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Seasonal holidays 2019

Please note that Nixon Flowmeters will close on Friday 20th December at 11.30 am and reopen on Thursday 2nd January 2020 at 8.30 am. We wish everyone a Happy Christmas and a Prosperous New Year,



Accuracy is very important when specifying & recommending the most suitable flow meter for an application. Once the flow meter leaves our factory, you naturally want to ensure you achieve the same high accuracy in your application. This is where a correct installation is all important. Below are some of the most common tips & requirements to ensuring the best possible performance of your flow meter/flowmeters. Also, some things to avoid too.

Connection type

The type of end connection on the flowmeter can sometimes make a big difference with the ease of installation & is one of the first things to be looked at when specifying your flow meter requirements.

What are your current pipework connections?
Are you restricted in terms of space?
Is the flowmeter something that needs to be quickly removed?

Threaded (for example, BSP) connections are some of the most common & easy to screw into your existing pipework. Flanged connections are another common & easy option, with typically 4 bolts fixing the flow meter into place. Wafer connections, while often a cost-effective solution & short in overall length, can often take some time to get the centre position correct. From a Hygienic point of view (for example, when using our BNO Hygienic turbine flow meter), Tri-clamp connections can be ideal as they are very easy to fit, seal & remove again if required.

Location of flowmeter in your system

Depending on the type of flowmeter specified or supplied, the position of the flow meter in your pipework can make a huge difference between a good accuracy & one that’s not was expected. It’s always a good idea to mount the flow meter in a section of pipework that’s always flooded. This is particularly true of Electromagnetic flowmeters, for example our Flomid. Half full pipes or those that contain pockets of Air can lead to inaccurate & fluctuating readings. Vertically downwards flows, while fine for some types of flowmeter (for example spring restrained flow meters like the DP65) can sometimes be quite turbulent which in turn, can again lead to fluctuating readings. It’s always a good idea to avoid situating the flow meter right next to the outlet of a pump or valve as this again can cause the flow to be quite turbulent.

Operating parameters

Going back to the specifying & recommending of a suitable flow meter, it’s important to know all details of the application as this can sometimes make a big difference. For example, the properties of the fluid - Is it a clean liquid? Is the Gas dry? What is the upstream Pressure? These all play a part when insuring a trouble-free flow meter installation.

If in doubt

If in doubt, or you need reassuring of the post possible type of flowmeter/location of installation, please do contact us. We have a great deal of experience in the best operating & installation practises for flowmeters. It’s in our best interests to ensure you not only receive the best type of flowmeter for your application, but the best possible advice in terms of correct installation too.

Alcoholic Flowmeters... Or rather, flow meters for use on alcohols. It is December after all.

The UK brewing industry has increased by around 60% over the past few years. There are now estimated to be around 3000+ micro-breweries in the UK alone, 300 of which were only started in the past year. This may be in part to tax breaks that were introduced – small breweries who produce less than 600,000 hectolitres each year (about 10-11 million pints) , qualify for a discount on the amount of duty they pay. Very small breweries who produce only 5,000 hectolitres each year, pay only 50 per cent of the duty compared to larger producers. This was called ‘the small breweries relief scheme. Time to change from manufacturing flow meters to producing beer perhaps? Maybe they will introduce a ‘small flowmeter manufacture relief scheme’. Similar things can be said of Gin, with the number of distilleries topping the 300 mark. A total number of 47 million bottles were sold in the past 12 months.

Where do Nixon Flowmeters' range of flow meters fit into all this?

We have two, fully certified, flow meters that can be used in hygienic applications. Our BNO series Turbine flow meters & also the Flomid Electromagnetic flowmeter. For this particular blog, we will discuss the benefits of using our Turbine Flow meter.

BNO series Turbine Flowmeter

The BNO series Turbine flow meters have been designed especially for use in the liquid food industries. The operating principle of the BNO series Turbine Flowmeter is the same as our NT industrial Turbine flowmeter but, has a slightly different type of construction. This is to ensure the absence of any bug traps & crevices where bacteria can lodge & breed.


