Angela Puls
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In our daily life we use plastics or polymers in many different forms whether as a disposable product such as packaging film or as a long-lasting component in the automotive industry, in construction or in sports equipment and toys.

Nowadays, plastics are tailor-made for the respective application, depending on the properties desired. In this way, properties such as hardness, mold ability (or formability), elasticity, tensile strength, temperature, radiation and heat resistance can be adjusted as well as the chemical and physical resistance can be adapted to the desired function.

This large variety can be modified within wide limits by the choice of the basic building blocks (macromolecules), the production process and additives. The respective macromolecules are polymers of regularly repeating molecular units. The type of crosslinking and the used additives determine the final properties of the material. In 2016, the world-wide production of plastics for bulk materials and films was over 300 million tons (source: BMBF) of which almost one third was produced in China. Europe and North America follow with slightly less than 20 percent each.

Precise dosing for operational efficiency and minimization of unnecessary waste

Typical additives in the plastics industry are antistatic agents, dyes, flame retardants, fillers, lubricants, colorants, stabilizers and plasticizers. Many of these additives are liquid. Precise dosing of the additives leads to operational efficiency and the minimization of unnecessary waste.

Additives are frequently added by use of needle valves, which is inexpensive, but always has a risk on malfunction because of fluctuation within the process (e.g., pressure and temperature). In particular the use of plasticizers is increasingly critical since some of these substances are directly absorbed by human beings or accumulate in the food chain.

With the proven CORI-FILL dosing technology, Bronkhorst offers an easy-to-use setup to ensure the required accuracy and reproducibility. By combining a mini CORI -FLOW with a pump or a suitable valve, fluids can be dosed continuously or as a batch into the reactor with high reproducibility. These systems can be integrated or used as an add-on in already existing processes and production lines.

mini CORI-FLOW flow meter combined with a Tuthill pump

mini CORI-FLOW flow meter combined with a Tuthill pump

5 Reasons why additive dosing with a Coriolis instrument supports process efficiency for plastic manufacturers

Frank Doornbos
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The first variable area (VA) meter with rotating float was invented by Karl Kueppers in Aachen in 1908. The device was patented in Germany that same year. Felix Meyer was among the first to recognize the significance of Kueppers’ work and implemented the process for offering the meter for sale. In 1909, the firm of "Deutsche Rotawerke GmbH" was created in Aachen (Germany). They improved this invention with new shapes of the float and of the glass tube. It didn’t take long for the new device to capture attention in Europe, the United Kingdom, and other areas.

VA flow meters (or purge meters)

Over time, different types of VA flow meters (also called purge meters) have been developed, usually in response to some specific need. Nowadays a purge meter usually consists of a tapered tube, typically made of glass or plastic. Inside this tapered tube there is the ‘float’ which is made either from anodized aluminum or ceramic. The float is actually a shaped weight that is pushed up by the drag force of the flow and pulled down by gravity. The drag force for a given fluid and float cross section is a function of flow speed squared only.

While the meters are still relatively simplistic in design, relatively low cost, low maintenance and easy to install they are used in many kinds of application. Despite these facts, the traditional VA meter has a number of drawbacks. For instance, graduations on a given purge meter will only be accurate for a given substance at a given temperature and pressure. Either way, due to the direct flow indication, the resolution is relatively poor. Especially when they are built into a machine, reading might be hard. Moreover, the float must be read through the flowing medium, so you can imagine that some fluids may obscure the reading.

