In the field of petroleum, chemical, water and other use of the largest flow meter, the most common is the ultrasonic flowmeter and electromagnetic flowmeter, why these two instruments will become the preferred widely used? Let's analyze their main advantages. 1. Wide range of applications. Electromagnetic flowmeter can measure a variety of acid-base liquid, sewage, pulp and other conductive media, and non-conductive ultra-pure water, pure water, water and other non-conductive liquid medium can be measured with ultrasonic flowmeter, so these two instruments each other After the combination can measure almost all common liquid.
2. High measurement accuracy. In the flow measurement can be said that the higher the better accuracy, the accuracy of these two instruments are very good performance, conventional accuracy of 1.0, slightly higher requirements of 0.5, up to 0.3, or even 0.2 accuracy, the current flow measurement Instrument performance is very good.
3. No pressure flow components without pressure loss. Neither the electromagnetic flowmeter nor the ultrasonic flowmeter has almost no parts inside the draft tube, so there is no obstruction to the media and no pressure loss. However, the electromagnetic flowmeter will be subject to some extreme pressure restrictions, then you can use the outer clip type ultrasonic flowmeter, the pressure will not have any impact on the flow measurement.
4. Easy to install. In general, industrial field measurement flow is a flange docking, inconvenience to destroy the existing pipe can be used outside the folder installation, very convenient.
5. Cost-effective. In addition to the requirements of ultra-high precision, the price of these two instruments are more close to the people, the public can accept.
Of course, these two instruments are not all advantages, some shortcomings will limit its use in a wider range of areas, such as ultra-high temperature conditions, these two instruments are poor performance. We look forward to new materials and new technology breakthroughs to make them more superior.
Electromagnetic flowmeter application of various causes of the error, such as fluid conductivity, fluid composition, electromagnetic flowmeter wall dirt.
Electromagnetic flowmeter is based on the principle of Faraday's law of electromagnetic induction to work, with conductive properties of the conductor in the magnetic field to do magnetic field movement, in which the downstream will produce induced electromotive force, the direction of the right hand in accordance with the rules. Therefore, the general application of electromagnetic flowmeter, the conductivity of the fluid have certain requirements, the application process to 5us / cm as a dividing line.
Electromagnetic flowmeter and ultrasonic flowmeter and so belong to the speed of the flowmeter, all of its affected factors include: fluid flow (fluid is evenly distributed), lining the scale.
1, the fluid flow caused by the error:
Liquid flow velocity V in the pipe axis symmetrical distribution, and in a uniform magnetic field, the flowmeter electrode on the size of the electromotive force and the flow velocity distribution of the fluid has nothing to do with the average flow rate of the fluid is proportional to, otherwise the induction of the electrode The electromotive force is different, so you must choose the fluid flow spoiler as small as possible to measure the pipe section to install the electromagnetic flowmeter to avoid unnecessary errors.
2, the lining of the dirt caused by the error:
In the chemical industry, water treatment enterprises, is the usual life of water measuring instruments ( water flow meter), we often see the inner wall attached to a layer of scale or chemical layer, do not underestimate this thin layer, which can change the electromagnetic flow meter electromotive force deviation , And then produce zero dislocation. So we often see some sewage treatment plants, in order to improve its measurement accuracy, often to clean the electrode inserted into the electromagnetic flowmeter.
At present, the electromagnetic flowmeter in the fluid measurement, energy-saving detection and other industries or occupy the role of the dominant market, with the electronic chip technology and computer computing efficiency, and gradually have been replaced by ultrasonic flowmeter trend.