• Minimum of bacteria breeding crevices

Unlike our NT industrial version, the BNO flow meter has a special construction, with stepped hangers (reducing the contact area between the internal bore of the flow meter) that contain a fixed spindle and a free spinning Rotor. This ensures the absence bacteria forming crevices

• Hygienic materials of construction

Made entirely from 316L Stainless Steel, with PTFE Carbon graphite bearing bush – All FDA approved materials.

• Steam Sterilizing

The BNO turbine flow meters are suitable for both SIP (sterilization in place) & also CIP (clean in place) applications. The contact parts (see above) are suitable for use on Steam & also Hydrogen peroxide cleaning methods.

• High accuracy & repeatability.

A turbine flowmeter is accurate to +/- 0.5% of reading & has a repeatability of +/- 0.1% of reading. This makes them ideal for batching & totalising applications.

• Portability
The BNO flowmeters have a self- generating pulse output, which means they can be supplied with a battery powered display unit, for example our 100 series. This means a completely self-contained package, with no external power supplies needed. The following image shows our model BNO 1000, with 1” Tri-clamp ends & the F110 display mounted directly on top.

• There are a wide variety of end connections available.

Machined from solid 316L Stainless Steel bar, the BNO flowmeters can be supplied with a wide range of hygienic end couplings. For example, tri-clamp, RJT, Din 11851, ISS etc. We can machine your preferred type/size.

A Turbine Flowmeter is a very traditional yet highly accurate form of flow measurement. A ferritic stainless steel rotor revolves within a non-magnetic housing, on the outside of which is located a pick off coil containing a permanent magnet. As the rotor blades pass the tip of the permanent magnet, the reluctance of the magnetic circuit is changed, and a small a.c. voltage is generated in the coil. The frequency of the a.c. voltage is proportional to flow rate, and the total number of pulses produced represents total flow passed through the Turbine flow meter.

The following image shows a cutaway version of our BNO series Hygienic Turbine Flowmeter.

Nixon Flowmeters was founded back in 1969, specialising in Flow measurement & manufacturing our own range of both hygienic & industrial high accuracy Turbine Flowmeters. We have our NT industrial version & also our dedicated BNO series hygienic design available. Many leading flowmeter companies in the UK and abroad have the confidence to put their name on our range of turbine flow meters, a sign of the high regard in which the product is held.

Advantages of using Turbine flow meters

• Suitable for both liquid & also gas flow measurement.
Turbine Flowmeters can be manufactured with different bearing designs which make then suitable for lubricating & non-lubricating liquids & also those of low to medium Viscosity & also dry Gasses.

• High Accuracy.
Turbine Flow meters have a linear accuracy to +/- 0.5% of reading, with a repeatability of +/- 0.1% of reading. This makes a Turbine Flowmeter one of the most accurate forms of flow measurement on the market today.

• Installation in different orientations & flow directions.
A Turbine flowmeter can be installed in both vertical & horizontal orientations - taking into consideration the recommended installation requirements of 10 x diameter of straight pipe before the flow meter & 5 x diameter after the flowmeter. Bi-directional (quadrature) versions can be supplied using dual pick-up coils to monitor the flow in both forward & reverse directions.

• Wide range of pipe sizes & end connections.
Both our NT & BNO range of turbine flow meters can be supplied in sizes from 3/8” up to 6” in size. All out Turbine flowmeters are machined in house from solid round 316L Stainless Steel bar. As a result, our Turbine meters can be supplied with a wide range of different end connections. The standard is a BSPP male thread, with 30 degree internals cone. Other examples are flanged Ansi or din, NPT, Ermeto, JIC, wafer design & various high Pressure couplings e.g. Weco 206 & 1502 hammer unions. Our dedicated Hygienic BNO series Turbine meter can e supplied with most types of hygienic coupling. For example Tri-clamp, RJT, din 11851 etc. It really is a case of whatever type of connection you require, we can machine it for you.