9 reasons why to use a thermal mass flow meter instead of a traditional purge meter

As for the current century, Bronkhorst has developed a thermal mass flow meter series (MASS-VIEW, as shown in picture 1) which is the digital high-tech alternative to the traditional VA flow meters. Thanks to today’s digital possibilities, many other advantages arise for many industrial processes and chemical plants.

bronkhorst-mass-view-flow-meter MASS-VIEW flow meter in application

  1. The MASS-VIEW flow meter series operate on the principle of direct thermal mass flow measurement (no by-pass); rather than measuring the volume flow it measures the actual mass flow, without the need of temperature and pressure correction.
  2. The digital OLED display provides an easy direct or relative reading of the actual flow. Herewith parallax errors are excluded.
  3. With this digital mass flow meter it is easily possible to obtain the accumulated flow. This availability of data gives insight in costs, leading to data driven decision making power.
  4. In contrast to the traditional VA meter which need to be mounted in a vertical position, this digital alternative can be mounted in any position.
  5. The flow path is made of sustainable aluminum rather than plastic or glass which is fragile.
  6. The instruments are standard equipped with 0-5V, RS-232 and Modbus-RTU output signals. Note that the traditional VA meters usually do not have any output signal available at all.
  7. As a standard feature, there are 2 built-in relays which indicate an alarm situation. Herewith, external devices can be controlled.
  8. Multi Gas; as opposed to traditional VA meters, which are produced for one particular fluid only, the digital alternative has up to 10 pre-installed gases available as a standard feature.
  9. Multi Range; traditional VA meters usually have a rangeability of 1:10 and one single full scale range only, the digital alternative has a rangeability of 1:100 as well as up to 4 pre-installed flow ranges.

Achieve a stable flow

A VA meter, whether it is a conventional or a digital one, can be equipped with a built-in needle valve. This needle valve enables the user to regulate the flow rate by means of a restriction inside the flow channel. As long as the inlet pressure is stable, the subsequent flow will be stable too. On the other hand, once pressure conditions are susceptible to change, the flow rate will become equally unstable. If this is not desirable, you’ll have to compensate these pressure fluctuations.

Flow control

Manual control valve

This effect can be eliminated by using a manual control valve like the FLOW-CONTROL series which keeps the pressure drop across the needle valve (delta-P) constant. This is accomplished by a second (normally open) valve, though it is operated by a membrane this time. The operating principle is based on a balance that forms between the pre-pressure, back-pressure and the spring force on the mebrane. A change in the pressure conditions leads to a change of the equilibrium and thus a change in the valve position as well (as shown in the picture below).

working-principle-control-valve Working principle of a pressure compensated control valve

Although Bronkhorsts’ pressure compensation technology is suitable for either gases and liquids, the nice thing about this is that both technologies, the digital VA meters and pressure compensation, lend themselves well to being built together. However, in that case it is applicable for gases only.

Learn more about the different models in the manual constant-flow control series

Ron Tietge
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We still often struggle with doing the dishes, and sometimes we just want our dirty dishes to magically disappear. If you do not have a dishwasher yet, you will definitely recognize this problem. However, manufacturers do their utmost best to make dishwashing as colourful as possible. You have probably noticed the large variety of detergents in your supermarket, so many choices! Mass flow controllers play an important role in the production process of these detergents. Let me explain why…

Colouring detergents

Detergent itself is transparent or white in colour. To change this, a small amount of colourant (or dye) is added to detergent and that’s the colour you see in the bottle; often green, yellow or red. The colourant does not add anything to the cleaning properties, however, it makes it more attractive and it will help the user to recognize a certain brand. For the manufacturer a consistent colour of the end-product is of major importance. Every bottle has to be the same colour, you should not see any colour difference between the bottles on the shelves (as the colour is part of their company branding).

What would be an appropriate way to dose these colourants? Pump control can be your solution.

Using Coriolis mass flow meters for accurate dosing

Dosing colourants can be done by using a pump. However, since this is volume flow it is not always the most accurate way. In these kinds of applications accuracy, and moreover, repeatability are crucial for the production process.

Important requirements in applications using colourant are:

  • Accuracy: the colourants used are in fact highly concentrated and have to be applied in extremely low doses. Furthermore, the colourants are rather expensive; therefore accurate dosing of the liquid is very much desired as well.
  • Repeatability: every bottle of detergent has to have the same colour, therefore the dosing of the colourant has to be consistent, always.

