Welcome to the May 2015 issue of fLowdown - a quarterly Newsletter from Titan Enterprises Ltd. written to keep you informed about the latest technological developments, applications advances and breaking news in the field of flow measurement.

If a particular feature interests you, do not hesitate to contact us or follow the link for further information. We welcome your feedback.

Trevor Forster (Managing Director)


Technical Tip

Trevor Forster is Managing Director of Titan Enterpises. His experience in fluid handling dates back to the mid 1960's when he started working on rotating seals and flowmeter design for third party clients. Drawing upon over 40 years of using innovative design and production techniques to produce elegant flow metering solutions for organisations around the globe, in this feature - Trevor offers you a useful technical tip.

What do IP ratings actually mean?

A vast number of products quote IP code numbers. What do these actually mean?

The IP Code (or International Protection Rating, sometimes also interpreted as Ingress Protection Rating*) consists of the letters IP followed by two digits and an optional letter. As defined in international standard IEC 60529 (edition 2.1), it classifies the degrees of protection provided against the intrusion of solid objects (including body parts like hands and fingers), dust, accidental contact, and liquids into electrical enclosures.

The standard aims to provide users more detailed information than vague marketing terms such as waterproof.

This IP standard is designed to cover all classes of equipment and most environmental considerations. Temperature is not covered within the standard as it is primarily concerned about physical ingress of anything that could harm the equipment or personnel. The tables below provides an introduction to the meaning of the relevant IP codes.

The first digit indicates the level of protection that the enclosure provides against access to hazardous parts (e.g., electrical conductors, moving parts) and the ingress of solid foreign objects.

Therefore a piece of equipment specified as IP65 would be dust tight and capable of preventing any water ingress from a water jet from any direction. There are other limits set on these conditions and in the example given the jet is applied for three minutes. For the one metre submersion test the test time is 30 minutes. For further information relating to IP ratings please visit http://www.iec.ch/

The National Electrical Manufacturers Association (NEMA) also defines standards for various grades of electrical enclosures typically used in industrial applications. Each is rated to protect against designated environmental conditions.

A typical NEMA enclosure might be rated to provide protection against environmental hazards such as water, dust, oil or coolant or atmospheres containing corrosive agents such as acetylene or gasoline. A full list of NEMA enclosure types is available from the NEMA website - http://www.nema.org/pages/default.aspx

Level Object size protected against Effective against
0 Not protected No protection against contact and ingress of objects
1 >50mm Any large surface of the body, such as the back of the hand, but no protection against deliberate contact with a body part.
2 >12.5mm Fingers or similar objects.
3 >2.5mm Tools, thick wires, etc.
4 >1mm Most wires, screws, etc.
5 Dust Protected Ingress of dust is not entirely prevented, but it must not enter in sufficient quantity to interfere with the satisfactory operation of the equipment, complete protection against contact.
6 Dust Tight No ingress of dust, complete protection against contact.

The second digit indicates the level of protection of the equipment inside the enclosure against harmful ingress of water.

Level Object size protected against Effective against
0 Not protected ---
1 Dripping water Dripping water (vertically falling drops) shall have no harmful effect.
2 Dripping water when tilted up to 15° Vertically dripping water shall have no harmful effect when the enclosure is tilted at an angle up to 15° from its normal position.
3 Spraying water Water falling as a spray at any angle up to 60° from the vertical shall have no harmful effect.
4 Splashing water Water splashing against the enclosure from any direction shall have no harmful effects.
5 Water jets Water projected by a nozzle (6.3mm) against enclosure from any direction shall have no harmful effects.
6 Powerful water jets Water projected in powerful jets (12.5mm nozzle) against the enclosure from any direction shall have no harmful effects.
7 Immersion up to 1m Ingress of water in harmful quantity shall not be possible when the enclosure is immersed in water under defined conditions of pressure and time (up to 1m of submersion).
8 Immersion beyond 1m The equipment is suitable for continuous immersion in water under conditions which shall be specified by the manufacturer. Normally, this will mean that the equipment is hermetically sealed. However, with certain types of equipment, it can mean that water can enter but only in such a manner that it produces no harmful effects.

