Gerhard Bauhuis
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The temperatures are sky high! All winter you've thought about going camping, travelling with your caravan and planning precious family trips. Finally now it’s the time to leave everything behind, and for a moment forget the busy daily live and struggling at home. However, everywhere you go Bronkhorst is travelling with you. Bronkhorst plays a role in many more applications than you think, even when you go camping. Let me guide you through some mainstream products you often see at a camping site, and the involvement of mass flow controllers.

Surface treatment

If you are travelling to your vacation destination by car, you will constantly look at some Bronkhorst solutions. Let’s start with the dashboard of your car. Many cars have a leather dashboard; at least, it looks like leather. A major company manufactures ‘skin’ that covers a car's dashboard, to give it this ‘leather look’. The skin is produced by spraying liquid, colored polyurethane into a nickel mold. A Coriolis mass flow controller combined with a valve forms the basis of this solution to accurately supply external release agent to the nickel mold surface.

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But also the foam within the dashboard is manufactured by using Bronkhorst products. To create foam, a gas is added to a mixture containing acrylonitrile-butadiene-styrene (ABS) or polyvinyl chloride (PVC), to give it the right volume. Too much gas will make the foam unstable, too little and you’ll get a heavy solid block. Therefore, it is utterly important that the correct amount of gas is added with an accurate gas flow controller.

Glass coating

If you look beyond your dashboard, you’ll look through the front window of your car. To control the light transmittance of glass, but also to make glass water repellent, protect it from mechanical and chemical stress, increase the scratch resistance and shatter protection, thermal mass flow controllers are used for the coating process. By controlling individually process gas flows, film thickness uniformity improvements are achieved.

Coating on headlights

When polycarbonate was introduced as a replacement for headlights glass in the early 1980s, new problems arose. Headlights are subject to a harsh environment. Due to the position in the front of a car, critical parameters for lifetime and performance are weather ability, scratches, and abrasion. To protect headlights from these factors, scratch and abrasion coatings have been developed that are sprayed on the headlights with the help of robots in which Coriolis mass flow controllers control the flow to the spraying nozzles.

Hydrophobic coating

However, surface treatment is not only applicable for glass and dashboards. If you have experience with camping, you will be familiar with how fierce the summer weather sometimes can be. The awning of your caravan needs to be water repellent - this also applies to your raincoat - to sustain the heavy rainfall now and then. To make fabrics and textiles hydrophobic, Empa - a research institute of the ETH Domain, applies plasma polymerisation to deposit thin, nanoscale layers on top of fabrics and fibers. For this, they are using a Controlled Evaporation and Mixing system, in short a CEM system. In one of our previous blogs ‘Hydrophobic coating, the answer to exercising in the rain’ you can read about this application.

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Odorization

Bronkhorst is also involved with many smaller attributes you will encounter on a campingsite. Most people still enjoy the comfort of gas for heating or cooking on the stove. But also with gas we are able to fire up the barbecue in no time at all, in comparison with the old-fashioned briquettes that are sometimes hard to ignite. When gas escapes from a pressurized cylinder, you’ll recognize this from its penetrating scent. However, like Sandra Wassink stated in her blog “How mass flow controllers make our gas smell”, natural gas is odorless. By controlled supply of odorants like Tetrahydrothiophene (THT) or Mecaptan with a mass flow controller, the scent is added to the natural gas on purpose.

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Let’s stay with the topic scent for a moment. For when we want to decrease the amount of mosquitos in our surroundings, we often light a citronella candle when we are getting tired of using the flyswatter. With the CORI-FILL dosing technology, Bronkhorst offers an easy-to-use setup to dose fragrances, like citronella, in candles. The addition of fragrance to a candle should be carefully monitored to ensure the candle burns cleanly and safely.

