SAW technology for Bürkert flowmeter

This review of Surface Acoustic Wave (SAW) techniques was first published in my regular column in the December issue of the journal “South African Instrumentation and Control” (SAIC), published by

The SAW (surface acoustic wave) technique offers fascinating opportunities for many different styles of monitoring sensor. The first example seen many years ago really impressed me: it was called TorqSense, a torque measurement sensor applied onto a drive shaft, with no external electrical connections to the shaft needed. This used a SAW device mounted on a quartz substrate: the input and output sensors for the acoustic waves are separated by the length of this substrate, which changes as the quartz is deformed by the torque. Feedback creates a high-Q resonant circuit, and the resonant frequency changes as the quartz is distorted. RF excitation and monitoring of this resonance from an external unit gives a measure of the torque: this has been offered commercially by the UK based Sensor Technology for over 10 years.

Since then SAW techniques and sensors have been studied and researched by many universities, and sensors have resulted that measure temperature, pressure, viscosity, humidity, and even chemical concentrations. The idea is to choose a substrate or acoustic delay-line material between the acoustic transducers that is influenced by the environment to be monitored, such that it is stretched, or the acoustic path length changes in some other way. A recent market status report, by Mordor Intelligence, suggests that the total market for all such SAW sensor systems will be almost $4Bn by 2018.

The clever part in creating a sensor is to modify the acoustic properties of the piezoelectric material between two sensors in some way. Chemical and biochemical sensors for monitoring liquids have been created using a lithium tantalate piezoelectric with a micron thick coating of PMMA or cyanoethyl cellulose, which is sensitive to the chemical target, and keeps the surface waves near the surface, which are therefore influenced by the liquid properties.

Industrial flow applications

After collaborating with such university research for some years, in 2014 Bürkert saw the opportunity to develop a liquid flowmeter using SAW transducers, which could give major advantages particularly in hygienic applications – one of its key market areas. In this case, the SAW transducers were to be used to launch the ultrasonic pulse into the pipe wall of the flowmeter, which then leads to transmission of the signal diagonally across the fluid flow. The pipe wall and the moving liquid create the variable length acoustic delay line between opposing pulsed sensors, and fluid movement creates the change in this delay.

Burkert261_FLOWave_SAW_flow_sensor_pic1_PR2548_58253Effectively, Bürkert was using the SAW transducers as the upstream and downstream sensors for a time of flight type ultrasonic flowmeter. But also there is no intrusion into the flow tube, so the meter is suitable for ultra-pure applications like pharmaceuticals, water for injection and so forth, as well as food and beverage applications.

Development and field testing has covered the last two years, with a careful product release for suitable applications – typically initially used on low conductivity clean liquids, such as water for injection (WFI) in the pharmaceutical sector. Indeed one field test unit was installed in the supply line of a production filling system for infusion bags. Now, the Bürkert FLOWave range of flowmeters, covering DN15 to DN50 pipe sizes, is fully available for sale. This range of sizes covers the smaller bores typical of industrial requirements, in contrast to the larger ultrasonic flowmeters available from other suppliers. FLOWave is designed for hygienic use, and certified to EHEDG and 3A standards. The pipe has hygienic style end connections, and is internally finished to 0,8 or 0,4 microns: it is fully CIP and SIP tolerant, and indeed has been used to control CIP cycles, as the unit also provides a temperature measurement of the flowing liquid. It uses four SAW transducers, two on each side of the sensor pipe section, therefore acting as a dual path flowmeter. Flow measurement performance over the range 1-10 m/sec flow velocity is 0,4% of reading.


The latest development work has introduced density measurement and an acoustic transmission monitor parameter, which allow indications of the viscosity, bubble and suspended solids content of the liquid. This is useful in CIP process control, and also for monitoring milk in the dairy, during filtration. Bürkert claim an advantage over other styles of flowmeter, in that the unit is small and light in weight when used on a skid. Other applications now being investigated are for wort concentration monitoring in breweries, and homogenisation control in paint manufacture. Highly viscous liquids, such as glue, are also being monitored, where the full bore obstruction-free design is important.


