We are delighted to celebrate being one of the select businesses recognised as winners of the 2016 Queen’s Award for Enterprise – the UK’s highest accolade for business success.

Litre Meter awarded Queen's Award for International Trade

Litre Meter awarded Queen’s Award for International Trade

Our award was received for Enterprise in International Trade and was in recognition of achieving significant year-on-year growth of export sales from 2013 to 2015.  In turn, this helped us achieve record increases in turnover and profits resulting in a Compound Annual Growth Rate of 48%.


CEO Charles Wemyss: ‘As a very specialist company working on an international basis from the middle of a field in Buckinghamshire it is an outstanding achievement to be recognised at the highest levels for our success.’


Litre Meter was established as a family business in 1975 by the current CEOs father, where it moved to Buckinghamshire in 1978. Today, Litre Meter is recognised as the world’s premier Flow Measurement Specialist, employing home grown talent in a converted barn in North Marston.  Our highly engineered products are used in various industries throughout the globe, such as the Oil & Gas sector, where they can be installed on platforms in some of the deepest seas and most arduous environments. We pride ourselves in using local suppliers for our materials, where possible and are proud to be an active part of the UK’s engineering heritage.


Notes for Readers

  • 249 Queen’s Awards (QA) have been announced in 2016 for outstanding business achievement in the fields of International Trade, Innovation and Sustainable Development. Winners of The Queen’s Awards can expect an invitation to attend a special reception at Buckingham Palace.
  • QA winners can also use The Queen’s Award Emblem in advertising, marketing and on packaging for a period of five years as a symbol of their quality and success.
  • The awards are made annually by HM The Queen and are only given for the highest levels of excellence demonstrated in each category.
  • To find out more about next year’s awards visit the Queen’s Award website.
  • 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.
  • 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.
  • 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 liquids at both low and high flow rates.
  • Since 2011 Litre Meter has been part of the TASI Group of companies which includes AW-Lake, KEM and TRICOR.
    Rotary Piston Litre Meter flow meter with Hub connectors for high pressure flow measurement

    Rotary Piston Litre Meter flow meter with Hub connectors for high pressure flow measurement


    Litre Meter FlowPod flowmeter instrumentation

    Litre Meter FlowPod flowmeter instrumentation

Litre Meter operate out of a barn in the rolling Buckinghamshire countryside - Hart Hill Barn

Litre Meter operate out of a barn in the rolling Buckinghamshire countryside – Hart Hill Barn

Are there any size limitations?

    When specifying flowmeters how does size affect meter selection?

  1. Can you specify the available pipe length? Some installations are very limited on installation length and meter selection can be pivotal. Assume that the number straight lengths before and after the meter (but, see below) isn’t relevant for the moment and all meters are available: If there’s only 1 diameter of straight pipe then the PD meter is probably the Number 1 choice. There’s likely very little room so larger meters like the Coriolis, which is a ‘bulky’ technology, are too long, even if they, too, need no straight lengths: that’s not strictly true but that’s another story entirely.
  2. Width: Does the unit have to fit in a narrow space? Perhaps there’s a wall one side -the meter can’t overhang that side, but is it then facing the right way?
  3. Does the installation space enable the unit to be provided with a local display – which is facing the right way? or will it need to be a remote mounted version?
  4. Is there access for maintenance? Is that all important termination panel just in front of you or is it tucked beyond a stem in a dingy corner of the installation. How good are you at holding a mirror?
  5. If it’s remote mounted – how far away can the display be? ie. what’s limit on the length of cable?
  6. If it’s remote mounted – is that panel mount, wall mount or post mount? Any special mounting considerations like weight, panel size, panel thickness?
  7. Height If it’s not a length or width then height might be an issue. Perhaps the meter can be/ needs to be installed upside down? Maybe there’s a bunch of pipe in close proximity.
  8. Are there weight limitations? On vehicle and aerospace installations the weight can be an overriding factor in meter selection. Are there weight reduction regimes? Changing the connection type or reducing a flow meter size or changing to a lightweight material can have significant effects on weight. A threaded turbine meter can be a tenth of the weight of a flanged coriolis.
  9. Does the meter type require straight lengths before (and after) the meter? Some meters are better than others. Some are much worse than others. A turbine meter needs a minimum 10 lengths before the meter and 5 lengths after. Orifice plates are meant to have more before depending on prior pipe configuration to ensure swirl is minimised.
  10. What comes before the straight lengths? If its two bends in 2 different planes then that’s a great recipe for swirl. Up to 100 lengths of pipe after that will be required to eliminate the swirl.
  11. What methods can reduce pipe lengths? One valid suggestion is to use flow straighteners or plates. These can be as little as 1 diameter long, but with a pressure loss, knock out some flow profile imperfections. They aren’t necessarily commercially available nor cheap. Perhaps, have a look at another measurement technique?

All in all consult the specialists.
Ten top tips for flowmeter selection

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Do you know your fluid?

Do you know your fluid? Is it what you think it is? Is it from a known source?

