As an indispensable product in industrial production, instrumentation has been widely used in daily life. However, as a precision instrument, there are many places that need attention in the use and daily maintenance of flow meters. Electromagnetic flowmeter is an intelligent instrument, and its maintenance is particularly important.If the medium measured by the electromagnetic flowmeter is relatively dirty for a long time, then after the electromagnetic flowmeter has been working for a period of time, dirt will be generated on the electrode. When the conductivity of the fouling substance is different from the conductivity of the measured medium, measurement errors will be brought about. The adhesion of sludge and oil to the electrode will also cause the instrument output to swing and drift. Therefore, in this case, we need to maintain and clean the electrodes of the electromagnetic flowmeter regularly. The following introduces several cleaning methods of electromagnetic flowmeter electrodes.1. Mechanical removalThe mechanical removal method is to achieve electrode removal by installing a special mechanical structure on the electrode. There are currently two forms:One is to use a mechanical scraper, a scraper with a thin shaft is made of stainless steel, and the scraper is drawn out through a hollow electrode. When the thin shaft is rotated from the outside, the scraper rotates close to the surface of the electrode end to scrape off the dirt. This kind of scraper can be manually or automatically scraped by a motor-driven thin shaft.The other is to install a wire brush for removing dirt in the tubular electrode, and the shaft is wrapped in a sealed O-ring to prevent fluid leakage. This cleaning device requires someone to frequently pull the wire brush to clean the electrode, which is not very convenient to operate.2. Electrochemical methodMetal electrodes have electrochemical phenomena in the electrolyte fluid. 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 electric double layer between the electrode/fluid phase. The study of the electric field at the interface between the electrode and the fluid has found that the molecules, atoms or ions of the substance have an enriched or poor adsorption phenomenon at the interface, and it has been found that most inorganic anions are surface-active substances with a typical ion adsorption law, while the surface of inorganic cations The activity is very small. Therefore, the electrochemical cleaning electrode only considers the case of anion adsorption. The adsorption of anions is closely related to the electrode potential, and the adsorption mainly occurs in the potential range that is more positive than the zero-charge potential, that is, the electrode surface with a different charge. On the surface of the electrode with the same charge, when the residual charge density is slightly larger, the electrostatic repulsion is greater than the adsorption force, and the anions are quickly desorbed. This is the principle of electrochemical cleaning.3. Ultrasonic cleaning methodThe ultrasonic voltage of 45-65kHz generated by the ultrasonic generator is applied to the electrode, so that the energy of the ultrasonic is concentrated on the contact surface of the electrode and the medium, so as to use the ultrasonic power to break the dirt and achieve the purpose of cleaning.4. Electric breakdownThis method uses alternating high voltage to be periodically added between the electrode and the medium, generally 30-100V. As the electrode is attached, its surface contact resistance becomes larger, and the applied voltage is almost concentrated on the attachment. The high voltage will break down the attachment and then be washed away by the fluid. From the perspective of safety, the use of the electrical breakdown method must be to clean the AC high voltage directly on the sensor signal output terminal when the flow meter interrupts the measurement, the signal line between the sensor and the converter is disconnected, or the power fails.
Regular cleaning of the electrodes will extend the service life of the electromagnetic flowmeter. It should be known that once the electromagnetic flowmeter fails, the maintenance cost will be relatively high. Only in normal use can be maintained regularly, in order to reduce unnecessary losses and maximize the value of the product.
Post time: 21-09-21