Special Report – Next Generation Flowmeters for Fluid Measurement and Control Solutions

Next Generation Flowmeters for Fluid Measurement and Control Solutions

S p e c i a l R e p o R t


Flow Measurement

Where Would we Use a Flow Meter?

Meters for Every Purpose

Flow Meters: The Next Generation

Accessorise the Flow Meter

Sponsored by

Published by Global Business Media

LowViscosity

HighViscosity

Call +44 (0)1296 670200

Whatever viscosity you are dealing with – and whatever fl uid – Litre Meter has the

meter for the job.

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SPECIAL REPORT: NEXT GENERATION FLOWMETERS FOR FLUID MEASUREMENT AND CONTROL SOLUTIONS


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ContentsForeword 2 John Hancock, Editor

Next Generation Flowmeters for Fluid Measurement and Control Solutions 3 Charles Wemyss, Litre Meter Limited

From the Old to the NewWhat’s Next?No Moving PartsBringing the Oil and Gas Industry up-to-dateLooking to the Future

Flow Measurement 7 John Hancock, Editor

Flow MeasurementWhy We Need Flow MetersUnits of Measurement

Where Would We Use a Flow Meter? 8 Peter Dunwell, Correspondent

Add WaterPower for the EconomyGoing with the FlowBack to the Future

Meters for Every Purpose 10 Francis Slade, Staff Writer

A Wide Range of Meter TypesCategoriesTraditional SystemsModern Technology

Flow Meters: The Next Generation 12 Peter Dunwell, Correspondent

Two Sides to the CoinMechanical Versus ElectronicHybrid DevicesLooking Forward

Accessorise the Flow Meter 14 Francis Slade, Staff Writer

Better ReadImpact on Selection ProcessGood Communications

References 15

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S P E C I A L R E P O R T


Flow Measurement

Where Would we Use a Flow Meter?

Meters for Every Purpose

Flow Meters: The Next Generation

Accessorise the Flow Meter

Sponsored by


LowViscosity

HighViscosity

Call +44 (0)1296 670200

Whatever viscosity you are dealing with – and whatever fl uid – Litre Meter has the

meter for the job.


www.litremeter.com

Foreword

For as long as people have used liquids, they’ve

needed to measure the quantities delivered to

them or used by them. For this purpose, even early

civilisations devised flow meters and we use them

more than ever today to manage processes as

disparate as irrigation, manufacturing, oil extraction

and taking a shower.

The first article in this Special Report traces the

development of flowmeters and describes the

distinction between New Technology and Traditional

Technology relating to flow management. From axial

turbine types to meters with no moving parts, the

article looks at advances that have been made and

what cutting edge meters might look like in ten year’s

time. It concludes that flowmeter technology will

continue to evolve and that the sound way to choose

the right flowmeter for any particular application is not

by trying to carry out research oneself, but to consult

a flowmeter specialist.

Although flowmeters been around for centuries, until

the advent of water metering, very few people even

realised they existed: flow meters are the unsung

heroes of all sorts of processes in the home, in the

factory and in the fields. There are few processes

in a modern economy which do not need, at some

point, to measure the flow and volume of liquid and

gas products, make processes more accurate and

facilitate fast, real time pricing of use. Things need to

be measured.

Because of their ubiquitous applications, there are

legion flow meter types using different principles

and equipment for that vast array of purposes to

which they are used. Traditionally they have been

mechanical, but today and for the future, a growing

number of new generation devices use electronics

and even more exotic technologies. While they

might well not be as well-known as other more

popular consumer technologies, flowmeters are

also benefitting from the great technological strides

forward that have revolutionised the way we live and

work today.

Technology is taking the meters themselves to new

levels of operational effectiveness while, at the same

time, interacting with other new generation devices to

make tomorrow’s flow meters better at what they do,

easier to manage and better able to integrate with a

wider network. Plus, as their capability grows, so the

range of applications also increases.

We look at how we got to the current position

with flow valves and what the future could be for

these devices.

John hancockEditor


2 | WWW.OFFShORETEChNOLOGyREPORTS.COM

John Hancock has been a journalist for nearly 25 years. He has written and edited articles and papers on a range of defence, engineering and technology topics as well as for key events in those sectors.



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Next Generation Flowmeters for Fluid Measurement and Control SolutionsCharles Wemyss, Litre Meter Limited

TyPES oF Flowmeters fall into many categories. one could use the involvement

of moving parts and electronics to define this. Mechanical meters, used and invented before domestic electricity was prevalent must be old Generation. These would include what you and I have outside our houses for the measurement of domestic water. They would also include meters in our gas supply for the measurement of our consumption of gas. The very first turbine meters credited to Woltmann in 1790 were considered for calculating the loss of energy in open canals. It would be true to say that these were used for counting or totalising flow rather than providing an instantaneous rate display or output.

