Ferdinand Luimes
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A Coriolis mass flow meter is known as a very accurate instrument and it has many benefits compared to other measuring devices. However, every measuring principle has its challenges, as also the Coriolis principle. It can be a real challenge using Coriolis instruments in low flow applications in the heavy industry where you may have to deal with all kinds of vibrations. In this blog I would like to share my experiences with you regarding this topic.

The Coriolis principle

Coriolis mass flow meters offer many benefits above other measuring devices. First of all Coriolis flow instruments measure direct mass flow. This is an important feature for the industry as it eliminates inaccuracies caused by the physical properties of the fluid. Besides this benefit, Coriolis instruments are very accurate, have a high repeatability, have no moving mechanical parts and have a high dynamic range, etc.

Read more about the importance of mass flow measurement and the relevance of Coriolis technology in a previous blog.

Do vibrations influence the measuring accuracy of a Coriolis mass flow meter?

In industrial applications, all kinds of vibrations with different amplitudes are very common. A Coriolis meter measures a mass flow using a vibrating sensor tube, which fluctuation gets intentionally out of phase when the fluid flows through. As explained in the video [link] at the end of this article.

This measurement technique is somewhat sensitive to unwanted vibrations with a frequency close to the resonance frequency of the sensor tube (this depends on the sensor tube design, e.g. 360 Hz) or a higher harmonic of this frequency (see picture below).

Image description Coriolis flow meters are only sensitive for the resonance frequency or a higher harmonic of this frequency

The likelihood of the occurrence of these unwanted vibrations is higher in an industrial environment. Coriolis flow meter manufacturers do their utmost to reduce the influence of vibrations on the measured value by use of common technical solutions, such as using:

  • higher driving frequencies
  • dual sensor tubes
  • different sensor shapes
  • mass inertia (mass blocks)
  • passive and active vibration compensation
  • pigtails

So yes, vibrations can influence the measuring accuracy of your Coriolis flow meter, but only if the vibrations have a frequency close to the resonance frequency. What can you do about this? This depends on the kind of vibration.

What kinds of vibrations do exist?

In an industry zone frequencies can be generated by:

  • environmentally related vibration sources (such as: truck, rail transportation, industry activities)
  • building-based vibration sources (mechanical and electrical installations, like air conditioning)
  • usage-based vibration sources (installed equipment and machines, e.g. pumps, conveyor belts).
  • These vibrations travel through a medium like the floor, in the air, through pipes or the fluid itself. If these vibrations disturb the Coriolis frequency, the measured flow could be incorrect in some extent.

To minimize the effects of vibration it is useful to identify these sources. Sometimes, it is possible to move the flow meter just a little bit, turn it (Coriolis flow meters are in most cases less sensitive to vibrations if the meter is rotated 90 degrees), make use of a big(ger) mass block, use flexible tubes or U-bend metal tubes, or use suspension alternatives.

How could you check the performance of a Coriolis flow meter?

A well performing flow meter and controller will give the best process result. Therefore, it is advisable to test a Coriolis flow meter in your application if you expect heavy industrial vibrations before you trust it to the full extent. Be careful when filtering the measuring signal. In some cases it makes sense (e.g. when a quick response isn’t required), but if you want to test the performance of a flow meter, filtering could blur your judgement.

Image description Coriolis flow meter in action

If in specific circumstances the Coriolis flow meter isn’t performing the way it should, the operator will see a shift in the process output – for example in an application dosing color to a detergent it can result in differences in product color by incorrect dosing and/or unexpected measuring signal behavior. In these cases it makes sense to check the raw measuring signal (without filters!), because it will give you a good insight in the performance of the flow meter. Ask your flow meter manufacturer how to switch off all signal filtering.

Standards regarding vibrations

Remarkably, the influence of external vibrations is not clearly defined in a standard for Coriolis flow meters. Several standards are written about vibrations, but none in respect to measuring accuracy in relation to vibrations. However, two useful standards in relation to vibration are:

  • IEC60068-2, Environmental testing for electronic equipment regarding safety
  • MIL STD 810, Environmental engineering considerations regarding shock, transport and use

As a user of Coriolis flow meters it is important to understand your application, especially about potential external vibration sources. As low flow Coriolis specialist we work together with knowledge partners like the University of Twente and TNO (a Dutch organization for applied scientific research) to get a continually improved understanding of this topic.

With in-house test facilities we are able to do special vibration tests. Together with the experience we gained from customer applications and custom made solutions, we are always aiming for improving our Coriolis flow meters to give our customers the best performance they need.