• Low Pressure drop.
The construction of a Turbine flowmeter allows for a very low Pressure drop, typically around 200-500 mbar, depending on size & liquid being measured.

As you can see, Turbine flowmeters are very versatile when it comes to flow measurement. If you’d like any further information on the different types available or, have a specific application you’d like to discuss, please do not hesitate to contact us.

A wide selection of displays can be matched with our pulse producing flowmeters. We have our own 99 series display units and are also a stockist of the Fluidwell range of instruments. Together we have a vast selection of models to complement our flow meters, from a low cost simple battery powered flow rate display units with GRP housing, up to sophisticated devices in rugged aluminium housings with retransmission facilities.

We keep several specifications of units on the shelf for quick delivery. One very popular model is the model F110-P-HA-PB which is the aluminium housed flowrate/totaliser with lithium battery power supply and scaled pulse and analogue outputs fitted as standard. The unit can display in most engineering units from litres, gallons and cubic metres with units per second, minute, hour or day.

Another ex-stock unit is the F012-P-HD-PB which has the GRP housing, lithium battery power and flowrate and total displays, again this model is fully configurable for any flow units and time interval. The F series is designed for use in harsh weather conditions like rain, snow or salty atmospheres and temperatures between -40 Deg C and +80 degC.

A whole family of instruments can be supplied with special features such as linearization and high/low alarm relays. Versions with RS232, RS485 & also Hart protocols are also available. Special versions of all instruments can be supplied for hazardous areas and have ATEX Ex intrinsically safe certification and a new model is even certified for ExD explosion proof areas. A model with a fully stainless steel housing as now available for harsh environmental conditions. Ideal for offshore use.

All units can be supplied mounted directly to the top of a flowmeter using a welded boss and stainless steel mounting stem, as seen in the photo below. The model F110 is mounted to our BNO series hygienic Turbine flow meter.

Nixon Flowmeter display

Display units can also be supplied that are suitable for surface or panel mounting together with lengths of pre-wired signal cable and connectors. We have even designed a special solution for metering chilled fluids with a close coupled indicator. We fit a silicon thermal barrier to prevent condensation entering the electronic housing.

Batch controllers can also be supplied from the same family of instruments. They can use two stage control and may be fitted with relays and power supply modules for controlling valves & pumps in batch filling applications. The display units can even be back lit to ensure readability in dark environments.

The D series of dedicated panel mount instruments is now available on a whole range of different models for every application. The instruments are supplied in a unique, robust IP66, IP67 (NEMA Type4X) panel mount front enclosure made of die cast aluminium, based on a popular DIN sized enclosure with a 144 x 72mm front. The enclosure withstands powerful water jets and even total immersion.

Whether it’s our NT range of Turbine Flow meters, OG Gear Wheel flowmeters or, any other type of pulse producing flow meter, we will have a display unit that’s suitable for even the most sophisticated application.

In 1831, a chap called Michael Faraday discovered Electromagnetic Induction. This became known as Faradays law. As a result, we now have electromagnetic type flow meters available.

If an electrical conductor is moved into an electrical field, an electrical voltage is induced in the conductor. This is perpendicular to the direction of motion & the magnetic field, whose magnitude is then proportional to the magnetic field strength & velocity of the movement.

The following diagram provides a slightly simpler explanation.

A voltage V is induced between a pair of electrodes when a conductive liquid flows in a pipe of diameter D at an average velocity vm, through a magnetic field B (which is perpendicular to the flow direction). This voltage, proportional to the average velocity of the liquid, is acquired by the electronic converter in order to be processed and converted to a flow rate measurement.
V = B ・ vm ・ D

V = Voltage across the electrodes
vm = Liquid velocity
B = Magnetic field strength
D = Pipe diameter

Electromagnetic flow meters

When an electrically conductive liquid flows through a magnetic field, perpendicular to the flow direction, it induces a voltage V proportional to the liquid velocity.

Two electrodes in contact with the liquid and positioned perpendicularly to the magnetic field, sense this voltage V.