From the Old to the NewThose using electricity or electronics with a moving part like a rotor are also Old Generation as turbine meters have been around for several decades, for example. The first of these were axial turbine types developed, in essence from Woltmann, in the Second World War for accurately determining the fuel consumption of military aircraft and torpedoes. The pickup or sensor with a magnet and rotating conductor enabled the number of rotations to be counted, totalised and used for rate display.

If we define Next Generation meters as having no moving parts so that the definition encompassed Thermal, Coriolis, Ultrasonic and Electromagnetic, then there would be a modern outlook. Apart from the fact that Faraday tried making an electromagnetic meter to measure the River Thames almost 200 years ago! He only failed because his instrumentation wasn’t sophisticated enough.

The obvious question to ask is: What is Next Generation, What is Current Generation and What is old Generation? We can be certain that old Generation does not mean unusable. We can also be certain that old Generation in some people’s eyes is more than adequate for various tasks. This article explores the provenance of some flowmeter technologies, what might be round the corner and how to select the best meter for each project.

Some new and not-so-new flow measurement techniques:

“New Technology”

• Coriolis, inertial force was first formulated by Gustave Coriolis in 1835 but MicroMotion didn’t release a commercial unit until 1977.

• Electromagnetic, proven by Faraday but commercially produced from 1952.

• Ultrasonic, from 1963• Vortex, using the van Karmann effect of

the generation of alternate vortices past a bluff body commercially from 1969, famously spotted by Leonardo da Vinci in 1504

• Thermal, hot wire anemometers were used from the early 1900s, commercially from the 70s.

• Sonar, unconventional and measures turbulence since 2003

• Optical, measuring the speed and direction of individual particles using a laser beam, in research labs in the 70s and 80s but only commercially used in flare gases.

“Traditional Technology”• Differential Pressure like an orifice plate

or Dall tube with a separate differential pressure transmitter. Also nozzles, pitots, Venturis and wedges. Still the most popular non-domestic meter type

• Positive Displacement, commercially pre 1830s for diaphragm gas meters with sheepskin diaphragms and sheet steel enclosures

• Turbine, first drawn up in 1790, commercially available post Second World War

• Variable Area, available for most of the 20th century



So if it’s not the methods of measurement we use that define ‘Next Generation’ what is it? Perhaps: intelligence? The rise of smart meters i.e. those with digital communications and with the ability to self-verify are undoubtedly modern but were defined decades ago and have been in use for many years.

What’s Next?Wireless communication is similarly up-to-the-minute. HART digital communication has been around since the mid-1980s when it was developed by Rosemount Inc. for a range of measuring instruments, not just flowmeters. The HART foundation was formed in 1993 and the wireless version came along in 2007. So quite modern but ‘Next’?

So, is it the flowmeters that inhabit university laboratories and the R&D departments of flowmeter manufacturers that constitute Next Generation? Can we speculate what a cutting edge meter might look like in ten years’ time?

No Moving PartsIt would be fair to say that this Future meter would have no moving parts. This improves the chances of long term use as it would not suffer from mechanical degradation either planned or unplanned. It would ideally be non-invasive i.e. it would fit on the outside of a pipe and nothing would actually breakthrough the pipe wall. Currently, just ultrasonic meters match this criterion so let’s say that’s less than likely and the meter will therefore be non-intrusive. The sensor will break through the pipe wall but won’t impede the flow or perhaps just negligibly. What will the sensor measure, what techniques will it employ? That’s the $64,000 question. A single sensor is less likely as there will have to be a reference point for comparison. Probably two sensors set apart, then, monitoring a property of the fluid. The clever part will be the intelligence of the signal processing; looking for perturbations in the signal amplitude and comparing it to the next sensor. Dumping thousands of comparisons for the sake of a few, locking onto patterns and pumping out

If we define Next

Generation meters as

having no moving parts

so that the definition

encompassed Thermal,

Coriolis, Ultrasonic

and Electromagnetic,

then there would be a

modern outlook.

CorIoLIS METErS UNDEr CoNSTrUCTIoN

Low Flow technology and the next ten years

There are various technologies that present themselves for low flow shown below. Many of the others mentioned elsewhere do not scale effectively. Coriolis: Most manufacturers concentrate on ½” and above. The issues of balance and producing thin wall tube to the required dimensional tolerances are hard to overcome. Smaller sizes exacerbate this.

