Maintenance and cleaning method of electromagnetic flow meter electrode

Abstract: The maintenance and cleaning method information of electromagnetic flowmeter meter electrodes is provided by excellent flowmeter and flowmeter manufacturers and quotation manufacturers. When measuring sewage, slurry and other media, the inner wall of the pipe and the surface of the electrode are prone to scaling and adhesion. When the conductivity of the fouling substance is different from the conductivity of the measured medium, it will bring about measurement errors. The adhesion of sludge and oil to the electrode will also be affected. More flowmeter manufacturers choose models and price quotations. You are welcome to inquire. The following is the details of the maintenance and cleaning methods of electromagnetic flowmeter electrodes. When measuring sewage, slurry and other media, the inner wall of the pipe and the surface of the electrode are prone to scaling and adhesion. When the conductivity of the fouling substance is different from the conductivity of the measured medium, it will bring about measurement errors. The adhesion of sludge and oil to the electrodes will also cause the output of the instrument to swing and drift. Therefore, maintenance treatment of the electrodes is required in some cases. For example, cleaning electrodes and replacing electrodes. The commonly used methods for electrode cleaning are as follows: (1) Electrochemical methods Electrochemical phenomena exist in metal electrodes in electrolyte fluids. According to the principle of electrochemistry, there is an interfacial electric field between the electrode and the fluid, and the interfacial electric field between the electrode and the fluid is caused by the electric double layer existing between the electrode and the fluid. The study of the electric field at the interface between the electrode and the fluid found that the molecules, atoms or ions of the substance have enriched or poor adsorption at the interface, and found that most inorganic anions are surface active substances with a typical ion adsorption law, while the surface of inorganic cations The activity is small, so electrochemical cleaning of the 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 telegraph surface with the opposite sign. On the electrode surface of 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, which is the principle of electrochemical cleaning. Some companies add a negative voltage of about 1.2.1.4V to the two electrodes in the form of common mode by adding the voltage drop of the two forward diodes to the signal loop. Because the voltage applied to the two electrodes is a negative DC common-mode voltage, the amplifier will not be saturated. The DC common-mode voltage is superimposed on the tiny alternating flow signal, the DC is isolated by the capacitor, and the common-mode voltage is suppressed by the preamplifier. The DC common-mode voltage will not affect the flow measurement. The DC negative voltage applied to the electrode forms a negative electric field, which can repel the substances attached to the electrode, so as to achieve the purpose of cleaning the electrode. This method can effectively, automatically and continuously carry out electrode cleaning in AC excitation. However, for low-frequency rectangular wave excitation, due to the high polarization voltage amplitude, the effect is not necessarily very good, so it is rarely seen recently. (2) Mechanical removal method The mechanical removal method realizes electrode removal by installing a special mechanical structure on the electrode. There are currently two forms: one is to use a mechanical scraper. A gua knife with a thin shaft is made of stainless steel, and the gua knife is drawn out through a hollow electrode, and a mechanical seal is used between the thin shaft and the hollow electrode to prevent the medium from coming out, so it becomes a mechanical scraper. When the slender shaft is turned from the outside, the gua knife rotates against the plane of the electrode end to scrape off the dirt. This scraper can be used manually or automatically with a motor-driven thin shaft. The other is in the tubular electrode, which is equipped with a wire brush for removing dirt, and the shaft is wrapped in a sealed“O”ring to prevent fluid leakage. This cleaning device requires someone to constantly pull the wire to clean the electrodes. (3) The ultrasonic cleaning method applies the ultrasonic voltage of 45~65kHz generated by the ultrasonic generator to the electrode, so that the energy collection of the ultrasonic wave becomes larger, and the applied voltage is almost concentrated on the attachment, and the high voltage will break down the attachment. , and then washed away by the fluid. Starting from safety, the use of the electric breakdown method must be when the measurement meter is interrupted, the signal line between the sensor and the converter and the converter is disconnected, and the AC (50Hz or 60Hz) high-voltage power is directly connected to the sensor signal output terminal in the event of a power failure. on the cleaning. (5) Increase the average flow rate in the measuring tube and use a small-pointed electrode to measure the medium that is easy to scale and adhere. Usually, a sensor smaller than the diameter of the process tube can be selected to increase the flow rate. Experience has shown that the average flow velocity in the pipe is higher than 2m/s, and the possibility of precipitation and adhesion is generally small. There are also measures to instantly increase the flow rate 3—5m/s (depending on the attachment situation) to scour the attachment layer. The electrode head protrudes into a pointed shape, which is subject to a large flushing force of the fluid (because the flow velocity of the tube wall is equal to zero, and the tip leaves the boundary layer of the tube wall and enters the flow velocity layer), so the possibility of adhesion and pollution is small. In addition, due to the large internal resistance of the signal of the small-area electrode itself, the change of the internal resistance of the signal caused by the adhesion and pollution of the electrode has little effect, so the impact on the measurement of the instrument is also small. I hope the above analysis will be helpful to everyone. Because it only works if it is used correctly. And we will provide you with this information in a timely manner. Guarantee the normal use of you and the product. The above is the whole content of this article. You are welcome to inquire about the flowmeter selection and quotation of our factory. 'Maintenance and Cleaning Method of Electromagnetic Flow Meter Electrode'
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