I. product overview

The intelligent electromagnetic flowmeter is an induction meter to measure the volume flow rate of the conductive medium in the tube according to the law of electromagnetic induction. Electromagnetic flowmeter can output 4-20ma current signal for recording, adjustment and control while meeting the requirements of field display. It has been widely used in chemical industry, environmental protection, metallurgy, medicine, papermaking, water supply and drainage and other industrial technologies and management departments.

In addition to measuring the flow rate of the general conductive liquid, the electromagnetic flowmeter can also measure the volume flow rate of solid-liquid two-phase flow, liquid flow with high viscosity and saline, strong acid, strong alkali liquid.

Ii. Working principle

The measuring principle of intelligent electromagnetic flowmeter is based on Faraday's electromagnetic induction law. The measuring tube of the flowmeter is a non - conductive alloy short tube lined with insulation material. The two electrodes are fixed on the measuring tube through the pipe wall along the pipe diameter direction. The electrode head is flush with the inner surface of the lining. When the field coil is excited by a two-way square wave pulse, a working magnetic field with a magnetic flux density of B will be generated in the direction perpendicular to the axis of the measuring tube. At this point, if the fluid with certain conductivity flows through the measuring tube, the cut magnetic field line will be induced to electromotive force E. The electromotive force E is proportional to the product of the magnetic flux density B, the inner diameter of the measuring tube d and the average velocity V. The electromotive force E(flow signal) is detected by the electrode and sent to the converter through the cable. After amplifying the flow signal, the converter can display the flow rate and output the pulse, analog current and other signals for flow control and regulation.

1. 

E = KBdV

Where, E-- is the signal voltage (V) between electrodes

B-- magnetic flux density (T)

D -- measuring tube inner diameter (m)

V-- average velocity (m/s)

In the formula, K and d are constants. Since the excitation current is constant, B is also a constant. Then, it can be seen from E=KBdV that the volume flow rate Q is proportional to the signal voltage E, that is, the signal voltage E induced by the flow rate has a linear relationship with the volume flow rate Q. Therefore, as long as E is measured, flow Q can be determined. This is the basic principle of electromagnetic flowmeter.

According to E=KBdV, parameters such as temperature, pressure, conductivity and liquid-solid composition ratio of liquid-solid two-phase fluid medium will not affect the measurement results. As for the flow state, as long as the axisymmetric flow (such as laminar flow or turbulence flow) will not affect the measurement results. So the electromagnetic flowmeter is a real volume flowmeter. For manufacturers and users, as long as the ordinary water calibration can be used to measure the volume flow of any other conductive fluid media, without any modification, this is a prominent advantage of the electromagnetic flowmeter, is not any other flowmeter. There are no moving and choke parts in the measuring tube, so there is almost no pressure loss and high reliability.

Three, performance characteristics

1. Simple and reliable instrument structure, no moving parts, long service life.

2. No flow blocking parts, no pressure loss and fluid blockage.

3. No mechanical inertia, fast response, good stability, can be applied to automatic detection, adjustment and program control system.

4. The measurement accuracy is not affected by the type of the measured medium and its temperature, viscosity, pressure and other physical parameters.

5. Different combinations of polytetrafluoroethylene or rubber lining and HC, HB, 316L, Ti and other electrode materials can adapt to the needs of different media.

6. Full digital volume processing, strong anti-interference ability, reliable measurement, high accuracy, flow measurement can reach 150: l.

7. Chinese menu operation, easy to use and easy to operate.

8. High definition backlit LCD display.

9. With two-way flow measurement and two-way total accumulation function, it has three integrators to display the positive cumulative value, the reverse cumulative value and the difference product calculation.

10. Output mode: current, frequency two-way output function and rs-485, MODBUS, HART interface.

11. Adopt SMD device and surface mount (SMT) technology, high circuit reliability.