Flow Technology Spotlight

In each issue of fLowdown we review a particular flow metering technique, its benefits, shortfalls and the applications to which it is best suited. In this issue we look at Differential Pressure Meters.

Differential Pressure meters (DP) …… still a force to be reckoned with.

By Trevor Forster

A recent report [Global Industry Analysis Inc.] stated that globally one in six new systems purchased in 2014 use differential pressure (DP) techniques and I have heard it stated that over 40% of existing flow measurement installations are DP devices. This surprised me. I was aware of the historic usage but assumed that engineers would today prefer to install more hi-tech equipment. Although DP methods are losing ground it is evident that demand for this traditional flow metering technology is still very strong. The only technology that exceeds DP devices for units sold was electromagnetic flowmeter systems which accounted for just under 18% of all units sold in 2014. For this reason I felt I should review differential pressure flowmeter techniques.

Having been around for quite some time - there are today hundreds of types of differential pressure flowmeters. To keep this feature article concise and readable we focus upon the common DP methods and simply mention some of the others.

The advantages of DP flowmeters are numerous and include that they are usually inexpensive ; based on an easily understood principle their construction is robust and simple ; they can be used to meter a wide variety of fluids and gases ; there is a long established and constantly rationalized database of published information relating to the technique and modern secondary instrumentation related to DP flowmeters is relatively inexpensive.

Orifice plates are usually based on concentric discs introduced into a pipe. These create a restriction which generates a pressure drop. Pressure tappings are then positioned in accordance with the chosen standard of which there are numerous. Typically these are one diameter upstream and half a pipe diameter downstream, this is to read the line pressure and the pressure at the lowest point (highest velocity) in the vena-contracta. Corner tappings are also used which effectively measure the impact pressure and something approaching the vena-contracta pressure. The pressure drop that is generated is proportional to the square of the flow thus the resulting delta P must have a square root extraction to give flow rate, double the flow quadruples the pressure drop. This has the disadvantage that a 100:1 range pressure sensor will only give a 10:1 operating flow range although a typical range for this type of device is normally more like 4 or 6:1.

Whole books have been written on this subject and the system may require regular checking to ensure long term accuracy. The flow must be "turbulent" as laminar flow has an entirely different characteristic. The upstream edge of the plate must retain a sharp edge to maintain accuracy so these cannot be used on abrasive or dirty fluids.

Laminar flow element: Unlike the square law relationship with an orifice plate a laminar flow element uses low velocity fluid not in the turbulent region. This has a great advantage in that the pressure drop across the element is directly proportional to flow. This makes these devices very useful for small flows usually of gasses.

The element itself is usually a type of honeycomb offering a large surface area and low fluid velocities. Due to the operating principle these devices are usually only used for low flows as large meters of this type are very expensive to manufacture.

Pitot tubes most commonly encountered by the general public on the outside of aircraft where they are traditionally used to measure the airspeed. In engineering they are used in a wide spectrum of applications. They can be impact, cantilever or static and each type generally has a square law characteristic the same as the orifice plate

The advantage of the Pitot is there is very little pressure loss, the disadvantage is it is a point measurement and a full tube traverse or a multi-hole type should be used in an attempt to integrate the velocities across the whole conduit. They are ideal for checking things like air flow in heating/cooling ducts but can be used on quite large pipes with liquids as well.

Venturi nozzles: In the illustration for the orifice plate the illustrated flow lines form a contraction and expansion of the fluid. If you make your pipe form following this shape no secondary vortices are formed und there is no extra turbulence in the system. This controlled flow does not impose a high pressure loss on the system and is very energy efficient as the flow is contracted and expanded slowly conserving virtually all the energy.

In technical terms the discharge coefficient is near unity and almost constant in all flow velocities in the turbulent region, close to the ideal. Square root extraction is still required however. Different manufacturers have developed their own versions of these meters making them more compact with little compromise of performance. They are expensive to produce and install.

