Electromagnetic flowmeter electrode daily maintenance
Electromagnetic flowmeter electrodes should be regularly cleaned and cleaned
Electromagnetic Flowmeter If the measured medium is relatively dirty for a long time, then after the electromagnetic flowmeter has worked for a period of time, fouling may occur on the electrode. When the conductivity of the fouling material is different from the conductivity of the measured medium, measurement errors will occur. The attachment of sludge and oil to the electrode will also cause the meter output to swing and drift. Therefore, in this case we need to regularly maintain and clean the electromagnetic flowmeter electrodes.
Electrode cleaning commonly used methods are the following:
1. Electrochemical Methods Electrochemical phenomena exist in metal electrolytes in electrolyte fluids. According to the electrochemical principle, there is an interface electric field between the electrode and the fluid, and the interface between the electrode and the fluid is caused by the double electric layer existing between the electrode/fluid phase. The study of the electric field at the interface between the electrode and the fluid reveals that the molecules, atoms, or ions of the material have an enriched or poorly adsorbed phenomenon at the interface, and that most of the inorganic anions are surface-active substances that have typical ion adsorption laws and the surface of inorganic cations. Very little activity. Therefore, the electrochemical cleaning electrode only considers the anion adsorption. Adsorption of anions is closely related to the potential of the electrode. The adsorption takes place mainly in the potential range that is more positive than the zero charge potential, ie, the surface of the electrode with an opposite charge. On the surface of the electrode with the same charge, when the residual charge density is slightly larger, the electrostatic repulsive force is greater than the adsorption force, and the anion desorbs quickly. This is the principle of electrochemical cleaning.
2. Mechanical removal method The mechanical removal method is achieved by installing a special mechanical structure on the electrode to achieve electrode removal. There are currently two forms: One is the use of a mechanical scraper. A scraper with a thin shaft was made of stainless steel, and the scraper was pulled out through the hollow electrode. A mechanical seal was used between the thin shaft and the hollow electrode to prevent the outflow of the medium, thus forming a mechanical scraper. When turning the thin shaft from the outside, the scraper rotates against the plane of the electrode tip to remove dirt. The scraper can be manually or automatically scraped by a motor-driven fine shaft. The other is in the tubular electrode, equipped with a wire brush to remove dirt, and wrapped in a sealed “O†ring to prevent fluid leakage.
3. Cleaning method Ultrasonic voltage of 45~65kHz generated by the ultrasonic generator is added to the electrode, so that the energy of the ultrasonic wave is concentrated on the contact surface between the electrode and the medium, so that the ability of the ultrasonic wave is used to crush the dirt and achieve the purpose of cleaning.
4. Electrical breakdown method This method uses AC high-voltage electricity periodically added between the electrode and the medium, generally adding 30~100V. As the electrode is attached, its surface contact resistance becomes larger, the applied voltage is almost concentrated on the attached matter, and the high voltage breaks down the attached matter and is then washed away by the fluid. The starting point for total safety, the use of electrical breakdown method must be in the flow meter interrupt measurement, the signal line between the sensor and the converter is disconnected, power failure, the exchange of high voltage directly in the sensor signal output terminal for cleaning.
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