as the ratio of the change in the output of the instrument to the change in the measured parameter that causes the change.

(4) Response time: When the measured parameter changes, it takes a period of time for the measured value indicated by the instrument to be accurately expressed. This period of time and the lag time between the change in the measured parameter is the reaction time of the instrument. Some are expressed as time constants (such as temperature measurement with thermal resistors), and some are expressed as damping time (such as resistance measurement with ammeters).

(5) Zero drift and range drift: It refers to the percentage of the average change value relative to the range after multiple measurements of the relative zero point and maximum range confirmed by the instrument. (end)