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 TechNews.co.za

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.

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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.

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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.”

ENDS

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.

600,000 flowmeters measure beer and lager flow

Titan Enterprises has established a long-standing working relationship with Vianet plc (formerly Brulines) for the supply of beer flowmeters for pub and bar automation projects. Over the last 20 year period Titan have delivered, and Vianet has installed, over 600,000 of these meters for beer and other bar flow measurement and automation applications.

Brulines, was formed in 1993 with the intention of providing pub chain owners with data on their bar activity via an electronic point of sale (EPOS) system. After trialling several other flowmeters, the company sought a solution to resolve flowmeter bearing lifespan problems and to overcome the unreliability of the optical detection method in beer.

beer-meter

The beer flowmeter

Following a collaborative approach to developing the solutions needed for the Vianet customer base, Titan Enterprises proposed an adapted version of its 800-series turbine flowmeter as the design included durable sapphire bearings proven reliable for many thousand hours operation, and a Hall effect detector which was not subject to problems with discolouration inside the pipe. After successful tests, a trial order for 400 units was placed in 1997, which after the subsequent field trials, was followed by an order for >5000 meters which were all delivered to the clients required timescales.

To ensure the flowmeter was ‘fit for purpose’, Titan additionally adapted the cable type as well as the body and increased the length to 10 metres. These adaptions enabled Brulines installations to be maintained in beer cellars with differing wire runs to the control panel without any junction boxes.

Twenty Years of Collaboration

With the widespread reliability of this product, Vianet turned again to Titan Enterprises in 1999 to develop for them an “intelligent” flowmeter (IFM) for their enhanced iDraught retail product. The specification for the IFM required that it should additionally measure temperature as well as determining the type of fluid in the line to detect line cleaning cycles which are essential for the dispensing of a good pint.

At the time, Titan did not have the technology to provide sensing electronics at a reasonable price so we produced a revised version of the beer flowmeter with the capability of being matched to a PCB designed, manufactured and installed by a third party.

After trialling and testing, this new IFM was introduced in June 2000 and supplied to Vianet at the rate of up to 3500 units a week. Mark Fewster, product manager at Vianet commented “Titan’s supply chain has always delivered to our quality and timescale needs”.

IoT Developments

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An intelligent flowmeter design

Since this first IFM introduction, close collaboration between the two parties has resulted in 5 iterations of the product with revised features as end user requirements have developed and evolved with the growth of the IOT (Internet of Things). Drawing upon this close working relationship, over a long period of time, Titan continue to work with Vianet on new solutions and offerings as the Vianet customer offering further develops.

This Titan Enterprises application story is based on a report in the Autumn issue of Flowdown, the regular news bulletin published by Trevor Forster, MD of Titan, from their Dorset, UK base.

The mystery of intelligent sensor diagnostics

The fashion, or trend, that has developed over the last few years for process and analytical instrumentation sensors is to use their on-board intelligence to monitor their own performance status. They achieve this by monitoring and tracking various diagnostic measurements – secondary parameters where consistent values are said to indicate the sensor is working as it should, and has not been subject to any changes since leaving the factory.

This approach is easily understood if you consider the possible effects of exposure of a sensor to excessive temperatures, which might soften the potting or glues holding a sensor to a ‘window’ – and it can be expected that this would be detectable. The addition of a diagnostic sensor, such as a temperature probe, within the sensor housing, could also be an option for checking the sensor condition, and alarming if the sensor exceeds a high or low set-point.

But how else do sensors check their own performance, and how relevant are these “checks”? This topic was discussed in the latest issue of the South African Journal of Instrumentation and Control, August 2017 issue: SAIC is a journal produced by technews.co.za.

Modern (intelligent?) sensors

So, over the past two years of attending and listening to presentations, and reading relevant articles describing the advantages of self-monitoring systems and sensor diagnostics, waiting for an engineer’s explanation as to how the clever monitoring system actually tells the factory instrument engineer anything, it is a bit of a disappointment to report that there seem to be no suppliers that actually make any significant disclosure. This applies across sensors ranging from ultrasonic and Coriolis flowmeters, electromagnetic flowmeters, level measurement systems using radar or ultrasonics, and level alarms. Obviously all the major suppliers are involved in such equipment, and compete with each other, but this secrecy seems a little extreme.

The problem is possibly that until a manufacturer can point to a failure that was detected – or anticipated – using their diagnostics, and decides to publish it, the user population has no idea what systems might actually work. But equally, by publishing a success for the diagnostics, the same manufacturer is saying that one of his sensors failed – and that is a very unusual event, these days. Plus also maybe not something they would wish to publicise.

The older approaches

The whole idea of diagnostics and sensor monitoring has been around for a long time. From personal experience with Bestobell Mobrey, in the 1980s, Mobrey launched an ultrasonic version of a float switch, the ‘Squitch’, which switched a two wire mains connection through a load circuit. When not alarmed it just sat there taking a small control current. For customer reassurance that it was operating in this quiescent state, there was a blinking red LED to show that the sensor was ‘armed’ and operating normally. Mobrey called that a heartbeat indicator, a term that is now used more widely.