A better solution here would be to combine your pump with a Coriolis mass flow controller; it will give you the opportunity to control your pump and therefore a precise and traceable way of dosing your colourant.

mini cori-flow + tuthill pump

Pump control

The unique method of combining your pump with a Coriolis mass flow controller makes the pump dose mass flow instead of the usual volume flow. Since real mass flow is independent of the fluid properties of the colourant, the accuracy will be inimitable.

A PID controller makes it possible to control the speed of your pump. This can be done by an external PID controller (however, this can result in a slow response and slow control) or by a Coriolis instrument with integrated PID controller (a separate control signal will control the speed of the pump).

Read more about pump control in my blog about using pump control to optimize detergent colour.

Coriolis mass flow controller with integrated PID controller

Bronkhorst has a Coriolis instrument in its portfolio with integrated PID controller. The advantage of using a Coriolis instrument with integrated PID controller is the so called ‘closed loop system’. The flow will be immediately corrected if there is a change in back pressure by making the pump run faster or slower almost instantly, keeping up the required accuracy.

Additional benefit of this stable control method is that the pump is made to run on a moderate speed, decreasing wear and thus increasing its service life, resulting in less downtime of production equipment. Dosing mass flow instead of volumetric flow means high accuracy, for all your available liquids.

example response time coriolis flow meter

Example of response time of a Bronkhorst Coriolis instrument (series mini CORI-FLOW) with pump. (red = set point, green = output and yellow is the fast control signal to control the pump).


Other applications where you can encounter these challenges with dosing colourants/dyes are in production processes of shampoos, soaps, fabric conditioner agents, (shaving) creams and tooth pastes. In a previous blog, I shared my thoughts about how pump control can optimize our detergent colour.

Mark Berenpas
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Quality is becoming more and more important for customers, but what is quality? Some people refer to quality as the accuracy of an instrument, others as the reproducibility of an instrument. I am writing this blog to let you know how we organize quality at Bronkhorst.

How does Bronkhorst deal with quality?

As Supplier Engineer at Bronkhorst, I have co-responsibility for the quality of our purchased parts. Together with our suppliers, we set up the supply chain using the Lean Six Sigma philosophy. The ultimate aim is to create a repeatable and reproducible supply chain, which is becoming more and more important for our Copy Exactly customers. By properly setting up the supply chain, we adhere to the ‘first time right’ principle, which reduces the chance of subsequent changes.

Cooperation between Bronkhorst’s Research & Development department, the supplier that produces the article and the measuring chamber that ultimately carries out the inspection is essential for setting up this reliable supply chain. If you know how a product is used, you can set up a good process. If you know the critical specifications of the function and the critical parameters of the process, you know what to measure in order to say something about the repeatability and reproducibility of the product.

Pilot Series Process

Once a design has been approved through a ‘Proof of Principle’, the release for the series can start. For this purpose, Bronkhorst has set up the ‘Pilot Series Process’. All new products undergo the Pilot Series Process, including our newest product, the ES-FLOW. The ES-FLOW is an ultrasonic Liquid Flow Meter/Controller, which has recently come on the market and works on the basis of ultrasonic measurement techniques.
Let’s take this as an example.

Pilot Series Process for the ES-FLOW, Liquid Flow Meter/Controller

An important part of the ES-FLOW liquid flow meter/controller is the stainless steel body of the instrument, which contains the measuring sensor. The technical requirements that this component must meet have been specified by the Research & Development department at Bronkhorst. Some of the important requirements of the ES-FLOW body include pressure resistance, leakage density and installation length.

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The supplier will then set to work and will carry out a number of tests during the production process to convince Bronkhorst and himself that the body of the instrument and the sensor meet all the requirements.

During the Pilot Series Process, extra data (including measurements) of the critical function specifications and the critical process parameters of the component is requested. In this way, we can obtain a good overview of the reproducibility and repeatability of the process and, based on that information, a decision can be taken to release the component, the so-called ‘Article Supplier Approval’ (ASA). As soon as the article is released with an ASA, the Purchasing department can order the article in large series from the supplier concerned.

