At present, with the acceleration of industrialization and urbanization! The demand for water for urban residents and industrial water has increased greatly, followed by the continuous expansion and continuation of the pipeline, and the measurement requirements for water have been put on the agenda.

On the main line, electromagnetic flowmeters are used as the basis for measurement, and water meters are used in the section of the branch line entering the household. The water meter can be measured once every time, which is nothing more than the occasional interruption of the water supply, which will not cause a major impact, but the electromagnetic flowmeter installed on the main line can not be disassembled every time it is tested, because once the water is stopped, it will cause a lot of inconvenience.

It is for this reason that the current more popular method of calibration of online electromagnetic flowmeters and other metering instruments is to series a Fuji ultrasonic flowmeter, and judge the degree and reliability of online meters through the reading of Fuji ultrasonic flowmeter.

Faced with the error of ultrasonic flowmeter and online instrument, how should we correctly analyze the reliability of online instrument?

This premise: In its calibration cycle, the Fuji ultrasonic flowmeter is generally not more than 12 months from the time of the last third-party calibration, which is considered within the calibration cycle.

In general, in my personal experience, if the error between the Fuji ultrasonic flowmeter and the online flow meter is within ±2.0%, the accuracy of the online meter can be considered acceptable. If it exceeds this range, it is considered that the online instrument has a certain deviation. You need to correct the online meter. Because the accuracy specification of the ultrasonic flowmeter is identified as ±1.0% (although the accuracy of the ultrasonic flowmeter is currently ±0.5%), if the accuracy of the on-site online measuring instrument is ±0.5% (there are also accuracy of ±0.2%), the error is allowed to ±1.5%, plus human factors, so the uncertainty is more appropriate to ±2.0%.

So how to minimize the impact of human factors?

First of all, we must choose the quality of the ultrasonic flowmeter, as a calibration instrument, its accuracy, repeatability, stability must have certain requirements.

In the field measurement, the scientific measurement method is based on the existing online instrument as the center, select two measurement points in the existing instrument equidistant two measurements, each measurement point, at the 1 point and 2 points of its section, each test once, and then the data of the four measurements before and after the accumulation and then divide by 4, the data obtained with the online instrument for comparison. The comparison of data is relatively reliable at this time.

The above views, only represent personal views, looking forward to peer exchange advice (18821150890), thank you!