Modern trends in long distance power links

Many of the changes in the way the world works lead to new opportunities for different technologies. This has led to a new approach to electricity distribution using HVDC – High Voltage Direct Current – transmission lines, operating at up to 800 kV. Such power transfer lines are now installed particularly around Europe, and across China.

When power stations were smaller, and based near the major population centres, they tended to serve a local area with electric power, and this was best delivered using AC transmission, via local transformers, to produce the 110–240 VAC power distributed to each street. (As an aside, even more locally around the power station, district heating schemes could distribute some of the power using thermal transmission.) To provide the electrical energy transmission further afield, higher voltage AC transmission lines were used to feed a major substation, then distributing the power to local transformers, creating local networks – like the branches of a tree.

Currently, the new solar farms and wind power sources have been built well away from the major centres of population, where the land (or sea) space is available, and the conditions are right. Plus, hydroelectric plants are necessarily placed near the river or water flows, naturally located in the hills. All these sites are at the end of the thinnest branches of the old ‘distribution tree’, so new transmission lines are needed to take the power back to the population centres.

Long distance transmission

China also faced this problem, with economic development and a growing demand for power by the population in the west of the country, with the major new power stations and hydro plants located in the east. For transmission of power over distances like 500 km or more, the reactive power flow due to the large cable capacitance limits the maximum possible transmission distance, as the power loss becomes high. The installation and maintenance costs for the necessarily taller and wider dual pylon AC overhead transmission lines, also becomes excessive.

For such long distance transmission, HVDC comes into its own economically because the line losses are much lower, as are the line installation and maintenance costs, since HVDC (at around 600 kV) can use a single overhead pylon carrying just two conductors, or can use a buried cable. The higher costs of the HVDC terminal equipment, needed at both ends to convert the power back to AC for local distribution, are more than offset by the savings in the transmission line costs. Plus the environmental impact of the HVDC underground cables is insignificant, compared to overhead AC transmission. The possibility of using underground cables means HVDC links can deliver power into cities and urban areas where the use of pylons and overhead cables would not be tolerated.

So, over the last few years China has installed 24 projects using HVDC power transmission: one of these used a 1670 km line carrying 8000 MW of power to the east. The supplier for 19 of these projects, including the largest one, was ABB Power Systems. ABB also claims to be the major supplier of recent HVDC power transmission projects throughout Europe, and the rest of the world.

Undersea links

In Europe there are many power networks, based around different standards that were developed by the different countries: these AC networks can run at different frequencies, and are not often synchronised. It makes sense to wish to trade power between networks, to make use of surpluses when these are available, and cover for power outages or other unforeseen events. Transferring power using HVDC links makes sense, firstly because the receiving terminal can convert the DC to an AC power source running at the same frequency as the receiving network, plus the local ­engineers can phase synchronise the generated AC power with their other sources.

The second big advantage of HVDC links is that they can run in economically constructed underwater cables, to islands and across major sea routes, such as from the UK to France, or Norway and Sweden to Denmark, Germany and Finland. The NorNed link, from Norway to the Netherlands, is the world’s longest submarine power cable, at 580 km length. Similar HVDC links are used to supply power from hydro schemes and wind farms in the north of Scotland, across the estuary of the Moray Firth to the heavily populated Inverness/Aberdeen area.

The growth of offshore wind farms has led to this green energy being sent onshore using an HVDC submarine cable, and also vice versa, in the sense that offshore oil production platforms are now being supplied with power from onshore, delivered by cable, and just converted to AC power on the platform – saving weight and complexity offshore. Plans are being made to extend this European network, with possible hydro-electric power being delivered by cable from Iceland to Scotland, and from Norway via the Shetland Islands, then also to Scotland.

More importantly, in an African context perhaps, solar farms in North Africa will be able to transmit power to Europe via Spain from Morocco and to Italy from Tunisia and Libya.

This article first appeared in my column in the South African Journal of Instrumentation and Control, November 2017 issue. SAIC is published by Technews in South Africa.

