Because the clamp on ultrasonic flow meter has many advantages such as very simple installation, high cost performance, maintenance-free, wide measurement medium, and wide range ratio. With the development of electronic technology and software, this ultrasonic flowmeter has gradually become one of the most popular forms of flow measurement.
Then, in the actual installation and use, how to improve the measurement accuracy of the ultrasonic flow meter? First, we need to determine the main factors that affect the measurement accuracy, and then make targeted improvements.
Because the clamp on ultrasonic water flow meter adopts the measurement principle of the time difference method, the flow meter emits an ultrasonic signal from the outer wall of the pipeline, and then measures the time for the ultrasonic wave to pass through the process of the pipeline material-fluid-pipeline material.
Therefore, the following points are the main factors that should be considered when evaluating measurement error.
1. Pipe size
When the set pipe size is different from the actual pipe size, such as the difference of the inner diameter size is about 1%, the error obtained by the flow conversion is a deviation of 3%. Before on-site installation, the actual outer diameter and wall thickness of the pipe must be measured. If the wall thickness cannot be determined, a thickness gauge can be used to measure.
2. Sensor installation error
The general standard is that the error of installation length ± 1mm can bring the flow error within 1%.
3. Fluid turbulence in the pipeline
When the straight pipe section is short (especially on the upstream side), the fluid is deflected, which will cause a certain deviation error, or when the liquid flow swirls, the indicated value will fluctuate. Be sure to ensure the proper straight run distance before installing the sensor.
4. Scaling or severe corrosion in the pipeline
If the scale deposits or the rust is too serious, the receiving wave may not be received, making the measurement impossible.
5. Changes in water temperature
Real-time calculation of fluid sound velocity to compensate for changes in fluid temperature (new sound velocity measurement system), but with a small amount of error.
6. Output when the fluid contains bubbles
When there are many bubbles in the fluid, it will also affect the accuracy of the actual measurement, and if the bubble content exceeds the capacity of the clamp on water flow meter, it will be impossible to measure.