The electromagnetic flowmeter is based on Faraday’s law of electromagnetic induction to measure the volume flow of conductive liquid! He has a series of advantages. The electromagnetic flowmeter has a wide range of applications. It is widely used in chemical, chemical fiber, mining and metallurgy, papermaking, sugar making, water supply, sewage treatment, port dredging, hydraulic machinery and other departments.The advantages of electromagnetic flowmeters are as follows:1. The transmitter is simple and reliable, there are no moving parts, and there are no throttling parts that hinder the flow of the measured medium, so there will be no clogging problems.2. Because there is no throttling, there is almost no pressure loss when the detected medium flows through the measuring tube of the transmitter. Only the resistance along this section of the pipe section is negligible.3. The electromagnetic flowmeter is a volume flow measuring instrument, which can not only measure a single conductive liquid, but also measure the flow of a liquid-solid two-phase medium without being affected by physical parameters such as temperature, viscosity, density, and specific gravity of the medium. . Therefore, the electromagnetic flowmeter can be used to measure the flow of other conductive liquids or liquid-solid two-phase media only after being calibrated with water.4. The electromagnetic flowmeter has a very wide range, and the range can be changed arbitrarily. For flow meters of orifice plate, venturi tube, etc., the maximum rated flow is determined by the pressure difference. When designing and calculating, it is selected according to the various parameters of the measured medium. Once the parameters change during use, measurement errors will be brought about, and it may even be impossible to use.5. Electromagnetic flowmeter has no mechanical inertia and is sensitive. It can measure instantaneous pulsating flow, and its linear shape is good, and it can be directly scaled. Therefore, the measurement signal can be directly converted into a standard signal output by the converter linearly, which can be displayed on the spot, or the signal can be transmitted over a long distance.6. Good corrosion resistance. Because the part of the electromagnetic flowmeter that is in contact with the measured medium is only the measuring tube lining and the electrode surface, suitable materials can be selected according to the physical and chemical properties of the measured medium.7. Easy to install. The transmitter can be installed horizontally or vertically, and the requirements for the front straight pipe section are lower.8. Easy to use, easy to maintain, and long life.Flow measurement of low conductivity liquids!Generally speaking, the electromagnetic flowmeter has electrical conductivity requirements for the measured medium, and it needs to have a certain electrical conductivity. For media with extremely low conductivity, such as petroleum products or organic solvents, the flow measurement will be restricted. This is because when the conductivity of the measured medium is extremely low, the contact resistance between the electrode and the liquid will increase, which will increase the internal resistance of the transmitter, and the influence of the distributed capacitance of the signal transmission county will also increase, which will attenuate the signal. , And produce a phase shift. At the same time, the interference potential is enhanced due to the decrease of conductivity. This is mainly caused by electrostatic induction. Therefore, the following measures are usually used for liquid measurement with lower conductivity:1. Reduce the internal resistance of the transmitter; on the premise of ensuring measurement accuracy, in order to be able to measure the flow of liquids with lower conductivity and extend the length of the signal transmission line, the internal resistance of the transmitter should first be reduced. The use of large-area electrodes or a three-electrode structure to reduce the contact resistance between the electrode and the liquid can reduce the internal resistance of the transmitter. At the same time, a low-noise preamplifier is set inside the transmitter to enable the transmitter to output with low impedance and high noise ratio.2. Increase the input impedance of the converter. 3. Shield drive circuit.
Post time: 21-09-21