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Ingenious cleaning of the electrode of the electromagnetic flowmeter

Electrochemical method
Metal electrodes have an electrochemical phenomenon in the electrolyte fluid. According to the principle of electrochemistry, 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 existing between the electrode/fluid phase. The study of the electric field between the electrode and the fluid reveals that the molecules, atoms or ions of the substance have an enrichment or a poor adsorption at the interface, and it is found that most of the inorganic anions are surface active substances, which have a typical ion adsorption law, while the surface of the inorganic cation Very little activity. Therefore, the electrochemical cleaning electrode only considers the case of anion adsorption. The adsorption of anions is closely related to the electrode potential. The adsorption mainly occurs in the potential range which is more positive than the zero charge potential, that is, the surface of the electrode 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 anion is quickly desorbed, which is the principle of electrochemical cleaning.
Mechanical removal method
The mechanical cleaning method achieves electrode removal by installing a special mechanical structure on the electrodes of the electromagnetic flowmeter. There are currently two forms: one is the use of a mechanical scraper. A scraper with a thin shaft is made of stainless steel, the scraper is taken out through the hollow electrode, and a mechanical seal is used between the thin shaft and the hollow electrode to prevent the outflow of the medium, thus forming a mechanical scraper. When the thin shaft is rotated from the outside, the blade is rotated against the plane of the electrode end to scrape off the dirt. This type of scraper can be manually or automatically driven by a motor driven fine shaft. The domestic electromagnetic flowmeter Xi'an Yunyi's scraper-type electromagnetic flowmeter has such performance, and the performance is stable and easy to operate. 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 kind of cleaning device requires someone to pull the wire brush to clean the electrode, which is not very convenient to operate. It is not convenient for the blade type electromagnetic flowmeter of Xi'an Yunyi.
Ultrasonic cleaning method
The ultrasonic voltage of 45~65 kHz generated by the ultrasonic generator is applied to the electrode, so that the energy of the ultrasonic wave is concentrated on the contact surface between the electrode and the medium, thereby utilizing the ability of the ultrasonic wave to crush the dirt to achieve the purpose of cleaning.
Electrical breakdown
This method is periodically applied between the electrode and the medium using AC high voltage, usually 30~100V. Since the electrodes are attached, the surface contact resistance becomes large, and the applied voltage is almost concentrated on the attached matter, and the high voltage will break down the attached matter and then be washed away by the fluid. In terms of total safety, the electric breakdown method must be used to clean the AC high voltage directly on the sensor signal output terminal when the flow meter is interrupted, the signal line between the sensor and the converter is disconnected, and the power is off.
The above describes the maintenance and cleaning methods of several electromagnetic flowmeter electrodes. In fact, if we can fully consider the measurement medium to pollute the electrode in the early stage selection, then we should choose the blade type electromagnetic flowmeter, which is very convenient. The maintenance and cleaning of the electrodes saves a lot of trouble. Xi'an Yunyi scraper type electromagnetic flowmeter is composed of display instrument, housing, upper coil, lower coil, electrode assembly, etc. The electrode assembly is a detachable scraper electrode structure, which is to put the signal electrode in the belt. On the scraper bar of the scraper, the signal electrode and the scraper bar are fixed in the electrode cup by the pressing nut, and the electrode cup is welded to the inner body body, and the signal electrode is separated from the inner watch body, the electrode cup and the compression nut by an insulating material. When the signal electrode needs maintenance and maintenance, just open the cover and turn the handle by hand to drive the scraper rod to rotate, so that the scraper attached to the signal electrode scrapes off the dirt on the surface of the signal electrode. After cleaning, the direction of the scraper is rotated. To the direction of fluid flow (the direction mark on the knob), the operation is very convenient.

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