Electromagnetic flowmeters, 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 will 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. Let's introduce several electromagnetic flowmeter electrode cleaning methods for your reference.

Electrode cleaning commonly used methods are the following:

　　 1. electrochemical method

The metal electrode has an electrochemical phenomenon 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 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 with 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 to use 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 the thin shaft is turned from the outside, the blade rotates against the plane of the electrode tip to scrape off dirt. The scraper can be manually or automatically scraped by a motor-driven fine shaft. Domestic electromagnetic flowmeter Xi'an cloud instrument scraper electromagnetic flowmeter has such performance, and stable performance, easy operation.

The other is in the tubular electrode, equipped with a wire brush to remove dirt, and the shaft is wrapped in a sealed “ O ” ring to prevent fluid leakage. This type of cleaning device requires that someone frequently pulls the wire brush to clean the electrode, and the operation is not very convenient, and it is not convenient for the scraper type electromagnetic flowmeter of Xi'an Yunyi.

　　 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 of the electrode and the medium, so that the ability of the ultrasonic wave is used to break the dirt and achieve the purpose of cleaning.

　　 4. Electric breakdown method

This method uses AC high-voltage electricity periodically added between the electrode and the medium, typically 30 to 100V . As the electrode is attached, its surface contact resistance becomes larger, the applied voltage is almost concentrated on the attachment, and the high voltage breaks down the attachment 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, the power failure of the AC high voltage directly in the sensor signal output terminal for cleaning.

The above describes the maintenance and cleaning methods of several kinds of electromagnetic flowmeter electrodes. In fact, if we can fully consider that the measurement medium will pollute the electrodes in the early selection, then we should choose the scraper type electromagnetic flowmeter, which can be very convenient. The maintenance and cleaning of the electrodes eliminates a lot of trouble. Xi'an Yunyi scraper electromagnetic flowmeter consists of a display instrument, a housing, an upper coil, a lower coil, an electrode assembly, etc., wherein the electrode assembly is a detachable scraper-type electrode structure. This structure is to put the signal electrode on the belt. On the scraper bar of the scraper, the signal electrode and the scraper bar are fixed in the electrode cup by the compression nut, the electrode cup is welded on the inner surface of the body, and the signal electrode is separated from the inner surface body, the electrode cup and the compression nut by the insulating material. Open ; 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 that is close to the signal electrode scrapes 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 sign on the knob), the operation is very convenient. Electromagnetic flowmeter electrode cleaning method

The following is the cleaning method after contamination of electrodes with several special media (only applicable to electromagnetic flowmeters that can be inserted into the electrodes) Electromagnetic flowmeter electrode cleaning method

( 1 ) For inorganic contamination , the electrode may be immersed in 0.1 mol/L dilute hydrochloric acid for 30 minutes , washed with pure water , and immersed in 3.5 MOL/L potassium chloride solution for 6 hours before use.

( 2 ) Immerse in 4% hydrogen fluoride solution for 3 ~ 5s , remove with distilled water, then soak in 0.1mol/L hydrochloric acid solution for several hours, rinse with distilled water, calibrate

( 3 ) For organic oil and oil film contamination , the surface of platinum or gold can be washed with detergent and washed with pure water , and then immersed in 3.5MOL/L potassium chloride solution for 6 hours.

( 4 ) The surface of platinum is heavily polluted by an oxide film . The surface of platinum or gold can be polished with toothpaste , then washed with pure water and then immersed in 3.5MOL/L potassium chloride solution for 6 hours before use.

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