LED lighting

However a candle can bring much light to your surroundings, you won’t take a candle with you when you dash to the camping toilets at night. Instead you will use a flashlight of course. The working principle of the LED (Light Emitting Diode) inside this flashlight is a technology where Bronkhorst plays its part. LED works via the phenomenon called electroluminescence, which is the emission of light from a semiconductor (diode) under the influence of an electric field. By applying a semiconducting material like Gallium arsenide phosphide for instance, the manufacturing of red, orange and yellow light emitting diodes is possible.

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I already told you so much, but frankly, it is just a tiny bit of all the camping applications we are involved in. Hopefully you got some more insights on the importance of Bronkhorst in many industries, even when you go camping.

Erwin Broekman

Why do we all (at least most of us) like candy, soda, cookies and cake? All these products contain sugar which makes it taste real good. But where does this sugar come from? All green plants make sugar through photosynthesis. Of all plants, sugar beets and sugar cane contain the greatest quantities of sugar; that’s why we usually use these two plants to extract sugar. In this blog we focus on the processing of sugar beets and the role that Bronkhorst flow meters have in this process.

Convergence Industry B.V. is a supplier of customized measurement and control systems for liquids and gases. In the process of getting sugar from sugar beets one of the customers of Convergence discovered that by using membrane filtration, it was possible to extract more components out of the sugar beet than sugar alone. For this a customized lab scale system for nano filtration was used.

Membrane filtration

Membrane filtrations is a high-quality purification process using sophisticated techniques. How does this work? A simple explanation of membrane filtration is comparing it with making coffee. If you pour water in a coffee filter filled with coffee beans, you want coffee as a result without the shell of the coffee bean. That’s what the filter is for. On another level this is similar to water filtration where you want to filter the ions so you can make drinking water out of seawater. As simple as that!

Collaboration with Convergence for membrane filtration

For the membrane filtration a ‘Convergence inspector Colossus’can be used. This is a fully automated customized lab scale system for nano filtration which makes it interesting. Felix Broens (Chief Technology Officer of Convergence Industry B.V.) explains how this system works:

”The nanofiltration system is fed with water in which a phosphatefree anti scalant is dosed. Using a high pressure pump the system is pressurized, causing a part of the water to pass to the membrane (permeate). The part of the water that cannot pass through the membrane (retentate) is led back to where the water has been fed. An extra pump in the recirculation conduit causes a higher velocity across the surface of the membrane, which reduces pollution on the membrane itself. The permeate can eventually be used as clean water for different applications.”

“The anti scalant is used to prevent scaling on the membrane, by forming a complex of metal-containing ions, which keeps them in the retentate stream so that they can be led out of the system. Because of using a phosphate free and biodegradable anti scalant, it doesn’t have any harmful effects on the environment.”

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Bronkhorst flow meters in membrane filtration

The heart of the nanofiltration system is a Bronkhorst Coriolis mass flow meter for controlling the process. It uses a Coriolis flow meter because it can measure density as well, which is important in case of sugary solutions. The flow meter is placed at the ‘clean’ side of the process, so behind the membrane where the permeate flow takes place (the purified product flow). The degree of separation of the membrane can be influenced by both flow speed and pressure. And thus a Coriolis flow meter with a wide range is the best option to cover a large test range.

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This Convergence system has made it possible for their customer to improve their process enormously. Before using the Convergence system it was a manual process that was rather time consuming and not always accurate. Nowadays the whole process is automated using client-specific Convergence software which makes it possible to accurately control the Coriolis mass flow meter with the pump and therefore, the permeate flow can now be controlled accurately and fast. This results in a good reproducibility, reliability, datalogging and shorter lead times for the experiment compared to as it was before. This customized lab scale system makes it possible to generate a sufficient amount of residue for testing purposes without making it necessary to upscale the process to a pilot plant.

Check out the Coriolis flow meters available for this application.

Contact Convergence for more information about membrane filtration.

Nicolaus Dirscherl
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Fish consumption is rising. With the increase of the world population and the need for nutritious food, health-conscious consumers are looking for alternatives to “a nice slice of meat”. And they end up eating more fish or vegetarian food.