Thermal: Microelectromechanical systems (MEMS), generally 0.01 mm to 0.1 mm in size, consist of a CMOS circuit on a thin silicon substrate. For lower flows these will replace a larger heated element and sensor. Liquids have a massively different thermal conductivity so the same device can measure at grams per hour rather than grams per minute.

Positive Displacement: Generally their purpose is to positively measure a trapped volume of fluid – either gas or liquid. Gas versions tend to be for higher flows with the most popular one being used for domestic gas measurement. At lower flow the leakage between successive volumes is too large for effective measurement. For liquids where there is more viscosity the PD meters work well. Developments focus on some novel types and constant improvements to existing designs. There is a law of diminishing returns as the smaller the mechanical parts are, the harder they are to manufacture accurately. Also, leak paths are proportionally larger.

One of the new types is the pendulum. This has one moving part with low mass and minimal friction loss, enabling it to respond to extremely low flow volume rates from 0.3 litres/hour. Unusually, this unit only works with viscosities up to 5 centiStokes.

The rotary piston meter also has one moving part. In terms of flow rate, like most PDs, these prosper on viscosity. At 10 cSt a typical meter will start measuring at 0.08 l/h and when water is measured this increases to 0.4 l/hr.

In line ultrasonic: What happens when the pipes reduce in size and the type where a sensor is clamped on the outside of the pipe is no longer applicable? The sensors are mounted inside the pipe usually contrived in the shape of a U so that the ultrasound is passed between sensors at the base of the U. By knowing the diameter of the tube and the velocity between sensors, the volumetric flow can be calculated. Liquid flow rates down to 2 ml/min can be measured.



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high strength signals. In fact, the real hurdles will be firstly customer acceptance and secondly, electronic component obsolescence.

Will the customer accept that this meter and will it continue to find the small perturbations in property? Can he see it in action? Does he get a sense of goodness in the signal, in the rejection rate? What if the pipe vibrates, if the temperature ramps up, if the ‘property’ disappears? Then we find out that metering and measuring is about confidence, experience rather than ‘Next Generation’.

Bringing the Oil and Gas Industry Up-to-DateThe Oil & Gas industry is relatively conservative, relatively slow moving. The prevalence of HART and 4-20mA signals decades after their introduction speaks volumes. Wireless, Bluetooth and fancy bus protocols are only just now making significant in-roads offshore. The creep of domestic innovation exemplified by the rise of the smart phone encourages instrument designers to bring their act up-to-date. Most instrumentation can only be compared with the most basic mobile phone. There is an inherent expectation that the modern user will have something easy-to-use, colourful and dangerously (?) customisable. The

smartphone has many different uses of course beyond that of making calls. Arguably, it’s an instrument display in its own right. The logical conclusion is that the meter ‘display’ will be with the operator the whole time, in his/her hand. The obsolescence of components that bugs the subsea side of the industry is irrelevant in the actual instrument as this is replaced by the mobile phone and it’s ‘app’.

That still leaves the problem of the fast-moving world of miniature components for the clever parts – that will always be a thorn in the side of designers. Just as with most technologies, we’re not trying to design something to last for 30 years; the likelihood is that it will be overtaken by a new Next Generation device in ten years and then again in twenty years. All we can hope for is that the unit is still working in ten and twenty years and only needs replacing in thirty.

To select the best flowmeter for each application it is not just a question of looking up the first flowmeter you thought of on Google. Nor is it asking the engineer on the next desk or even consulting the internal specification guides issued by your employers. And it certainly shouldn’t be by selecting the cutting-edge meter of the day. It should be by consulting a flowmeter specialist – a specialist that has a wide range

PD METErS For LoW FLoW AND hIGh PrESSUrES



of solutions, not just one that is shoe-horned into every application. Ideally, an independent specialist who can give unbiased advice and who will, if necessary, recommend an external solution.

Looking to the FutureIn conclusion, the Next Generation of flowmeters is already operating, they’re already proven and they’re probably on the specification lists. Most applications can be met, more than adequately, by existing techniques. But the manufacturers aren’t standing still. They’re continually leveraging current technology with creeping demands. It’s more evolutionary than revolutionary but we’re all getting there – safely, economically and technically.

ContactLitre Meter LimitedHart Hill BarnGranborough RoadNorth MarstonBuckinghamMK18 3RZT: 01296 670200F: 01296 670999E: [email protected]: www.litremeter.com

About Litre Meter1. Litre Meter, based near Buckingham, UK, was

established in 1975 and specialises in the custom design and manufacture of instruments for measuring and controlling fluids.

