Principle and structure of electromagnetic flowmeter
The measurement principle of FE20 electromagnetic flowmeter is based on Faraday's law of electromagnetic induction: when the conductive liquid cuts the magnetic field line in the magnetic field, an induced potential is generated in the conductor,
The induced potential is E:
In the formula: K——–instrument constant
In the formula: B————magnetic induction intensity
In the formula: V————the average flow velocity in the section of the measuring tube
In the formula: D——– measure the inner diameter of the pipe section
When measuring the flow rate, the conductive liquid flows through the magnetic field perpendicular to the flow direction at a speed V, the flow of the conductive liquid induces a voltage proportional to the average flow rate, and the induced voltage signal directly contacts the liquid through two or more The sensor electrode is detected, and sent to the converter through the cable for intelligent processing to realize the display of the instantaneous flow of the fluid, the display of the accumulated flow, and the communication between the flow data and the control system. There are no moving and blocking parts in the measuring tube, so there is almost no pressure loss and high reliability.
FE20 Electromagnetic Flow Features…Advantages
●Electromagnetic flowmeter is an instrument for measuring volume flow, and the measurement results have nothing to do with physical parameters such as flow velocity distribution, flow pressure, temperature, density, viscosity, etc.;
There are no moving parts in the measuring tube, which is convenient for maintenance and management, so the service life of the sensor is long; there are no blocking parts, because there is no pressure loss;
The conductivity of the liquid to be measured can be as low as 5μS/cm, and with various lining materials, it can be used to measure the flow of various acids, alkalis, salt solutions, and mud, pulp, pulp and other media with high accuracy;
Usually ±0.5% ±0.2%;
●Because the induced voltage signal is formed in the whole space full of magnetic field, it is the average value of the pipe section, so the straight pipe section required by the sensor is short, generally 3D before and after 5D;
●On the sensor part, only the lining and electrodes are in contact with the liquid to be measured. As long as the electrodes and lining materials are selected reasonably, they can be resistant to corrosion and wear, ensuring long-term use;
●Bidirectional measurement system, which can measure forward flow and reverse flow;
●High-definition backlight LCD display, Chinese and English menu operation, easy to use, simple to operate, easy to learn and understand;
The converter has reliable performance, high precision, low power consumption, stable zero point, convenient parameter setting, LCD display, which can display parameters such as cumulative flow, flow rate, and flow percentage;
●Using 16-bit embedded microprocessor, fast operation, high precision, programmable frequency low-frequency rectangular wave excitation, improved measurement stability, low power consumption;
●Full digital processing, strong anti-interference ability, reliable measurement, high precision, flow measurement range up to 150:1;
●Ultra-low EMI switching power supply, using a wide range of power supply voltage changes, good EMC resistance;
●With digital communication signal output such as RS485, RS232, HART and Modbus.
FE20 Electromagnetic Flow Characteristics…Limitations
●Electromagnetic flowmeter cannot measure gas, steam and liquid containing a large amount of gas.
●Electromagnetic flowmeter can not be used to measure liquid medium with very low conductivity at present. The conductivity of the measured liquid medium cannot be lower than 5μS/cm, which is equivalent to the conductivity of distilled water. It is powerless for petroleum products or organic solvents.
●The insulating lining of the measuring tube is limited by the temperature, and the electromagnetic flowmeter cannot measure high temperature liquid, and it is suitable for the temperature of the measuring medium ≤180°C ●The measurement principle of the electromagnetic flowmeter is based on Faraday's law of electromagnetic induction, so it is easily affected by external electromagnetic interference sources .
The liquid medium used to measure electrical conductivity requires that the electrical conductivity should be greater than 5μs/cm (the electrical conductivity of tap water, raw water is about 100…5000μs/cm, which can be used to measure various acids, alkalis, salt solutions and mud, ore pulp, paper pulp It is mainly used in petrochemical, steel, electric power, metallurgy, textile, food, pharmaceutical, paper and other industries as well as municipal environmental protection, water conservancy and other fields .