Maintenance points of electromagnetic flowmeter

Electromagnetic flowmeter is a flowmeter product based on Faraday's law of electromagnetic induction. The measuring tube of the flowmeter is a short tube lined with insulating material and non-magnetic alloy. Two electrodes are fixed on the measuring tube through the wall along the tube diameter. Today we mainly introduce the maintenance points of electromagnetic flowmeter, hoping to help users better apply the product.

1. Comprehensive inspection of electromagnetic flowmeter: appearance inspection, converter characteristic test, measurement value calibration, measurement of each voltage, measurement of insulation resistance, circuit confirmation, etc.; checking zero drift and adjusting zero point are very important. Online inspection often omits the inspection of sensor operation and only performs converter calibration, so as to compare the online inspection results with historical data to determine whether the instrument should continue to be used, repaired or updated.

2. Verify the working condition of the electromagnetic flowmeter: Verify the electromagnetic flowmeter for any abnormalities through online inspection. Check the flow sensor and converter separately for pipelines that cannot stop the flow of the medium, use analog signal devices and other general instruments to test the converter with high calibration accuracy, check the insulation resistance and copper resistance of the excitation coil including the excitation connection cable, as well as the excitation current output by the converter, and check the magnetic field strength and other indirect methods. Check the contamination/deposition of the electrode and lining and clean them. In addition to the zero point check, check the electromagnetic flowmeter separately, and also check the flow sensor, converter and connection cable.

3. Check the connecting cables: This check includes checking the conductivity and insulation resistance of each core of the signal line and the excitation line, and checking whether the grounding of each shielding layer is intact.

4. Inspection of electromagnetic flowmeter converter: This inspection is to use a universal instrument and an analog signal device that matches the flowmeter model to replace the sensor to provide flow signals for zero adjustment and calibration. Calibration includes zero point inspection and adjustment, set value inspection, excitation current measurement, current/frequency output inspection, etc.

5. Inspection of electromagnetic flowmeter sensor: indirectly evaluate whether the magnetic field strength has changed by inspecting the excitation coil and the excitation current measured by the converter; measure the electrode contact resistance to evaluate the contamination of the electrode surface and the condition of the lining adhesion layer; check the insulation resistance of each part to determine the degree of deterioration of the parts, so as to estimate the change in flow value introduced by the change in flow area before and after cleaning the adhesion layer.