Sandra Wassink
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This weekend it’s the Easter Weekend! It’s the top selling season if you look at chocolate gifts. If you have a look in the supermarket now, you will find chocolate eggs, easter bunnies and bonbons in many variations. In our office we also have a large bowl filled with colourful chocolate eggs already, delicious!

And if we talk about various flavours of chocolate, that’s part were flow instruments come into the picture.

Chocolate confectionery industry

I would like to share my findings within the growing chocolate confectionery industry and the trends in using flavours. Who else can do this better than a woman you should think, as 75% of the women report that they indulge in chocolate, against 68% of the men.

Chocolate… a growing worldwide market of $100 billion once started with a simple choice between Milk, Dark or White chocolate. Nowadays the choice in variations is huge due to flavourings.

Chocolate as a seasonal gift is still very popular. Around the holidays we tend to buy more chocolate. The top selling season for chocolate is not Valentine’s Day, as you might think, but Easter. Besides treating yourself with chocolate, there is an emotional aspect. Chocolate can have a positive effect on your mood, especially with young adults. A popular reason for the increasing sales. The majority of the chocolate buyers are looking for options with mix-ins as opposed to the conventional unflavoured varieties.

Chocolate production

Flavour and textures

The global chocolate market has seen considerable innovation in flavour and texture. New product development continues to be imaginative, with more exploration of flavours and textures in addition to the traditional sweetness. However, the consumer base tends to be rather traditional as the most popular flavours still are Hazelnut, Caramel and Almond.

Older consumers tend to have a lower engagement with chocolate. The lack of interest reflects their desire to eat healthy. To regain this group of adult customers, companies have turned to tactics such as using alcohol flavours, organic ingredients, and premium positioning such as dark chocolate with Limoncello or chocolates filled with sweet liqueur.

Coriolis flow meter dosing block

Healthy lifestyle

It may come as a surprise, but a healthy lifestyle, which is one of the major trends worldwide, is also responsible for a substantial growth of the chocolate market and that’s not without reason. Chocolate, specifically dark chocolate with more than 85% cocoa, can offer beneficial health benefits. This results in labels mentioning:

  • Rich in fiber, iron, magnesium, copper, manganese and other minerals
  • Powerful source of antioxidants
  • Protective against cardiovascular disease

The growing awareness of the health benefits of dark chocolate is one of the reasons why consumption of chocolate is increasing. With the rising popularity of dark chocolate, the sales for other variations are also going up. People are seeking other ‘healthy’ variations, such as sugar-free, gluten-free, kosher or fair trade chocolate. Due to these ethical claims, the industry has seen an enormous growth in variations.

In order to enhance a healthy image for chocolate, functional ingredients such as fibers, proteins, micronutrients, quick energy (guarana extracts), green tea extract, or chia seeds are more and more often added to the chocolate.


The increasing demand for chocolate also has its downside. About 3 million tons of cocoa beans are consumed annually of which more than 70% are produced by four West African countries: Ivory Coast, Ghana, Nigeria and Cameroon. Cocoa is a delicate crop and trees planted a quarter century ago have hit their production peak and the land they grown on are not as fertile as it once was. A large rehabilitation of land and trees is necessary to prevent the loss of crop production. Also climate changes are taking their toll.

This results in high costs for raw materials and unstable economic conditions in cocoa-producing nations. To prevent a supply shortage, a number of well-known chocolate producing companies have decided to invest in rehabilitation of the land and trees to make sure that cocoa will be available in the future. This happens in a time that developing countries such as China, India, and Russia expect to increase their chocolate sales volume by 30%.

Mass Flow Meters in your production process

Due to the enormous growth of chocolate variations, using flavours and functional ingredients, 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 flavours and functional ingredients. Using the Coriolis instruments for additive dosing means less downtime between batches, traceability of ingredients, and higher product consistency and quality.

Watch our video about an additive dosing solution for the confectionery market.

