The LDB intelligent type electromagnetic flowmeter consists of sensor and converter. It is based on Faraday's law of electromagnetic induction, which is used to measure the volume flow of conductive liquid with conductivity greater than 5μs/cm. It is an inductive meter for measuring the volume flow of conductive medium. In addition to measuring the volume flow of general conductive liquid, it can also be used to measure the volume flow of strong corrosive liquids such as strong acid and alkali and uniform liquid-solid two-phase suspension liquid such as slurry, pulp and paper pulp. It is wdely used for flow measurement of petroleum, chemical, metallurgy, textile, papermaking, environmental protection, food and other industrial sectors and municipal management, water conservancy construction, rivers and other fields.

Electromagnetic flowmeter working principle

According to the principle of Faraday electromagnetic induction, a pair of detecting electrodes are mounted on the wall of the pipe perpendicular to the axis of the measuring pipe and the magnetic line of force. When the conductive liquid moves along the axis of the measuring pipe, the conductive liquid cuts the magnetic line of force to generate an induced potential.The induced potential is detected by the two detection electrodes and the value is proportional to the flow rate. The value is: E=K·B·V·D

Where: E- induced potential;

K-the factor related to the magnetic field distribution and the axial length;

B-magnetic induction intensity;

V-conductive liquid average flow rate;

D-electrode spacing; (measure inner diameter of the pipe)

The sensor transmits the induced potential E as a flow signal to the converter. After a series of digital processing such as amplification and conversion filtering, the instantaneous flow rate and the accumulated flow rate are displayed by the dot matrix liquid crystal with backlight. The converter has 4-20mA output, alarm output and frequency output, and has RS-485 communication interface, and supports HART and MODBUS protocols.

Electromagnetic Flowmeter Installation Precautions

1. Installation location

The pipe must be completely filled with liquid, which is critical, otherwise the flow display will be affected and measurement errors will occur. The pipe structure must be designed to ensure that the flow pipe is always filled with fluid.When the fluid is diverted or combined with solid particulate deposits,vertical installation is recommended, but for vertical installations,it need to follow the fluid direction from bottom to top to ensure that the pipe is full of fluid.

Installation location

Avoid air bubbles. If air bubbles enter the flow pipe, the flow display will be affected ,and measurement errors will occur. When the fluid contains air bubbles, the pipe must be designed to prevent air bubbles from accumulating in the flow pipe. If there is a valve near the flow measuring pipe, place the pipe upstream of the valve as much as possible to avoid pressure reduction and bubble generation.

Avoid air bubbles

2. Installation direction

If the electrode is perpendicular to the ground, bubbles gathered at the top or deposits deposited at the bottom can cause measurement errors. Install the separate type flow pipe junction box and the integrated type converter on top of the pipe system to prevent water from entering.

Installation direction

3.Direct pipe section requirements

Do not install anything near the flow pipe that may interfere with the magnetic field, the induced signal voltage, and the flow field distribution of flow pipe. In general,it is necessary to ensure a 5D of straight pipe section for the upstream and a 3D of straight pipe section for the downstream. If there are interference flow parts such as elbows and valves, the length of the straight pipe section required should be larger. It is highly recommended to install the valve at the downstream end to avoid flow fluctuations in the flow pipe and to avoid counting from the empty pipe status.

Maintain stable fluid conductivity

Avoid installing the flowmeter in a position where fluid conductivity is not uniform.If chemicals are injected near the upstream end of the electromagnetic flow meter, flow visualization may be affected.To avoid this situation, it is recommended to change the chemical injection to the downstream end of the flowmeter.If it is necessary to inject from the upstream end, use a straight pipe section long enough (about 50D) to ensure that the fluid is thoroughly mixed with the chemicals.