Erwin Eekelder
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More and more companies in varying industries are trying to make the transition to low flow solutions. Especially in the chemical industry and food & pharma market the trend is to focus on continuous manufacturing, waste reduction, lower downtime and more flexibility. In these industries the availability of ultrasonic flow meters for liquids suitable for 1” pipe lines or larger are enormous, but it is much harder finding solutions for smaller line sizes. Conventional ultrasonic flow meters use either the Doppler Effect or Transit Time measurement. These techniques are practically suitable for large bore sizes.

But what about ultrasonic flow meters for flow rates lower than 1500 ml/min or even 200 ml/min?

Due to the complexity of physics and technology there are not many measurement principles present in this particular flow area, especially ultrasonic flow meters. Therefore the big challenge was to find a solution to use ultrasound in tubes with very small diameters. In close collaboration with TNO (Netherlands organization for applied scientific research) Bronkhorst managed to develop an innovative instrument using Ultrasonic Wave Technology. This technology is applied in the new ES-FLOW™ series for measuring liquid volume flows between 4 to 1500 ml/min independent of liquid density, temperature and viscosity with an accuracy of 1% of rate ± 1 ml/min.

How does Ultrasonic Wave Technology work?

The ES-FLOW™ is based on ultrasonic wave technology. Measuring is done in a straight stainless steel tube with an inner diameter of 1.3 mm, without obstructions or dead spaces. At the outer surface of the sensor tube multiple transducer discs are located which create ultrasonic waves by radially oscillation. Every transducer can send and receive, therefore all up- and down-stream combinations are recorded and processed. By accurately measuring the time difference between the recordings (nanosecond range) the flow velocity and speed of sound is calculated. Knowing these parameters and the exact tube crosssection, the ES-FLOW™ is able to measure liquid volume flows. The distinctive character of this flowmeter is that it’s capable to measure the actual speed of sound, meaning that the technology is liquid independent and calibration per fluid is not necessary. Next to that the speed of sound can be used as an indicator of the type of fluid present in the flowmeter.

transducer discs and sensor tube picture1: transducer discs and sensor tube  

Four reasons why to use the ES-FLOW™ Ultrasonic flow meter:

1. One sensor for multiple liquids

Many companies have changing process conditions and make use of various liquids like additives or solvents. As the ES-FLOW™ technology is fluid independent, recalibration is not needed with liquid changes. Also non-conductive liquids as demi water can be measured.

2. Easy to clean and reduced risk of clogging

Cleaning processes are often time consuming. Due to the straight sensor tube design with no dead volume, particles have reduced chance of clogging the instrument. Cleaning can be done in a few minutes therefore the amount of down time will be limited.

3.Vibration insensitive

Ultrasonic measurement is not sensitive for vibrations as it doesn’t rely on frequencies or rotations. It is also irrelevant if the flow is laminar or turbulent.

4. Integrated PID controller and fast response

The on-board PID controller can be used to drive a control valve or pump, enabling users to establish a complete, compact control loop with fast response time.

Erwin Eekelder
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As the demand for natural and healthier ingredients (such as sweets with vitamins) increases, manufacturers of chocolate and sweets often decide to change the existing artificial flavours, aromas and colours, into more natural additives. Because these additives are more expensive and have changing fluid properties (e.g. density and viscosity), traceability and an accurate process are desired.

The desired flow solution should provide detailed process information, more efficient production lines, better product consistency and higher quality of the overall process. For this we have developed an ultrasonic flow meter for small liquid volume flows called the ES-FLOW.

Confectionery market

Worldwide the confectionery industry is expected to grow towards 275 billion dollar in 2025, an enormous market. Looking into that, America is number 1 in terms of candy retail volume, but if you measure the consumption per capita, it seems the European countries win the battle. Germany has the highest consumption per capita (according to market data and estimates from Euromonitor in 2016).

Market suppliers continuously learn from the market to keep adding value to the daily life of their customers. A sustainable supply chain, improvement of the well-being of consumers and continuous product innovation are required to support the long term needs of this market.

Chocolate production

Continuous production process

At the same time, trends have been observed in recent years towards a continuous production process, prevention of waste, shorter downtimes and higher flexibility, not only in the food sector but also in the chemical industry.

The use of additives – flavours, aromas and colours - requires that small flow rates are measured and controlled. For this, not many solutions can be found. Nowadays many confectioners use dosing pumps and rely on positive displacement. But how to be sure that the desired volume was actually displaced? Was the pump head completely filled with liquid? Or did (partly) dry-running occur?

Dosing pumps are often calibrated or programmed for a set fluid and flow rate. For changing process conditions or production changeovers this usually needs to happen again, which could lead to long down times. The ES-FLOW ultrasonic volume flow meter has an integrated PID controller that can be used to operate pumps and valves. This allows the user to build a complete automated control circuit with fast response times.

Real time flow measurement and control for flow rates lower than 1500 ml/min or even 200 ml/min?

In close collaboration with TNO (a Dutch organization for applied scientific research) we managed to develop an instrument using Ultrasonic Wave Technology. This technology is applied in the ES-FLOW ultrasonic flow meter series for measuring and controlling liquid volume flows between 4 to 1500 ml/min independent of liquid density, temperature and viscosity with an accuracy of 1% of rate ± 1 ml/min.

“Want to know how this Ultrasonic Wave Technology works? Read all about it in our blog How to measure low flow rates of liquids using ultrasonic wave?”

ES-FLOW ultrasonic flow meter

Recalibration is unnecessary

Many companies have changing process conditions and often use a variety of additives and solvents. The ES-FLOW ultrasonic volume flow meter is liquid-independent, therefore recalibration is not needed. Also non-conductive liquids, such as distilled and demineralised water or solvents can be measured. In addition to this, the sensor is insensitive to surrounding vibrations.

Hygienic Design

The instrument is designed according to hygienic standards with a self-drainable straight sensor tube, surface roughness ≤ 0.8 µm and no dead volume. Therefore particles or bacteria cannot accumulate easily and contaminate the sensor tube. As a result the cleaning process only takes a few minutes, which minimises downtimes.

Find out the working principle of the for very low liquid flow rates:

Read more about the Pilot Series Process for the ES-FLOW ultrasonic volume flow meter

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.