Electromagnetic flowmeter is the new flow measurement instruments with the rapid development of electronic technology. It is based on Faraday's law of electromagnetic induction, is used to measure the volume flow of conductive fluid. Because of its unique advantages, it has been widely used in a variety of industrial conductive liquid measurement. For example, measuring a variety of acid, alkali, salt and other corrosive liquids; all kinds of flammable, explosive media; all kinds of industrial sewage, pulp, mud and so on.
Electromagnetic flowmeter is a volume flow measurement instrument, which is not affected by the temperature, viscosity, density and conductivity of the measured medium (within a certain range) during the measurement. Therefore, the electromagnetic flowmeter only needs the water calibration, and then it can be used to measure the flow of other conductive liquid, without the need for additional amendments.
Electromagnetic flowmeter without mechanical inertia, responsive, can measure the instantaneous pulsating flow, and with good linearity. Therefore, the measurement signal can be directly converted into a standard signal output directly with the converter, can be both local display and long-distance transmission.
Although the electromagnetic flowmeter has the above characteristics, but now it has some shortcomings, so it has some certain restrictions in application as following:
Electromagnetic flowmeter cannot be used to measure the gas, steam and liquid containing a lot of gas.
As the measurement tube insulation lining material is limited by the temperature, the current industrial electromagnetic flowmeter cannot measure high temperature and high pressure fluid.
The electromagnetic flowmeter is affected by the velocity distribution. Under the condition of axisymmetric distribution, the flow signal is proportional to the average flow rate. Therefore, the electromagnetic flowmeter must also have a certain length before and after the straight pipe.