By akademiotoelektronik, 22/01/2023

Ultrasonic flowmetry: more precise devices and more suited to the needs of operators

In the field of water, two types of applications predominate in flowmetry: full driving flows, and free surface flows (watercourse, canals, wastewater pipes).The selection of a flow meter is based on many parameters including the properties of the fluid and the characteristics of the measurement environment: upstream/downstream configuration of the measurement section, size and material of driving, compliance with the axial symmetry of thespeed field ... etc.

Electromagnetic flowmers (DEM) measure fluids whose conductivity is greater than 1 μs/cm.According to the principle of the faraday induction law, the electric field created around the flow induces an electromagnetic force directly proportional to the flow of flow of the fluid.Very precise, these devices have a very good measurement range and operate without mobile parts.They adapt to any diameter of piping through a cuff without causing charging loss.Electromagnetic technology occupies a predominant part on small and medium diameters.David Cohen, president of Engineering measures, fixes the threshold limit of electromagnetic dynamics around the 300mm DN."The rocking between an ultrason and an electromagnetic is around DN 300mm.A DEM is essentially dependent on the diameter.Even if there is no proportionality, the greater the diameter, the higher the cuff installation cost.This is the reason why electromagnetic technology is predominant in number of devices but not necessarily in market share in euros ".

Coriolis mass flowmeter allow you to simultaneously measure different variables: mass flow, density, temperature, viscosity of a product and the content of dry matter, with an uncertainty range of the order of 0.1%.The principle of measurement is based on the force of Coriolis which is generated when a system simultaneously undergoes rotation and translational movements.A Coriolis flow meter has oscillating tubes to generate this effect.The passage of the fluid as a function of its mass and its speed will exert a deformation of one or more tubes.If the advantages of the mass measurement reside in the variety of applications and its insensitivity to changing and hostile environments, technology remains unsuitable for low pressures and limited to DN400 diameters.

Introduced more than 40 years ago in the field of water, ultrasonic flowmetry is based on the use of sensors that are both issuers and receivers.The technology is divided between the so -called transit (or flight time) ultrasound and those with doppler effect, to favor if the liquid is loaded or in the presence of gas bubbles.In the first case, a beam of ultrasound is sent from one probe to another with a certain angle compared to the flow.The sound wave emitted in the direction of the flow will have a shorter journey time than that emitted in the opposite direction.This difference is directly proportional to the flow speed.In the second case, the speed of flow of the liquid is assimilated to the speed of the particles present in the fluid.The latter is measured by comparing the frequency variation of the reflected wave on the particle compared to the wave emitted.

Transit time or doppler effect, the two technologies are based on insertion or external sensors.In the latter case, they are mounted outside the driving and can be installed without interruption of the process.

Favor the application and need of the customer

Comme toujours en métrologie, le résultat et la précision de la mesure dépendent de l’adéquation de l’appareil avec le besoin exprimé. « L’appareil universel n’existe pas, pas plus que l’appareil parfait, estime David Cohen chez Engineering Mesures. Le bon choix résulte souvent d’un compromis ».

From manufacturer to the distributor, alternatives and advice multiply to help the operator make their choice.

Thus, anxious to make the most of each technology, manufacturers like Krohne, Endress+Hauser, Siemens or Fuji Electric, offer an extended choice of devices based on diversified measurement principles.This is also the case of Kobold Instrumentation, This Industry, RS Hydro or Engineering Measures, which have endeavored to build a widest possible debit offer to support the operator in the selection of technology most suited to its application."Unlike a manufacturer who will be tempted to push the technologies he masters, our approach consists in selecting, without a priori, the most appropriate technology," said David Cohen at Engineering Measures.Same remarks made by Stéphane Couteau de Th Industrie.We are not prisoners of technology.Faced with the variety of issues encountered, the diversity of fluids to be measured and the specificity of each application, we proceed by elimination.We go to the site, we identify the requirements of the installation and we eliminate the principles of measurement which are not compatible with the project, as well as those whose operating principle is too close to the limits of the possibilities of thedevice ".Beyond the principle of measurement, the diversity of the offer is also expressed through the functionalities of the instrument.Engineering measures thus distributes Siemens for the most demanding and micronics applications for simpler applications."We must be able to provide solutions adapted to all applications, even the simplest, without imposing on the operator of the features he does not need," explains David Cohen.This is the application that must guide the choice of the instrument, not the technique or the brand ".

