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Electromagnetic Flowmeter
Published on:2014-12-20 9:16:51 Hits:

Electromagnetic Flowmeter 


Electromagnetic flowmeter is 60 years with the development of electronic technology and the rapid development of a new type of flow measurement instruments. It is made according to Faraday's law of electromagnetic induction, used to measure the volume flow of conductive fluid. Because of its unique advantages, has been widely used to measure a variety of conductive liquids industry. For example, to measure a variety of corrosive liquid acid, alkali and salt; variety of flammable and explosive medium; a variety of industrial wastewater, pulp, mud, etc.

The main features of electromagnetic flowmeters are:

① simple electromagnetic flowmeter transmitter structure, no moving parts, there is no obstruction of fluid flow restrictor parts, so it will not cause any additional pressure loss when the fluid passes through, but it does not cause problems such as wear, clogging other issues, particularly suitable for measuring solid particles with pulp, sewage and other liquid-solid two-phase flow, and a variety of viscous slurry and so on. Also, due to its structure with no moving parts, it can be attached to an insulating lining and corrosion resistant material made of electrode selection, play a very good corrosion resistance, so that can be used by a variety of corrosive media measurement.

② electromagnetic flowmeter is - kind of volume flow measurement instruments, in the measurement process, it is not the temperature measured media. Viscosity, density, and conductivity (in a certain range) effects. Thus, just after the electromagnetic flowmeter calibrated with water, can be used to measure the flow of other conductive liquid, without requiring additional other modifications.

③ electromagnetic flowmeter measurement range is extremely wide, the same electromagnetic flowmeter range of up to 1: 100. In addition, the electromagnetic flowmeters with only average velocity is proportional to the measured medium, with the axis of symmetry of the distribution of the flow state (laminar or turbulent) irrelevant.

④ electromagnetic flowmeter no mechanical inertia, responsive, and can measure the instantaneous flow pulsation, and good linearity. Thus, the measured position signal converter to convert directly into a standard signal output linearly, may indicate, also long-distance transmission.

Although electromagnetic flowmeter has excellent characteristics described above, but it also has some shortcomings, that are subject to certain restrictions on use. Have the following main points:

① electromagnetic flowmeter gas, vapor and a liquid containing a large amount of gas can not be used for measurement.

② electromagnetic flowmeter is not currently used to measure the conductivity of the liquid medium is low, the measured conductivity of the liquid medium is not less than 10 -5 (S / cm), equivalent to the conductivity of distilled water. Petroleum products or organic solvents also powerless.

③ As the measuring tube temperature insulation lining material is limited, the current industrial electromagnetic flowmeter can not measure the temperature and high pressure fluids.

④ electromagnetic flowmeter flow velocity distribution by impact, under conditions of axial symmetry in the distribution, and the average flow rate signal proportional to flow rate. So, before electromagnetic flowmeters must have before a certain length of straight pipe.

⑤ electromagnetic flowmeter susceptible to external electromagnetic interference.


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