The widely used electromagnetic flowmeter for measuring liquid flow is an instrument used to measure the velocity and flow of conductive fluids based on the principle of Faraday's law of electromagnetic induction. It is very suitable for flow detection and measurement of industrial backwater, ore pulp, lye, acid solution, etc.
1. The working principle of electromagnetic flowmeter
Under a uniform magnetic field, according to Faraday's law of electromagnetic induction, if a conductor moves in a direction perpendicular to the magnetic field, the induced electromotive force generated by it is
U=H×D×V (1)
In the formula, U is the induced electromotive force; H is the magnetic field strength; D is the width of the conductor; V is the speed of the conductor in the magnetic field.
The flow rate of the conductive fluid in a pipe with an inner diameter of D can be set as Q, then:
Q=V×π(D/2)2(2)
From formula (1) and formula (2), we can get:
U=4×H×Q/π×D (3)
It can be concluded that for a certain pipeline, under a certain magnetic field, according to the conductive fluid flowing through the pipeline, the induced electromotive force U can be measured, and the flow rate can be determined
2. Features of electromagnetic flowmeter
According to the working principle, the electromagnetic flowmeter has the following characteristics:
(1) Its measurement is not affected by the temperature, pressure, density, and viscosity of the fluid; the internal flow of the flow meter pipe is smooth, there is no throttling part, no resistance to the fluid, no pressure loss; no moving parts in the detection part, it will not happen Drip and other phenomena
(2) Electrical measurements can be made directly without the need for conversion of other physical quantities like other flow meters; a flow meter can be used to measure the flow of forward and reverse fluids
(3) The output voltage (electromotive force) is proportional to the flow rate of the fluid, and does not need to undergo mathematical conversion. Compared with other flow meters, its measurement accuracy is higher and the range ratio is wide.
(4) The inner village of the flowmeter has a wide range of options to adapt to different measurement media requirements. Polytetrachloroethylene plastic and alumina ceramics can be used to achieve strong corrosion resistance and abrasion resistance, so that it can be measured Highly corrosive fluids such as strong acids and alkalis.