Viscosity, varies with temperature. Is flow measurement going to be affected by viscosity change due to temperature anyway? Might be if the temperature range is large and it’s a Variable Area meter… Will the fluid be changed through the life of the system, introducing different viscosities; meter choice is important here.
Viscosity change over time. due to volatility of light compounds it’s likely, especially if exposed to the atmosphere, that viscosity will increase over time. Possibly if water is leaking into the flow stream or condensation in the process that the viscosity will decrease.
Viscosity changes due to pressure. These are known but fairly small changes compared with temperature effects. Viscosity can double between atmospheric pressure and 2,500bar.
Specific Gravity, Density. These are often quoted in Material Safety Data Sheets (MSDS). For some flowmeters it’s irrelevant, especially if the measurement principle is volumetric; for others, like VA it’s fundamental. And remember density changes with temperature. In general, if you want a mass flow rate or total then use a mass flowmeter (and vice versa).
Thixotropic? A shear sensitive liquid can be tricky for some measurement principles. To preserve the fluid at normal viscosity the rate may have to radically reduced. Typical thixotropic liquids encountered are paints. When stirred they change from a ‘gel’ to a more free flowing liquid.
Corrosion issues: chemical compatibility. Perhaps the first property that is investigated in meter selection is the chemical nature of the fluid being measured. Is it going to corrode any of the components or will it react with the materials and change some dimensions or shape? If a table found on the internet indicates that polypropylene is ‘compatible’ with fluid X will it be suitable for some close fitting parts where just a 1% expansion will stop the meter going round. 1% may indicate, to some people, that it is compatible.
Build up, formation. Slow or fast deposition on the inside of the pipe and other, more sensitive parts, inside a flowmeter may affect the internal diameter used for rate calculations on velocity based devices or the weight of a rotating part or simply stop a part meshing or rotating.
Solids content and solids size. Generally expressed as a percentage, the amount of particulate and the size of that particulate will govern the metering method. And it may not be obviously so. Some of the latest paints have small amounts of additive to give the paint a special quality. These will block a tightly toleranced PD meter or it’s bearings.
Filter size. Is it filtered? Is the filter mesh in the filter bowl or has it been removed because it keeps clogging up?! What level of filtration, NAS class, mesh size, is designed in and what level has been achieved. Is it well filtered but then stored in an open container?
Lubricity. This parameter is frequently ignored and frequently not known. It can have an effect on some flowmeters.
Homogeneous? It’s usually taken for granted that fluids are homogenous i.e. the same consistency at any point. A typical non-homogeneity is air entrainment, perhaps a few bubbles or a stream of bubbles. In extremis, this might be slugs of air passing through. Most flowmeters can’t cope with this phenomena but some make a decent estimation and more than a few will recover after the air passes.
Anodic acceleration of corrosion. This problem occurs when the fluid acts in concert with two dissimilar materials in the pipeline – for example, the flowmeter body and the pipework. The measured fluid acts as an electrolyte, depositing or removing material depending whether the materials act as anodes or cathodes. In some instances another wetted part may see accelerated corrosion.

All in all, consult the specialists.

Ten top tips for flowmeter selection.

Sign up for FlowSight, the Litre Meter newsletter.

What is a flow meter and how does it work?

Flow gauge, flow indicator, liquid meter, flow meter – they’re all the same thing; depending on the industry they may have different names, but their function remains the same: to measure flow.

In the simplest of terms, a flow meter is a device which is used to measure the quantity and/or flow rate of a gas or liquid as it moves through a pipe. Some flow meters measure the amount of fluid that passes through the pipe in a given time, while others measure the total amount of fluid or gas that has passed through the flow meter. Sign up for FlowSight, the Litre Meter newsletter.


How do flow meters work?

Flow meters consist of three parts: a primary device, a transducer, and a transmitter. As the fluid passes through the primary device, the transducer senses it; the raw signal from the transducer is then sent to the transmitter and turned into a usable flow signal.

Mathematically speaking, a flow meter typically uses the following equations:

  • Q = A · v – Where the volume of fluid passing through a flow meter is equal to the cross-sectional area of the pipe (A) multiplied by the average velocity of the fluid (v).
  • W = r · Q – Where the mass flow of fluid passing through a flow meter (A) is equal to the fluid density (r) multiplied by the volume of the fluid (Q).


Different types of flow meter

There are a number of different types of flow meter available, each one suited to a different purpose, but always with the same goal of measuring the flow of a fluid or gas through a pipe.

  • Positive displacement flow meters: As the only meters to measure the actual volume, positive displacement meters work by repeatedly filling and discharging fluids from a chamber. Also known as volumetric flow meters, or rotary piston meters due to the way in which they operate.

    Rotary Piston flow meter with Hub connectors

    Rotary Piston Positive Displacement flow meter with Hub connectors

  • Inferential flow meters: These types of meters don’t measure volume, mass, or velocity. Instead they measure the flow of a fluid by inferring its value from other measured parameters such as differential pressure.
  • Velocity flow meters: The flow of fluid through the pipe is measured by the velocity of the flowing stream in order to determine the volume of the flow.
  • Mass flow meters: A mass flow meter, also known as an inertial flow meter, measures the flow rate of the mass of fluid as it travels past a fixed point during a specified unit of time.