V = B ・ v ・ d

V = Measured voltage at the electrodes
v = Liquid velocity
B = Magnetic field density
d = Distance between electrodes

Michael Faraday

There are some great benefits to using Electromagnetic flowmeters.

• Low Pressure drop.
Because there are no moving parts inside the flow meter, the Pressure drop is very low. This makes them ideal for applications where there isn’t much upstream Pressure in the system.

• Suitable for both clean & dirty liquids.
No moving parts also means Electromagnetic flow meters are suitable for liquids where there could be the presence of suspended particles, solids etc.

• Installation.
So long as the pipework is full/flooded, Electromagnetic flowmeters can be installed in both horizontal & vertical pipes (when installed vertically, a downwards flow is recommended).

• Pipe Sizes.

Electromagnetic Flow meters can be supplied to cover from very small DN3mm bore pipe, up to much larger DN2000mm sizes. The Flomat insertion Flowmeter, because of its very small form factor, makes for a very cost effective solution for flow measurement in very large bore pipework.

• Digital displays & outputs.

Electromagnetic flowmeters can be supplied with a digital display, showing flowrate, total & also accumulated total. These can be direct mounted on top of the flowmeter itself or, separate. A wide variety of outputs are available, for example 4-20mA, pulse, high & low alarm contacts & also HART/Modbus versions.

If you have an application where you think an Electromagnetic flowmeter may be to suitable, please do not hesitate to contact us.

Tecfluid is proud to celebrate the collaboration with Nixon Flowmeters Ltd as one of its main partners for more than fifteen years. Therefore, we would like to interview Mr. David Nixon, Managing Director, to understand from his point of view about all these years doing business with Tecfluid.

We would really appreciate if Mr. David Nixon could answer the following questionnaire.



Q. Why did you decide to work with Tecfluid fifteen years ago? Was it the first time you worked with a Spanish supplier?

A. We had represented a German Flowmeter company for many years. That company had been taken over by a large organisation which failed to run the business properly. Subsequently, we lost access to the range of products we had been selling.

It so happened that Tecfluid had represented the very same company many years ago, so the product range that had been developed was very similar and it was a perfect fit for our business. It was the first time we had worked with a Spanish supplier. I was so impressed on my first visit to find a modern, totally self-contained manufacturing facility

Q. Did you find any difficulties in the market when introducing Tecfluid products? If yes, how did you solve them?

A. I think Tecfluid was almost unknown in the UK when we started. I took the decision to be very open about our sole agency agreement and advertised Tecfluid openly as one of our main trading partners.

Q. What were the first reactions of your clients regarding Tecfluid products?

A. It takes time; change is something people do not take to easily. It is only when customers can be persuaded to try the products that they gain confidence in the quality and reliability.


Q. Which is your preferred Tecfluid product? Why this one?

A. We like the traditional products like the Variable Area Flowmeters and Spring Restrained Flapper types. Even in 2018 there is a strong demand for these tried and tested instruments.

Q. Which Tecfluid products are in most demand among your clients?

A. Again we like the traditional variable area and spring restrained flowmeter.

Q. What do you appreciate the most about Tecfluid service and/or products?

A. Good quality, reasonable price and solid, reliable service.

Q. Which are your main types of clients? In which industries do they operate?

A. I can honestly say we don’t have ‘typical’ clients. It can be anything from a man with a pond in his back garden to nuclear industry and everything in between. One of the challenges is dealing with specialist buying companies that act on behalf of blue chip clients, and don’t understand anything about the product they are purchasing.


Q. What do you think about the evolution of Tecfluid in the last 15 years? What were the implications of this evolution (if applicable) for Nixon Flowmeters Ltd?

A. I am so pleased to see Tecfluid still in the hands of the family that started it all. As I said right at the beginning of this interview, I have seen what happens when companies are taken over by organisations that do not have the wellbeing of the company at heart.

Q. What aspects do you think could be improved concerning our company and products?

A. I believe some of the electronics could do with some improvement, we have some worries over the reliability of the Electromagnetic Flowmeters in particular.

