Electromagnetic flow meter: principle of operation and metrological characteristics

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2018-11-25 02:00:42

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Electromagnetic flow meter – a technological device that is commonly used for metering the coolant flow rate measurement of liquid and gaseous substances. Unquestionable advantages of such systems are: the implementation of the design using minimum number of mechanical elements, the lack of hydrodynamic resistance, the higher the accuracy of the registration parameters.

Electromagnetic flowmeter-principle of operation

electromagnetic flowmeterDevices of this category are equipped with conductors, in which the superposition of the magnetic field with lines of force, produces an electromotive force. Formed in the conductor the direction of the current perpendicular to the direction of the magnetic field. The specified pattern is fully revealed in the so-called Faraday's law, which explains the principle of electromagnetic induction.

When you replace a conductor with a flow of fluid, which conducts electricity, get a concept, according to which, in fact, operates the electromagnetic flow meter. Such devices can be equipped with permanent or electric magnets, which are powered by alternating current.

In the measurement region of the meter tube is made of non-magnetic non-conductive material. Often the specified area is equipped with insulating panels of inert plastic. The use of such elements contributes to obtain the most accurate readings in the process of measuring the characteristics of the working environment.

Areas of operation

electromagnetic flowmeter PremIn which areas used electromagnetic flowmeter? The greatest proliferation of such devices have been in the field of energy and water resources. In particular, using such devices in the regeneration of heating systems.

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Currently, the electromagnetic flowmeter is widely used in chemical, metallurgical, food industry. To use devices this category resort construction companies, ore-dressing enterprises, medical institutions.

Electromagnetic flow meter is essential in the organization of automatic control systems of working media flows, where the main role plays the degree of delay measurement. Apply the device in tracking the rapidly changing costs of liquid and gaseous substances.

Metrological error

electromagnetic flowmeter principleShows long-term practice of operation of measuring instruments with a constant magnetic field, their average error is about 1-2,5%. Specified disadvantage becomes noticeable when measuring indicators libpulseaudio environments. In this case, there are often additional error cause which is the polarization of the electrodes, which is reflected in the change in resistance of the transducer device.

The Decrease in the percentage of metrological errors in the flow meters with a constant magnetic field promotes the implementation of the design kalamalay and carbon electrodes or conductors with the platinum and the tantalum coating.

As for devices with alternating magnetic field, it lacks polarization of the electrodes, which can lead to errors in the indicators. However, such devices are other effects that distort the signal:

  1. The Transformer effect – when the liquid passes through the conductors which form the coils, connecting the wiring and the electrodes form a transformer electromotive force. To compensate for the specified action in the measuring circuit of the flowmeter with an alternating magnetic field are injected magnets with switchable constant current or the compensating circuit.
  2. Capacitive effect – caused by a substantial potential difference between the connection wiring and the system responsible for the formation of a magnetic field. The error in this case kompensiruet by careful shielding of system elements.

Calibration of electromagnetic flowmeter

electromagnetic flowmeter promagHow to perform the calibration of electromagnetic flowmeter? The most accurate method here is static weighing (mass method). To implement use of exemplary weights and shut-off valve that operates in the regime of “start-stop”.

In the course of operations the net amount of working fluid is determined according to the weight of containers before and after filling with the passage of the fluid through the flow meter during a specific time period.

The Advantages of the method of verification is:

  • Precision measurement of normalized flow;
  • The possibility of correlation of the results with the values corresponding to state standards;
  • The possibility of the verification of the flowmeter, which operates with hot fluids;
  • Process automation.

Types of flow meters

In Addition to the electromagnetic flowmeter, there is a wide variety of other devices for measuring characteristics of the working media flowing through pipelines. Currently, based on the principle there are the following groupsustroistv:

  • Teplovye;
  • Ultrazvukovye;
  • Varenye;
  • Karoliniskiu;
  • Mehanicheskie;
  • Microrespirometry.

Next, briefly review the features of electromagnetic flow meters of each type.

Heat flow

peterloo electromagnetic flowmeterThe Principle of operation is based on the local change in the properties of the working fluid, for example, temperature in a stream with a subsequent measurement on a remote station from the place of impact. The method facilitates the calculation of the average speed of the substance in the conductive paths.

In this way may be subject to change other characteristics of the substance, for example, chemical composition. However, in most cases, this approach is not valid, often necessary, operation of the flow meters in hospitals.

Ultrasonic flowmeters

The Operation of devices of this type is built on the ability of sound waves to spread in the mobile environment. By identifying the source of ultrasound and the receiver can judge the speed of flow of the working medium according to the travel records of a wave at a certain period.

Vortex

In devices of this plan, the main functional element acts as a spherical or disc-shaped target. The detail is fixed on the fixed elastic rope. When passing through the system a flow of working medium acts on a target, causing it to shift. This, in turn, causes deformation of the cable, the changes which are recorded by special load cells. The information obtained contributes to the formation of judgments about the direction and speed of flow of the material.

