How to prevent the electrode of electromagnetic flowmeter fouling production?

　　Electromagnetic flowmeter as an important instrument in industrial production and process control, its accuracy and reliability is directly related to production efficiency and product quality. However, in the process of use, the electrode of the electromagnetic flowmeter is often due to direct contact with the medium and produce dirt, which in turn affects the measurement accuracy and service life. Therefore, the prevention of electromagnetic flowmeter electrode fouling, is to ensure the normal operation of the instrument is the key. In this paper, we will introduce in detail how to prevent electromagnetic flowmeter electrode fouling.

　　First of all, it is crucial to understand the composition of the measured medium. Different media contain different chemical compositions, such as calcium, magnesium and other ions, which are easy to form scale in the fluid. Therefore, in the selection and use of electromagnetic flowmeter before, the composition of the measured medium should be analysed in detail, to minimize the content of substances that can easily lead to scaling. For example, if the medium contains a high concentration of calcium, magnesium and other ions, you can consider pretreatment of the medium, such as softening, filtration, etc., in order to reduce the concentration of scaling substances. For some media containing solid particles, filtration devices can be used to remove larger particles and reduce particle deposition and scaling on the electrode surface.

　　Appropriately increasing the temperature of the fluid can also reduce the solubility of certain substances, thereby reducing the possibility of scaling. However, it should be noted that the temperature should not be too high, so as not to cause damage to the flowmeter or affect the measurement accuracy. At the same time, increasing the flow rate of the fluid can also effectively reduce the deposition of dirt on the electrode surface. Higher flow rates can make dirt less likely to adhere to the electrode, but also help to wash out the already formed scale. However, the flow rate should not be too high, so as not to produce excessive pressure and wear on the flowmeter. Therefore, in the actual application, according to the characteristics of the medium and the design requirements of the flowmeter, reasonable setting of the fluid temperature and flow rate.

　　Selection of suitable electrode materials is also an important measure to prevent fouling. Different electrode materials have different corrosion resistance and anti-fouling ability. For example, tantalum electrode has good corrosion resistance and anti-fouling ability, suitable for some corrosive and easy to scale the medium. Titanium electrode also has good corrosion resistance and wear resistance, to a certain extent, can reduce scaling. For some special media, you can choose a specific electrode material according to the characteristics of the medium, such as Hastelloy, platinum-iridium alloy. These materials not only have excellent corrosion resistance and anti-fouling ability, but also ensure the measurement accuracy and extend the service life.

　　In addition to the choice of electrode material, the appropriate lining material can also reduce the risk of electrode scaling. The choice of lining material should be based on the temperature, pressure, corrosivity and other factors of the medium for comprehensive consideration. For example, polytetrafluoroethylene (PTFE) lining has excellent corrosion resistance and non-stick properties, which can effectively prevent the adhesion of dirt on the inner wall of the electrode and measuring tube. Polyurethane liners also have good abrasion resistance and anti-scaling properties. Selection of appropriate lining materials can not only reduce the generation of dirt, but also protect the internal structure of the flowmeter from corrosion and wear.

　　When installing an electromagnetic flowmeter, make sure it meets specifications and avoid installing it in a location that is prone to vortexing, sedimentation or scaling. For example, it should be far away from the elbow of the pipeline, valves and other parts of the pipeline, and choose the location of the longer straight pipe section to install the flowmeter. Installation should ensure that the flowmeter and pipeline connection is tight, no leakage and loose, so as to avoid scaling due to fluid leakage or unstable flow. In addition, the installation of the flowmeter should be checked regularly to ensure that it is in good working condition.

　　Establishing a regular cleaning and maintenance programme is also an important measure to prevent electrode fouling. Cleaning can be done using appropriate cleaning agents and tools, such as soft brushes and ultrasonic cleaners. During the cleaning process, care should be taken to protect the electrode material from damage. At the same time, the corrosion and wear of the electrodes should be checked, and the damaged electrodes should be replaced in time. The integrity of the liner should also be checked, and if it is broken or detached it should be repaired or replaced in time. Regular cleaning and maintenance not only removes dirt from the electrode surface, but also identifies and deals with potential problems in a timely manner, ensuring the accuracy and reliability of the flowmeter.

　　In addition, some electromagnetic flowmeter adopts special anti-fouling technology, such as electrode coating, ultrasonic cleaning and so on. Electrode coating can increase the surface smoothness of the electrode and reduce the adhesion of dirt. Ultrasonic cleaning, on the other hand, can remove the scaling on the electrode surface by emitting ultrasonic vibration. These techniques not only improve the flowmeter's anti-fouling ability, but also extend the service life and reduce maintenance costs.

　　In practice, mechanical descaling methods can also be used. Mechanical descaling is the physical removal of dirt from the electrode surface. You can use stainless steel with a thin shaft knife, through the hollow electrode to lead the knife, the thin shaft and hollow electrode between the choice of mechanical sealing to prevent the media outflow. When the shaft is rolled from the outside, the scraper rolls against the electrode tip and removes the dirt. This method can be operated manually or the fine shaft can be driven by a motor to automatically scrape. However, it should be noted that mechanical descaling may cause some damage to the electrode surface, so it should be operated with caution when used.

　　Electrochemical cleaning is also an effective descaling method. The principle of electrochemical cleaning is to use the interfacial electric field between the electrode and the fluid to remove dirt by changing the electrode potential. The adsorption of anions is closely related to the electrode potential, when the electrode potential changes, the adsorption state of anions will also change, so as to achieve the removal of dirt. Electrochemical cleaning has the advantages of easy operation and good cleaning effect, but it requires specific equipment and electrolyte, and may produce harmful gases, so it is necessary to take appropriate safety measures when using it.

　　Backflush cleaning is a method of flushing the electrode surface using the reverse flow of fluid. Close the downstream valve of the flowmeter and open the upstream valve, so that the fluid flows in the reverse direction to flush the electrode surface. This method is simple to operate, no additional equipment, applicable to the fluid containing sand, small particles and other solid impurities. However, the cleaning effect is limited, only to remove the loose dirt on the surface, and the reverse flow may cause damage to the internal structure of the flowmeter.

　　In summary, the prevention of electromagnetic flowmeter electrode fouling need to start from a number of aspects. Understand the composition of the measured medium, reasonable setting of the fluid temperature and flow rate, select the appropriate electrode and lining materials, to ensure that the installation specifications, the development of regular cleaning and maintenance programmes and the use of special anti-scaling technology and mechanical descaling, electrochemical cleaning and other methods, can effectively reduce the electrode fouling. In practical application, appropriate measures and methods should be selected according to specific conditions to ensure the accuracy and reliability of electromagnetic flowmeter, providing strong support for industrial production and process control.