Nozzle devices are an attempt to produce a device that maintains some of the characteristics of the Venturi with the simplicity of an orifice plate. They have several advantages, they are compact, inexpensive (comparatively) to produce can handle dirty fluids as they do not have a sharp edge as mentioned in the orifice plate section. Corner tappings are usually used and the square root extraction is required.

For certain applications in gasses a version of this type of meter can be used called a “sonic nozzle”. These use the characteristics of gasses to give a constant flow and are very useful as a calibration reference as the throughput is fixed provided a certain upstream pressure is exceeded and the velocity of the gas in the throat is “sonic”. A simple and effective reference device.

Variable aperture devices is a big area as well and I am not going to attempt to cover all the meters in this category. Many are probably not considered as differential pressure devices as their operation appears different to the meters described above but they do use a differential pressure to make them work so in my mind belong in the same category.

Even my pond filter has a meter from this category. It is a simple drag/target meter with a moulded, hinged flap which is driven open by the mass of the fluid hitting it and the pressure drop behind causing the flap to open. Anything less than 45° open and the filter need’s a clean.

Commercial, well-engineered versions of this type of flow meter are available. Rotameters also fall into the same category as the height of the ball or specially shaped float is driven by differential pressure operating against gravity or in more industrial versions a spring.

Although this technology is slowly receding there does appear to be some very good reasons to continue with this low-tech, highly reliable method of measurement. Titan is concentrating its future development program on the Atrato ultrasonic meter as this technology appears to be the fastest expanding method of flow measurement.

How do I measure?

In this issue of fLowdown we discuss in ‘How do I measure’ an issue of general interest to many of us –  beer!

How to measure a pint of beer

In the UK weights and measures standards mean that for every half pint of beer served there should be a maximum error of ±3ml or around 1% per half pint (284.1 millilitres). Surprisingly a one pint is also to be served within ±3ml making this volume served potentially twice as accurate as the half pint. For general dispensing your average pub uses “brim fill” glasses these deliver the required volume when the beer is just about flowing out of the glass. This why staff often lose a good portion before it gets put on the counter and the reason the floor behind the bar becomes very sticky. In some areas of the country customers prefer a “head” on their pint and this results in rather less than a full pint being served unless the establishment uses 22 ounce glasses, a pint is 20 ounces. Such glasses have a line at one pint and space for the head. The variety of beer glasses and manual dispensing can often lead to short measures and a discussion with the person dispensing the beverage ! In practice the trade norm is accepted to be 95% beer and a maximum of 5% head.

Automatic dispense systems, such as those found in sports venues where rapid service is a necessity are a result of many customers all wanting to be served at the same time. Automatic dispense systems have to conform to the basic ±3ml specification. A measuring device is incorporated inside the dispensing machine to ensure the correct volume is dispensed at the touch of a button which speeds up serving dramatically. Both in the UK and internationally - Titan flowmeters have been chosen as the flowmeter of choice in such systems. It is quite a challenge to repeatedly deliver a pint of beer in four or five seconds within ±3ml and with an acceptable amount of froth. Beer at sporting events is typically served in squishy plastic containers. Such malleable plastic glasses are over-sized as it is impossible to carry the beer without pressing the sides slightly hence reducing the volume. The entire beer dispensing set-up has to be weights and measures approved. When Titan first tested its beer meters we used a calibrated flask similar to the one in the pictures below.

These calibrated flasks have a parallel, narrow neck and are marked with the actual volume and the permissible tolerances. As the beer is likely to be frothy we used a drop of surfactant to break the surface tension on the bubbles thereby enabling the volume accurately.

As well as beer, cider and Guinness dispensing - Titan has also been involved with designing and supplying flowmeters for the dispensing of, red, rose, white and mulled wine and in other parts of the world spirits and cocktail mixes.