Q. What do you think are the main challenges for the instrumentation industry players in your country?

A. The main challenge for the UK is now the result of the Brexit referendum where the UK has voted to leave the EU. We now seem to be left with a group of incompetent politicians upon whom we have to rely to make hundreds of important decisions over our future. Already we have seen the pound nose dive in value.

This, at the very least, makes it more challenging to sell European products.

Q. Could you please share with us any anecdote from the last fifteen years of business collaboration with Tecfluid?

A. A few years ago Tecfluid held a European sales meeting at the factory. Part of the itinerary was a coach tour of the Barcelona tourist sites. Raul was giving an excellent commentary on the tour bus.

Everyone knows the sun always shines in Barcelona so we were all dressed in light summer clothing. Well it poured down; we all got absolutely drenched walking to see the Sagrada Familia and the Olympic stadium. In more than 10 visits to Barcelona I have never seen it rain like it did that day!

Thank you very much for taking time out for this interview. Your opinion has always been very important for Tecfluid in order to continue improving its range of services and products. We hope to count on you as one of our main clients for many more years.

Kind regards,

The Tecfluid Team.

They go by many different names; variable area flow meter, rotameters, float type flowmeters and even carrot flow meters. They can be deployed in many varied applications – dosing, monitoring, control applications are just a few examples.

They are also available in a wide range of materials; some are designed, manufactured and made suitable for measuring the flow of the most aggressive liquids and gasses.

Additionally, as a result of being very cost effective, robust and versatile, they are one of the most commonly used types of flowmeter in industry.

Principle of operation

The fluid or gas which is to be measured flows upward through a vertical conical tube (or sometimes a conical float). The diameter of the tube increases in an upwards direction. The flowing liquid or gas lifts the float in the tube to a height so that the annulus has an area which results in an equilibrium of the forces acting on the float.

See diagram below:

• Af = Float area

• Ac = Flow measuring tube area

• Pf = Float weight

• E = Fluid thrust

• Free area of flow: Al = Ac-Af

This applies to plastic and glass tube variable area flowmeters. Stainless steel versions utilise a calibrated fixed orifice, with a conical float.

• E = Force of the fluid flow

• Pf = Weight of the float

• Free area of flow : Al = Ao – Af

• Where:

Ao = Calibrated orifice area

Af = Float area

In this case the area changes due to the conical shape of the float.

Advantages of Variable area Flow meters

Variable area flowmeters can be used on liquid, gas and also steam applications. Custom calibrations are available for changes in the following:

• Density

• Viscosity

• Pressure

• Temperature.

They are an economical form of flow measurement, due to cost effective range of materials and construction.

They are of a simple design and thus easy to read, both close up and also from a distance. Because of this they have the following attributes:

• Easy installation

• No requirement of a power supply (unless fitted with a transmitter or alarm)

• Direct reading (visible float or pointer)

• High repeatability

Variable area flow meters can be supplied in sizes from ¼” up to 6”. Connections can be threaded or plain ended, flanged & even hygienic. They can be installed with minimal straight upstream and downstream pipe and are suitable for both safe & ATEX hazardous areas.

A spring restrained versions is also available, suitable for mounting in horizontal & vertically downwards flow directions. Valves & flow regulators can be built into the units for controlling and regulating the flow of liquids and gasses.

A variable area flowmeter can be used for measuring very small flows (glass and plastic versions) and also large flows (stainless steel) of liquids, gasses and steam. Different materials of construction are available; plastics, glass, stainless steel and special versions made from hastelloy.

Custom scales can be produced in-house, using our specially developed scaling program. A choice of flow units such as cc’s, litres, M3, KG and percentage as examples, can be printed on the scales, as well as specific liquids, gasses at varying temperatures and pressures

Different versions available

Plastic Tube DFM – Low cost, all plastic, options for alarms & a 4-20mA transmitter

Glass tube NFX & 6001 series – Low cost, protective frame, options for alarms & a 4-20mA transmitter

Stainless Steel M-21 &SC250 – Robust construction. IP65 or IP67 rated versions make them suitable for offshore use & harsh environments. PTFE lined & Hastelloy wetted versions available. Constant flow regulators available of the model M-21, for use when the inlet & outlet Pressure is variable.