2. The company has particular expertise with offshore and sub-sea flow measurement and has supplied flowmeters for these applications throughout the world. The company’s VFF flowmeter was developed specifically for the petrochemical industry.

3. Litre Meter also pioneered the development of the Pelton wheel flowmeter, an accurate and versatile technology that has since been used across many industries to measure a variety of low viscosity materials at both low and high flow rates.

4. The company is also UK distributor for other flowmeter technology including Euromag Electromagnetic, Sierra Thermal, TRICOR Coriolis, KEM PD meters and Sierra Vortex Mass gas flow meters.

5. Litre Meter is part of the Tasi Group of companies which includes AW Lake, KEM and TRICOR.

Just as with most

technologies, we’re

not trying to design

something to last for

30 years; the likelihood

is that it will be

overtaken by a new

Next Generation device

in ten years and then

again in twenty years.



Low Flow

High Flow

Call +44 (0)1296 670200


meter for the job.


www.litremeter.com

Flow MeasurementJohn Hancock, Editor

Flow MeasurementFlow measurement is the quantification of bulk fluid movement. Flow can be measured in a variety of ways. Positive-displacement flow meters accumulate a fixed volume of fluid and then count the number of times the volume is filled to measure flow. Other flow measurement methods rely on forces produced by the flowing stream as it overcomes a known constriction, to indirectly calculate flow. Flow may be measured by measuring the velocity of fluid over a known area.1

Why We Need Flow Meters“The ability to measure things is a major part of our lives and has been since the earliest days of mankind. From the days when we measured out food in handmade baskets, our need to measure things has grown with us. Measuring product is how we assign value to that product, for instance a basket of fruit may have the value of the hindquarter of a cow.” This neat and succinct definition from Flowmeters UK2 nicely sums up the need for measurement.

It continues; “With agriculture came the need to measure… in new ways. Water had to be measured so crops got enough water but not too much. In times of drought or other seasons when water was not as available the measuring of water was done to ration it and ensure there was enough to last until there was more rain.” We measure materials, liquids or gases to assign them a value or to ensure that the correct quantity is used in a process.

Measuring dry goods was always going to be the easier task as they are materially stable and could be placed into containers of known quantity or could be weighed. However, for liquids there were additional challenges from the very nature of the materials – not stable and usually in movement (flowing) so not so easily contained at the time when measurement is needed. Even ancient civilisations had to be able to measure flow rates in order to be able to manage their use of liquids (especially precious water). At its simplest, a flow meter might have been as basic as counting the number of full buckets hauled up from a well to irrigate a field or fill a cistern. It sounds very crude but would

meet the basic purpose of flow measurement – to control quantities delivered.

Units of MeasurementHowever, for a measurement to be useful, there needs to be agreed and recognised units of measurement. For liquids this can either be by volume or mass (weight). It is also necessary to know the temperature of a liquid if the volume measurement is to be useful because liquids to some extent and gases, to a very large extent, vary in density at different temperatures which means that for a given weight, the volume of the product will also vary. For liquids, various units are used depending upon the application and industry, but might include gallons (U.S. liquid or imperial) per minute, liters per second, bushels per minute or, when describing river flows, cumecs (cubic metres per second) or acre-feet per day. In oceanography a common unit to measure volume transport (volume of water transported by a current for example) is a sverdrup (Sv).

Whatever unit of measurement is used to ascribe a value to a flow of liquid, the different measurement criteria are usually referred to as

for volumetric flow rate and for mass flow rate. And, whatever unit or criteria of measurement is used, there will need to be a flow meter of some type to capture the required information.

Why we need flow meters and how we interpret their data

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At each point where

measurement takes

place, there will need to

be a measuring device

which, for most cases

will be a flow meter,

a device that measures

a liquid or gas.

Where Would We Use a Flow Meter? Peter Dunwell, Correspondent

IF ThE ability to measure a flow was once an important means to manage water for crops

and people, today there are multiple factors that specify quantities of given materials and liquids to be used within the processes of modern life. It might be in a formula, the regulations that govern how a process is conducted, the allocation of fuel to power a given function or, as it ever has been, the need to value a product according to quantity. Whichever of these is the case, our need to be able to measure the quantities of gases and liquids fed into the processes of modern life continues to grow into the future. And always, at each point where measurement takes place, there will need to be a measuring device which, for most cases will be a flow meter, a device that measures a liquid or gas by capturing the speed at which it flows, i.e. the volume that passes in a known time.