For custody transfer flowmeters, the classic approach to validate confidence in the reading is to use two meters in series, and check that both give the same answer. This has progressed to having two separate ultrasonic flowmeters mounted in the same flowtube, on some installations.

For the more safety conscious plant there are often requirements for duplicated sensors for such duties as high level alarms, where two different technologies are used by the sensors – e.g. by mixing float, capacitance or ultrasonic level alarms.

The modern approach

It seems that the ultimate approach is to let the sensor supplier link into your plant automation and data system to interrogate the sensor, and he will verify the measurement and performance diagnostics on a regular basis. With many and varied sensors, this leads to a lot of external interrogation of your plant assets, and possible worries over losing control of your plant.

Overall, it begins to look as though it is becoming impossible for a discerning plant engineer to decide which supplier has the best performing diagnostic system to monitor the relevant sensor’s performance. Rather like opening the bonnet of a modern car, and deciding it would be best to take it to a garage!

At a recent lecture on this subject, held by the InstMC Wessex section in co-operation with Southampton University, a detailed discussion concluded that the sensor suppliers now have all the real expertise in-house and a normal plant engineer could not be expected to cover the depth of this technology for all the many sensors and other equipment within his control. In the end the decision as to ‘which supplier to use’ returns to your own previous experience, including the service and support that has been and is now on offer, and the suitability of the product for the money available for that sensor task.

Fashions in sensor technology

I confess it was 50 years ago when I started looking at new technology for sensors. Back then, colleagues and I updated the old WW2 mine detector, using really low frequency (i.e. 1 kHz) magnetic waves to discriminate between ferrous and non-ferrous items, and assess the size and range of the target by the signal phase measurement. Here the electronics used ‘modern’ operational amplifiers, on a ‘chip’.

The 1980s

Ten years on, in the ’80s, the technology coming into vogue was ultrasonics, replacing float systems to make liquid level switches, and then, still using analog electronics, the first Doppler ultrasonic flowmeter appeared. With the availability of digital microprocessor circuitry, timed pulses transmitted through the air down to the surface of a liquid led to non-contact liquid level measurement, and major success in the automation of sewage sump pumping systems. (The success lasted maybe 30 years, as when the mobile phone business created low cost microwave components, similar systems based on radar began to take over in this market.)

The next leap forwards in the mid-’80s was the time-of-flight ultrasonic flowmeter – actually achieved with discrete digital circuitry, which was faster than the available microprocessors. The technology was originally developed at Harwell, for measuring liquid sodium flows in nuclear reactors, but these flowmeters found major application in monitoring clean water flows, primarily in water distribution mains. Over the next 25 years the technique was picked up by commercial interests, and continually refined, introducing clamp-on sensor systems, and adapting the technique for gas flows as well. Even domestic gas meters were introduced using the same principle. Eventually the microprocessor speed became fast enough to achieve the flow measurement accuracy needed – using multiple sound paths – for the fiscal measurement of oil flows, which is now one of the major applications, along with similar gas flow measurement tasks.

Other sensors where I was not initially involved were in the fields of gas detection – where for flammable gases, Pellistors created a major business area – and fire detectors. It seems that UV and IR fire detection systems are still seeking the best approach. Possibly because of the awareness brought about by the Internet, the pace of change and the commercial opportunities, the large corporations are quick to acquire small spin-off companies from university or other research after any small success, because of what technology they may have discovered: they do this ‘just in case’, to protect their market position.

Current developments

The area I see as most important currently, and a fruitful area to flag up for research projects, is in any style of optical analytical measurement sensor. Specifically, the component that brought this into industrial instrumentation was the tuneable diode laser (TDL), developed prior to 2005 for the telecommunications industry, to transmit telephone conversations and data down fibre-optic cables. Around 2007 Yokogawa acquired a business from Dow Chemicals, which used TDL sensors for near-infrared absorption (NIR) measurements of a gas mixture, which gave the proportions of oxygen, carbon dioxide and monoxide, and water vapour. This allowed the unit to be used as a combustion analyser for industrial furnaces, boilers etc.

Over the last 10 years this area of technology has grown in importance, and in its capabilities. Spin-off companies have emerged from various universities, like Manchester and Glasgow. A significant task in these developments is the application of the solution to an industrial problem: it needs the two factors of solving both the technical design and the industrial application. Cascade Technologies was established in Glasgow in 2003, and their analysers were initially targeted at marine flue gas emissions monitoring. From 2013 they added a focus on pharmaceutical gaseous leak detection, and also the process industry, on ethylene plants. Their technology allows multiple gases to be measured simultaneously. The Cascade business has now been acquired by Emerson.