What type of flow meter do I need?

There is no one-size-fits-all solution when it comes to flow meters. It largely depends on the industry you’re in, and what the flow meter will be used for. Here at Litre Meter we’re the flow meter experts, so we can help you to choose which type will work best for your needs, but here are a few questions to ask yourself before looking into purchasing a flow meter for your company:

  • What gas or liquid do I want to measure?
  • What level of accuracy do I require?
  • What is the temperature and viscosity of the fluid?
  • Does the fluid flow continuously or intermittently?
  • Will the meter be mounted in a safe or hazardous location?
  • What are the minimum and maximum flow rates?
  • What is the maximum pressure at the location?
  • What level of pressure drop is allowable?
  • Is the fluid compatible with the materials used in the flow meter?

Each type of flow meter has a different set of applications and constraints, so the best way to choose the right one is to use the application of the equipment, rather than the technology, to guide you in your choice. Once you know the answers to some or all of these questions speak to us and we can help you to determine which flow meter will best suit your needs.

Top tips for selecting the right flowmeter for you

At Litre Meter, we want to make sure that you get the most for your money when it comes to buying a flowmeter, so we’ve put together our top tips for selecting the right device for you…

Made to quantify the rate that liquid or gas moves through it, flowmeters are required by test and measurement professionals to provide results in a wide variety of applications where accuracy is critical. This includes measurements for familiar household things like heating, ventilating and air conditioning to aerospace and agriculture.

Type of flowmeter

There are different types of flowmeter to suit different purposes and applications. By simply profiling the gas or liquid it is measuring, it’s possible to discover how it behaves when flowing through a pipe. You can then narrow down the choice of device to best cope with the conditions of the application. If you’re unsure about how to do this, get in touch with a professional and they’ll be able to help.


There are a number of different uses for flowmeters, and as we’ve just mentioned, whatever you intend to use it for will affect your range of choice. You must consider temperatures needed, the turndown ratio, whether or not it has to be user-friendly for the workplace, and the type of liquid or gas that it is measuring the rate of. For example, if fluid containing traces of silt or sediment is flowing through the pipeline, we’d suggest that you use an ultrasonic Doppler flowmeter.

Chemical compatibility

It’s really important to take into account the materials involved in the process you intend to carry out with the flowmeter. Some materials are not compatible and this can have an effect on both the fluid or gas quality and the flowmeter’s durability. Check each material separately against a reputable chemical compatibility table, and checking your selection with the manufacturer of the fluid is also a wise idea to avoid any potential problems or issues.


Whilst buying a cheaper device may tempt you by saving you money initially, it could actually end up costing you more in the long run. Don’t let short-term savings sway you and think about it practically; a higher priced flowmeter can be more cost-effective in its quality, its back-up and its durability.

LongevityVFF with FlowPod instrument.

Talking of durability, before purchasing the device, you should find out how long it typically lasts. Ask the supplier about its failure rate or the type of application you need it for. This may have an impact on the price, but by evaluating the total life cost of it, you will most likely find it to be worthwhile.


It’s also important to think of the installation before selecting your flowmeter. Consider exactly where and how it will be installed as this can hugely affect its accuracy and efficiency. You must think about the type of meter and whether it’s affected by any obstructions in the pipeline like joints, bends or valves as these could cause distortions to the flow.  This is all worth doing because if the device is installed correctly in a suitable application, it will be more accurate and will ultimately save you money.

If you need help in selecting the best flow meter for the job, our Litre Meter team will be happy to help. Simply get in touch via our Contact Form or give us a call on 01296 670200.

We want your opinions

Survey 1We recently launched two new annual opinion surveys – building on a number of surveys that we have conducted in the past –to examine industry trends.

The new surveys look at the challenges facing manufacturing and production, regulation, safety, international standards and general trends. One lucky respondent will win a Kindle for taking part.

One survey is specifically for oil and gas, the other is for the general process sector.

Meeting the requirements of safety standards including safety integrity levels (SIL), pressure equipment directive (PED), positive material identification (PMI), ISO17025 and the control of major accident hazards (COMAH) can help to avoid the potential failure of a critical component which could lead, in the worst case, to a catastrophic failure of a process and loss of life.

There has been increased focus on safety issues in the offshore and process sectors over recent years. We want to make sure that our manufacturing focus is on safety in relation to both the environment and industry trends.

Issues surrounding the environment and hydrocarbon releases, asset aging and life extension drive the focus on safety. We want to be able to help in the process of recognising hazards and reducing risk as well as help engineers to take ownership of risk and asset integrity through proving assertions about the functionality and construction of instruments.

Asset integrity management ensures that the people, systems, processes and resources that deliver integrity are in place, in use and will perform on demand over the asset’s lifecycle.

Being able to prove assertions about the manufacture and functionality of equipment are vital in this process.

That’s why we are seeking the views of design engineers, industry leaders and decision makers across industry.

To take our survey – and perhaps you could win a Kindle – visit or and spend just a few minutes answering the questions.

