Electromagnetic flowmeter is a new type of flow measuring instrument developed rapidly with the development of electronic technology in the 1950s and 1960s. The electromagnetic flowmeter is a meter that is based on Faraday's law of electromagnetic induction and is used to measure the volumetric flow of conductive liquid. Due to its unique advantages, it has been widely used in the flow measurement of various conductive liquids in industrial processes, such as various acidic, alkali, salt and other corrosive media; various slurry flow measurement has formed a unique application field. Then this article will detail the structure of the electromagnetic flowmeter and the specific information.
In the structure of the electromagnetic flowmeter, the electromagnetic flowmeter is composed of an electromagnetic flow sensor and a converter. The sensor is mounted on an industrial process pipe. Its function is to linearly convert the liquid volume flow value flowing into the pipe into an induced potential signal and send this signal to the converter through the transmission line. The converter is mounted not far from the sensor, it amplifies the flow signal sent by the sensor and converts it into a standard electrical signal output proportional to the flow signal for display, accumulation and adjustment control.
According to the excitation current method, there are DC excitation, AC excitation, low frequency rectangular excitation and dual-frequency rectangular excitation. Several types of excitation waveforms.
According to the system of output signal wiring and excitation (or power) connection, there are four-wire and two-wire systems.
Classified by converter and sensor assembly, there are separate and integrated models.
Classified by flow sensor and pipe connection methods, with flange connection, flange clamp connection, sanitary connection and threaded connection.
According to whether the flow sensor electrode is in contact with the liquid to be tested, there are contact type and non-contact type. Classified by flow sensor structure, there are short tube type and insert type.
Classified by use, there are general-purpose, explosion-proof, sanitary, anti-invasive and submersible types.
1 The electromagnetic flowmeter transmitter has a simple structure, no moving parts, and no throttling components that hinder the flow of fluid, so it does not cause any additional pressure loss when the fluid passes, and it does not cause such as wear and blockage. Such problems, especially suitable for measuring slurry with solid particles, liquid-solid two-phase fluid such as sewage, and various viscous slurries. Similarly, because it has no moving parts on the structure, it can be made of corrosion-resistant insulating lining and selected anti-corrosion materials to achieve excellent corrosion resistance, making it suitable for measurement of various corrosive media.
2 Electromagnetic flowmeter is a kind of volume flow measuring instrument, it is not subject to the temperature of the measured medium during the measurement process. The effect of viscosity, density and conductivity (within a certain range). Therefore, the electromagnetic flowmeter can be used to measure the flow of other conductive liquids only after water calibration, without the need for additional corrections.
3 The range of the electromagnetic flowmeter is extremely wide, and the range ratio of the same electromagnetic flowmeter can reach 1:100. In addition, the electromagnetic flowmeter is only proportional to the average flow velocity of the measured medium, and is independent of the flow state (laminar or turbulent flow) under the axisymmetric distribution.
4 Electromagnetic flowmeter has no mechanical inertia, sensitive response, can measure instantaneous pulsating flow, and linear. Therefore, the measurement signal can be linearly converted into a standard signal output directly by the converter, which can be indicated locally or transmitted over long distances.