Electromagnetic flowmeter is a new type of flow measuring instrument, the 60's along with the development of electronic technology is developing rapidly. It is based onFaraday's law of electromagnetic induction is used to measure the volume flow,conductive fluid. Because of its unique advantages, measurement has been widelyapplied to various kinds of conductive liquid industry. For example, measurement of various acid, alkali, salt and other corrosive liquid; all flammable, explosive medium; all kinds of industrial wastewater, paper pulp, slurry.

The main characteristics of the electromagnetic flowmeter is:

Transmitter structure of electromagnetic flowmeter has the advantages of simple structure, no moving parts, no throttle parts hinder fluid flow, so when the fluid throughdoes not cause any additional pressure loss, at the same time, it will not cause such as wear, clogging and other problems, especially suitable for measurement of solid particles with slurry, sewage and other liquid and solid two-phase flow, as well as various viscous slurry. Likewise, due to its structure, no moving parts, so it can bethrough with corrosion resistant insulating lining and selective electrodes made ofcorrosion resistant materials, has good corrosion resistance, so that the measurementcan be used for all kinds of corrosive media.

The electromagnetic flowmeter is a kind of volume flow measurement instrument, in the process of measurement, it is not affected by the temperature of the measured medium. The viscosity, density and conductivity (within limits) effect. Therefore, just as water electromagnetic flowmeter calibration, can be used to measure other conductive liquid flow, without the need for additional correction.

The range of the electromagnetic flow meter wide, the same set of the electromagnetic flow meter measuring range ratio can reach 1:100. in addition, electromagnetic flowmeter is only proportional to the average flow velocity of the measured medium,and the axial symmetrical distribution of flow (laminar or turbulent).

The electromagnetic flowmeter without the mechanical inertia, sensitive reaction, canmeasure the instantaneous flow pulsation, and good linearity. Therefore, the signalcan be determined directly by the converter linearly into standard signal output, can be indicated, also can be long-distance transmission.

Electromagnetic flowmeter has the excellent properties, but it still has some shortcomings, so that be in the use of restricted. Mainly has the following several points:

Containing a large amount of gas in the measurement of gas, steam and liquid by theelectromagnetic flowmeter can not.

The electromagnetic flowmeter is not currently used in liquid medium measuring very low conductivity, conductivity can not be measured liquid medium was lower than in 10- 5 (S / cm), conductivity is equivalent to the distilled water. The petroleum products ororganic solvent also incapable of action.

③ the measuring pipe insulation lining material by the temperature limit, theelectromagnetic flowmeter is also cannot measure the fluid of high temperature and high pressure.

The electromagnetic flowmeter is influenced by the distribution of velocity, the axial symmetrical distribution conditions, traffic signal and the average velocity is proportional to. So, before and after the straight pipe of electromagnetic flowmeterand there must be a certain length.

The electromagnetic flowmeter is easily affected by external electromagneticinterference.