The versatile VFF

Litre Meter was founded 40 years ago as a manufacturer of industrial flowmeters. Today, the company still manufactures flowmeters, but with a slight shift in focus – more than 80% of its products are designed specifically for the harsh conditions of the offshore oil and gas industry.

The shift towards offshore supplying happened largely due to Litre Meter’s ability to engineer new products, as many offshore oil and gas rigs require custom-built flow measurement solutions for chemical injection; however, the ability to engineer new products has sometimes been a setback for Litre Meter, as the majority of orders would often require custom engineering despite the company’s extensive catalogue of standard products.

Litre Meter defines its company by the strapline, ‘Specialist flow measurement engineering’, representing four of its unique and client-oriented company principles:

  • Specialist: Litre Meter is a specialist manufacturing company, focusing solely on products for measuring flow, rather than level or pressure.
  • Flow: its products drill down into the finer flow details, such as flow rate and flow total.
  • Measurement: its products measure flow accurately – they are not flow switches or flow indicators.
  • Engineering: although it offers a catalogue of standard products, Litre Meter can engineer bespoke solutions for unique challenges.

The VFF series

Litre Meter’s shift in focus began a little over 25 years ago, when it first adapted a standard industrial flowmeter for use on a North Sea oil rig. The popularity and success of this custom device led to the eventual production of their flagship range: the Viscous Fluids Flowmeter (VFF) series.

The VFF series is hugely popular and very adaptable, but its standard range has still been largely overshadowed by a flood of custom orders – until recently. One of the innovations for the 2015 range of VFFs included a new by-product: the FlowPod. The device itself is two-wire and fully HART compatible, with stainless steel housing. It opens up the popular VFF series to an even wider range of low-flow applications, and gives even the most obscure requirements near-instant access to Litre Meter’s innovative engineering without the need for custom designs.

Introducing the FlowPod

Flow Pod direct mount

The FlowPod mounts directly on the VFF flow meter.

Litre Meter decided quite early on that the FlowPod would be its only supporting instrument, and it has completely transformed the way the VFF range can be used.

Designed as Exi and Exd from the outset, the FlowPod was built in an enclosure small enough to be mounted directly onto the meter body, and gives Litre Meter an innovative method of incorporating extra functionality like reverse flow and redundancy measurement.
For Litre Meter, introducing the FlowPod to the VFF range was a great way to combine multiple design elements, gathered over 30 years of experience, to make an impressive and useful meter with a focus on utility plus weight and size reduction.
The 2015 VFF range includes more than 800 end-user drawings, representing more than 115,000 meter combinations and covering almost every conceivable possibility. While previously, around 80% of Litre Meter’s sales were for custom products, the introduction of the FlowPod means that only 5–10% of meters will now need any extra engineering at all. Most customers can simply access instant PDFs of general arrangement drawings, parts-list drawings and lifting diagrams, together with STEP files, as part of their Litre Meter quotation.
For Litre Meter, this means a faster sales cycle and more revenue; for the customer, it means much faster quotation, production and manufacturing times. 2015 has already been a big year for Litre Meter, and by raising its game and producing a range of meters without equals, it has truly cemented itself as a top-tier supplier of flowmeter technology to the chemical injection industry.

First published in Gas Technology Review



IMG_9572 LF03 white bgWe recently re-designed our popular VFF (Viscous Fluid Flowmeter) range of positive displacement flowmeters. The innovations in VFF technology make it ideal for bespoke flow measurement.

Innovations include a new compact size and design with reduced weight using high strength material specifications for high pressure applications. The new range of meters is suitable for low and high viscosity liquids at pressure ratings from 414 bar right up to 4,000 bar (60,000 psi). The range covers the measurement of fluids from 0.3 centistokes (cSt) to 100,000 cSt and flow rates of 0.0008 l/hr to 16,200 l/hr.

We have 40 years’ experience in successfully designing and manufacturing bespoke flowmeters for extreme environments for the most demanding industries and applications.

The VFF series has been distilled into one series to meet the specific requirements of chemical injection flowmetering. The new 2015 VFF range uses the same ultra-reliable rotary/oscillating piston technology that Litre Meter has developed and refined over the past 30 years. With one moving part the flow meter is a robust and low maintenance component within a chemical injection system.

The VFF range has a wide of standard options so we can quickly respond to fulfill most chemical injection enquiries. A full drawing package is available detailing every option in either PDF or STEP formats.

Specifying the right meter for a system is now even easier to specify with a new VFF meter software, a step-by-step builder that takes the user through all the meter options available. When the meter has been selected the user can search the Litre Meter database of over 400 general arrangements and parts listing drawings. For more details the user can browse 3D STEP files for the correct meter to download and insert into the skid assembly.

Meters are constructed from 316L stainless steel, Duplex Super Duplex, titanium and 6Mo. Other materials are available on request. Standard connections include NPT, Autoclave, ANSI flanges, Grayloc hubs, Galperti hubs and Techlok hubs. Two wire Exia and 2/4 wire Exd versions are available and 4-20mA, HART7 communications is standard with new pickup sensor capabilities.

Other innovations in the 2015 VFF range include a new rotatable and positionable Exd approved display union, new sensing options with increased reliability, reverse flow detection and increased resolution.

