The accuracy of the electromagnetic flowmeter is an important indicator for evaluating its measurement accuracy. The following is a detailed analysis of the accuracy of the electromagnetic flowmeter, which is expressed and summarized in points:
1. Accuracy range
The accuracy range of the electromagnetic flowmeter is usually between ±0.2% and ±1.0%, depending on different manufacturers and models. This means that under ideal conditions, the deviation between the measurement result of the electromagnetic flowmeter and the true value will not exceed this range.
2. Factors affecting accuracy
The liquid to be measured contains bubbles: The presence of bubbles may cause the electromagnetic flowmeter to be unable to accurately distinguish between liquid and bubbles, causing measurement errors.
The measured liquid is not full in the pipeline: The liquid in the pipeline is not full, and a large number of bubbles are filled above, which will also affect the accuracy of the electromagnetic flowmeter.
Short-circuit effect of conductive deposits: Due to the gradual deposition of conductive materials, the flow signal may be short-circuited, resulting in measurement errors.
The conductivity of the liquid exceeds the allowable range: The output impedance of the electrode depends on the conductivity of the measured liquid and the electrode. When the conductivity is lower than the lower limit, the electromagnetic flowmeter will not work properly or the numerical display will slow down.
Spatial electromagnetic interference: If the cable between the sensor and the converter is long and there is strong electromagnetic interference around, the cable may introduce interference signals, resulting in display distortion, nonlinearity or large-scale shaking.
Asymmetric flow of the measured fluid: Non-axisymmetric velocity distribution and cyclotron current will affect the output and produce large measurement errors.
Vibration at the installation site: The electromagnetic flowmeter has strict requirements on the vibration of the installation site, and it must be installed in a place with less vibration, otherwise it will cause measurement errors.
3. Measures to improve accuracy
Choose the appropriate model and specification: Choose the appropriate electromagnetic flowmeter model and specification according to the measurement medium, flow range, pipe size and other factors.
Perform regular calibration: Calibrate the electromagnetic flowmeter regularly to eliminate errors and maintain its accuracy. Calibration methods include direct measurement method (real flow calibration method), indirect measurement method (dry calibration), on-site "flow comparison" and standard device calibration.
Pay attention to installation and maintenance: Install and maintain according to the instructions to ensure that the electromagnetic flowmeter is in good working condition. For example, keep away from strong magnetic fields and vibration sources to ensure that the liquid in the pipeline is full and the flow rate is evenly distributed.
In summary, the accuracy of the electromagnetic flowmeter is affected by many factors, but by selecting the appropriate model and specification, performing regular calibration, and paying attention to installation and maintenance, its measurement accuracy can be effectively improved.