Specific species of wild fish are getting more and more scarce in open water due to the huge impact of industrialised fishing fleets and overfishing. The sea can not provide the increasing demand. Fortunately, in a trend towards sustainable food production, fish farming is gaining increasingly interest.

Fish farming

Fish farming is the aquatic peer of farming cows, sheep or chicken. For many, many years, we as humans have been farming our main food - have it grown in greenhouses, in stables, or in the fields. Whatever we need, we try to fulfil our demand - more and more in a sustainable way, with respect for natural resources. Fish farming is heading in the same trend.

When people hear about fish farms, they might think of an aquarium, a little pond or a floating net. But in Norway, a major player in fish farming, people think on a larger scale. A typical fish cage near the Norwegian coast has a diameter of tens of meters containing 200,000 to 300,000 salmon. In the near future, these designs will upscale to 1 or 2 million salmon. Only in Norway, at the beginning of 2018 more than 3500 cages for fish farming were floating in the sea. And ‘Norway’ is expanding their knowledge and technology across the world, where people are interested in large scale harvesting of fish in the sea - or maybe also on land.

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Salmon is a typical example of a fish that can be fish farmed. They need cold water - seven to nine degrees Celsius is what they like most - which is why this aquaculture is happening in the northern hemisphere, off-shore in the fjords. Moreover: salmon is a very popular fish, often found on the menu all around the world - so there is a high demand.

Aeration

In fish farming, aeration is literally of vital importance. In addition to food, the fish need oxygen that is supplied in the form of tiny air bubbles (‘aerated’) to the water. But aeration has more advantages.

Also in the early days, lice were a major disease that salmon suffered from. Since salmon lice had an impact on harvest, the fish farmers had to look for solutions. For some reason - maybe it was an experiment or it happened by accident - they started to purge air from the bottom of the cage. And they observed that the movement of the fish started to change. Instead of circling day in and day out - as salmon normally do - they started to move around the cage and became more agile. If the salmon are more agile, the muscles have to work more, and meat from moving animals has a better quality. At the same time, the fish farmers detected that aeration helped them to create a more thermal friendly water environment, with an advantageous temperature, conditions and amount of oxygen. With result that the occurrence of salmon lice reduced. So aeration had - and still has - two advantages: improving the salmon quality, and reducing the unwanted lice. By the way: the words purging and aeration have the same meaning. ‘Aeration’ has the word air inside.

Aeration of fish farms using mass flow controllers

The process of aeration is very simple - like in any aquarium you have at home - and yet can lead to very nice results as we saw above. The air bubbles can be generated by natural water currents (off-shore, down-hill), pumps, impellers, variable area flow meters or - as we do at Bronkhorst - by mass flow controllers and compressors. Here, a compressor generates compressed air from the surrounding atmosphere, and feeds this to the mass flow controller for controlled aeration of the water in the fish cages.

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To run fish farms remotely controlled and without much manpower, as much automation as possible is required. This also involves automated feeding. When the fish are fed, the air purging needs to be interrupted to give the fish the opportunity to hunt for the food before it floats out of the cage. In between the feeding periods, the aeration improves the condition of the water and the salmon. Here, it helps that mass flow controllers are remotely controlled from the control room at land. The aeration is stopped when the feeding starts, and when the feeding is over, the previous set point will automatically return and the water condition is as stable as it was before.

But there is more: mass flow controllers provide a potential for saving energy due to better conditions in the cage. The accuracy of the devices is important here. Every cubic meter of air you save by being more accurate - faster control or opening of valves - is of direct influence to your costs for running the compressor. Moreover, in stormy weather you can reduce the aeration, but during a long dry period without water movement, more air bubbles are needed. So essentially, this accuracy and flexibility leads to a better controlled environment.

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With MASS-STREAM mass flow controllers we have a robust instrument, which is performing well in the harsh northern surroundings. By Bronkhorst standards, this kind of aeration is a ‘high flow’. Typical air flows for a fish cage are in the range between 600 and 1400 liters per minute.