We are excited about the new range. The new compact and lightweight design has been developed specifically for integration within chemical injection skids. Its footprint is further reduced because positive displacement flowmeters don’t require straight lengths of pipe in the system before or after the meter.

We have also responded to industry demands with regard to lifting requirements for offshore by adding lifting eyes manufactured from certified forged material to every meter that weighs 16 kg or more.

New reed sensors now available

IMG_9574 sensor white bgWe have launched new sensor solutions to complement our revamped range of VFF flowmeters.

Our reed sensor package has been improved and now comes in a 316 stainless steel enclosure which is easy to install within the VFF range. The sensor comes complete with two reed switches that can be set for reverse flow detection or redundancy.

The sensor is tested to one billion pulses and environmentally tested in accordance with BS EN 13628-6: 2006. It is temperature rated to -20 to +80°C and it is available with the two or four wire Flowpod – the new explosion proof flow indication display unit for Litre Meter positive displacement flowmeters.

The non-wetted part has an M6 connector and the sensor is compact and designed for use at high pressures.

The new optional field sensor package comes in the same robust 316 stainless steel housing in order to make the sensors interchangeable with one another. The field sensor enables the output resolution of the VFF meter to be increased by a factor of twelve and it can still detect reverse flow.

Litre Meter strengthens South Asia team

LM1 - Claus Weihermueller(1)As part of part of the TASI group of companies Litre Meter now has new representation in Singapore. A new KEM/TASI Flow office in Singapore has been established with Claus Weihermueller appointed as regional manager of KEM/TASI Flow Asia Pacific & Middle East Operations. 
Claus has spent the past 15 years working in the field of flow metering and has been living and working in Singapore for eight years. He will promote and further expand the KEM/TASI business in the region, including Litre Meter.

Slim line customisation

Litre Meter’s ability to highly customise its meters has led to the company winning a significant order to supply meters to a company that produces hydraulic systems to the oil and gas industry. The fluid to be measured was Castrol Transaqua HT 2, with a viscosity of 3,95 cSt at 20 degree Celsius. The meters were bespoke slimline ones with a wide turn-down to allow for additional meters on a skid.

VFF positive displacement meters had to be made to operate at different pressures and flow ranges with different connections ranging from a VFF8 meter with a design pressure of 44 Bar, a scale of 0.3-30L/min with 25mm Female BSPP or equivalent size connections up to HP20 Flowmeters designed to work at a pressure of 950 Bar with a scale of 0.1-10L/min and 3/8” MP Autoclave connections.

All the flowmeters were located and certified for in Zone 2, Gas group IIB and Temperature class T3 so had to be EEx D or E. The minimum accuracy had to be within ±1.0% of full scale and the meters were constructed from 316SS quality stainless steel for all wetted parts.

The solutions provided were:

VFF8/690bar/AGPVD/V/9/16″AE MP

VFF8/1035Bar/AGPVD/V/9/16AE MP

HF20/207Bar/AGPDV/V/1″NPT all with


Significantly we were able to offer measurement over the whole of the flow ranges required which competing flowmeter manufacturers were not able to deliver. In addition, the bespoke slimline VFF8 1035bar on drawing enabled the end user to get an additional meter on the skid without having to increase the available space.

Now we are 40

LM1 - Mug shotLitre Meter is 40 this year and to celebrate we are giving away commemorative mugs.

To get yours while stocks last email us at and we will get one in the post.

See you at ACHEMA

Staff from Litre Meter will be at the ACHEMA exhibition in Frankfurt in 2015. We will be joining over 3,000 other exhibitors at the show.

ACHEMA will this year be focusing on products, technologies and solutions for the bio-based economy, industrial water management and innovative process analytical technology. At Litre Meter we have solutions for flow control and measurement in all three areas.

To register for the show visit the ACHEMA website.

Next Generation Flowmeters for Fluid Measurement and Control Solutions

Charles 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 New

Those 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 pick-up 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.

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” (15mm) 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.

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 Parts

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

The Oil & Gas industry is relatively conservative, relatively slow moving. The prevalence of HART and 4-20 mA 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 of solutions, not just one that is shoehorned into every application. Ideally, an independent specialist who can give unbiased advice and who will, if necessary, recommend an external solution.

Looking to the Future

In 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.

Safety research highlighting key ‘drivers’

Results of our first survey into safety issue in the oil and gas industry have shown that concerns over risks to personnel and the environment are key drivers for the implementation of international safety standards for instrumentation.

It will be interesting to see how the results of that survey ? which concentrated on Safety Integrity Levels (SIL) ? compare with the results of the second (still current) survey which focuses on the Pressure Equipment Director (PED). You can take part in our PED survey until 5 September by going to One lucky participant will win a Kindle for taking part.

Our ‘SIL survey’ gathered the opinions of senior engineers worldwide with technical design and management roles within their organisations. It showed that when specifying flowmeters and other instruments, environmental safety (70 per cent) was cited as the main reason for safety standard compliance, followed by business-critical concerns including personnel safety (59 per cent) and maintaining process integrity (65 per cent).

