Electromagnetic flowmeter classification

Electromagnetic flowmeter is a kind of induction meter according to Faraday's law of electromagnetic induction to measure the volume flow of conductive medium in the tube. The exciting coil in the pipeline generates a magnetic field, and the measured medium flows through the pipeline to cut the magnetic field line, and generates the induced potential on the two detection electrodes, and its size is proportional to the speed of fluid movement. The measuring pipe is electrically isolated from the fluid and the measuring electrode by means of a non-conductive lining (rubber, tetrafluorofluoride, po, etc.). After the voltage signal converter is processed, and then processed by the microprocessor, the output signal is linear with the flow rate, which is used by the rear instrument for recording, adjustment and control, and can also communicate with the upper computer through RS485.

1. Characteristics

Electromagnetic flowmeter has no moving parts and protruding parts in the fluid, with high reliability, used to measure a variety of acid, alkali, salt solution, pulp, syrup, sewage, beer, wort, such as conductive fluid flow and other suspended solids, gasification steam and viscous substance flow. In addition, due to its good sealing performance, it can also be used for tap water and underground sewer systems.

2. Application

Electromagnetic flowmeter is now widely used in power, chemical, environmental protection, metallurgy, medicine, paper making, food, water supply and drainage and other industrial technology and management departments, used to measure a variety of acid, alkali, salt solution, pulp, syrup, sewage and other conductive fluid flow, sanitary electromagnetic flowmeter is made of stainless steel, can be used for beer, wort, medical water and other flow measurement.

3.Measurement accuracy

Electromagnetic flowmeters are not affected by changes in fluid density, viscosity, temperature, pressure and conductivity, and the sensor induced voltage signal has a linear relationship with the average flow rate, so the measurement accuracy is high, generally 1%. Because this sensor must maintain a proportional relationship between the resistance in the pipeline and the impedance of the measurement circuit, when the conductivity of the measured medium is about 10 ohms · cm, it begins to produce difficulties in manufacturing, and when the conductivity is lower, the thermal noise level increases significantly with the increase of the internal resistance.

4, The advantages of electromagnetic flowmeter

Measure the open flow in the pipe, so there is no additional pressure loss; There are no moving parts in the measuring pipe, so the sensor life is extremely long. Only the lining and electrode of the sensor part are in contact with the measured liquid, and as long as the electrode and lining materials are reasonably selected, they can be resistant to corrosion and wear. The anti-corrosion electromagnetic flowmeter can be made of special materials to make electrodes and linings, and can measure almost all corrosive media.

5,Installation environment requirements

A. The sensor should be installed in a dry and ventilated place, avoid damp and easily flooded places, and try to avoid direct sunlight and rain.

B. Avoid installation in places where the ambient temperature is too high. The electromagnetic flowmeter of a body structure is also subject to the ambient temperature of electronic components, which is lower.

C. There should be no strong leakage current on the pipeline where the sensor is installed, and it should be far away from the equipment with strong electromagnetic field, such as large electrical equipment and large transformers, so as to avoid electromagnetic field interference;

D. The pipeline or ground where the sensor is installed should not have strong vibration, especially a type instrument;

E. The ambient temperature of the converter installation is between -10 and 45℃; Relative humidity of air ≤ 85%; No strong vibration at the installation site; The surrounding air does not contain corrosive gases; Converters should be installed indoors as much as possible. When installed outdoors, measures should also be taken to prevent sun and rain.