Similar approach to Kobold Instrumentation and TH Industry."Thanks to our many measurement technologies as well as the wide variety of materials available, we are able to optimally define the solution that is most suitable for the measurement of liquids in all pressure or temperature conditions and for anyflow scale.It is thus possible to best meet the customer's need, ”confirms Jacques Marionneau, Managing Director at Kobold Instrumentation.

La diversité des approches crée des complémentarités appréciables pour l’exploitant. Plus qu’une relation de concurrence, la relation entre fabricants et distributeurs intègre davantage une dimension de coopération et de services.

For This Industry, on very large installations, ultrasound technology deserves to involve teams from its manufacturer Systec, because to obtain reliable measurements, you have to treat studies, modeling, carry out a good channel profile.The priority remaining the relationship with the operator.

Transit time or doppler effect: each techno its field of applications

Reconnue pour l’exhaustivité de sa gamme de débitmètres à ultrasons et pour son expertise dans la gestion de projets hors standard, Ultraflux revendique son rôle de précurseur dans l’instrumentation ultrasonore. L’entreprise affiche une vingtaine de solutions basées sur le principe de différence des temps de transit ultrasonores allant de la mesure de débit non intrusive à la mesure intrusive, permanente ou ponctuelle, sur tout type de fluides et à travers tout type de matériaux. « Dans le domaine des ultrasons par temps de transit, nous sommes les seuls à proposer à la fois des débitmètres pour conduites en charge, sur écoulements à surface libre (canal ouvert, petite rivière ou conduite partiellement remplie), des sondes externes ou “clamp-on”, et des sondes intrusives et sondes mouillées » explique Laurent Bonfils, directeur commercial chez Ultraflux. Pour ce spécialiste, la technologie par temps de transit est la seule technique non intrusive qui permet de faire une mesure de débit robuste sur la section complète d’un tuyau, d’une rivière ou d’un canal. Elle offre une grande dynamique de diamètres et de mesures sur des petits et gros débits, de bons résultats en étiage comme en crue ; elle prend en compte différents profils de vitesse allant jusqu’à 8 cordes, et grâce à la précision des appareils permet de mesurer des deltas de temps en nanosecondes. « Nous sommes cependant toujours très prudent quand il s’agit d’eaux très chargées. En fonction de la granulométrie, de l’aération à 20/25 g/l, nous préconisons un essai avant validation. Pour des eaux chargées ou très aérées, nous touchons aux limites du temps de transit. C’est là que l’effet Doppler prend éventuellement le relais. Il offre toutefois de moins bonnes précisions ». Les débitmètres à effet Doppler sont en effet bien placés pour mesurer l’écoulement de liquides comportant des réflecteurs de sons, des particules en suspension (à partir de 5 %) ou des bulles de gaz (supérieures à 100 microns). Grâce à des capteurs piézoélectriques situés dans le transducteur et au niveau de l’extrémité de la sonde, le débitmètre envoie des ultrasons dans le liquide en écoulement au travers de la paroi de la conduite ou depuis l’extrémité. En suspension dans le liquide, les réflecteurs réfléchissent ces ultrasons qui sont alors enregistrés par le récepteur. Lorsqu’ils se déplacent sur le trajet de transmission sonore, la différence entre les deux fréquences aboutit à la conversion du débit de liquide en différentes unités définies par l’utilisateur.

Doppler effects of the IQ ™ range require no civil engineering."Whether in open channels or in partially filled or loaded closed pipes, the fact that these devices cover a large field of the wet section makes them very precise," explains Dany Engel, ADCPro product manager.

Fixed as in laptop, the field of application of ultrasound is constantly widen

Les débitmètres à ultrasons développés par Ultraflux, Flexim, Aqualabo, Cometec, Systec ou encore Prisma Instruments se déclinent en appareils fixes ou mobiles. Bien entendu, les usages ne sont pas les mêmes, les besoins et donc les exigences non plus.

The fixed version of the devices is particularly suitable for continuous measurements on permanent installations.The debitmeters of the Deltaware C-F (Fixed) range of Systec, distributed in France by TH Industry and labeled Duk S3, L4, F3, C3, EG and K by Kobold Instrumentation use two sensors mounted in opposition from each other inpipelines to operate simultaneously as a transmitter and receiver of ultrasonic signals.The devices display a level of ± 0.7 % of the measured value.The Aqualablates Multi-VOIES 460 Aqualabo flow meter has 4 ultrasonic or 4-20MA inputs to simultaneously multiply the measurement points or record other parameters (pH and temperature for self-surveillance for example).On the sensor, the compensator has been exteriorized and decoupled to the maximum of the body to allow a simple glance to read the performance that arises from it.