Add WaterPerhaps the most basic use for a flow meter would be the measurement of water delivery or consumption. Water has always been a precious commodity and is a finite component in the ecosphere, whereas the principle drivers of how much water is used, the populations of plants, animals and people, is far from finite but grows apace. Whether it is used for consumption, irrigation, in an industrial process or to carry waste away, what was always a precious resource has become even more valuable and proportionately scarce, and is effectively rationed in parts of the world through pricing; pricing that is achieved through measuring consumption for which we do and will increasingly need flow meters. Flow meters are also used to manage the problem of losses through leaks which, again, are increasingly becoming the objects of public concern and governmental regulation.

Power for the EconomyThe other obviously valuable commodity in liquid form today is oil and its many derivatives used to fuel our whole way of life. Here we’ll find what

may be the most commonly recognised flow meters built into the pumps that deliver fuel to our transport and heating systems. Accurate measurement of fuel delivery can become a key input to many economic systems. We also need to be able to manage liquid flows as part of the vast chemical industry. As extractable mineral resources become increasingly scarce, greater quantities of the materials with which products are made rely on plastics. These will range from the traditional use of plastics for toys and household items to more quality critical products such as car parts and aircraft wings. To ensure that plastics have exactly the right qualities, the ingredients have to be so accurate that flow meters have become a key part of the industry.

Another good example of why flow meters are necessary to modern life would be fuel management for an airline in an age when carbon emissions are subject to strict limits in most parts of the world and especially in Europe. In fact, in our increasingly environmentally sensitive and regulated world, flow meters are used on both sides of the equation: not only to measure fuel being introduced to processes but also to measure waste quantities generated by those processes.

The many applications where accurate measurement matters

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Because, we need to measure our uses of so many liquids at so many times, the places where flow meters would be useful are legion. They have “applications in medicine as well as in chemical engineering, aeronautics, and meteorology.”4

Going with the FlowThe traditional place where we think of flow meters being placed is in pipes, one of the commonest means of transporting liquids and gases around and able to deliver the product right to where it is needed. Depending on the liquid being transported, the flow rate might be needed to maintain safety or to allocate supplies to different parts of a

system and/or to measure deliveries for pricing purposes.

Not all conduits are closed pipes. Sometimes, liquids are carried along open courses where flow rate will sometimes be important for the same reasons that apply with piped systems but often for reasons of safety, to predict or avoid flooding, for instance. These conduits are often referred to as ‘Open Channel Flow’.

Evolution.net from Mitsubishi tells us that; “The ‘open-channel’ refers to any conduit in which liquid flows with a free surface. Included are tunnels, non-pressurized sewers, partially filled pipes, canals, streams, and rivers. Of many techniques available for monitoring open-channel flows, depth-related methods are the most common. These techniques presume that the instantaneous flow rate may be determined from a measurement of the water depth, or head. Weirs and flumes are the oldest and most widely used primary devices for measuring open-channel flows.

“Weirs and flumes are distinguished as ‘rate meters’ in that they are used in open pipe or channels that do not flow full. They fall into the general category of ‘head-area’ meters and are used extensively in the measurement of irrigation water as well as the primary device for municipal and industrial wastewater applications.” 5

If open channel water conduits are the large end of where flow meters are used, healthcare and medical applications often include the smallest, finest and most finely calibrated end of that spectrum. Many modern medical treatments rely heavily on precise quantities of drugs being delivered to the patient, another application for the ubiquitous flow meter.

Back to the FutureBut we mustn’t forget that one of the most ancient applications for flow meters continues to this day in the management of irrigation water for agriculture and horticulture. As with so much else in life, feeding people has become a far more tightly managed process with exact quantities of each element used to produce food, whether directly or through animal husbandry, being vital parts of the process.

Although not the most high profile of technologies, flow meters are used at every stage of modern life to ensure that we make the best and most efficient use of liquid and gas resources.

As with so much else in

life, feeding people has

become a far more tightly

managed process with

exact quantities of each

element used to produce

food, whether directly

or through animal

husbandry, being vital

parts of the process.



Turbine flow meters have

much less impact on the

liquid or gas that they

are measuring and so

can allow the system in

which they operate to

achieve higher flow rates

and less pressure loss

than would be the case

for displacement meters.

Meters for Every Purpose Francis Slade, Staff Writer

FLoW METErS may not seem very exciting pieces of equipment and most of them

function out of sight which means that it is easy to think of them as all being more or less the same. But these key pieces of equipment for managing the inputs to and outputs from life, comprise a broad group of components which have been developed over centuries into a range of devices from the simple mechanical models that have always worked at all sorts of tasks, to the sophisticated, IT integrated models of today and tomorrow. To describe them all would take more space than is even available in a White Paper of this size.

