Beijing Control Instrument ProductionIntelligent electromagnetic flowmeterIt is an induction instrument that measures the volume flow rate of conductive medium inside a tube based on Faraday's law of electromagnetic induction. It uses embedded microcontroller technology to achieve digital excitation, and adopts CAN fieldbus on the electromagnetic flowmeter. It belongs to the domestic * * and has reached a good level of technology in China. Electromagnetic flow meters can not only meet on-site display requirements, but also output 4-20mA current signals for recording, regulation, and control. They have been widely used in industrial technology and management departments such as chemical, environmental protection, metallurgy, medicine, papermaking, and water supply and drainage. In addition to measuring the flow rate of general conductive liquids, electromagnetic flow meters can also measure the volumetric flow rate of liquid-solid two-phase flow, high viscosity liquid flow, and salt, strong acid, and strong alkali liquids. |
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The instrument structure is simple, reliable, without moving parts, and has a long working life.
There are no flow blocking components, and there is no pressure loss or fluid blockage.
No mechanical inertia, response * *, good stability, can be applied to automatic detection, adjustment, and program control systems.
The measurement accuracy is not affected by the type of measured medium and its physical parameters such as temperature, viscosity, density, pressure, etc.
The use of different combinations of PTFE or rubber lining and electrode materials such as HC, HB, 316L, Ti, etc. can adapt to the needs of different media.
There are various types of flow meters available, including pipeline type and plug-in type.
Using EEPROM memory, the storage of measurement and operation data ensures safety and reliability.
● It has two forms: integrated and separated.
● High definition LCD backlit display. |
Technical Specifications |
Table 1 |
Applicable Pipe Diameter |
DN25 to DN2600 (non-standard below DN25) |
electrode material |
316L (stainless steel), HC (Hastelloy C), HB (Hastelloy B), Ti (titanium), Ta (tantalum) |
Applicable Medium |
Liquids with conductivity>5us/cm |
measurement range |
0.1-10m/s (expandable to 15m/s) |
upper range limit |
0.5～10m/s,**1～5m/s |
accuracy class |
0.3 level, 0.5 level, 1.0 level (differentiated by caliber) |
output signal |
4～20mADC, Load ≤ 750 Ω; 0-3KHz, 5V active, variable pulse width, * * effective frequency output: RS485 interface |
work pressure |
1.0MPa, 1.6MPa, 4.0MPa, 16MPa (special) |
fluid temperature |
-Reference lining material for 20 ℃~80 ℃, 80 ℃~130 ℃, 130 ℃~180 ℃ |
ambient temperature |
Sensor -40 ℃~80 ℃; Converter -15 ℃~50 ℃ |
ambient temperature |
≤ 85RH (at 20 ℃) |
Cable outlet size |
M20×1.5 |
power supply |
220VAC±10%; 50Hz±1Hz; 24VDC±10% |
power waste |
≤8W |
Shell protection level |
Integrated: IP65 Split type: Sensor IP68 Converter IP65 |
Grounding ring material |
1Cr18Ni9Ti (stainless steel), HC (Hastelloy C), Ti (titanium), Ta (tantalum), Cu (copper) |
flange connection |
Standard GB9119-88 (DIN2051, BS4504) |
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working principle |
Intelligent electromagnetic flowmeterThe measurement principle is based on Faraday's law of electromagnetic induction. The measuring tube of the flowmeter is a short tube lined with insulating material and non-magnetic alloy. Two electrodes are fixed on the measuring tube through the wall in the direction of the pipe diameter. The electrode tip is basically flush with the inner surface of the lining. When the excitation coil is magnetized by bidirectional square wave pulses, it will generate a working magnetic field with a magnetic flux density of B in the direction perpendicular to the axis of the measuring tube. At this point, if a liquid with a certain conductivity flows through the measuring tube, it will cut the magnetic field lines and induce an electromotive force E. The electromotive force E is proportional to the magnetic flux density B, and the product of the inner diameter d of the measuring tube and the average flow velocity V. The electromotive force E (flow signal) is detected by the electrode and sent to the converter through a cable. After amplifying and processing the flow signal, the converter can display the fluid flow rate and output signals such as pulses and simulated currents for flow control and regulation. |
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E＝KBdV
In the formula, E represents the signal voltage (V) between the electrodes
B -- Magnetic flux density (T)
D -- Measuring the inner diameter of the tube (m)
V - Average flow velocity (m/s)
In the equation, K and d are constants. Since the excitation current is constant, B is also constant. Therefore, from E=KBdV, it can be seen that the volume flow rate Q is proportional to the signal voltage E, that is, the signal voltage E induced by the flow velocity is linearly related to the volume flow rate Q. Therefore, as long as E is measured, the flow rate Q can be determined, which is the basic working principle of electromagnetic flowmeter.
According to E=KBdV, parameters such as temperature, density, pressure, conductivity, and liquid-solid composition ratio of the measured fluid medium will not affect the measurement results. As for the flow state, as long as it conforms to axisymmetric flow (such as laminar or turbulent flow), it will not affect the measurement results. Therefore, electromagnetic flowmeter is a true volumetric flowmeter. For manufacturers and users, as long as ordinary water is used for actual calibration, the volume of any other conductive fluid medium can be measured without any correction. This is one of the * * advantages of electromagnetic flow meters, which is not available in any other flow meters. There are no active or obstructed components inside the measuring tube, so there is almost no pressure loss and it has high reliability. |
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Product Selection |
1. Range confirmation
It is advisable for the measured medium flow rate of a general industrial electromagnetic flowmeter to be between 2-4m/s. In special circumstances, the lower flow rate should not be less than 0.1m/s and the higher flow rate should not exceed 8m/s. If the medium contains solid particles, the commonly used flow rate should be less than 3m/s to prevent excessive friction between the lining and the electrode; For viscous fluids, the flow velocity can be chosen to be greater than 2m/s. A higher flow velocity helps to automatically eliminate the effect of viscous substances attached to the electrode, which is beneficial for improving measurement accuracy. Under the condition that the range Q has been determined, the size of the flowmeter diameter D can be determined based on the range of flow velocity V mentioned above, and its value can be calculated by the following formula: |
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Q: Flow rate (/h)
D: Inner diameter of pipeline (m)
V: Flow rate (m/h)
The range Q of the electromagnetic flowmeter should be greater than the expected flow rate value, while the normal flow rate value should be slightly greater than 50% of the high scale of the flowmeter's full range. |
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