Risks of injury to personnel (70 per cent), risk of explosion (65 per cent) and damage to the environment (50 per cent) were the chief concerns relating to the consequences of equipment failure. Business concerns including costs of shutdown (25 per cent) and damage to equipment (15 per cent) were of less significance.

While the majority of companies in the oil and gas sector comply with an international safety standard for instrument specification a significant number ? almost 40 per cent ? do not, the survey found. However, most of these stated that they will be seeking to comply with an international safety standard in the future where relevant.

One of the aims of the research was to find out to what extent engineers use SIL in specifying equipment and what reliance they place upon it.

Almost 40 per cent said that SIL level 1 was the minimum acceptable for instrumentation in their operations with 22 per cent citing level 2, 26 per cent stating level 3 and just 13 per cent saying that the highest level (level 4) is the minimum acceptable.

We wanted to make sure that our manufacturing focus is on safety in relation to both the environment and industry trends. These figures show that by complying with SIL we have a reliable benchmark for safety and reliability.

SIL was considered to be an effective measure of safety performance by 70 per cent of respondents but 54 per cent believed that a lack of consistency in applying SIL across all functional safety standards significantly affects trust in products designed to work in particular SIL level environments.

Now we are asking a similar range of questions about PED ?and with a similar purpose.

There has been increased focus on safety issues in the offshore sector over recent years. We want to make sure that our manufacturing focus is on safety in relation to both the environment and industry trends.

To take the PED survey visit and spend just a few minutes answering the questions.

SIL is the degree of likelihood that a safety instrumented function will operate effectively when it is required to. Four SILs are defined within the European Functional Safety standards based on the IEC 61508 standard, SIL 4 being the most dependable and SIL 1 being the least, taking into account such things as the development process and safety life cycle management.

Litre Meter, Company of the Year

Text from Industrial Process News article, issue 622

It gives us great pleasure to present Litre Meter Limited with the prestigious and highly sought after Industrial Process News Flow Measurement ?Company of the Year?.

Speaking with CEO Charles Wemyss and Industrial Process News Editor Thomas Gill, we unveil the reasons why Litre Meter Limited has been selected for this prestigious award, why the company has been so successful over the past twelve months and how they have weathered the economic crisis.

Thomas explained: ‘If I’m being honest, it didn?t take much deliberation when selecting our Company of the Year. From our research, Litre Meter were head and shoulders above the rest in the category and have proven their worth especially over the past twelve months.

‘As we all know, weathering the economic downturn is crucial for all businesses and very difficult at that. But Litre Meter have managed to not only sustain their position in such difficult times but have also seen some encouraging signs, continually moving forward, and this was the real clincher for the team at Industrial Process News.’

Charles explained: The last time we won an award was back in 2005 and that was a springboard to part of our success, and we are hoping that this will generate the same outcome. It feels great to know that our hard work and dedication has been noticed. A job well done I say.

The past twelve months has been fantastic for us, as we have seen significant growth, acquiring more orders than the previous two years combined. This has particularly been driven by our presence in the Oil & Gas sectors. We are now in a position where we are very busy exporting, have a huge level of stock and have a large back log of orders that we are currently working on. Having so much business has given us a great deal of confidence.

To be honest the current economy hasn’t affected our business at all, which has allowed us to take strides forward in the industry. As the majority of our business is executed abroad, we haven’t had to shelter ourselves from any hardship in the UK. Our sales in the UK have risen and we are expecting, once the UK economy is stabilising, home-grown business to get even better, opening more doorways.

Our forecasts were significantly exceeded with a 29% rise in sales over budget and a 91% rise in bookings compared to 2012.

Our most successful product has been the LF05, part of the VFF range, which has been available for its first full year in 2013. Particularly successful in the Oil & Gas industries, the LF05 has pulled along other flowmeter sizes with its success, plus accompanying  instruments and accessories.


A simple construction with only one moving part and reed switch pulse output, the LF05 is a positive displacement flowmeter with 316 stainless steel body. With a PVD coated titanium rotor only, the LF05 is hazardous area approved as standard. Available with any end connections to your individual applications, the product has a flow range of 0 to 30 I/hr and is accurate to ±1% linearity, ±0.5% linearization and ±0.25 repeatability.

Other Litre Meter 2013 innovations have included: LF03 estimated at 60% flow rates of the LF05; a new connection type ? ½ inch OD tube; and QR codes on each meter, with links to material certs, calibration certs and instructions via the internet.

Looking ahead, we are aiming for more of the same. We currently have four times more orders, and we are looking to utilise our additional resources and information to increase production for the forthcoming years. With more resources available our ability to plan ahead has dramatically increased and we continue to grow and innovate.?

Company Profile:

Founded in 1975, Litre Meter Limited is a world-leading designer and manufacturer of flowmeters, which are installed on a wide variety of applications across the UK, Europe, America, as well as the rest of the world. Litre Meter works in a number of high profile industries including Oil and Gas, Aerospace, Automotive, Marine, Mining, Power Generation, and many others.