The results of the Pilot Series Process also form the basis of the component’s measuring plan, describing which specifications must be inspected in what manner when the product in the series is delivered.

Working with Pilot Series ensures that the knowledge of both the developer and the supplier comes together and that the measuring chamber knows what and how to measure in order to monitor the process functionally. The introduction of the Pilot Series enables Bronkhorst to reduce the risk of interruptions in the series and create a reliable supply chain together with its suppliers.

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This entire process helps Bronkhorst to deliver high-quality products, which we consider a top priority.

More information about the ES-FLOW™ series can be found on the website and YouTube.

Rob ten Haaft
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For many years, Mass Flow Controllers (MFCs) and Mass Flow Meters (MFMs) have been used in Analytical instrumentation. There are some distinctive applications like carrier gas control or mobile phase control in Gas Chromatography (GC) and Liquid Chromatography (LC). I discovered that there are a lot more applications of Mass Flow Controllers in analyzers then I could imagine when entering the world of Mass Flow Controllers after many years working in Analytical Chemistry.

One application I would like to focus on in this blog is Mass Spectrometry or shortly, as chemists like to use abbreviations, MS. Mass Spectrometry comes in many forms and is often coupled to Gas Chromatography and Liquid Chromatography. A Mass Spectrometer coupled to a Gas Chromatography (GC) is called a GC-MS and a Mass Spectrometer coupled to a Liquid Chromatography (LC) is called a LC-MS.

Where are Mass Spectrometers applied?

The market for Mass Spectrometers is huge and expanding. The instruments are used for Analytical Research in general but increasingly important in Food Research. Research concerning aging of whiskey and fingerprinting of red wine to determine the origin of the grapes are some examples. Another emerging market is Biopharmaceutical Research where Mass Spectrometers are used to study proteins and how these proteins are digested in living organisms. There are even Mass Spectrometers on Mars (!), where the martian soil is studied.

schematic mass spectrometer

Figure 1: Mass Spectrometer(schematic)

What is a Mass Spectrometer?

The Mass Spectrometer is often compared with a weighing scale for molecules. Every molecule is built up from atoms and every atom has its own atomic mass and this is “weighted” by a Mass Spectrometer. Before it can weigh the different atoms that are present in one sample, the atoms have to be separated from each other. This is done by charging the atoms (to form ions) and using a magnet to deflect the path that the ion is following. The lighter the ion, the more influence the magnet has and the bigger the deflection. The detector detects where the ion hits and this is a measurement of the weight.

The place where the ionization takes place is called the ion source and there are a lot of different types of ion sources, depending on the matrix of the sample and on the ions that you want to form. The ionizing part is the most interesting part from a Mass Flow point of view because in this part different gases are used, depending on the technique of ionization.

There are two main techniques: hard ionization and soft ionization. With hard ionization techniques, molecules in the sample are heated and fragmented down to atomic levels giving information about the atomic structure of the molecule. With soft ionization techniques the molecule stays more intact giving mass information of the molecule. This is used in Food and Pharma research and has become very popular in the last decade.

Let’s look into detail to one of the most popular soft ionization techniques, the Electrospray Ion Source. The EIS vaporizes the liquid (coming from a Liquid Chromatograph, for example) by leading gas alongside a charged needle to form an aerosol spray. Leading a counter gas flow through the formed spray will evaporate most of the liquid that you do not want to measure, leaving the charged droplets going into the Mass Spectrometer.

atmospheric pressure chemical ionization electrospray ionization electroscopy

Figure 2+3: Electrospray ionization (ESI)

Mass Flow Controllers and Evaporation used in Electrospray Ion source

The interesting part is that the flow needs to be very constant as you want the process of forming droplets and evaporating solvent to be the same, day after day and at different locations with different circumstances. An important parameter in this reproducibility is the gas flow. By using Mass Flow Controllers for Nebulizer gas and Evaporation or Drying gas, the ion source will always have reproducible gas flows.