The progress made in fixed versions have contributed to expanding the scope of these devices.

The two ranges of Flexim Intrrusive Fixed Dutch, the F721 WD and F501, offer high precision performance.Thanks to couples developed and tested in the field for more than 10 years, they allow to keep the measure even when the frost has dissipated, and do not cause any maintenance operation.

To approach the accuracy of an DEM with an ultrasonic flow meter, or in the context of large projects, the use of multi -tone flowmers in external probes makes it possible to integrate the profile on two orthogonal diameters and to reduce the uncertainties.The sensors are isolated from fluid reducing the risks of erosion and corrosion and can be dismantled without depressurization of driving and without extraction tool.The cables are protected in the body of the flow meter.Watered transmitters are located in an area of the device and designed specially to optimize maintenance and safety."Thanks to its expertise and research teams, Ultraflux is able to meet very specific specifications," emphasizes Laurent Bonfils.This type of project, often critical, requires on the part of operators to estimate the precision, even the likelihood of this or that measure prior to the installation.We note a real evolution of the needs of industrialists who now require correlating all large projects to a CFD (Computational Fluid Dynamics) modeling of flow champs depending on the geometry of the piping (upstream and/or downstream disturbances))to guarantee the precision of the measure ”.

Intended for demanding applications, UF 831 UF 831 flow meter, uses Double DSP (Digital Signal Process) technology for echo measurement in difficult conditions.This device has, among other things, up to ten input/output modules, a recorder of more than 500.000 data and an optional communication module allowing it to dialogue with most current protocols (including Ethernet).The device includes an uncertainty range of ± 0.5% of the measurement and can be used on DIM DN 10000 diameter pipes and with a temperature of -10 ° C at 50 ° C.

Developed by Nivus, the Nivuflow 600 has been specially designed for the measurement of full behavior.Appropriate for

l'acquisition du débit dans des milieux liquides clairs ou faiblement chargés, le système de 4 cordes peut être exploité grâce à des modules d´extension optionnelle, jusqu’à 32 cordes de mesure. L´installation de l’équipement est sans contact et dispense l´interruption du processus.Le développement d’appareils clamp-on et d’appareils portatifs, de plus en plus faciles à utiliser, a également contribué à élargir les applications (voir EIN n° 405). Bien que leurs mesures soient moins précises que celles fournies par les capteurs à insertion, les progrès accomplis ces dernières années permettent d’afficher une incertitude inférieure à 1 % et leur ouvrent de nombreuses applications dans le domaine de l’eau : contrôles ponctuels de débits, comparaison de valeurs, vérification de l’efficacité d’une pompe, détection de fuites…

TECFLUID's non-intrusive flow meter, is based on the transmission of ultrasonic signals through a pipe or circulates a liquid.The operating principle is based on transit time.Two non-intrusive ultrasonic transducers mounted on a pipe alternately send an ultrasonic signal first in one direction and then in the opposite direction, the difference in round trip time of the ultrasonic wave is proportional to the average speed ofliquid flow.The electronics are programmable directly on the converter or by communication with connection to USB port and Winsmeter software.Flow/totalization/4-20ma/2 alarms.Non -intrusive sensors are available for pipes ranging from DN to DN 2000 mm.

« Les appareils de terrain permettent également la mesure de débit d’eaux de qualités variables y compris sur de hautes pressions. La technologie mobile est particulièrement intéressante pour les applications de maintenance, les campagnes de vérifications, de tests sur différents sites et à différents points du process. Outre la mesure du débit, les mobiles permettent également des mesures thermiques et calorimétriques », détaille Jacques Marionneau. Ces deux approches offrent en effet un grand nombre de variantes et d’options, et notamment la possibilité de faire un bilan calorifique et des tests d’équilibrage thermique. Les débitmètres à ultrasons portables fonctionnent avec une batterie rechargeable et disposent d’une autonomie moyenne allant de 5 heures à 70 heures. Pour ces applications, Systec a développé le modèle DeltawaveC-P non intrusif, par colliers, pour tuyauteries de DN10 à DN 6000.

Improvement of performance (especially for wireless versions) also helps expand their field of application.They help, for example, to better dimension the devices."Until a recent period, the cuff was dimensioned according to the size of the piping without really asking the question of the flow that passed on," explains Damien Jacquier at Krohne.Thus, on a DN100 pipe, we put a cuff in DN100.Today, the clamp-on allows you to record and verify the flow that really transit in the pipe for a few days which allows you to better size the devices and thus obtain more precise measures ".The dimensioning of a device placed on a network often rests only on an average flow.But on certain applications, for example in sectorization, the operator is looking for small flows that materialize a leak, which require a good level of precision.Hence the interest in being able to reduce the size of the equipment.