Download our brochure (Ultra) low flow Coriolis competence for the confectionery industry.

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:

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

Bronkhorst calibration centre

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.

certificate Bronkhorst Calibration Centre

James Walton
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New Year's marks a time not only for resolutions, but also reflection. We are very delighted that our blogs have been received so well! This past year there were again many interesting stories to tell, how could it be otherwise given the industries in which we operate. I would like to share our top 5 best-read blogs of 2017 with you.

1) The importance of mass flow measurement and the relevance of Coriolis technology Why is Mass Flow Measurement important within process industries and what are the strengths of Coriolis Flow Meters and Controllers? Given the number of readers of this blog, this is a frequently asked question.

2) A typical day at Bronkhorst’s flow meter Calibration Centre We followed Mandy Westhoff, one of our Calibration Centre operators at our headquarters in Ruurlo, during her daily routines to get a realistic view on the activities of the Calibration Centre. A unique moment for readers to gain more insight about this challenging and important work!

3) How to measure low flow rates of liquids using ultrasonic waves? In June 2017 we were proud to launch our ultrasonic flow meter, the ES-FLOW™, for measuring and controlling liquid volume flows. In collaboration with TNO (Netherlands organization for applied scientific research) we were ably to develop this instrument using Ultrasonic Wave Technology. More in-depth information on this subject can been found in this blog post.

4) Bronkhorst, its share of a clean – solar – energy future Sustainability and clean energy remains a hot topic. CO2 reduction is one of the major trends worldwide in the energy market. The global focus on CO2 reductions matches perfectly within the Bronkhorst principles regarding respect for nature and environment.

5) How low can you go? Well, this recent blog of Marcel Katerberg is not very low on our rankings. If you are keen to learn more about how to handle ultra low flow, then you definitely should read this blog.

Furthermore, I would like to thank our guest bloggers of this year, who were so generous spending their time in crafting an interesting blog contribution.

Frank Nijsen (Quirem Medical), Bram de la Combé (Green Team Twente), Maarten Nijland (Veco B.V.), Jeremy Lowe and Ian Brown (Anglian Water Services), Jens Rother (Rubolab GmbH), and Kees Jalink (NKI – Netherlands Cancer Institute)

I am confident that you will enjoy reading these blog posts - if you haven't read them already. But for now, I wish you on behalf of our whole team great health, happiness and success in the coming year.

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Dr. Jens Rother
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It is real common nowadays to use 3D printing techniques as process optimization in industrial production evironments. In our Bronkhorst premises in Ruurlo we also use 3D-printers for our own product and process development. 3D-Printers are indispensible within our production environment, it has brought us a new and very accessible and flexible way of manufacturing.

Within a few hours, we can evaluate the design of a component: will it really work in the way we expected it, does it really fit? You can read all about our experiences here in our blog ‘Product & process optimization by use of 3D printers’

But it also goes the other way around. Not only do we use 3D printers in the production proces of flow meters, but these flow meters and flow controllers are also used inside 3D-printers as well.

In this blog I would like to share an application with you explaining how mass flow meters are used in the 3D printing machines of one of our German customers in the machine building industry.

Selective laser melting (SLD)

3D-printing, also known as additive manufacturing, is a technique where products are made by building a product layer by layer. This is the opposite of machining operations such as drilling or milling, where pieces of materials are removed to yield the product.

Selective laser melting (SLM) is a 3D-printing technique where a layer of powder is deposited, after which a part of these powder particles is selectively melted together by means of laser heat.

The customer is a machine builder who makes 3D-printing machines that print metal parts out of steel, aluminium or titanium powder using this selective laser melting technique. Their customers are in the fields of aerospace, automotive and medicine & dental. High purity inert gases are necessary around the metal powder bed within the 3D-printer.

Example 3D Dental SLM

Application requirements

It is essential to have a gas atmosphere around the to-be-melted metal powder particles that is oxygen-free, to prevent the metal from oxidation during the laser melting. To that end, an inert shielding gas has to be applied: argon gas for steel and titanium, and nitrogen gas for alumium.