New Products

Novel Ultrasonic Water Meter Technology

Titan Enterprises has built and trialled a half inch bore, water meter and achieved an accuracy better than ±2% over a 250:1 flow range using an external power supply. Based upon Atrato ultrasonic flowmeter technology the new device easily satisfies all the required water industry performance standards and fits within the 110mm desirable mounting length. Existing solid state water meter products tend to be complicated, expensive to produce and frequently do not satisfy all of the performance requirements. Atrato’s patented small bore ultrasonic flow metering technology offers many benefits for this application including the potential for low power operation, higher flow models and a wide flow range (400:1), consequently Titan are seeking to license the technology to a suitable partner for commercial exploitation.

Note: The world domestic water meter market is estimated to reach over 30 million units this year. The majority of these will be "smart" meters requiring power to operate. The sub-meter and heat transfer markets are reported as being the fastest growth sector.

Measuring Refrigerant Flow

A new high pressure version of the 900 Series turbine flow meter has been developed for measuring refrigerant flow. Adapted with steel reinforced polymer components, to give a pressure rating of 40 Bar, the low inertia turbines of the 900 Series flow meter are ideal for measuring the low viscosities (0.3 to 0.4 centipoises) encountered with volatile refrigerant fluids measured in the liquid form. With careful sensor selection the pressure drop through the 900 Series flow meter is low enough to prevent gas break-out and ensure reliable flow measurement.

The new flow meter is designed to give high performance (+/- 0.1% repeatability) across 6 flow ranges from 0.05 to 15 litres per minute. It's chemically resistant components make it the ideal choice for the metering of a wide range of fluids from -25°C to +125°C. To ensure the highest degree of inertness to metered fluids the flowmeters polymer components are moulded in an FDA approved grade of PDVF and mounted in a 316 stainless steel body.

Future Focus

In this occasional fLowdown feature we look at a topical area of development in our industry. We welcome your feedback on this feature and your suggestions (click here) for further 'Future Focus' topics that we might address?

Good Vibrations...

Coriolis versus Ultrasonic flow meter technology: which will be the winner?

Coriolis and Ultrasonic flow meters are reported to be the fastest growing flow measurement market sectors with most of the leading suppliers spending a lot of money on research and development to stay ahead of the game. This makes perfect sense as there are a lot of good reasons these meters are desirable.

1. Both Coriolis and Ultrasonic flowmeters have no moving parts. This makes them very reliable. There is, in fact, a very small vibration in both devices but at such low levels as to be considered irrelevant.

2. Both Coriolis and Ultrasonic flowmeters typically employ a clean pipe bore design which results in a low pressure drop. Purist may argue that some of the Coriolis meters have curved tubes but even so there is nothing in the pipe. There are straight pipe versions available. Often the reduction in pipe size to accommodate the desired flow rate is the major pressure loss associated with the installation not the actual meter itself.

3. Both Coriolis and Ultrasonic flowmeters are capable of excellent, long term accuracy. This makes them very reliable and hence reduces their in-service costs. Consequently both techniques can be expected to have a lengthy service life.

4. Both technologies are capable of measuring liquid and gases with Coriolis meters able to measure mass flow directly.

Where there is a difference in Coriolis and Ultrasonic flowmeter technologies currently is in the range of pipe size they are applicable to. It is relatively easy to make a very large ultrasonic meter but difficult to make small ones and the converse is true for Coriolis. Small bore Coriolis meters are quite easy to make but larger bore meters very difficult. Coriolis and ultrasonic flow meters consequently compete most in the ½” to 6” (12mm to 150mm) diameter line sizes. Below this pipe diameter range, Coriolis flow meters currently win hands down, that is with the exception of the novel Titan Enterprises Atrato ultrasonic flowmeter developments. Above the stated pipe size range ultrasonic essentially has a free run although at least one company is developing a 400mm Coriolis flow meter. Interestingly Titan Enterprises Atrato ultrasonic technology has difficulty being scaled up and our current maximum pipe size is currently 12mm - exactly where other ultrasonic meters tend to start having problems and Coriolis meters are strong.