Diabetes plant for Novo Nordisk chooses Emerson

Another Novo Nordisk greenfield pharmaceutical project has chosen Emerson Automation Solutions to achieve a fast project start-up: this Emerson release gives the following information.

Emerson advises: “Global healthcare company Novo Nordisk has awarded Emerson a $40 million automation systems and services contract for a new US-based drug manufacturing facility to help battle the global diabetes epidemic. The largest project in its history, Novo Nordisk’s new $2 billion plant in Clayton, North Carolina, will leverage Emerson Project Certainty methodologies and automation technologies to help ensure the plant achieves a tight project construction schedule to meet a construction target of 2020.

The new 825,000-square-foot production facility will help the Danish drug company increase manufacturing capacity and meet its goal of doubling production of diabetes drugs over the next decade. According to the Centres for Disease Control and Prevention, more than 29 million Americans are living with diabetes, with another 86 million living with prediabetes.

“Our extensive experience in the life sciences industry and integrated offering for capital projects and automation perfectly positions us to help Novo Nordisk deliver its largest project in history,” said Mike Train, executive president, Emerson Automation Solutions. “Together we can design and deliver this world-class manufacturing facility to be ready on time, and to quickly deliver these important diabetes medicines.”

Novo Nordisk will implement elements of the Emerson Project Certainty approach to help reduce project complexity and achieve the tight project schedule. This transformational approach leverages automation technology, which serves as a central nervous system in a plant, and new methodologies, to reduce costs and complexity and accommodate late-stage project changes.

Novo Nordisk selected Emerson’s integrated portfolio of automation technologies and services, including its DeltaV distributed control system (DCS) and Syncade manufacturing execution system (MES). Emerson will also provide smart automation technologies including valves and measurement instrumentation.”

ABB automation increases capacity 10x for Tate & Lyle food additive plant

When Tate & Lyle acquired Biovelop, a Swedish manufacturer of oat based food ingredients in 2013, the factory in Kimstad, Sweden was modernized and expanded by installing automation systems, variable speed drives, motors, motor control cabinets  and valve positioners from ABB Automation. In 2016 the remodeled plant celebrated the first anniversary of operations with the new systems and significantly increased production capacity.

The global market for specialty food ingredients, including health and wellness products, is growing, with annual sales of $51 billion and annual growth rate of 4-5%. Oat ingredients have been actively involved with this trend as they offer some key nutritional and functional benefits. In particular, oat contains beta glucan, a soluble fiber that has been shown to lower cholesterol and reduce post prandial glycaemic response – claims that have been approved by the European Food Safety Authority (EFSA). In fact, it was these properties of the grain that made the sector an attractive one to Tate & Lyle, and triggered the decision to diversify its portfolio into this sector.

“We have seen a more than tenfold increase in capacity with the same number of shift operators compared to four years ago,” said Annika Werneman, Tate & Lyle plant manager. “It’s a huge change in such a short time, and it means that we’ve gone from a low-level facility to one that can deliver high quality product to our customers globally.”

Advanced automation technologies in the plant run critical food processing equipment -including pumps and decanters: material handling machinery is also used to transport the dry food products. ABB delivered automation equipment that included 85 variable speed drives (VSDs), with power ratings ranging from 0.37 kW to 55 kW, as well as ABB MNS 3.0 motor control cabinets and low voltage motors. ABB also delivered 44 Digital Electro pneumatic positioners (TZID-C) , which use the Hart protocol to communicate with the control valves.

“We needed a process that was highly automated and could run 24 hours, seven days a week, all year long,” Werneman continued. This meant building a system that enabled Tate & Lyle engineers to digitally interact with the system, commission (start) devices, and diagnose performance deviations or failures from anywhere in the world. This not only helps ensure operational consistency, but also reduce the total cost of ownership by enabling staff to manage the processes without being physically present at each site.

