Welcome to the January 2016 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)

 

Trevor's
Technical Tip

Trevor Forster is Managing Director of Titan Enterprises. 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 issue - Trevor offers you useful technical tips on:

Selecting Materials for Aggressive Media Flow Applications.

For the purposes of this feature I have defined aggressive media to include corrosive and abrasive flows and also measurements made at higher temperatures. Corrosive materials are commonly encountered in flow measurement and they present a series of problems. Typically corrosion resistance changes with temperature, a material which offers good chemical resistance at 20°C may be severely attacked at 100°C .

So when selecting the best flowmeter material for your corrosive media application consideration should be made not only for the normal running conditions but the extremes under an “unusual event”.

What if you have a fluid that has all three of the “aggressive” characteristics listed above? Flow meter manufacturers try to use the most widely chemical resistance materials for their standard products to maximise the applications for which they can be used. Elastomeric seals are usually interchangeable but the flowmeter body is normally metal or polymer. Below is a chart detailing some common flowmeter body and seal materials, their maximum operating temperature and fluids for which they offer acceptable durability as well as fluids they should not be used with.

Material
(Max operating temperature)
Acceptable fluids Not recommended for use with
316 Stainless steel (400°C) A good general all rounder, good for most oils, solvents, glycol, neutral aqueous solutions, hydrogen peroxide, food and medical products. Attacked by strong acids (hydrochloric, hydrofluoric, phosphoric, sulfuric ), plating solutions,ginger oil, bromine.
PTFE (200°C) A good material for many chemicals but has poor mechanical properties.
PVC (60°C) For lower temperature use only. Good with aqueous solutions, some organic solvents and mild acids and bases. Very unhappy with aromatic hydrocarbon based liquids and some strong acids.
PVDF (100°C) Available in food and drug approved grades. Good with most solvents and many acids. Severely affected by basic materials, acetone, ethyl acetate, methyl acetone, nitrous oxide.
PPS (200°C) Good all-rounder for aqueous solutions, hydrocarbons, weaker acids and bases, oils and ketones. Attacked by chlorine, hydraulic oil, hydrochloric acid and sulfuric acid.
PEEK (250°C) Good all-rounder with a very long list of compatible liquids. Attacked by some concentrated acids such as sulfuric and nitric.
Seals - EPDM (130°C) Offers good weather resistance and can be used with a wide range of fluids. Severely affected by hydrocarbons, oils, fats and some acids.
- Fluorine rubber (Viton© 150°C) A good general all-rounder, resistant to many hydrocarbon based fluids and chlorinated solvents. Although a good general seal material it is attacked by benzene, carbon tetrachloride, diesel fuel, hydrofluoric acid, many oils and sulfuric acid.
- Nitrile (90°C) Offers limited use for certain hydrocarbons, many alcohols, some fluorocarbons and hydraulic oil. Attacked by carbon tetrachloride, ether, Freon 11, hydrofluoric acid, MEK, nitric acid & many natural oils.
- Neoprene (100°C) For lower temperature fluids only. Good with aqueous solutions, organic solvents, most acids and bases. Severely affected by aromatic hydrocarbon based liquids, some oils and strong acids.
- Perfluorinated elastomers
           (Simrex©, Kalrez© etc. 260°C)
Another great all-rounder but at a cost. These seals are expensive and are challenged by only a few chemicals.

Disclaimer: the above chart is a rough guideline only. Full consultation should be undertaken with all component suppliers when aggressive chemicals are being handled.

To discuss your aggressive media flow application with Titan Enterprises click here

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 Electromagnetic flow meters.

Electromagnetic flow meters.

Informed opinion indicates that electromagnetic flow meters are the third fastest growing sector after meters based upon ultrasonic and Coriolis technologies. The fundamental operating principle of electromagnetic flow meters is extremely simple - put a moving conductor in a magnetic field and this will induce a voltage at ninety degrees to the field and the movement ... Flemings right hand rule.

In the illustrated electromagnetic flow meter, coils on the top and bottom of the pipe provide the magnetic field and electrodes placed at 90° to these provide the electrodes to measure the induced voltage in the moving conductor on the third axis (the fluid). So much for the basic theory, in 1839 Faraday famously attempted to measure the velocity of the UK’s Thames River using the earth’s magnetic field and a pair of electrodes across the river. One problem with constant magnetic fields are that they produce a dc voltage which in turn causes polarisation on the electrodes which can affect results over time. Electromagnetic flow meters use an alternating voltage which negates these long term errors. Of course the fluid must be conductive for electromagnetic flow meters to work so a large number of liquids are excluded. As a consequence this shortfall has spurred developments being done using ultrasonic and Coriolis alternative technologies. Modern electromagnetic meters can work with very low conductivities and more research is being done to increase the sensitivity even further. Obviously the higher the fluid conductivity the easier the measurement is to make as the relative output voltage will be higher for a given fluid velocity. These meters can be extremely accurate and operate over a wide choice of pipe sizes and flow turndowns.


