Summary
CGD series electromagnetic flowmeters are hi-tech products by utilizing micro-intelligence technology and could be divided into two kinds: field display type(integrated) and remote display(separated). They could measure volumetric flow of conduct electricity corrosive fluid media such as acid, alkali & salt solutions, and solid-liquid two-phase suspend liquids.
Measure principle
The principle of the transducer is based on Faraday's Law of electromagnetic induction. When an electrically conductive liquid passes through a meter tube situated in an alternating magnetic field and perpendicular to the lines of magnetic force, it cuts the lines of magnetic force, an induced electromotive force (induced EMF) is generated. The induced electromotive force is expressed as follows:
E = KBVD
K = meter's constant
B = magnetic induction density
V = average flow velocity of liquid in measure tube
D = inner diameter of measure tube
When flow of the liquid being measured, liquid passes through magnetic field and perpendicular to the lines of magnetic force, the conduct electricity flow of liquid generates an voltage which is in direct proportion to average flow velocity (volumetric flow). Therefore, measured flowing liquid must have min. conductivity. The induced electromotive force is detected by a pair of electrodes which are in contact with liquid directly and is transmitted to an amplifier through cable. The amplifier changes the induced electromotive force into uniform output signal.
The measuring method has following advantages:
1.No resisting parts in the measuring tube, therefore no attached pressure loss.
2.The signal is a average volume in cross section of the measured tube, as it is formed in the space filled with magnetic field. Hence, the straight pipe between the plane of electrodes and upstream plane from transducer is relatively shorter, and it is 5ˇÁDN(DN is diameter nominal).
3.The tube and electrodes are contact with measured liquid only. So long as selecting the proper electrode and lining material can meet the requirements of corrosion-resistance and wear resistance.
4.Output signal from transducer is an induced electromotive force which has linear relationship with average flow velocity.
5.The measured results have no relation with the physical parameters of liquid, such as pressure, temperature, density, viscosity and conductivity (no less than min. conductivity). High sensitivity, and reliable operation.
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