Such interactivity was enabled by the ABB fieldbus automation for the drive controls, providing flexibility as well as remote monitoring of the plant performance. “I like that ABB designed the system so that the fieldbus responsible for device control is split from the fieldbus used for asset management,” explained Leo Dijkstra, power & controls team leader Europe at Tate & Lyle. “This ensures that I can make any changes to the configuration of the devices without the risk of the whole network going down.”

At Tate & Lyle, they place great importance not just on what they do, but how they do it. “We are working continuously wherever we can to reduce the environmental footprint of our operations,” said Dijkstra. ABB was well placed to help as it has developed a portfolio of products and solutions that improve industrial energy efficiency.

“In our pump applications alone, we are using up to 50 percent less energy thanks to the variable speed drives, and these have been running non-stop for the last two years without a single failure,” Dijkstra continued. “What’s more, ABB was so quick to deliver products that we even had the first VSD delivered in just a few days.”

Although the nearest ABB support is only a ten-minute drive away from the Kimstad factory, the fieldbus flexibilities in the drives enable Tate & Lyle to rely on its own staff to handle the ABB equipment remotely. “Our work with Tate & Lyle illustrates the benefits of digitization, which can yield immense productivity and output gains from existing facilities,” said Petter Hollertz, area sales manager at ABB. “The improvements at this plant also show what great teamwork between the equipment supplier and the user can accomplish, as we worked together as true partners on this project.”

E+H acquires Blue Ocean Nova

A new Endress+Hauser press release says the company is further expanding its portfolio of products, solutions and services in the field of process analytical measurement, by  acquiring Blue Ocean Nova AG, a manufacturer of innovative inline spectrometers for monitoring quality-relevant process parameters. 

Blue Ocean Nova will operate under the umbrella of the Endress+Hauser centre of competence for liquid analysis headquartered in Gerlingen, Germany: the 15 employees currently located in Aalen, Germany will be retained. “The intelligent process sensors developed by Blue Ocean Nova will enhance our offering in the field of process analytical measurement, adding a strategic building block,” said Dr Manfred Jagiella, Managing Director of Endress+Hauser Conducta GmbH+Co. KG. As a member of the Group’s Executive Board he is also responsible for the analytics business. 

Innovative concept


The process sensors developed by Blue Ocean Nova cover the relevant optical spectroscopy regions of UV-VIS, NIR and MIR to analyze liquids, gases and solids inline. The innovative technology allows the spectrometer to be directly integrated into the measurement probe, even in explosion-hazardous areas. The sensors can furthermore be automatically cleaned and easily integrated into process control systems.

The systems from Blue Ocean Nova are utilized in the food & beverage, oil & gas, chemicals and life sciences industries for applications such as concentration and moisture measurements and for measuring relevant quality parameters. The technology enhances the Group’s portfolio, which already encompasses Raman spectroscopy, tunable diode laser absorption spectroscopy (TDLAS) and process photometers.

Extensive experience

Blue Ocean Nova was founded by Joachim Mannhardt and Stefan Beck in 2015, bringing extensive product development experience in the field of industrial spectroscopy and process analytical measurements to the company. “Endress+Hauser opens the door to international markets and customers for us,” explains Stefan Beck. Joachim Mannhardt adds: “We’re convinced that our technology will be an ideal enhancement to Endress+Hauser’s optical portfolio.”

Endress+Hauser acquired Blue Ocean Nova effective 31 October 2017. Both parties agreed not to disclose the details of the transaction. Joachim Mannhardt and Stefan Beck will remain on the management team of the innovative company. “With this acquisition, we are continuing to pursue our strategy of strengthening the process analytical measurement portfolio and in the future supporting our customers from the lab to process,” says Manfred Jagiella.


Confusion over radar level measurement

We have learned not to get too confused over suppliers using buzz-words and clever marketing names, but recently it seems the major level measurement system vendors have been introducing new and higher radar frequency systems as their latest development – and therefore, by implication, maybe the best. We were used to 6 GHz, and then 26 GHz radar frequencies, but why should we suddenly go to 80 GHz? Then, perhaps just to add a little excitement to the mix, Endress+Hauser started talking about 113 GHz!


The E+H radar line up that offers 113GHz!

