The manufacturer of electromagnetic flowmeter describes the calibration requirements of electromagnetic flowmeter
Although the electromagnetic flowmeter has been calibrated before leaving the factory, it needs to be calibrated again due to the different measurement site environment and fluid characteristics. The electromagnetic flowmeter manufacturer will introduce the on-line calibration requirements of the electromagnetic flowmeter.
1. Conduct safety insulation test on the excitation coil of electromagnetic flowmeter, which shall be greater than 20m Ω.
2. Test the resistance of the sensor electrode of the electromagnetic flowmeter to the ground. If the resistance value is between 2-20kf, accompanied by charge and discharge, and the resistance of the two electrodes is similar, it is good.
3. Test the analog output and frequency output of electromagnetic flowmeter converter, observe its linear change, and calculate its large linear error, which shall not exceed ± 0.5%.
4. The copper resistance of the excitation coil of the electromagnetic flowmeter shall be tested to ensure that it is the same as the original factory value.
5. For electromagnetic flowmeter above DN 1200mm, push stage NB shall be tested, and the current error shall not exceed 12mA.
6. Test the excitation current of the converter of the electromagnetic flowmeter, and observe the value of its output and the original current of the converter, and the error shall not exceed ± 0.5% 25mA 。
7. Generally, 1 ~ 3 flow points are selected for online calibration of electromagnetic flowmeter, and the calibration times of each flow point shall not be less than 3 times. The calibration flow point shall be the same as or close to the flow point required for the actual operation of the flowmeter, or shall be selected according to the calibration point requirements specified by the user.
8. In the calibration process, the flow stability of each flow point shall be within 1% ~ 2% - flow method, while the total amount method can be within 5%. When completing the verification process of one flow point, the temperature change of verification medium shall not exceed 1 ℃, and when completing the whole verification process, it shall not exceed 5 ℃.
The above is the calibration requirements and specifications of electromagnetic flowmeter.
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