Litre Meter is a member of the TASI Flow Division, as well as the Institute of Manufacturing at Cambridge University, FPAL, Achilles, Institute of Measurement and Control and Northampton Chamber of Commerce. Litre Meter hold ISO9001:2008 approval.

Charles Wemyss, Chief Executive of Litre Meter Limited, commented: ?When flow measurement is critical, consult the specialists. Litre Meter has been leading the field since its founding, with a well established reputation for the design, manufacture and supply of flowmeters of all kinds.?

Firstly, Litre Meter pioneered the development of the Pelton Wheel flowmeter: an accurate, effective and versatile design suitable for many different fluids including acids, chemicals, fuels, spirits and water, at both high and low flow rates.

Then since 1986, Litre Meter has developed the popular VFF meter (literally, Viscous Fluids Flowmeter) for low flow & high pressure applications for the offshore industry particularly for chemical injection. And in 2011 the company supplied the largest ever chemical injection flowmeter order for the Gulf of Mexico.

Litre Meter?s portfolio for the UK now includes flowmeters of all kinds, including rotary meters, gas flowmeters, helical screw flowmeters, electromagnetic and ultrasonic flowmeters to handle a wide range of viscosities, flow rates and pressures, aggressive liquids and hazardous or adverse environments. They have particular expertise in measuring low flow rates and flows at high pressure.

‘To fulfil our customer’s needs in the UK we also distribute other flowmeters from many flowmeter manufacturers. For gas flow we offer Sierra thermal mass gas flowmeters, vortex flowmeters, Ritter gas meters, Hoffer turbine meters and Ritter gas sampling bags. Sierra also manufacture thermal mass gas flow controllers,’ added Charles.

For more information please don’t hesitate to contact one of the team on 01296 670200 or email: Alternatively, to view a full product portfolio or download spec sheets visit



Safety first – new safety survey launched

There has been increased focus on safety issues in the UK offshore sector over recent years. With that focus in mind we at Litre Meter want to make sure that our manufacturing focus is on safety in relation to both the environment and industry trends.

According to the most recent raw data available from the Health and Safety Executive in Q3 of 2013 there had been 27 offshore hyrdrocarbon releases in the UK. This represented a significant reduction in HCR releases in response to the HCR reduction plan initiated by Step Change in Safety ( in 2010.

The HSE has defined asset integrity as the ability of an asset to perform its required function effectively and efficiently while protecting health, safety and the environment. Asset integrity management was defined as the means for ensuring that the people, systems, processes and resources that deliver integrity are in place, in use and will perform on demand over the asset?s lifecycle.

Issues surrounding the environment and hydrocarbon releases, asset aging and life extension drive the focus on safety. We want to be able to help in the process of recognising hazards and reducing risk as well as help engineers take ownership of risk and asset integrity through proving assertions about the functionality and construction of instruments.

Litre Meter has therefore launched the first in a series of oil and gas industry safety surveys that will be introduced throughout 2014. The first survey concentrates on safety integrity levels (SIL) and one lucky respondent will win a Kindle for taking part.

SIL is the degree of likelihood that a safety instrumented function will operate effectively when it is required to. Four SILs are defined within the European Functional Safety standards based on the IEC 61508 standard, SIL 4 being the most dependable and SIL 1 being the least, taking into account such things as the development process and safety life cycle management.

The Litre Meter survey aims to find out to what extent engineers use SIL in specifying equipment and what reliance they place upon it.

To take the SIL survey visit and spend just a few minutes answering the questions.

Chemical injection – from Africa to Arctic

Two articles in the current issue of Offshore magazine cover very different areas of the world ? West Africa and the Arctic.

They also cover very different scenarios. One is talking about ‘brownfield’ development – extending the life of existing fields and brining new reserves online through existing infrastructure. The other is focused on new technologies and challenges in safely exploiting hitherto unreachable reserves.

The common element is that both articles mention chemical injection as a key technology. This is, of course, an area in which Litre Meter has considerable experience.

Over the past year we have shipped a large number of meters to be used subsea, on a variety of chemicals, over a wide range of flows at high pressure and calibrated at specific viscosities. For example, Litre Meter rotary piston flow meters are part of systems used to control the amount of ‘antifreeze’ injected into pipelines at high pressure (430 bar) in subsea gas exploration on fields in the Caspian Sea and the North Sea.

‘Antifreeze’ fluids like methanol are used as thermodynamic inhibitors, which lower the freezing point of gas hydrate. They are injected into pipelines where there is a risk of hydrates (dew) forming then freezing at low temperature.

The antifreeze prevents gas hydrates solidifying as crystals and blocking pipelines – which can result in a costly shutdown and the risk of explosion or unintended release of hydrocarbons into the environment.

Litre Meter has also recently shipped flowmeters for use in chemical injection skids on a number of fields in the Gulf of Mexico and the Persian Gulf off Dubai. These meters are used in the flow measurement of wax dispersants and pour point depressants (PPD) to control their use to a very high tolerance.

Wax dispersants break apart and prevent the reformation of hydrocarbon sludge deposits and improve flow by reducing the viscosity of the fluid. PPDs are used to reduce the viscosity of oil and to maintain flow rate by preventing the build-up of wax crystals at low temperatures.