Mass flow controllers for other types of aeration

Mass flow controllers are suitable for other types of aeration - also again in aquaculture and agriculture. If you grow salmon, you need to breed the fish, which normally occurs on land. Fish eggs and young fish are even more vulnerable to changes, so the environment has to be more stable than for grown fish. Depending on the type of fish, the balance of oxygen in the water is delicate and has to be controlled accurately.

In algae farming, carbon dioxide gas is one of the food components for these species to grow, which needs to be supplied under defined conditions.

A very well-known application of aeration is in food & beverage industry. As you might know, every soda or carbonised drink is a liquid purged with carbon dioxide gas. Related to that: when packaging food, the packaging is purged with nitrogen to remove the oxygen before the food enters the packaging, as one of the steps to prolong the shelf life of the food.

“Fish farming with controlled aeration by mass flow controllers will support the focus on good fish quality, control of diseases and increase of the yield” according to Nicolaus Dirscherl, Managing Director of M+W Instruments GmbH.

For more information about the usage of mass flown controller in a fish farming application, please check our application story Aeration in Fish Farming.

Marcel Katerberg
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For us, as supplier of flow meters and flow controllers for low flow rates of gases and liquids, the most essential thing is supplying a proper working measuring device of high quality to our customers. Therefore, quality control is important. As a final step in production, we calibrate all our flow meters to provide accurate flow measurements.

As manager of the Bronkhorst Calibration Center I sometimes experience misinterpretation concerning calibration and its meaning. Occasionally calibration gets confused with concepts like re-calibration and adjustment. Therefore, in this blog I want to clarify these concepts.

What is the difference between calibration and recalibration of flow meters?

In short, calibration is nothing more than comparing the output of a measuring device with a reference. For Bronkhorst devices this can be done by a Bronkhorst service office, Calibration Centre or by the end user if they have the right equipment. Re-calibration is a popular word for doing a ‘re-‘check and is often referred to as when a purchased flow meter has been sent back to the factory for a periodic calibration check. So, re-calibration is actually the same as calibration, the flow instrument will be compared to a fixed reference, again. In principle calibration does not involve any adjustment.

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What is adjustment and when is this necessary?

In practice, the most essential thing for the customer is to have a proper working measuring device, and therefore, subjecting a meter to a periodic calibration check is also called a calibration “as found”. If the meter shows a deviation outside its specification limit, adjustment is advised. Adjustment can be carried out by a Bronkhorst service office, a (Bronkhorst) calibration center or by the customer if he has the right equipment. The instrument will be adjusted to indicate the true value again. After the adjustment the instrument will be subjected to a calibration “as left” and that comes with the calibration certificate.

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Why is calibration necessary?

Every instrument is subject to aging, wear and dirt. In order to ensure the instruments measure values representing the truth, a periodic check is often recommended. For some applications a periodic check is even required due to legislation, norms or directives.
Minor deviations can be caused by aging of mechanical and analog electric components, this is almost unavoidable. If the deviation is more than a few percent, this is usually caused by dirt or wear. In this case full service, repair and new adjustments are recommended for the instrument.

Check out the top 4 questions about calibration on our FAQ page:

  1. How often should I perform a calibration check on my mass flow devices?

  2. How to interpret the data and terminology on Bronkhorst calibration certificates?

  3. In case of an emergency, can I clean, repair and calibrate the instruments myself?

  4. Is it possible to use the flow meter/flow controller for gases other than they are calibrated for?

Bronkhorst Global Service Offices & Calibration Centre

At Bronkhorst Global Service Offices and at our Calibration Centre in Ruurlo (NL) we are capable of calibrating and adjusting Bronkhorst flow devices and also third party instruments within our scope. Learn more about our Calibration Centre.

Besides that, Bronkhorst Calibration Centre has been accredited as ISO 17025 compliant by the Dutch Accreditation Council (RvA), providing international recognition of its technical competency and qualification. Read our blog about the Bronkhorst Calibration Centre.