The current massive R&D spend on Coriolis and Ultrasonic flow meter technologies would indicate that the cross over between the technologies is likely to intensify as other manufacturers expand their product ranges into unfamiliar territory. It is going to be very interesting in the next few years to see how each technology finds its market niche with the ultrasonic likely to remain less expensive and the Coriolis the more desirable due to its inherent mass flow capability.

To learn more about Atrato ultrasonic flow meter technology please click here.

Bulletin Board

To enable you to make informed decisions about the flow metering challenges facing your organisation this newsletter feature keeps you up-to-date on the latest literature, hints and tips, initiatives and company news from Titan Enterprises.

Flowmeter Calibration – 10 Key Considerations

Flowmeters have become ubiquitous. There is hardly any part of modern life that is not touched by these devices and because, or in spite of this, the calibration procedures for these meters is even more important. Today engineers and scientists rely on flow meters to maintain or improve the financial viability, quality and safety of a product / process and as such require regular calibration to ensure they are operating within acceptable limits. What are the key points to consider when calibrating or re-calibrating a flowmeter?

1. How often should I re-calibrate my flowmeter?

Flowmeters will not hold their calibration indefinitely and the calibration interval will be dependent on the type of meter and the application. Mechanical meters will wear and electronic ones can suffer minor degradation in the electronics or mechanical damage from impact or corrosion.

2. Should I return the flowmeter to the manufacturer for re-calibration?

This is a good course of action as the manufacturer is best placed to ensure that the meter is serviced and returned to an acceptable standard.

3. Is calibration in-situ with a reference standard in-line with the device on test practical?

Full installation criteria must be observed to ensure that one flowmeter is not corrupting the data produced by another flowmeter. There are several suppliers who will hire the required equipment and give installation recommendations e.g. www.Flowhire.co.uk.

4. Can I calibrate the flowmeter myself?

This can be quite simple with small flowmeters (12mm diameter and below) but with larger meters is often impractical. However there are some factors (detailed below) that you need to consider before you continue down this route.

5. Do you have a traceable reference standard?

This requires either a secondary flowmeter or a standard that is approaching an order of magnitude better accuracy than the errors you wish to measure. For example if you have a set of scales and you wish to measure 100Kg with an accuracy of ±1% the scales should be accurate to ±0.1Kg.

6. Is your reference standard traceable to national standards?

Taking the example in ‘5’ above, when were the scales last calibrated? Do you have a certified reference weight to check the mass recorded?

7. If you are recording flow rate do you have an accurate timing method?

The same resolution requirements are desirable for time as mass. With a linear flowmeter this is less important and becomes a second order effect but for non-linear devices such as the differential pressure meters it is very important.

8. Are you calibrating your flowmeter with actual fluid used in the process?

This guarantees that the answers are correct for your fluid.

9. Are your calibration and process operating conditions identical?

A lot of flowmeters are parameter specific and if the temperature, viscosity, density or flow rate changes the calibration will shift. Ensure that the calibration conditions, not just the fluid, are representative of the actual running conditions.

10. Is your process flow rate constant?

If the flow rate of your process is not constant - calibration must be performed over the entire operating range. This is particularly important if the meter is not installed in line with the manufacturer’s recommendations. Often it is not possible to conform to the installation instructions and in this case calibration in-situ is essential to ensure optimal flow meter performance.

At Titan Enterprises we employ commercial piston provers which use the displacement of a known volume by a piston as the reference to calibrate our flowmeters. These calibration devices are calibrated regularly against a traceable standard and retain their original ±0.05% repeatability. To learn more about flow calibration at Titan Enterprises please visit www.flowmeters.co.uk/calibration.htm

Case Study: Improving the Reliability of a Glass Bottle Making Plant

Titan Enterprises reports on the development of a 'dirty water' ultrasonic flowmeter for (www.graphoidal.com).

