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Combination of electromagnetic flowmeter and ultrasonic flowmeter

Feb 27, 2017

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.