Watch our video explaining the Coriolis principle:

Read more about the importance of mass flow measurement and the relevance of Coriolis technology in a previous blog.

Check out our success story using Coriolis mass flow controllers for odorization of our natural gas.

Jos Abbing
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Industrial low flow applications have to cope with a wide variety of environmental and process conditions, but what does this mean when we talk about ‘industrial’? Knowledge about the specific application and low flow fluidics will help a lot to prevent slipping. We often refer to ‘uncontrolled macro-environments’ for equipment, when we talk about ‘outdoors’. However, it can also be a room or factory without (local) climate control in which equipment is experiencing comparable temperature and humidity variations as outdoors. What is important in low flow applications and what kind of challenges do you encounter? Let me share my ideas in this blog.

What is IP-rating?

I experienced that IP-rating is not always interpreted correctly. Having the highest possible IP-rating is often mistaken with having an ‘industrial-device’. But what does the IP-rating actually indicate? The first digit of an IP-rating only refers to dust ingress protection and the second digit refers to the liquid ingress protection.

Therefore, a higher IP-rating does not always mean that the instrument is better and more suitable for your application. Hence, it can even make things much worse in practice. A reason for this is that even the tightest IP-rated constructions may breathe in and out, caused by internal and external temperature variations. This can lead to internal condensation, especially in high humidity environments, if no further precautions are taken.

The importance of dedicated low flow equipment

Not surprisingly, things are often a lot smaller in low flow applications. The other side of this coin is that common process and environmental disturbances have a proportional larger impact on these low flow applications compared to traditional ‘normal’-flow applications.

In general, an industrial flow instrument, like a flow meter, needs to be suitable to a lot of external influences, such as resistance to corrosion and impact or pressure ratings. These requirements often lead to selecting more standard industrial flow meters instead of specialized low flow instruments. This is not always the best solution for the required low flow ranges and can lead to unsatisfactory results.

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What we want to achieve is to have rigid flow measurement and control, suitable for the application during the economic lifetime of the installation. Therefore, it would be best to select the best flow instrument fit for purpose. In case of low flow applications I therefore recommend to use dedicated low flow equipment. These flow meters are designed and tested for these kinds of applications.

Our industrial low flow mass flow meters and controllers can be equipped with integrated control valves or dedicated pumps, especially designed for low flow purpose. Stable control characteristics are combined with signal-to-noise ratio plus being proportionally less sensitive for disturbances.

Bronkhorst industrial low flow instruments

We gladly support you in process and environmental equipment selections including system design aspects, starting with selecting the most suitable measuring and control principles. Our flow meter product portfolio contains laboratory-style and light-industrial flow meters to heavy-duty IEC-Ex/ATEX-rated industrial versions (…having a “high” IP-rating as well).

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Drive your low flow control reliable and safely!

Our product manager for liquid technologies, Ferdinand Luimes, explains how to deal with vibrations using Coriolis mass flow meters.

Visit us at the Hannover Messe (April 1-5, Hall 11, booth A50)) and have a sneak preview at our new industrial Coriolis flow meter.

Dr. Roland Snijder
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This week we have a guest blog from Dr. Roland Snijder, Medical Physicist Resident at Haaglanden Medisch Centrum (NL). To obtain his PhD degree at the Utrecht University, Roland worked as a researcher on the multi-infusion project at the department of Medical Technology & Clinical Physics of University Medical Center Utrecht (UMC Utrecht). His research focused on investigating physical causes of dosing errors in multi-infusion systems. In this research flow characteristics of multi-infusion setups were investigated using Bronkhorst Coriolis flow meters. In this blog Roland explains more about his research.

What is infusion?

Most patients admitted to the hospital are treated with medication (pharmaceuticals). Especially in critical care, a substantial amount of patients require intravenous therapy. Intravenous therapy means that a solution of pharmaceuticals are administered directly into the veins. The process of administering pharmaceuticals directly into the veins is called infusion and is done using a vascular access device (e.g. a catheter), which is inserted into the vein.

The importance of an accurate flow

Often patients in critical care, most notably young and premature patients, suffer from conditions that require the intravenous administration of very potent and short acting pharmaceuticals. These pharmaceuticals typically require a very accurate administration where deviations in flow- and thus dosing-rate can easily result in dosing errors. For this reason, infusion or syringe pumps are used.

On top of this, vascular access to the patient is typically limited and therefore many infusion pumps have to co-administer through one catheter (multi-infusion), making the entire pharmaceutical delivery process complex and hard to predict. Because dosing errors are common in clinical practice, it was clear that more research was required. Many of the results of this research can be found in the PhD-thesis: “Physical Causes of Dosing Errors in Patients Receiving Multi-Infusion Therapy”.