A Wide Range of Meter TypesFor instance, Flowline lists 12 categories6 of flow meters and flow measurement solutions…

• Clamp On Ultrasonic Flow Meters;• Differential Pressure Flow Meters;• Electromagnetic Meters;• Coriolis Meters;• Open Channel Radar Flowmeters;• Open Channel Ultrasonic Flowmeters;• Thermal Mass Flow Meters;• Turbine Flow Meters;• Data Loggers, ATEX, Web Enabled;• WirelessHART;• Vortex Meters;• River and Stream Gauging.

… and that’s just categories! Within each category there are many specific meters tailored to meet a number of criteria such as size or nature of the job.

CategoriesPerhaps the first breakdown should be how the meter is fitted. The Free Dictionary tells us that there are two types of fitting.7 “’Invasive’ flow meters are coupled into the pipe and derive the flow rate from the rotation of a turbine or paddle wheel that is moved by the liquid. ‘Non-invasive’ meters use two ultrasonic transducers that clamp on the outside of the pipe at a prescribed distance from each other based on the pipe’s composition and diameter. They derive the flow rate based on the transit time of ultrasonic pulses sent from transmitter to receiver. In liquids

with high solid or gaseous content, rather than measuring transit time, the amount of frequency shift is detected.”

Traditional SystemsProbably the most common flow measurement devices in the UK are known as piston meters, rotary piston devices or semi-positive displacement meters – the sort that are used to measure domestic water usage. Displacement meters, though, can affect the flow of what they are measuring. That might not matter too much in a domestic situation but, in other circumstances it might. Another important criterion for meters is the extent to which they impede the flow of the liquid or gas they are measuring.

Turbine flow meters have much less impact on the liquid or gas that they are measuring and so can allow the system in which they operate to achieve higher flow rates and less pressure loss than would be the case for displacement meters. Turbine flow meters are used for the measurement of natural gas and liquid flow. They are also the meter of choice for large commercial users, fire protection, and as master meters for the water distribution system.8 Strainers are generally required in front of the meter to protect the measuring element from gravel or other debris that could enter the water distribution system. What displacement meters and turbine meters share in common is that they use a mechanical action to gauge the velocity of flow whether

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that is displayed by purely mechanical means or with the help of electronics. There are also meters that read pressure differentials before and after the liquid being measured has passed through a deliberate constriction of known dimensions in the pipe. While this might sound more sophisticated than the purely mechanical systems, the method has been used in various forms since Roman times.

Modern TechnologyWhile these types of meters will, no doubt, remain popular and useful for the foreseeable future, there are a number of modern technology based meters now available either to meet measurement requirements that did not previously exist or to do the same tasks as the longer established devices but better or more robustly. Mechanical meters, given the environments in which they work and the fact that they usually need to be in the flow being measured, suffer some disadvantages including the restrictive effect that they have on flow rates. This is not simply an aesthetic matter; when flow rates reduce, energy is lost and efficiency of the transport and delivery system is reduced. That means cost. Also, a device which is constantly in movement and immersed in liquid, no matter how well it is built, will eventually suffer wear and tear from the effects of the liquid – corrosion, blockage, etc.

Looking to the future, the kinds of devices that will increasingly take centre stage will include thermal mass flow, electro-magnetic and optical flow meters. These ‘Next Generation’ meters don’t have moving parts but use a number of other methods to gauge flow velocity. They largely do not need to be immersed in the liquid they are measuring so will be more robust, need less maintenance and will not impede the flow rate. Also, because they are based on electronics, they are more easily able to communicate their measurements to remote monitoring stations.

Another method that requires no moving parts is using sound waves in either an ultrasonic flow meter, one that uses the Doppler effect, or a beam drift meter. All use the effect of movement on sound waves to measure flow.

Some would contend that the electromagnet flow meter comes near to being the perfect flow measurement device, “… because it has no restriction in the flow line, can accurately

measure liquids almost impossible to handle with other meters, has a linear output that is directly proportional to flow, and has the ability to measure bi-directional flow. The only limitation on liquid measurement is that it must meet a minimum standard of electrical conductivity.”9

So, far from being an homogenous group of devices, flow meters are among the most diverse that we use and can range from the simplest mechanical devices to the most sophisticated electronic equipment, which will certainly dominate the future.