Our solutions department can design compact gas modules for analytical applications to supply gases for ion-source combined with other gas flows with high accuracy and good reproducibility. Combining components like pressure switches and/or shut-off valves with the flow channels can give a compact gas handling module to fit in the small footprint demanding designs of the Mass Spectrometers. Furthermore, the changes on leaks are decreased significantly as the whole manifold can be leak and pressure tested before it is shipped to the customer.

If you would like to learn more about Bronkhorst customized flow solutions, you can watch this Video or visit our website.

James Walton
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Why using a Controlled Evaporation and Mixing system can decrease food waste

We are all aware that the current level of food waste cannot be sustained if we have a hope of reducing food poverty across the world. This is not just a Western issue; globally food is lost or wasted at different points in the supply chain. Today’s technologies, such as sterilization, can help reduce this spoilage. However, the strict compliance requirements will ask for continuous improvement of this technology. An analysis from the Food and Agriculture organization of the United Nations highlights some discrepancies;

• In developing countries food waste and losses occur mainly at early stages of the food value chain and can be traced back to financial, managerial and technical constraints in harvesting techniques as well as storage and cooling facilities.

• In medium- and high-income countries food is wasted and lost mainly at later stages in the supply chain. Differing from the situation in developing countries, the behavior of consumers plays an important role in industrialized countries.

So, where can we make a difference?

Looking at the graph of food losses below, and the statements above, we can see that it is worthwhile to invest in production techniques, potentially to increase the shelf life of packaged food. This would have a positive impact on the waste of food in developed countries.

Food losses


One of the ways to improve these figures 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.

Bronkhorst share in extension of the shelf life

Sterilisation of packaging to extend shelf life is not something new, it already has been done for years. I believe the first aseptic filling plant for milk was already presented in 1961. However, it is a technology which has been improved tremendously throughout the years and still is improving. Bronkhorst has an extended range of instruments which can support you in this process. An ingenious development in this area is a Controlled Evaporation and Mixing system (also called a CEM), as one compact solution for industrial processes such as sterilization. The compact solutions consist of various type of instruments, such as liquid and gas flow meters and an evaporator.

Using Controlled Evaporation Mixing (CEM) systems for sterilisation

The challenge given to Bronkhorst via a customer that was using a Hydrogen Peroxide (H2O2) mix (containing 35% of H2O2 and water) to decontaminate carton and plastic packaging for liquid and cream filling. Using a mix of H2O2 is an excellent way to do this, because it is great at killing bacteria and can be easily evaporated. Bronkhorst is an experienced supplier of this kind of solutions.

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To get the best production with minimal waste you need to:

  1. Dose the correct amount of H2O2 mixture
    • Too much and the final product is spoiled
    • Too little and the residual bacteria is too high
  2. Avoid de-gassing of the H2O2 mix
  3. Have a controlled flow that condenses on the inside of the package
  4. Limit the flow. If it’s too high it will increase drying time at the end of sterilisation

The best result for this application was given by vapour generation combined with a Coriolis mass flow meter. Because H2O2 mixtures are not particularly stable this results in changing physical properties. Adding a Coriolis mass flow meter to the CEM made the measurement of mass flow medium properties independent. Furthermore as the Coriolis instrument is capable of measuring medium density, it can be used to monitor the concentration and thus watch over quality of H2O2.

Using a CEM system has some real advantages:

  • Stable temperature of vapour
  • Stable concentration of condensation because of a controlled dew point of the mixture
  • All of the above is possible because the gas, liquid and mixing temperature are controlled

Benefits as perceived by the customer

  • Stable liquid mass flow, even if physical properties vary
  • Monitoring the concentration and quality of the H2O2
  • Monitoring and traceability of the sterilisation process
  • Mass flow control of liquid
  • Mass flow control of gas
  • Direct control of dew point through control of gas and air mixture
  • Increased use-by-date
  • Longer life of fresh food


Controlled Evaporation System