Image description Fig 1. Example of a multi-infusion setup in clinical practice.

Flow measurement with Coriolis flow meter

We conducted a large amount of measurements to learn more about the flow characteristics of multi-infusion setups. These measurements were conducted using Bronkhorst Coriolis flow meters (series mini CORI-FLOW). These flow meters allowed us to measure the flow rate of infusion pumps very accurately, precisely and independent of the density of the solution being measured (although most of the solutions were similar to water).

The flow meters were also chosen because of the suitability for very low flow rates, infusion flow rates may be as low as 0.1 ml/h. Ultimately it is, of course, the dose rate or mass flow rate of the pharmaceutical administered to the patient that is important.

To measure this we used an absorption spectrophotometric setup, which enabled us to measure the concentration of a substance in a solution, i.e. a pharmaceutical or pharmaceutical-analogue. To convert density (e.g. µg/l) to a mass flow rate (e.g. µg/h), the cumulative flow rate (e.g. ml/h) of the infusion setup has to be measured as well.

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First we used a precision balance for this but later in the research project we used the mini CORI-FLOW flow meter. The data from the precision balance was rather noisy, whereas the flow meter provided very clean data, which improved our measurements substantially.

However, one point of caution that has to considered is that flow meters do produce a pressure drop resulting in intrinsic flow resistance. The implications of this and how the measurement setup relates to a clinical situation is thoroughly explained in the PhD-thesis.

The research concluded that a wide variety of infusion components all had a particular, usually significant influence and, importantly, medical personnel is usually not aware of the implications this has for infusion therapy. Awareness of the underlying mechanisms of these effects through education and technical innovation were recommended. The Coriolis flow meters from Bronkhorst proved to be very suitable for gaining insight in the different mechanisms of infusion pump system failure.

Further reading: R.A. Snijder - Physical causes of dosing errors in patients receiving multi-infusion therapy (ISBN: 978-94-028-0382-2) Link: https://dspace.library.uu.nl/bitstream/1874/341035/4/Snijder2.pdf

About the author:

Dr. R. A. (Roland) Snijder (1985) is Medical Physicist Resident at Haaglanden Medisch Centrum (NL). He obtained a master’s degree in Biomedical Engineering at the University of Groningen with a specialization curriculum in the area of medical physics (medical instrumentation and imaging). In his master thesis, conducted at the University Medical Center Groningen, he investigated the effects of using computed tomography (CT) for lung cancer screening. After finishing his master thesis in 2012, Roland went on to pursue a PhD degree at the department of Medical Technology and Clinical Physics of University Medical Center Utrecht (UMC Utrecht).

Want to learn more about calibration of infusion pumps? Read the blog of Marcel Katerberg, explaining the calibration techniques to improve infusion pump performance.

Mandy Westhoff
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A direct translation of the word ‘accreditation’ is providing trust. To measure this form of trust, standards are made to measure the expertise, impartiality and the level of continuous improvement of an organization. Laboratories that are accredited to the international standard ISO/IEC 17025:2005 have demonstrated that they are technically competent and able to produce precise and accurate test and/or calibration data.

Why are precise and accurate measurements important? For an example: If you pay the bill at the fuel station you trust that the amount you have to pay is an accurate equivalent of the amount of fuel which you filled-up. The same counts for many additional processes in which measurement equipment are used to secure the outcome of your process. An ISO/IEC 17025:2005 test certificate is the highest international level of calibration security which can be provided for measurement equipment. Bronkhorst is a proud owner of an accredited in-house ISO/IEC 17025:2005 Calibration Centre (BCC).

In this week’s blog I would like to take you with me to get a glance at our Bronkhorst Calibration Centre (BCC). This has been accredited since 2010 for gas, pressure and liquid flow calibration services.

For this, I followed Mandy Westhoff, one of our calibration centre operators, during her daily routines to get a realistic view on the activities of the calibration centre.

Why do flow meters have to be calibrated?

In general, all flow meters will be calibrated as a final step in production. The instrument with certain parameters will be compared with a fixed reference in certain environmental conditions, to provide real flow measurements.

Measuring equipment is used to secure the outcome of a process, process owners have to be able to rely on these measurements where high accuracy and – more and more – traceability play an important role, for example in the Pharmaceutical market. It is a way of risk management.