Flow solution with MASS-STREAM mass flow controller

For the end user of SLM's 3D-printing machine, there are two ways to establish a nitrogen atmosphere: either from the in-house nitrogen supply mains - if present - or from a nitrogen generator, which is an accessory to the 3D-printer. In the latter option, Bronkhorst becomes involved.

Flow scheme

Pressurised air from a compressed air supply or a compressor is supplied to the nitrogen generator, and its molecular sieve separates the air flow into two flows. Constituents such as oxygen, water vapour and argon are removed, and nitrogen with high purity (grade 5.0) remains.

Downstream of the generator, a mass flow controller (using direct through-flow measurement technique) is installed to control the nitrogen flow to the 3D-printer. This controller works in two operating modes.

Prior to the printing process, the 3D-printer has to be flushed, in order to establish the shielding gas atmosphere. To this end a high nitrogen flow of 60 to 90 liters per minute is necessary. Next, during the printing process itself, a small nitrogen flow of 3 to 10 liters per minute has to be supplied, for refreshing purposes and to compensate for leakage.

Read more about this application using 3D-printing of metal products

Check out the mass flow controller (MASS-STREAM™ D-6300 ) used in this application

Marcel Katerberg
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When it comes to accurately measuring and controlling flow rates in the range of 1 gram/hour and lower, not only a good mass flow controller is essential, but also a proper designed system and the presence of other important components come into play. As in any system, it will be as strong as its weakest link.

How to control low flow rates

For controlling low flow rates, the weakest link is usually not the mass flow sensor. A mass flow controller is capable of accurately measuring and controlling the flow rate, at its position in the system. However, there is no absolute confidence that this flow rate is accurate further up- or downstream of the flow controller. If no countermeasures are taken, the exact desired flow rate will not be delivered to the process. As the flow rate minimizes the relative internal volume of system components, such as piping, filters and valves, seem to increase. This affects the dynamics of the system as the response time will slow down resulting in a loss of direct control. So, when a set point is given and this is assumed to reach the process, expectations might not be met.

For instance, a popular setup to force a flow through the system is to make use of pressurized gas. However, gas will dissolve in the liquid to a saturation level proportional with the gas pressure. The dissolved gasses appear again as bubbles downstream in the system where the pressure has decreased. If a gas bubble passes the flowmeter or valve or enters the process it disturbs the stability of the flow.

Practically for low flow rate processes, it is sometimes hard to understand why and when the system works correct. And so many questions arise. Is the purity of the media correct? Are the process temperatures as they should be? Is the set rate or dosage correct? Is the pressure stable?

Challenges which can occur within low flow process

  • For the lowest flow rates it is hard to verify if, at any time, the flow entering the process is as expected. As mentioned, there may be various underlying causes:
  • Dissolved gasses in the liquid and uncontrolled gas bubble entrapment and release
  • Dynamic effects of multiple fluid transmission lines: e.g. in medical multi infusion systems
  • Compliance of the system: e.g. in plastic tubing or plastic syringes
  • Local heating and fluid expansion: due to the internal volume and power dissipation of solenoid valves
  • Ripple on the flow delivery when using pumps

‘Check out our blog about how to handle ultra low flow

Influence of dissolved gasses

This blog focusses on the influence of dissolved gasses in the liquid and the possible countermeasures. When dissolved gasses in the liquid undergo a pressure drop through the system, gas bubbles tend to appear. The bubbles not only cause discontinuity in the flow but also tend to change the flow rate in between the gas bubbles. Several experiments have been carried out to investigate the phenomena and match it with known theories.

Schematic setup ML120

Low flow experiment with Coriolis mass flow meters

In figure 1 a setup is shown of two Bronkhorst low flow Coriolis mass flow instruments (mini CORI-FLOW™ ML120) in series. The first instrument is a mass flow meter. The second instrument acts as a controller, controlling the flow with an accurate onboard proportional valve positioned in front of its sensor.