This article was first featured in the journal South African Instrumentation & Control in September 2017, a journal published by Technews

Let’s dispel a few myths. Firstly, in the same way that lasers for fibre-optic communications systems made the technology available to create infrared optical systems for process gas analysers, and mobile phone technology possibly provided the hardware for the first radar level measurement systems; the 80 GHz versions are a result of measurement technology made commercially viable on the back of production investment in the distance measurement systems and parking sensors used in modern cars. So the suppliers take the available sensors and chipsets to create a new industrial product, and then have to find the best applications – in this case, the ones that might benefit from the 80 GHz.

Secondly, E+H do not have a 113 GHz system, this is a marketing statement, made to catch attention – ‘with a wink’ is their expression. They claim a ‘complete radar competence of 113 GHz’ because this is the sum of the many different frequencies their different sensors use! These are 1, 6, 26 and 80 GHz.

So why have different frequencies?

Possibly the best explanation for the applications suited to the different frequencies has been provided by the Rosemount measurement division of Emerson, in their “Engineer’s Guides”. The Emerson expertise stretches back many years, having acquired the Saab Tank Radar business. Per Skogberg, from the Gothenburg HQ in Sweden, separates the devices into low, medium and high frequency, to generalise.

Radar signals are attenuated, i.e. they lose signal strength as they pass through the air, or vapour, above the liquid. High frequencies are more severely affected than lower. When the air has moisture, steam or liquid droplets (from spray or filling) present, the attenuation is higher. Equally in solids applications, dust particles have the same effect. So low and medium frequency radar are best when there is dust or moisture present.

At lower frequencies, the wavelength is longer (30-50 mm), so surface ripples in a tank have a small effect. At higher frequencies, surface ripples and foam on the surface can be a problem. But the shorter wavelength of the high frequency units (4 mm) allows accurate operation over short ranges, for example in small tanks. The higher frequency units can use a smaller sensor construction, so the unit is easier to install. The beam angle is narrower, so it can be aimed at a smaller target area and therefore can be positioned more easily to avoid any obstructions in the tank. But even this can be a disadvantage, as the installation needs to be exactly vertical and any turbulence of the surface during filling or stirring can cause the signal to be lost temporarily, in larger tanks.

When reading these suggestions, it is important to remember that Emerson does not offer an 80 GHz unit yet, so their marketing approach would naturally bias users to look at low and medium frequency units. The suppliers of high frequency units (Vega, Krohne and E+H) would point out that in many liquid storage tanks the surface is undisturbed, since any foam, turbulence and significant ripples (>2 mm) caused by filling or liquid transfer will only cause short-term interference. Plus the small antenna size and short range performance make 80 GHz units very useful for smaller process vessels and tanks.

Radar system types

There are two types of radar systems, Guided Wave Radar (GWR) and Free Space Radar. The GWR systems use a conducting rod, or similar, extending down into the liquid, often working in a stilling chamber attached to the main process tank. These operate at low microwave frequencies, and are independent of surface turbulence and foam. They are useful for shorter range measurements and interface measurement between liquids, as well as long ranges.

The Free Space Radar systems are more widely used, since they are top-mounted with nothing in the tank: indeed, some can operate through non-conducting windows in the tank roof. Low and medium frequency radar systems generally transmit a signal pulse and measure the liquid distance by the time delay for the returned pulse. High frequency (80 GHz) systems use an FMCW radar measurement, where the frequency of the transmission is swept, and the frequency difference of the returned signal is measured to assess the distance. The FMCW technique is also used at 26 GHz in some recently launched sensors.

Radar systems can transmit their measurement data using 4-20 mA, fieldbus systems like HART, FF, Profibus PA and Modbus, or indeed via wireless systems like Bluetooth. The low and medium frequency pulsed radar systems generally operate over a two-wire interface: some of the higher frequency FMCW systems require more power and use a separate power connection.

Major applications

Simple low-cost radar level measurement sensors have been specifically designed for water industry use, in sewage sumps and flume flow measurement, by Vega and Endress+Hauser. Vega suggest that 40,000 such sensors are now in use in the water industry, mainly in Europe, and claim their total output of such sensors exceeds 550,000 units over the last 25 years.