‘Next Generation’ meters

don’t have moving parts

but use a number of other

methods to gauge flow

velocity. They largely do

not need to be immersed

in the liquid they are

measuring so will be

more robust, need less

maintenance and will not

impede the flow rate.



Meters themselves

will need to operate

in increasingly hostile

conditions as resources

such as sub-sea or

arctic oil and gas fields

are exploited. Such

conditions might make

traditional mechanical

flow meters less

attractive with their need

for maintenance.

Flow Meters: The Next Generation Peter Dunwell, Correspondent

EvErything thEsE days has to match up to a range of standards for the ‘green’ or

‘environmental’ agenda. For flow meters this impacts in two directions.

Two Sides to the CoinOn the one side, it probably has increased the market for flow meters to help comply with the plethora of regulations that seek to translate standards into operational criteria. Whether the concern is to limit quantity, so as to meet environmental regulations or to know levels of usage at points in a system in order to manage the cost of a process, flow meters will be employed to take measurements.

On the other side of the coin, the meters themselves will need to operate in increasingly hostile conditions as resources such as sub-sea or arctic oil and gas fields are exploited. Such conditions might make traditional mechanical flow meters less attractive with their need for maintenance. In short, moving parts need to be kept moving and some of the conditions in which meters now operate are not conducive to that. Also, there is the simple cost factor that maintenance anywhere requires labour and other costly resources whose use businesses try to minimise. And mechanical devices have to be physically read whereas modern practice would prefer a device that can communicate with a remote hub.

Mechanical Versus ElectronicThere will always be a place for the mechanical or mechanically based flow meter; however, for an increasing number of new tasks and for more efficient practice of traditional tasks, the next generation of flow meters will better fit the bill. Although they differ in many ways from mechanical devices, the most important development is that next generation flow meters have no moving parts. This means that they don’t need to be placed into the stream that they are measuring but instead can either be

embedded in the conduit wall or even attached to the outside of the conduit. They do not impede the flow they are measuring. It also means that they have fewer parts that can wear and, even when they do require maintenance, can be accessed without having to disrupt the system.

Because they use electronics, next generation devices can be equipped to communicate with a central hub to not only be read remotely but also to be read more often, or even continuously.

That is not to say that the next generation of flow meters has been entirely trouble free. For instance, Flowmeter Directory reports that early thermal mass flow technology devices had to be calibrated before being installed and often, where the device was replacing an older volumetric technology that could not provide the same level of accuracy, users found that the flow rate they had specified – based on the reading of the prior device – was not, in fact, the actual mass flow rate. This often meant that they had to send the mass flow meter back to the factory for re-calibration. New ‘smart’ mass flow meters utilize microprocessor technology to solve this problem – by allowing the operator to change

As requirements change, so devices evolve to match new conditions

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the instrument’s full scale, as well as other flow parameters. Additionally, because the instrument’s electronics stores calibration data, these devices can be ‘field validated’ to ensure accuracy.10

Also the Flowmeter Directory suggests another emerging trend is adding multivariable capability to the instrument. Multivariable flow meters are one of the fastest-growing segments of the flow meter market; they provide more information about the process, at less cost than buying comparable components separately. Because the thermal meter uses a temperature sensor to measure flow, it is fairly simple to output a temperature reading in addition to the mass flow reading.

Hybrid DevicesThere are devices that utilize both mechanical and electronic systems. Vortex flow meters place a shedder bar in the path of the fluid. As the fluid passes this bar, disturbances in the flow called vortices are created. The vortices trail behind the cylinder, alternatively from each side of the bar. The frequency at which these vortices alternate sides is essentially proportional to the flow rate of the fluid. A sensor is used for measuring the frequency of the vortex shedding. The frequency is measured and the flow rate is calculated by the flow meter electronics.11

Industry has a continuing need for devices that can accurately measure the flows involved in so-called ‘mass related’ processes such as chemical reactions, heat transfer, etc. To cope with this, a number of mass flow meters have been devised, the most commonly available and utilised of which is the coriolis meter. “Its operation is based on the natural phenomenon called the coriolis force, hence the name. Each coriolis meter consists of one or more flow tubes. As fluid enters a vibrating coriolis tube, the particles accelerate (due to the vibration) exerting a force on the inlet side of the tube. As fluid leaves the tube, the particles decelerate and exert a force in the opposite direction from the inlet. 0The resulting forces angularly deflect the tube(s) an amount that is inversely proportional to the mass flow rate within the tube. The angular deflection is optically measured.”12

Looking ForwardSome new generation devices are designed to cope with particular conditions. The ultrasonic flow meter, for instance, is designed to work well with ‘dirty’ liquids or liquids that have particulates or bubbles in the flow.13

No doubt there will be further developments in flow meter technology partly to address new regulatory or market driven requirements and partly because people will see applications in the field for other new generation technology – a smart phone app? One thing is certain; for as long as we need to know how much volume is passing through any form of conduit, we will need flow meters.

