Electromagnetic flowmeter (EMF) is the 20th century 50 ~ 60 years with the development of electronic technology and the rapid development of new flow measurement instruments. Engineers make the electromagnetic flowmeter according to Faraday's law of electromagnetic induction. They use it to measure the volume flow of electrically conductive liquids. Because of its unique advantages, industries have widely used it in industrial processes to measure the flow of a variety of conductive liquids. Such as, a variety of acids, alkalis, salt and other corrosive media; a variety of slurry flow measurement, the formation of a unique field of application.
In terms of structure, electromagnetic flowmeter consists of electromagnetic flow sensor and converter two parts. A sensor is installed in the industrial process pipeline. Its role is to linearly transform the volume flow rate value of the liquid flowing into the pipeline into an inductive potential signal. Then, through the transmission line, it sends this signal to the converter. The converter is installed in a place not too far from the sensor. It amplifies the flow signal sent by the sensor and converts it into a standard electrical signal proportional to the flow signal for output. This output is used for display, accumulation, and regulated control.
The main pros of electromagnetic flowmeter are as follows:
1. High measurement accuracy
The electromagnetic flowmeter sensor has a simple structure. There are no movable parts in the measuring tube and no throttling parts that could obstruct the fluid flow. When the fluid passes through the flowmeter, it does not cause any additional pressure loss. This makes the electromagnetic flowmeter one of the flowmeters with the lowest energy consumption during operation.
2. Wide measurement range
The output of an electromagnetic flowmeter is only proportional to the average flow rate of the measured medium and has no relation to the symmetrical distribution of the flow state (laminar or turbulent). Thus, the electromagnetic flowmeter has a very wide range.
Its measurement range can reach up to 100:1, and in some cases even up to 1000:1 for the flow range it can operate in. It can measure the flow rate of dirty media, corrosive media, and turbid liquid - solid two - phase flow. This is because there are no parts in the measuring tube of the instrument that obstruct the flow. Also, the measured fluid only comes into contact with the measuring tube lining and electrodes. The material of these components can be selected according to the nature of the measured fluid.
For example, with polytrifluoroethylene or polytetrafluoroethylene lining, can measure a variety of acids, alkalis, salts and other corrosive media. Engineeres use wear - resistant rubber lining. It is particularly suitable for measuring slurry with solid particles, which causes wear and tear. This includes cement slurry and other liquid - solid two - phase flows. It is also suitable for measuring various fibrous liquids and turbid liquids like pulp.
3. Strong adaptability
The electromagnetic flowmeter is a volume flow measurement instrument. During the measurement process, factors such as the measured medium's temperature, viscosity, density, and conductivity (within a certain range) do not affect it. Therefore, after calibrating it with water, we can use the electromagnetic flowmeter to measure the flow of other conductive liquids. EMF without mechanical inertia, sensitive response, can measure the instantaneous pulsating flow, but also can measure the positive and negative flow in both directions. Industrial electromagnetic flowmeter caliber range is very wide, from a few millimeters up to a few meters, and the domestic caliber of up to 3m flow calibration equipment, electromagnetic flowmeter for the application and development of the foundation.
Reliable and stable electromagnetic flowmeter reliability is very high, usually, its average trouble-free time can reach more than 3 years. At the same time, because of its simple structure, easy maintenance, so also has a high stability. In addition, electromagnetic flowmeter can also realize automatic diagnosis and alarm function, which improves the reliability of the equipment.
Siemens SITRANS FM MAG 6000 7ME6920 Electromagnetic Flow Transmitter
The main cons of electromagnetic flowmeter are as follows:
1. High requirements for the fluid medium
EMF requires the fluid medium to have a certain level of conductivity. Usually, we need the measured fluid medium to have a conductivity of not less than 5μs/cm. If the conductivity of the measured fluid medium is too low, it will cause the measurement accuracy to decline or make the flowmeter unable to work properly. Therefore, when choosing to use an electromagnetic flowmeter, we need to strictly screen and control the conductivity of the measured fluid medium.
For example, we cannot use it to measure gases, steam, and liquids containing large amounts of gas. We cannot use it to measure liquid media with very low conductivity, such as petroleum products or organic solvents and other media. Currently, the electromagnetic flowmeter cannot assist in such measurements.
2. Installation environment requires high
EMF installation environment has an important impact on its normal operation. Electromagnetic flowmeter susceptible to external electromagnetic interference. In the installation, you need to ensure that the sensor part of the vertical and horizontal req uirements, otherwise it will have an impact on the measurement accuracy. At the same time, the electromagnetic flowmeter for the pipeline impurities and vibration is also more sensitive, so you need to take appropriate measures to protect and avoid interference.
3. Commissioning and maintenance difficulties
Electromagnetic flowmeter commissioning and maintenance is relatively complex, requiring professional and technical personnel to operate. At the same time, because of its internal parts are more precise, so it needs to be frequently maintained and serviced. If there are failures or abnormalities in the use of the process, the need for timely processing and repair to ensure its normal operation.
Conclusion
The limitations of the measuring tube lining materials and electrical insulation materials in an ordinary industrial electromagnetic flowmeter prevent us from using it to measure high - temperature media. Without special treatment, we cannot use it to measure low - temperature media either. We do this to prevent condensation outside the measuring tube (frost) from damaging the insulation.
Whether you're an industrial pro or a hobbyist interested in measuring instruments, we'd love to hear your thoughts on the pros and cons of electromagnetic flowmeters. Let us know about accuracy, applicability, maintenance costs, and more!To obtain the most competitive quote, please contact our ANTLETS team.