Graphoidal Developments is at the forefront of designing and manufacturing advanced lubrication and coating systems for the glass container and tableware industries. Their expertise is in precise pumping, control of mixing, dosing and spraying of the lubricants and coatings which form a vital part of the glass production process, both in hot end and cold end areas. Graphoidal Developments first started using Titans turbine flowmeters over twenty years ago. They install flowmeters in their water lines to monitor the application of the coolant to the shears which are used to cut semi-molten glass in bottle making machines. The accurate application of a lubricant and coolant is critical to the reliability of the whole machine. Initial installations of Graphoidal machines in Europe, fitted with Titan flowmeters, proved very reliable. However as the success of the Graphoidal machines spread worldwide a flow monitoring problem became apparent. Older glass bottle making plants often had steel piping which rusted. The deposition of rust in the water coolant lines not only abraded the machines bearings but also rendered the turbine flowmeters inaccurate. Graphoidal recognised in some locations a regular supply of clean potable water was not possible and excessive filtering (to remove rust) with the corresponding pressure drop and reduced service intervals were not options.

As a result - Graphoidal approached Titan Enterprises to develop an alternative flowmeter that would be immune to the 'dirty water' problem, could operate over a wide dynamic flow range, had identical electronic outputs and would fit into the same space as the existing turbine flowmeter. It became apparent that Titan’s proprietary Atrato ultrasonic flowmeter technology offered a solution but required modification to fit in the desired space and reduction of the sophisticated electronics to help meet target unit prices. Titan Enterprises started with a blank sheet of paper and used a bit of lateral thinking to solve the problem. The pipe connections on Graphoidal machines were fixed so Titan chose to turn the Atrato flowmeter sensing element to be 90° to the fluid path with a manifold to make the connections. Unfortunately this made the meter just too big for the available cabinet space. Titan then experimented with bending the flow passage around 180° whilst still carrying the ultrasound. Using unique algorithms this technique proved to be successful so the sensors could be placed on the manifold and both the flow and the ultrasonic signals being bent around a 28mm diameter 180° arc. In addition the flowmeter electronics were re-designed to match the customer’s specification and any extraneous functions not required by Graphoidal machines eliminated. The closure for the housing was made into a robust plastic cover to keep the costs down.

While the resulting product is more expensive than the turbine flowmeter it replaced its advantages far outweigh the drawbacks. Each meter has an identical 'K' factor so no individual calibration of a Graphoidal machines PLC is required. A single ultrasonic flowmeter is able to cover multiple flow ranges enabling reduced inventory to be held by Graphoidal. As the Atrato ultrasonic flowmeter has no moving parts, there are no parts to wear out due to rust abrasion. The flowmeter has proven itself highly reliable, even in some of the former troublesome plants, so far fewer call outs for faulty measurement systems due to inferior water supplies have been required. Consequently Graphoidal’s customers are happy and the company’s reputation has further improved within the industry.

To discuss a potential OEM flowmeter development with Titan Enterprises click here.


Some humorous asides for the Engineers amongst us:

There are three engineers in a car; an electrical engineer, a chemical engineer and an Microsoft engineer.  Suddenly the car just  stops by the side of the road, and the three engineers look at each other wondering what could be wrong.
The electrical engineer suggests stripping down the electronics of the car and trying to trace where a fault might have occurred. 
The chemical engineer, not knowing much about cars, suggests that maybe the fuel is becoming emulsified and getting blocked somewhere.
Then, the Microsoft engineer, not knowing much about anything, comes up with a suggestion, "Why don't we close all the windows, get out, get back in, open the windows again, and maybe it'll work!?"

How many software engineers does it take to change a light bulb?
None. That’s a hardware issue.

A project manager's most important ability is to foretell what will happen tomorrow and next month and next year - and to explain afterwards why it didn't happen.

Click here for a printable version of Flowdown.

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Titan Enterprises Ltd, Unit 2, 5A Cold Harbour Business Park, Sherborne, Dorset, DT9 4JW
Telephone: +44 (0)1935 812790 - Fax: +44 (0)1935 812890 - Email: sales@flowmeters.co.uk