Sludge deposits are typically composed of varying concentrations of hydrocarbon, asphaltene, paraffin, water and inorganic materials. They are commonly found in storage tanks and vessels, production and transportation pipelines, process systems and hydrocarbon-producing formations where they have an adverse effect on the flow of crude oil from the well head.

Our expertise is nicely summarised in our new chemical injection brochure which highlights the enormous success of the VFF meter over the past few years in solving chemical injection measurement problems around the world.

With 3,000 VFFs in active use on chemical injection Litre Meter has demonstrated a depth of experience and knowledge that is unmatched in the low flow arena. The brochure provides further detail of the VFF range in one eight-page document.

Positive displacement meters: pros, cons and selection

Positive displacement flowmeters, sometimes known as PD meters, have been around for more than 100 years. They are commonly used in a wide range of applications from domestic water measurement to measuring ultra flow rates of chemical at high pressures subsea.

First off – what is a “positive displacement” meter? Well, as the name suggests it involves the positive displacement of a volume of fluid – this is usually a liquid but there are some units suitable for gas. There is a chamber and inside the chamber, obstructing the flow, is a rotor.
The shape of the rotor and chamber vary greatly with each meter type but they all provide an output for each rotation. Most meter designs therefore lend themselves to being totalisers. Most can have the flow rate calculated from this primary data.
An accurate PD meter will have minimal ‘leakage’ across the rotor seal. This is generally minimised with the use of more viscous liquids and accuracies of ±0.1per cent are sometimes quoted. On the other hand rotary piston flowmeters are used by the water industry in the UK for measurement of water over a normal flow range to accuracies of ±2 per cent.
Because they measure a volume precisely it does not matter if the flow is pulsing. They will follow the increase and decrease of flow found in reciprocating pumps of all types. With higher viscosities the turndown ratio can be high. Even with water 100:1 is not uncommon and 3000:1 is possible at 250cSt. Few applications require this but it does enable measurement of ultra low flow rates without miniature parts or normal flow measurement at minimal pressure drop.
Most meters are simple to maintain as they have only one or two moving parts and are coupled with simple readouts that are easily understood in the field. There is no requirement for straight pipe lengths like that might be needed for electromagnetic or turbine devices. They can be connected directly to elbows or valves and in most cases in a variety of orientations.
Designs are relatively easy to adapt for high pressure applications eg over 100 bar.
All PD meters require clean fluid so a filtration level of 100 micron is usual. Some meters can actually block the flow if a larger particle is trapped in the wrong place. Many meters are not made in high specification materials and therefore corrosion can be a concern. An all plastic or all 316SS meter is the exception rather than the rule. As the application flow rate increases the size of the PD meter seems to increase by a square law! It is rare to find meters over 12-in in size although they exist at these elevated sizes for the prime reason of accuracy – frequently being utilised for custody transfer reasons.
In the author’s opinion, the most common PD meters are as follows:
  • Rotary Piston: As mentioned above these form the basis of domestic water measurement but the design of the rotary piston that oscillates in a circular chamber with a fixed web has been modified and extended to ultra low flows and high flows, as well as high pressures and for food applications. A good all-rounder.
  • Spur gear: The fluid rotates two gears and is forced around the outside of the gears and the inside of the chamber. Depending on the location of the sensor these can yield very high pulses per litre values useful in batching and fast acting processes.
  • Diaphragm (or bellows meter): These are common in many people’s home as their domestic gas meters. When the gas flows through it alternately fills and empties bellows causing levers to crank a shaft providing an output. Very useful for wide-ranging gas totalisation.
  • Oval Gear: Quite similar to the spur gear where two oval gears mesh together and sweep the chamber. The volume displaced is much larger than the round gear. Fairly low cost and some designs available in plastic.
  • Nutating Disc: This meter is the hardest to understand but is effective. The rotor is a circular disc attached to a ball. The shaft on the ball is inclined. As the disc rotates in a spherically sided chamber the disc and therefore the shaft wobble creating an output.
  • Helical Screw: Possibly the most accurate PD: meter two intersecting cylindrical bores are fitted with 2 interlocking helical screws. As the fluid passes through they rotate. On standard applications the author has observed differences of just ±0.37 per cent of reading over 50:1 turndown over annual recalibrations over 10 years – quite an achievement. Also common nowadays fitted on petrol pumps.
  • Slide Vane: Historically the most accurate of PD meters with the rotating element having a number of moving blades that rotate about a fixed cam. Linearities have been claimed of ±0.02 per cent.
  • Others: If we go back to Felix Wankel’s seminal work on rotary machines we see that there are as many designs for PD meters as there are pumps. He explored in a rational way the various shapes of rotor and chamber. While the majority don’t see the light of day in the marketplace this brief essay illustrates the variety in general use, and this is without discussing the Roots meter, wet gas meter and multi rotor designs.
Two decades ago the PD meter was considered to be old technology and likely to be overtaken by more modern electromagnetic and ultrasonic devices. Nowadays the PD meter still represents good value and can provide excellent measurement in a wide variety of duties.