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Chris King
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A flow meter’s specifications are pivotal elements in choosing which one is right for your application. Two important statistics are its accuracy and repeatability. Let’s start with explaining what these two parameters mean:

Flow Meter Accuracy

Accuracy is how close the measurement is to the true value. In flow meters, that means how close the output of the meter is to its calibration curve. This is expressed as a percentage, e.g. ±1%. It means that any given reading can be in error 1% above or below the calibration curve. In general it can be said the lower the percentage, the more accurate the meter. However, this also depends on the specification of either FS (Full Scale) or Rd (Reading). The meaning of Full Scale and Reading will be explained later in this blog. Flow meters are becoming more and more accurate, especially with the advent of mass flow meters.

Flow Meter Repeatability

Repeatability is producing the same outcome given the same conditions. In other words, a flow meter should produce the same readings when operated under the same variables and conditions. This, too, is expressed as a ± percentage. While accuracy usually takes the spotlight in the measurement world, repeatability is the foundation on which accuracy rests. You can have high repeatability without high accuracy but you cannot have high accuracy without high repeatability. It is not helpful if the meter is highly accurate only once in a while. If your data is unreliable, if you get different numbers under the same circumstances and setup, there is no way those numbers can all be accurate.

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Is accuracy always important?

No one wants an inaccurate meter, but not all applications require high amounts of accuracy. It may be acceptable to stray further from the calibration curve if you are only looking to get an idea of how much is flowing through a pipe. It isn’t acceptable if you are mixing pharmaceuticals for consumption or volatile elements. How accurate your meter needs to be is important when selecting a flow meter, because usually the more accurate a meter, the higher the price.

When you see an accuracy specification, it should be expressed as a percent of Full Scale (FS) or Reading (Rd or RD). The difference between those can be significant.

Read our blog “Is the high accuracy trend right?”

What is Full Scale (FS)?

The definition of Full Scale is “Closeness to the actual value expressed as percentage of the maximum scale value.” With Full Scale, the error remains the same but the percentage changes as the flow goes up and down the flow range. If the accuracy is calibrated 1% of 200 ln/min then the error is 0.01 x 200 ln/min = 2 ln/min. If the flow is 100 ln/min, the error is still 2 ln/min or 2%, a much bigger percentage.

What is Reading (Rd or RD)?

The definition of Reading (Rd) is “Closeness to the actual value expressed as percentage of the actual value.

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With Reading, the accuracy is the percentage of what is being read. The percentage stays the same, no matter where the flow is in the flow range. If it is 1% at 200 ln/min it would be 1% at 100 ln/min. So the error for a 200 ln/min flow would be 2 ln/min but for 100 ln/min it would be 1 ln/min rather than the 2 ln/min of Full Scale. Depending on the application, the difference between Full Scale and Reading can quickly add up and have a significant impact on the end product.

Full Scale (FS) versus Reading (Rd)

Full scale is actually a carryover from mechanical gauges when readings were dependent on physical marks on a dial. Digital meters now can give much more precise readings, so high-end meters generally use Reading rather than Full Scale.

Although you don’t want an inaccurate flow meter, not all applications require high amounts of accuracy.

In terms of mass flow, accuracy requirements can change the type of sensor being discussed. If you need very high accuracy you can have a Coriolis flow meter, if high accuracy is less important, you may need a Constant Temperature Anemometry (CTA) or other sensor type.

See out Coriolis flow meters.

View our CTA flow meters.

James Walton
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Anglian Water Services cleans water to the highest standard, delivers it to millions of homes, and carefully manages it to ensure it never runs out in an area of the UK. They started a project to optimize and further control dosing of phosphates in the public water system.

