How to correctly detect the electromagnetic flowmeter sensor to ensure the stable operation of the instrument

After decades of development, manufacturers of electromagnetic flowmeters at home and abroad have sprung up like mushrooms after rain. As an instrument that effectively measures the volume flow of conductive media, the main components of electromagnetic flowmeter include sensors, flow conversion and processing instruments. Its main features are no throttling and flow obstruction components, not easy to clog, good corrosion resistance, wide range of applicable media, measurement accuracy is not affected by physical parameters such as temperature, viscosity, density, pressure, specific gravity of the measured medium, and its indication is independent of the type of calibrated liquid within a certain conductivity range.
 
In addition to measuring the flow of general liquids, electromagnetic flowmeters can also measure the volume flow of liquid-solid two-phase liquids, high-viscosity liquids, salts, strong acids, and strong alkali liquids. They can be widely used in cement, chemical, textile, metallurgy, mining, papermaking, medicine, water supply and drainage, food and beverage, sugar making, brewing and other industrial technology departments, especially in the field of environmental protection. At present, electromagnetic flowmeters have become an effective tool for environmental protection departments to quantitatively manage enterprise sewage discharge.
 
Since electromagnetic flowmeters are often used to measure conductive liquids such as tap water, sewage, and seawater, it is easy to contaminate the electrodes or precipitate and scale in the measuring tube wall after running for a period of time. The attached scaling layer in the measuring tube of the electromagnetic flowmeter should be removed in time, otherwise the instrument will not work properly. Practice has proved that regular inspection of electromagnetic flowmeter sensors is the most effective means to avoid failures. What is the specific method? Let me introduce the specific steps to you.
                           


Test equipment:
500MΩ insulation resistance tester and a multimeter.
Test steps:
 
Step 1: When the pipeline is full of medium, use a multimeter to measure the resistance value between the terminals A, B and C. The resistance value between AC and BC should be approximately equal. If the difference is more than 1 times, it may be that the electrode is leaking, or there is condensed water adsorbed on the outer wall of the measuring tube or in the junction box.
 
Step 2: When the lining is dry, use an MΩ meter to measure the insulation resistance between AC and BC (should be greater than 200MΩ). Then use a multimeter to measure the resistance between terminals A, B and the two electrodes in the measuring tube (should be in a short-circuit connection state).
If the insulation resistance is very small, it means that the electrode is leaking, and the entire flow meter should be returned to the factory for repair. If the insulation has decreased but is still above 50MΩ and the inspection result of step one is normal, it may be that the outer wall of the measuring tube is damp, and the inside of the shell can be dried with a hot air blower.
 
Step 3: Use a multimeter to measure the resistance between X and Y. If it exceeds 200Ω, the excitation coil and its lead wires may be open or in poor contact. Remove the terminal board for inspection.
 
Step 4: Check the insulation resistance between X, Y and C. It should be above 200MΩ. If it has decreased, use hot air to dry the inside of the shell. During actual operation, the decrease in coil insulation will lead to increased measurement errors and unstable instrument output signals.
 
Step 5: If it is determined that the sensor is faulty, please contact the manufacturer of the electromagnetic flowmeter. Generally, it cannot be solved on site and needs to be repaired by the manufacturer. The key points of
 
electromagnetic flowmeter troubleshooting include the following:
Electromagnetic flowmeter only needs periodic visual inspection of the meter, check the surrounding environment of the meter, clean the dust, ensure that no water or other substances enter, check whether the wiring is good, check whether there are new strong electromagnetic field equipment installed near the meter or new wires across the meter. If the measuring medium is easy to contaminate the electrode or precipitate and scale in the measuring tube wall, it should be cleaned and cleaned regularly.