The performance indicators of the flow meter mainly include accuracy, repeatability, sensitivity, response time, zero drift and span drift.
1. Accuracy: Also called accuracy, that is, the accuracy with which the measurement result of the flow meter is close to the real value. Can be expressed in absolute or relative error:
(1) Absolute error = measured value-true value
(2) Relative error = absolute error / true value
No flow meter can accurately measure the true value of the measured flow, only the ability to make the measured value close to the true value. In practical applications, the accuracy of the standard instrument indication value can only be used as the true value of the measured parameter, and the difference between the indication value of the flow measurement instrument and the standard instrument is the measurement error. The smaller the error value, the higher the reliability of the measuring instrument.
2. Repeatability: refers to the percentage of the difference between the measured value and the average value relative to the maximum scale range when the same flow meter is used to repeatedly measure a certain measurement point under the same measurement conditions. This is one of the important indicators of the stability of the flow meter , and generally needs to be checked during commissioning and daily verification.
3. Sensitivity: refers to the sensitivity of flow meter measurement. The ratio of the amount of change in the output of a commonly used flow meter to the amount of change in the measured parameter that caused the change is expressed.
4. Response time: When the measured value changes, the measured value indicated by the flow meter always takes a certain period of time to be accurately displayed. The time lag between the change of the measured parameter and the measured parameter is the response time of the meter. Some are expressed in time constants, and some are expressed in damping time.
5. Zero point drift and range drift: refers to the percentage of the average change value relative to the range after measuring the relative zero point and the maximum range confirmed by the flow meter for multiple times.