Coriolis meters

Structurally, these devices consist of a tube that is exposed to vibrations that originate from an external generator. In the absence of fluid in the system, the oscillations cause the simultaneous acceleration of all parts of the tube. As the passage through it of the liquid comes into action the so-called Coriolis force that is directed in opposite directions for the input and output substances. This leads to a phase shift of the vibration of the conductive tube and gives the ability to capture the metrics.

Microrespirometry

electromagnetic flowmeter ersvTo this category measuring devices are flow meters, which feature miniature design. Dimensions of a device due to its scope. These devices satisfy the needs of medical institutions and the enterprises for manufacture of chemical products.

According to the principle, each miniature fixture is a conventional flow - meter of the solenoid. However, due to the possibility of operating in cramped conditions the cost of such devices is much higher.

Mechanical flow meters

In the specified group includes devices that constructively deprived of electronic elements. The flow rate here is measured due to the effect of environment on mechanical turbines.

Despite the affordable price of these meters, their accuracy leaves much to be desired. Another disadvantage is the use of moving parts that can become a barrier to the movement of gaseous or liquid substances. However, despite this disadvantage, mechanical flow meters find wide application in the domestic environment, if necessary, taking into account the flow of water.

Electromagnetic flow meters – common models

calibration of electromagnetic flowmetersLet's look at demand electromagnetic flowmeters which are most in demand in the domestic market.

Electromagnetic Flowmeter “stem” is designed to measure the volume and flow rate of conductive liquids. Readings are displayed on the outside, convenient for registration as a user of the device. Such devices are suitable for operation in conditions of large industrial complexes, are used for maintenance of objects of housing and communal services (in the systems of accounting of water and thermal energy).

Promag electromagnetic flow Meter suitable for the registration of indicators of working environments with high temperatures. Is a complex functional electronic device. Used primarily as a part of modular structures in the implementation of high-tech processes in the industrial fields.

“Peterloo” – electromagnetic flow meter designed for measurement of the volume and volumetric flow of liquids transported by pipeline. Devices of this brand are sought after in the field of power engineering, housing and communal services and industry. Distinctive features of such measuring instruments speaker: the placement of an electronic snap-ins in a separate, well-protected body, protection against unauthorized access, provision of convenient graphic displays with backlight.

Electromagnetic flowmeter “ARSW take-off” currently being the most common metering devices at the facilities of housing and communal services. Apply to register a volumetric flow rate of both cold and hot water.

Electromagnetic Flowmeter “RISE”has no pressure loss on the measured parts of the pipeline, without need to install additional filters. Information on indicators can be displayed for frequency, pulse or logical output, depending on the needs of the user. Flowmeter “the rise of the EHR” the solenoid has a function of control over the emptying of the pipeline. The only comparative disadvantage of such systems is the necessity of installation on straight sections.

In conclusion

As can be seen, electromagnetic flow meter performs highly accurate, functional measurement device. Primary converters of these devices do not contain protruding inside the pipe elements, the textured parts and narrowing of the profile. These features ensure a minimal error in the readings. In addition, electromagnetic devices allow cleaning and maintenance of the pipeline without dismantling the system elements.


Article in other languages:

BE: https://tostpost.com/be/hatn-tul-nasc/18811-elektramagn-tny-rashodomer-pryncyp-dzeyannya-metralag-chnae-haraktarys.html

DE: https://tostpost.com/de/gem-tlichkeit/18633-elektromagnetische-durchflussmesser-wirkungsweise-und-messtechnische-e.html

ES: https://tostpost.com/es/la-comodidad-del-hogar/18555-el-medidor-de-caudal-electromagn-tico-principio-de-acci-n-y-metrologic.html

KK: https://tostpost.com/kk/domashniy-uyut/18884-elektromagnitt-rashodomer-zh-mys-steu-princip-zh-ne-metrologiyaly-sipa.html

PL: https://tostpost.com/pl/komfort-domu/19476-przep-ywomierz-elektromagnetyczny-zasada-dzia-ania-i-charakterystyka-m.html

PT: https://tostpost.com/pt/o-aconchego-do-lar/19317-o-medidor-de-vaz-o-eletromagn-tico-princ-pio-de-a-o-e-metrologicheskay.html

TR: https://tostpost.com/tr/domashniy-uyut/18816-elektromanyetik-debimetre-al-ma-prensibi-ve-n-n-metroloji-zelli-i.html

UK: https://tostpost.com/uk/domashn-y-zatishok/19051-elektromagn-tniy-vitratom-r-princip-d-ta-metrolog-chna-harakteristika.html






Alin Trodden - author of the article, editor
"Hi, I'm Alin Trodden. I write texts, read books, and look for impressions. And I'm not bad at telling you about it. I am always happy to participate in interesting projects."

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