Test setup ML120 coriolis flow meter

In this specific case the fluid is pressurized using compressed air to force the liquid through the system. As the pressurized air comes into contact with the liquid, it will dissolve into the liquid proportional to the gas pressure. This experiment is to investigate the influence of dissolved gas in the liquid and the use of a degasser as a countermeasure for gas bubbles.

Experiment without degasser

Picture 3 shows the outcome of the experiment when the setup has run for a few hours without a degasser. Clearly visible is the effect of gas bubbles passing the sensor of the flow controller. This can also be seen in the density measurement of the second instrument. The density drops each time a gas bubbles passes the instrument. The density is directly measured by the Coriolis instrument. A Coriolis instrument is capable of measuring density by a change in natural frequency of its vibrating measuring tube when liquid is flowing through it.

Measurement results without degasser

As expected the gas bubbles are generated by the valve in the mass flow controller as there the pressure drop occurs. As this valve is in front of its meter (in instrument 2) the mass flow meter detects the gas bubbles and thus the mass flow controller responds to it by controlling the valve. The physical effect of gas bubble generation occurs at any place in the system with large pressure drop, in most cases directly behindthe control valve. This effect is independent of measuring principle or type of control valve. Another remarkable phenomenon is that there is a difference in between the measured flows of both devices. It seems that the first instrument (mass flow meter) shows a lower flow rate of about 3% less than the flow rate measured by the second instrument (mass flow controller).

An explanation for this is that a generated bubble downstream of the control valve causes the volume flow to expand and pushes the liquid forward. As the mass flow controller will maintain its set point value of 1 gram/hour the flowrate is “slowed down” to maintain the correct mass flow. Therefore the flowrate through the first flowmeter is 3% less in between the bubbles.

Average deviation from set point

Table 1: Average deviation from set point of 1g/h of measured mass flow rate

There is a difference in volumetric flow rate before and after the appearance of the gas bubbles. However, the average mass flow rate in the instruments in both experiments is within specification and thus the same, as shown in table 1. This table shows the average deviation from 1 gram/hour of each instrument in both experiments over the entire dataset as shown in the charts.

The 3% error matches ‘Henrys law,’ which tells us that the solubility of air in water is 22 milligram/liter per bar. If this number is divided by the density of air, the volumetric expansion explains the 3% increase in volume flow after the gas bubbles appear. So the total volume flow is 3% higher due to the gas bubbles and the mass flow drops to nearly zero at a gas bubble in 3% of the time. This explains why the average mass flow, including the gas bubbles, remains the same compared to when the gas was disolved.

Countermeasures for gas bubbles

In order to take out the dissolved gas before problems appear, a HPLC (high-performance liquid chromatography) degasser is used. This device uses a permeable tube to degas the liquid. The permeable tube is positioned inside a vacuum chamber where the vacuum is maintained by a small onboard vacuum pump. The device extracts most of the dissolved gasses in the used liquid.

‘Have a look at our blog ‘Chromatography, history and future trends’ to learn more about Chromatography.’

Furthermore, as the liquid is well degassed it is capable of easily dissolving any remaining small bubbles that are left behind in the system. In this way the system will end up fully filled with liquid without any pockets left with gas. As gasses are compressible, a properly degassed system makes the system stiff and very responsive. A system like this is capable of generating a continuous and stable flow towards the process with good control behavior.

Experiment with degasser

Picture 4 shows the measured outcome where the degasser is put up in front of the Coriolis mass flow instruments. It is clearly visible that the system can run for several hours without any drops or glitches in mass flow or density. Apparently, no air bubbles are present in the system or generated by the control valve. The small deviation between the instruments is within the specified accuracy of 0.2% of reading ± 20 milligram/hour zero stability.