Because they use

electronics, next

generation devices can

be equipped to

communicate with a

central hub to not only be

read remotely but also to

be read more often, or

even continuously.



By equipping meters

with microprocessors,

appropriate software

and communications

facilities, they can now

be read either from a

remote station in a fixed

network or, where that is

not practical, by a simple

‘drive by process’ which

will allow many more

devices to be read.

Accessorise the Flow Meter Francis Slade, Staff Writer

WhILE ThE principles by which flow meters function have changed little

over centuries, the way they achieve that has ref lected the developments in technology in the wider world. But it isn’t only in their operation that meters can benefit from modern technology.

Better ReadOne of the revolutions of our age has been the communications revolution through which we now find ourselves able to converse and interact with people anywhere in the world at any time and in real time. Some of this communication technology can be applied to improve the reading of flow meters. For instance, by equipping meters with microprocessors, appropriate software and communications facilities, they can now be read either from a remote station in a fixed network or, where that is not practical, by a simple ‘drive by process’ which will allow many more devices to be read in a working day than if the operative had to leave the vehicle and visually read every one.14

Equally, the communication can flow the other way with microprocessors on flow meters being able to accept commands from the remote station for tasks such as re-calibrating to reflect changes in the product being transported in the conduit.15

Impact on Selection ProcessApart from the obvious benefit of being able to operate a better service with fewer resources, using modern communications can change the considerations taken into account when selecting a flow meter. Omega Engineering publishes a document to help with selecting a flow meter in which it is stated that; “When choosing flow meters, one should consider such intangible factors as familiarity of plant personnel, their experience with calibration and maintenance…”16 which, of course would be important if they were likely to be

the ones undertaking those tasks. But with remote calibration and regular condition reporting from the device to the centre, local staff experience will be less of an issue.

Of course, there are a host of other considerations to include in any deliberations about selecting a flow meter. Not only the type of liquids or gases to be measured but also how the user wishes to receive the measurements and what levels of functionality are required of the meter.

Good CommunicationsThere are so many options as to how a meter might communicate with the rest of the network and with the centre. The easiest is over a hard wired telephone system or using broadband to upload data either at intervals or continuously. For billing or daily usage measurement, the communication can be at intervals, whereas if the measurement is safety related, continuous would be best. But hard wired systems only work where they are present and some of the places where flow valves need to work are too remote to have access to a telephone system. In those cases either a cell-phone network or satellite communication will be needed.

Whatever communications are used, a technology such as Bluetooth will assist in the job of remotely operating the meter and, in particular, when operational criteria need to be amended to reflect changed products or conditions (see above). Also, the continual miniaturisation of components means that flow meters can be made for ever more constricted or difficult to access places. And last, but not least, it cannot be long before an app is produced by one of the meter manufacturers so that operators with smart phones or tablets can be remote from the device but don’t need to be in the remote operating centre.

New technologies are revolutionising the operations of many processes – flow meter management will not be the exception to that rule.

It isn’t only in the operation of the device but also in how it works

with the rest of the network where technology can assist



references:

1 Wikipedia http://en.wikipedia.org/wiki/Flow_meter

2 Flowmeters UK http://flowmeter.uk.com/


4 The Free Dictionary http://encyclopedia2.thefreedictionary.com/flow+meter

5 Mitsubishi http://forums.evolutionm.net/water-alcohol-injection-nos/378065-info-about-all-flow-meters.html

6 Flowline http://www.flowline.co.uk/

7 The Free Dictionary http://encyclopedia2.thefreedictionary.com/flow+meter



10 Flowmeter Directory http://www.flowmeterdirectory.com/flowmeter_thermal_mass_evolution.html

11 Wikipedia http://en.wikipedia.org/wiki/Flow_meter#Vortex_flowmeters


13 Flowmeters UK http://flowmeter.uk.com/fm-types2.html

14 Universal metering http://www.universalmetering.co.uk/pdf/smartFlow.pdf

15 Flowmeter directory http://www.flowmeterdirectory.com/flowmeter_thermal_mass_evolution.html

16 Omega Engineering http://www.omega.co.uk/prodinfo/flowmeters.html

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Special Report – Next Generation Flowmeters for Fluid Measurement and Control Solutions

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