Precision of the measure: constant progress

Reste le délicat problème de la précision de la mesure, notamment quand un haut niveau de précision est requis. « En conduites pleines, qu’il s’agisse d’un capteur ultrasons à insertion ou d’un capteur externe, on n’atteindra jamais la précision d’un débitmètre électromagnétique dont l’incertitude de mesure tourne autour de 0,25 %, souligne d’emblée David Cohen chez Engineering Mesures. En ultrasons, on ne sait pas faire mieux que 1 % et encore, sous certaines réserves ».

On the ultrasonic cufflink flowmers, it is possible to make an emission surface of ultrasound perpendicular to the measurement channel.There will therefore be no deviation from the ultrasonic beam in the case of a change in the speed of sound propagation in the measured liquid.The location of the strip holders on the tube is therefore independent of the nature of the measured liquid (temperature, chemical composition).In addition, the construction of the measurer being carried out at the manufacturer (and not carried out on driving), it is possible to carry out a very precise positioning of the measurement probes (distance between probes and angle of the measurement channel).The reliability and accuracy of the speed measurement will be satisfactory on a great dynamic of scale: precision better than +/- 0.5% of the value measured for a speed between 0.5 and 18m/s and the measurable minimum speed will be around 0.1m/s.Some devices can be used for commercial transactions.

The fact remains that due to the very design of the clamp-on, it is impossible to provide a calibration certificate on a bench for this type of device and thus obtain a traceable and guaranteed measurement.The precision of the measure is therefore around 1 to 3%.Clamp-on devices, however, claim improved measurement accuracy.This is the FST030 sitrans case of Siemens, of Engineering Measures which digitizes the signal instantly after the measurement, which minimizes external influences and optimizes the signal-outlet ratio.Thanks to its frequency of updating the 100Hz data and its integrated algorithm, it claims a detection of the smallest fluctuations of the flow with a constant precision of 0.5 to 1% of the flow and high stability of the zero point.Same thing for the FLT 10PN of Flow Lab Technologies or the SEFlow 400 Portable developed by Flexim which claims 30 years of experience in the field of non -intrusive ultrasound for industry and advanced applications.The SEFlow 400 offers autonomy of several months and makes it possible to recover data dedicated to monitoring night flows on a drinking water network.For more than 5 years, the manufacturing has been based on Sewerin's expertise to distribute its 3 ranges of non -intrusive non -intrusive flowmers.

Pour améliorer la précision de la mesure et obtenir de meilleurs résultats, les gammes génériques et labellisées deSystec proposent en standard une fonction oscilloscope qui permet de vérifier facilement que le point de mesure est pertinent. Pour TH industrie, la force de son offre en débitmètres à ultrasons réside dans la sélection de Systec, un fabricant de référence dans la mesure industrielle, qui maîtrise toute la chaîne de production des équipements, donc les capteurs.

More autonomous, more communicating and easier to exploit devices

Les principes de fonctionnement et de mesure sur lesquels reposent les ultrasons n’a pas évolué. La partie électronique de l’équipement a, en revanche, été complètement revue, avec plusieurs conséquences, notamment en matière de traitement du signal. « En temps de transit, tout repose sur la lecture et la mesure du temps de transit entre l’aller et le retour de l’onde ultrasonique et donc sur l’horloge interne du microprocesseur, explique David Cohen chez Engineering Mesures. Celle-ci étant de plus en plus précise, il est possible d’avoir des précisions de mesure, inatteignables il y a seulement quelques années. De même, des processus internes au niveau de l’électronique permettent de poursuivre la mesure et de repousser les limites même en présence de bulles de gaz ou de particules solides ».

Parks management is also considerably simplified.Heartbeat at Endress+Hauser allows you to visualize the state of health of the sensor directly on the display, to edit operating reports and to repatriate the data directly on the supervision.These new features give a predictive character to maintenance, which makes it possible to anticipate breakdowns and faults, and thus to reduce the costs of exploitation of the flow ratemeters.For compulsory checks, Heartbeat Verification examines the operation of the device and automatically generates a report.On certain installations, Endress+Hauser offers Trustsens temperature probes which carry out traceable self-calibration, allowing to increase the availability of equipment.