The functionality of orthophosphoric acid in the public water system

Public water systems commonly add phosphates to the drinking water as a corrosion inhibitor to prevent the leaching of lead and copper from pipes and fixtures. Inorganic phosphates (e.g. phosphoric acid, zinc phosphate, and sodium phosphate) are added to the water to create orthophosphate, which forms a protective coating of insoluble mineral scale on the inside of service lines and household plumbing. The coating serves as a liner that keeps corrosion elements in water from dissolving some of the metal in the drinking water. As a result, lead and copper levels in the water will remain low and within the norms to protect the public health..

What was the original process ?

In the original process a down-steam analyser was in-place to measure the concentration of orthophosphoric acid in the main flow. The measurement results were checked against the required concentration and used to adjust the pump speed and therefore the level of orthophosphoric acid in the main flow. With this process Anglian Water Services can secure copper and lead concentration levels in the water acceptable to protect the public health. Nevertheless the process had room for improvement, which will be discussed in this blog.

The original process of record

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What are the limitations in the original process?

The reactive feed-back loop mechanism for dosing phosphates was not a preferred working method. We could not react quickly enough to the changing main flow to reduce or increase the dose proportionally. We had to ensure that we dosed to a level meeting the legal requirements assuming the station was processing maximum flow. Secondary costs were added to the system by needing double redundancy on the analyser to ensure there is no break in the measurement of orthophosphoric acid levels.

Project objectives

  1. Reducing phosphate levels.
  2. Reducing the cost of meeting legal environmental standards for the business.
  3. Remove the downstream analyser and redundant spare in the process of record.

Two sensor technologies were evaluated to enhance the process ; Differential Pressure and Coriolis technology. The Differential Pressure instrument was the most cost effective and allowed us to meter the Orthophosphoric acid flow as a volume, it would take an analogue signal input and adjust the dose proportionally to the main flow.
The Coriolis Mass Flow Meter utilizes direct Mass Flow Measurement, which is preferable over volume flow for this application and is more accurate and repeatable, but is more expensive. It would also take an analogue signal input and adjust the dose proportionally to the main flow.

Image description Combination of mini CORI-FLOW with Tuthill pump

Making a decision appeared to be based around return on investment. Essentially the time taken to generate sufficient savings. However, during the demonstration of the Coriolis Mass Flow Meter we learned something new that would change the direction of our final design. The Coriolis Mass Flow Meter gave the density of the fluid being metered as an output.

Why was this important?

Phosphoric acid it sold in diluted concentrations , usually 80% in solution. What we have found is that there is a variation in the actual concentration at the point of use.

At this point we already knew that either the Differential pressure or Coriolis technology could support us to enhance the process of record. Now we had the chance to go to the next level and take a previously unavailable but very important parameter and use it to really refine the dose ratio.

The extra density parameter available with the Coriolis Mass Flow Meter made the decision for us. Dosing would now be controlled proportionally to the main flow and the density/quality of the phosphoric acid being used.

The enhanced process

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What are the projected benefits using Mass Flow Meters:

As we look to go live on the first five installations of this technology, we are projecting the following:

  1. Stable concentration of orthophosphoric acid in the public water system.
  2. Maintaining the public health commitments of the Water Industry.
  3. Decreasing the addition of phosphoric acid into the environment by significant levels.
  4. Two-fold cost reductions: by eliminating the down-stream analysers and the consumption of phosphoric acid.

At Anglian Water Services they live with a Love Every Drop approach. The Love Every Drop approach is a vision for how they believe a modern utilities company should be run. That vision means creating a country with a resilient environment that enables sustainable growth and can cope with the pressures of climate change. Creating infrastructure that is affordable and reliable, meeting the needs of customers, communities and the environment. We want our people and our communities to be resilient too. Phosphoric acid is connected with the concept of planetary boundaries according to Rockström et al. 2009. Anglian Water Services was able to reduce the consumption of phosphoric acid in their processes without sacrificing the quality of the water. This fits with the way they run their business.

Download the brochure for our [Liquid Dosing Module](https://www.bronkhorst.com/getmedia/f64e57bd-e31a-4a3a-a18b-cc08d22ef310/Water-Treatment-LDM.PDF ).