As you can see, variable area flowmeters are very versatile when it comes to flow measurement. If you’d like any further information on the different types available or, have a specific application you’d like to discuss, please do not hesitate to contact us.

One of the most common questions asked about flowmeters is - ...’what flowmeter would you recommend for my application?’...

To the untrained eye, flow meter technology may initially seem like navigating a minefield. There are so many varied and different types of flow meter technology available. However, it needn’t be if you’re armed with some basic on information about what your application will be, we can quickly narrow the search down.

To help you though the potential minefield, we have listed below some of the most common questions we would ask before recommending a suitable flowmeter for your application.

Liquid or gas flow measurement?

Some types of flowmeter technology can be used on both liquid & gasses. However, while some flow meters will the flow of gases or liquids, they have to be calibrated appropriately. For example, our range of variable area flow meters can be supplied with either liquid or gas scales for ease of deployment and use.

The same applies to our own in-house range of Turbine flowmeters, which can be fitted with bearings suitable for either low Viscosity liquids or dry gasses. In addition, flowmeters can be supplied with analogue or digital readout for ease of logging and/or interpretation.

Flow rate indication, totalisation or both?

Flow meters can be supplied to give you a visual (either analogue or digital) indication of the current flowrate through the pipe or a totalised flow. Versions with a non-resettable totaliser, similar to a domestic type water meter are available as well as the re-settable type.

Our range of 100 series displays fitted to our Turbine flowmeters, can display both the flowrate & have a resettable & non-resettable totaliser function.

The flow range

The flow range is a vital factor when specifying & sizing a flowmeter, as too is the internal bore of the pipe in which the flow takes place. The flow range refers to the minimum flow you need to the flowmeter to measure / read down to and also your anticipated maximum flow. Most flowmeters operate most accurately over a 10:1 turndown. As an example, see below:

• 10-100 l/min. An Electromagnetic flowmeter

The aforementioned flow meter can operate over a slightly larger turndown, although at a slight reduction in accuracy. We always try and size the flowmeter so that your typical nominal flowrate is around 50% (mid-point) of the flow range.

Pipe size

Equally as important to the flow range when specifying a flowmeter is the size of the pipe in which it is going to be installed. We can supply flowmeters to cover anywhere from 5mm up to 2000mm pipes. Connection types from threaded (for example BSP, NPT, SAE etc.), flanged (ANSI, Din), high Pressure (WECO) & also dedicated Hygienic type (RJT, Tri-clamp, DIN11851). Large pipe sizes can be accommodated using an Ultrasonic flowmeter.

These are non-invasive clamp-on type flow meters that strap directly onto the outside of pipes. Because they aren’t inline (inside the tube), they tend to be a much more cost-effective option on very large pipes.

At the other end of the spectrum, our range of small Glass tube variable area flow meters, the NFX, are very small ¼” units & can measure (both liquids & gasses) just a few cc/min.


Typically, accuracy is defined in two different terms as follows:

• Percentage of reading (AR)

• Percentage FSD (Full-scale deflection).

A flowmeter with an accuracy stated as AR (of reading) will be the same over the full range of the flowmeter. Flow meters with an accuracy based on FSD will find the error increases as the flow rate falls. For applications where high accuracy is required such as custody transfer, dosing & filling machines and other critical measurement applications, a flow meter with accuracy based on the percentage of reading is required. Our Turbine flowmeters, for example, have an accuracy of +-/ 0.5% AR (or reading) & repeatability of +/-0.1

For more information about flowmeters and to find out which is right for your particular application, contact Nixon Flow Meters today.

Seasonal holidays 2017

 Please note that Nixon Flowmeters will close at 11.30 on Friday 22nd December 

 and open again at 8.30 on Tuesday 2nd January 2018.