Another closely market-focused supplier of NIR analytical systems is TopNIR Systems of Aix en Provence, in France, actually a spin-off business from within BP. TopNIR use their systems to analyse hydrocarbons – both crude oil and processed products – to allow a refinery operator to know how to most profitably blend the available components into a final product, as well as to minimise any quality give-away in blending the different grades of gasoline and diesel. TopNIR quote the annual benefit to a typical refinery at $2 to $6 million, with an implied investment spend of up to $2 million!

This article was first published in the May 2017 issue of “South African Instrumentation and Control” published by Technews.co.za

©Processingtalk.info

Emerson to work with Flexim

Emerson Automation Solutions and Flexim, the clamp-on ultrasonic flowmeter specialists, are to collaborate, to help process customers optimise their flow process design, flow meter selection and flow meter installation on capital projects. This will enable them to reduce execution risk and costs.

With customers under severe pressure to reduce schedule and cost targets on capital projects, Emerson project teams, using the Flexim clamp-on, ultrasonic flow metering portfolio in combination with the broader Emerson in-line flow meter products, are able to consult early and throughout the project cycle to reduce engineering, piping and installation costs as well as schedule risk.

Flexim non-intrusive flow meters are the market leaders in clamp-on, ultrasonic technology and provide the best reliability and the most advanced capability when addressing difficult applications with a non-intrusive flow solution. This co-operation will improve delivery of the exact flow solution needed by clients while supporting  ‘Project Certainty’ – the Emerson approach that is said to enable top-quartile performance in capital projects.

By empowering project teams with flow expertise to work with clients early in project phases, Emerson has consistently eliminated cost, accommodated change and reduced complexity on capital projects. The non-intrusive nature of the Flexim ultrasonic flow meters makes this product a powerful contributor to reduced engineering, piping and installation costs as well as schedule risk, given that it can be installed after piping is fabricated. Emerson and Flexim will collaborate to ensure less time is spent on engineering and installation by selecting the optimal flow solution for a given application and applying the most comprehensive flow portfolio available.

“In today’s market, we are seeing that our customers are looking for us to advise them early in their project cycle on technology to ensure streamlined and cost-effective project execution,” said Bret Shanahan, vice president of flow solutions, Emerson Automation Solutions. “We are pleased to be working with Flexim to provide our clients with the most appropriate flow solution that can be applied and support greater capital efficiency.”

“Flexim is excited to partner with Emerson on capital projects; our flexible, world-class, non-invasive meters are a perfect fit with the experienced Emerson project teams,” said Guido Schwanekamp, managing director for sales and marketing at Flexim. “Together we will be able to offer fully customised solutions that are tailor-made for a wide variety of capital projects, reducing capital expenditures while increasing efficiency for our clients and reducing total cost of ownership at the same time.”

Platon/Roxspur acquired by TT Electronics

It’s always interesting when your old company gets taken over, once again! Particularly when you thought it was being screwed up, by the acquirers. So I was disappointed to have missed a news release nearly 15 years later, about a subsequent take-over in 2014.

The event was that Roxspur Measurement & Control was acquired by TT Electronics for GBP8m in July 2014. The good news was that the TT annual report for 2014 suggested that Roxspur provided a GBP0.4m operating profit, included in their results at the end of 2014.

Roxspur was absorbed into the TT Electronics Industrial Sensing and Control division,  which had a sales revenue of GBP61m in 2015, and an operating profit of GBP11.4m. So Roxspur is now a small-ish cog in this much bigger wheel.

TT Electronics describes itself as manufacturing a comprehensive range of temperature, pressure, flow and level products designed for aerospace, industrial, oil and gas, power generation and water management applications through its Roxspur sub-brands Brearley, Platon, Sensit and Nulectrohms. The TT Electronics total sales revenue in 2015 was reported as GBP524m, with an operating profit of GBP30m. So Industrial Sensing and Control is in fact a very significant part of the whole.

I, and everyone else, have to hope that the succession of acquisitions that were imposed on the Platon  variable area glass and metal tube flowmeter measurement business after 1999, have brought some of the employees some benefit.  Over the previous 8 years the Basingstoke based team had built the flow measurement business, which included the well known pre-Internet Flowbits catalogue, into a GBP10m business. So this small part of the corporate group at that time was probably worth more than GBP8m. It faced the biggest business trading profile challenge ever, with the arrival of the Internet, just as it was hyped into a broader paper based catalogue for industrial engineers, renamed as “Controlbits” by the new acquirers.

There are still paper catalogues around, in 2016, but hyped up earnings expectations appeared to kill off the Platon catalogue. The chaos catapulted me, after a year recovering from being made redundant, into a new career, which I do not regret. It also spawned some spin off start-up companies, which have done well. Even the Platon Pension scheme, which had to be the subject of a Government funded rescue, has at last started to pay out some of the pensions due, as from 2015.

So there were benefits! Ironically I did, at that time, and maybe still have, a minimal number of shares in TT Electronics!