Several of these devices use simple Bluetooth interrogation and programming from a handheld PDA: E+H demonstrates this at its facility in Maulberg, working on the stream that runs through the factory complex, as seen below.

Micropilot_FMR10_FMR20_on test stream at Maulberg, with operator using Bluetooth

Both E+H and Vega produce further industrial units for use on process vessels, and storage vessels for solids and liquids. Recently, E+H has extended its capability to add long-range units, such as the 80 GHz FMR62, working at up to 80 m range, with an accuracy of 1 mm. Other units work up to 125 m range, at 3 mm accuracy. These units will eventually be aimed at the large petrochemical industry storage tank markets, and specifically are working towards use for custody transfer duties.

Krohne have similarly announced a new range of its 80 GHz Optiwave sensors. Some of these can even operate at up to 700°C, for example for use on molten salt vessels in solar power plants. Lower specification units rated at up to 150°C can be used through a tank roof made of plastic, or similar materials. Suitable for small or narrow tanks, the unit can measure ranges of up to 100 m. Krohne also offers lower frequency Optiwave systems for use on solids and powders, or to electronically monitor the float position in magnetic level indicator columns attached to process vessels.

Postscript: Krohne is organising a webinar with the title “80 GHz Radar Level – Allrounder or Overrated?” to discuss their recent developments with such systems. This webinar will take place on 18th October 2017 at 3pm London time/10am New York time.

Protect your flowmeter IP

trevor-forsterThe following comments come from Trevor Forster, the MD of Titan Enterprises, a specialist flowmeter manufacturer based in Dorset, UK. He recounts his experiences over the development of a new style of time-of-flight ultrasonic flowmeter, later called the Atrato, in their latest newsletter, called the Titan Flowdown. It is an interesting experience and maybe holds some lessons for all.

“A few years ago, Titan Enterprises filed a patent application for some new ultrasound technology we had been developing over the previous 12 months. On examination by the patent authority it transpired that someone else had the exact same idea and had filed some three months before us. Annoyingly this competitive filing was nine months after we had our first thoughts and six months after our first successful experiments. There were two valuable lessons here:

  1. File your ideas as soon as possible.
  2. Do not waste time in developing a completely viable idea before protecting the intellectual property behind the innovation.

As a consequence of this setback we had to revisit what we wished to achieve with our ring technology development. This project involved development of an ultrasonic device which was tolerant to variations in tube diameters due to the material, temperature or pressure. Our new idea was to section the device annulus into several segments which where independently acoustically coupled to the pipe but joined electronically. The benefit of this innovation is that it would provide us with a “flexible” crystal which can accommodate variations in the tube diameter as well as having a consistent acoustic connection.

Our developmental options were to make drawings, get the specially shaped crystals manufactured and then perform the tests. Alternatively we chose to get some miniature diamond cutting saws with appropriate boring burrs and make our own segmented crystals from existing larger crystals which we use on another ultrasonic meter. This enabled us to prototype and test our idea much more quickly.

The initial tests on the new device were extremely promising which gave us sufficient confidence to file our patent application while more accurate components were being manufactured and tested. This technology has formed the basis of our soon to be released Metraflow ultra-pure flowmeter and our developments with a new 1350 bar flow device.

The initial disappointment was a valuable lesson in getting intellectual property registered as quickly as possible especially with any rapidly developing technology.”


Editor’s comment:

From previous discussions about this development, the initial research and testing of the flowmeter concept was undertaken in co-operation with a University, using a research student, so the development was not completely ‘under wraps’, under the control of the company. Nevertheless in a fast developing technology area, many minds are grappling with similar perceived problems and solutions, so parallel work would have been going on elsewhere: an early patent filing is very important under such conditions! The ultra-pure nature of the Metraflow flowmeter arises as the flow tube is a simple straight glass or similar tube, and the ultrasonic transducers are all external. To register to receive further info on the Metraflow, please email Titan.