Throughout the years, we have noticed a distinctive increase in ISO/IEC17025:2005 calibrations in our calibration centre. An ISO/IEC 17025 calibration is often required as this is the highest level of calibration available in the market.

What kind of calibrations can be done in the calibration centre?

The Bronkhorst Calibration Centre is an independent department within the Bronkhorst organization and therefore not subjected to any commercial influences whatsoever.

It can be said that the tasks of the calibration centre are twofold:

1.The BCC acts as an in-house lab which maintains all calibration standards used within the Bronkhorst organisation

2.The BCC acts as an external calibration lab which performs ISO/IEC 17025:2005 calibrations for anyone who wants this certification on their instruments, for both Bronkhorst instruments and other brands. Moreover, the BCC can perform adjustments on new and existing flow meters and controllers and calibration devices.

The Bronkhorst Calibration Centre, an external calibration lab

The scope of the calibration centre includes calibration of gas flow, liquid flow and pressure.

About 60-70% of the performed ISO/IEC 17025:2005 calibrations are ‘as found’ calibrations on used instruments. Many of our customers, especially in the Pharmaceutical market, Universities and Automotive industry, will send their instruments once a year for calibration. So they have a reliable instrument calibrated according to the highest level of calibration security which they can use as a reference for their own calibrations on-site.

To offer the highest standard of precise and accurate test and/or calibration data the environment of the laboratory is fully controlled. The calibration will be executed in a high-tech lab under conditioned circumstances by 21°C ± 2°C and a humidity of 50 ± 20%, which is outstanding. Even sunlight through the windows has been avoided and movement of people has been minimised as much as possible. Non-authorized personnel is not allowed to enter the calibration centre.

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Can you explain the calibration process in the calibration centre?

After the acclimatisation process and setup, the operator will conduct a leakage test using the Flowbus Piston Prover (FPP). This test will be done prior to every calibration as a security check to maintain the high level of quality assurance.

After approval of the environmental conditions, the calibration starts. A standard calibration is performed on several measurement points. On these measuring points the accuracy of the instrument will be determined.

After a successful calibration the instrument is provided with a label mentioning the date of calibration and certificate number, so all can be traced back to the calibration dossier. The BCC coordinator will check if everything is done by protocol and all ISO/IEC 17025:2005 calibration dossiers will be sent to the BCC Officer to perform a final check.

How about training?

All our calibration operators are trained to perform gas, as well as pressure and liquid calibrations according to the ISO/IEC17025:2005 standard. Furthermore, we are taught how to maintain calibration devices, such as cleaning glass tubes and the chemicals which are used for calibration procedures.

Is it dangerous to do this type of work?

Training is the most important part. All our operators are highly competent and skilled employees. But still, all activities are primarily centered on human work. To keep the risk level as low as possible, everything is monitored closely during the calibration process and all materials used are checked on a regular base.

What makes your job interesting?

You never have a dull moment in this job, every day is different. The service you provide is always different, because it is customer specific. It is a nice idea that you can contribute to a successful customer’s process.

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Learn about the Bronkhorst USA local service and support capability

Read more about the Bronkhorst Calibration Centre

Angela Puls
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In the food industry there are many applications in which gases or liquids need to be measured or controlled. For example, these applications include the aeration process or the dosage of additives, like flavors and colourants. Indirectly, surface treatment applications like the sterilization of packaging is of high importance as well. Bronkhorst has published many stories regarding the omnifarious and demanding food industry and I would like to share some of these stories with you.

Image description Additive dosing for confectionery industry

There is a huge variation in candy available on the market, each brand with its own taste, texture and appearance. Erwin Broekman had the opportunity to visit Haas-Mondomix, a machine builder that is specialized in equipment for the food industry. With ultrasonic volume flow meters, Haas-Mondomix measures the amount of additives - flavourings, colourings and acids - that are added to the main stream of the production process. Please read the blog to learn more about this application.

In the chocolate confectionery industry, there’s an ever increasing number of variations in flavours as well. Due to this enormous growth, mass flow meters and controllers find their way into the confectionery industry. Coriolis flow meters in combination with a pump are an ideal solution for dosing flavors and functional ingredients. Read more about dosing flavor into chocolate.

Aeration within the production process of delicacies like ice cream and cake

Ice cream is made by freezing and simultaneously blending air into a brewage of fat, sugar and milk solids. Air makes up anywhere from 30% to 50% of the total volume of ice cream, so aeration is crucial during production. A side effect of adding air to ice cream is that it tends to melt more quickly. Thus, for attaining an optimal structure of the ice cream, it’s important to have a stable inlet air flow in the production process with a constant cream/air ratio. This can be achieved by using a mass flow controller. Read the blog about the production of ice cream, and get to know your favourite summer treat.