Measurement result with degasser


In many low flow fluidic control systems the fluid is pressurized with a gas. When gas is entrained in the liquid flow it can appear as dissolved gas or as gas bubbles. In both cases it has no significant influence on the average mass flow. However, gas bubbles tend to disrubt the stability of the flow. The effect can be monitored by a fast and accurate flow meter. This physical effect occurs in any low liquid flow system with dissolved gases and pressure drop downstream and is independent of measuring principle or type of control valve.

It is recommended to use a degasser for generating a continuous, stable and responsive system towards the end process, especially in low flow measurements of liquids. An ideal solution for these low flow measurements would be a degasser in combination with a Bronkhorst mini CORI-FLOW ML120 mass flow meter/controller, as is used in this experiment.

As this mass flow controller has its control valve in front of the meter, the sensor is capable of monitoring the actual flow in the system. This results in an optimal and direct process control. The flow controller can be used for (ultra) low flow applications up to 200 gram/hour.

• These (ultra) low flow applications can be found in the Semiconductor market as described in our brochure ‘Low Flow Coriolis Competence’.

• Download the application story describing use of (ultra) low flow measurement in microfluidics.

• Read more about measuring very low flow leak rates in the automotive industry)

Yann Le-Guenniou
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In this blog, I would like to share an application of our flow instrumentation at one of our customers in which we needed to deal with high temperature and high pressure. This customer – an energy research organisation - investigates a catalysed chemical reaction of a mixture of hydrocarbon compounds.

Catalysts are being used to accelerate a chemical reaction without actually being consumed. So a small amount of catalyst is sufficient to obtain a large amount of reaction products.

Solid catalysts are often small, highly porous particles, with a large internal surface area in a small volume. This internal surface contains active sites on which the reaction takes place. Gaseous or liquid chemicals diffuse into the pores of these particles, and react at the catalytically active sites to reaction products that diffuse out of the particle. Often, these reactions occur at extreme process conditions.

What were the application requirements? A simple and reliable solution had to be found to inject a liquid flow at a high pressure. This injection has to take place at 30 to 60 bars, and needs to result in a stable flow without pulsation. Furthermore, the liquid flow needs to be controlled accurately, and during the process it has to be known how much liquid actually has been injected.

Which solution did the customer choose? The solution comprises a Coriolis mass flow meter that controls a HPLC piston pump at the inlet side of the reactor and an independently operating back pressure controller at the outlet side. The tested Coriolis mass flow meter (mini CORI-FLOW ML120) has proven to be a very stable and accurate mass flow meter. The WADose HPLC pump gives a very stable flow without pulsation. The combination of an HPLC pump and mass flow meter works as a mass flow controller. The control valve of the Coriolis mas flow meter is not necessary, as the pump is used as an actuator.

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The pump can handle a liquid viscosity of max. 40 mPa.s at the upstream side. The maximum operating temperature is 70 °C. The temperature of the furnace that contains the reactor tube with small catalyst particles is much higher. The pressure at the reactor tube outlet has to remain at a high value. Beyond the outlet there is a cold trap for water or oil condensation, a back pressure controller with control valve that can handle pressure differences up to 400 bars and an exhaust to atmospheric pressure.

The pressure controller can handle gas and liquid in a very stable controlled flow. Especially at very small flow rates, this pressure controller has a much better control performance than a mechanical pressure reducer. The exhaust is used to remove gas that has been produced at the reaction.

The pump has three control modes: pressure, volumetric (only the speed of the piston is controlled) and mass flow. The latter is a special feature that can be offered, and is convenient from a chemist’s point of view. As the flow can be controlled directly, the exact number of moles injected to the process is known.

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Control and monitoring occurs via the digital interface. The mass flow measure and setpoint, density, temperature and counter value are visible via this single digital interface.

The success of this setup has been demonstrated by a recent order of three additional pumps. For more details have a look at the application story 'Catalysis at high pressure'.

Want to learn more about flow management in catalyst research? Have a look at our Webinar ‘Flow Management in Catalyst Research’