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Aeration is also a crucial process in the production of whipped cream. This is done at Hansa Industrie-Mixer, a worldwide company that operates in the field of mixing machines and foam generators for the food and non-food industry. Hans-Georg Frenzel, technical director at this company, explains how mass flow controllers are important in the production of cake in his blog.

Steralisation of food packaging to reduce food waste

However, all that food production does have a downside; food waste. Globally food is lost or wasted at different points in the supply chain. One of the ways to reduce food waste is to improve the sterilization of the packaging that food is placed in, to reduce spoilage and increase shelf life. This is the point where Controlled Evaporation Mixing (CEM) systems come in the picture. James Walton explains Bronkhorst’s share in the extension of the shelf life.

Hopefully you’ve learned some more about the role of flow meters and controllers in the food industry. Bronkhorst has a wide range of products for this particular industry, as can be seen on the ProSweets this year.

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Bronkhorst is present at ProSweets Cologne, from the 27th of January till the 30th of January in combination with the Internationale Süßwarenmesse ISM. Visit us at the ProSweets 2019, Hall 10.1, Booth A020! https://www.bronkhorst.com/about/trade-shows/prosweets-2019/

Walter Flamma
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Working as an Industry Specialist for the Food, Pharma and Beverage market at Bronkhorst High-Tech, it’s needless to say I continuously monitor these markets, to find out where we can be a solution provider. One of the trends in the beverage market I have encountered is fast batch dosing of additives. Additive dosing is a typical application in which flow meters can be used. Let me explain where this applies in the beverage industry and why additive batch dosing has to go with high speed.

The trend of small batch production

Traditionally, many industries make large batches of one product (mass production), and the beverage industry is no exception for that matter. However, due to the development of wider product ranges and diversification, which many companies face, this traditional way of production lacks the flexibility and efficiency which is often required these days. Companies optimize their processes, to be more resilient and responsive to risks. Nowadays, the trend is to make batches depending on the actual demand.

There is a demand to be more flexible and cost efficient on many levels. In the beverage industry this involves easier changeover from one flavour product to another by minimum cleaning. To keep the additive dosing system separated from the main product stream (like water), most parts of the filling line will be kept untainted from additives. This will save time, cleaning liquid and therefore costs, when changing product.

The necessity of fast batch dosing

Most types of filling lines produce a high output. This demands an additive dosing system which provides fast batch dosing with high repeatability and accuracy. How can fast batch dosing be achieved properly? Important with fast batch dosing is the right amount of additive in the pre-defined dosing time. This amount is usually very small and the dosing time can sometimes be very demanding. A dosing time from several milliseconds up to a second is not unusual in the beverage industry. To accurately dose small amounts of additives at such speed can be a challenge and requires excellent flow control.

Bronkhorst solutions for fast batch dosing

We can offer several flow solutions to ensure the required accuracy and reproducibility for (fast) batch dosing. One way is by combining a Coriolis mass flow meter with a pump or suitable valve. With this system, fluids can be dosed in a controlled way into the production process.

Another option would be to use an ultrasonic volume flow meter instead. The hygienic designs of our ultrasonic volume flow meters and their capability for cleaning in place - CIP - make these flow meters a good match for the beverage industry.

Image description Figure 1. ES-FLOW Ultrasonic Volume Flow Meter

The advantage of both the Bronkhorst Coriolis flow meter and ultrasonic volume flow meter is that they are equipped with an integrated batch dosing functionality. This dosing technology allows batch dosing of small amounts of liquid additives with only a minimum of tolerance. The firmware is equipped with a “learning function” to correct even the smallest tolerances automatically (e.g. during start-up of the instrument or change of supply batches). The setup is customized to fulfill all requirements of the production; it can be integrated easily in already existing processes and production lines. Moreover, with this batch dosing functionality, quick and complex regulation with PLC or SCADA is not necessary anymore.

Image description Figure 2. Bronkhorst Dosing Technology scheme with mini CORI-FLOW mass flow meters

So whether you choose for Coriolis or Ultrasonic flow technology, our flow instruments can offer the solution for higher throughput, flexible machines, more rapid changeover and less product waste in the beverage industry. If you want to learn more on how Ultrasonic flow technology has proven itself to be a solution for additive dosing in candy manufacturing, please read the story of my colleague Erwin Broekman on how candy gets its own taste, texture and appearance.

Read more about additive dosing.