Problem Solved

In this new feature we look to bring you an example of a customer application that was solved by a flow meter development by Titan Enterprises. In this issue of fLowdown we report on developments made for Agrochemical specialists – Stored Crop Conservation Ltd. (www.storedcrop.co.uk).

Hygiene and the elimination of pests and fungus is a major problem in the growth and storage of bulk crops in modern agriculture. From the preparation of the buildings used for the food production through to the silos containing the mass storage of products cleanliness is essential to ensure the quality of the produce. Even when produce is being put into storage the application of various chemicals extends the life of the products.

Stored Crop Conservation Limited (SCCL) has produced a system of "fogging" these spaces with a very fine mist which ensures the whole volume is coated with the appropriate chemical. The company has developed its own equipment and methods which ensure a much more even treatment than conventional methods. These chemicals are often regulated substances and careful control of the application volume is critical.

For nearly 15 years the company has been using Titan flow meters for the recording of the amount of chemical used. On current generation SCCL machines the volume of dispensed chemicals is recorded using Titan 900 series mini-turbines flow meters. These flow meters are coupled to a panel indicator recording total volume throughput on a re-settable display. In this way the machine operator can check the desired dosage for an area against the actual volume of chemical used ensuring safe dispersal of these controlled chemicals. To ensure consistent reliable measurements, SCCL’s in-house calibration rigs utilise Titan's highly accurate oval gear (OG) flow meters.

For further information on the 900 Series mini turbine flowmeter please click here.

How do I measure?

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

Titan’s interest in measuring blood flow was initiated by an enquiry for a set of meters to record the flow of blood substitute around a model of the human circulation system.

Blood is fundamental to life and is pushed around your body by a positive displacement pump with simple flap valves to prevent back flow. The speed of this pump varies from around 50 to 200 beats per minute and the pressure pulse is an unusual shape:-

The main pressure peak is from the heart pulsing, the notch is the aortic valve closing and the remaining pressure is from the elasticity of the arterial system. These pressures induce the flow and the main flow is caused by the resilient structures contracting after being stretched by the pressure pulse and being locked off by the aortic valve closing.

Surprisingly the highest flow range is after the heart contraction and aortic valve closure, this is the resilience in the vessel walls pushing the blood with the “retained” pressure. The changes in velocity are very dynamic and differing parts of the flow curve are affected by different parts of the circulation system. Consequently knowing where the flow is unusual could help diagnosis of circulatory problems. This complete blood pumping cycle is around 600 milliseconds (ms) with the individual elements as short as 4ms or 2ms for a patient with a rapid heart rate. Interestingly the velocity of the blood within the arterial system varies from 0.3 to 400mm per second, which is an incredibly wide velocity range.

So how do you measure this? The simple answer is with difficulty. Obviously blood vessels cannot be cut to insert a flow meter so some form of clamp-on system must be used. Electromagnetic technology with capacitively coupled electrodes, light and ultrasonic flowmeters have all been used. Ultrasound has been quite successful in this area initially with Doppler shift technology where reflections from the cells within the blood and later with time of flight systems. To accurately record the more rapid changes in flow, a suitable meter must have a fast response time of at least 200Hz and preferably 4 or 500Hz to catch all the transients. The latest generation of time of flight meters have a clip-on assembly which consists of a pair of ultrasonic crystals placed at an angle and a reflector positioned at the “focal point” of the two waves. These sensors are available in a range of sizes to suit the blood vessel size.

The phase shift between the upstream and downstream signals are effectively the velocity within the vein. On a practical front these sensor assemblies have to be capable of being sterilised or are supplied pre-sterilised and disposable. These very small sensors work down to 0.7mm diameter vessels with typical accuracies of ±5%. Laser Doppler is also proving to be quite successful.

So you can see while we have not yet reached the complex goal of accurately monitoring blood flow around the human circulatory system we have made significant strides forward in being able to measure blood flow in individual veins and arteries.

Product Updates

Recording on the Atrato Ultrasonic Flowmeter Data

A new data recording version of its Atrato ultrasonic flowmeter software interface has been developed by Titan. Easy to set-up and use the Atrato flow recorder enables data recording via an external computer. With features that provide monitoring, reporting and management of flow data - the Atrato flow recorder delivers a continuous picture of your process and a reliable alternative to restrictive and costly manual metering.


Introducing the Pulsite Solo

Titan will be launching in 2016 a range of display instruments. The first introduction will be a battery powered rate and total meter - the Pulsite Solo. This digital display instrument has been designed for use with switch, coil and magnetic sensor inputs. With housing constructed from rugged polymer and sealed to IP65 specifications the Pulsite Solo enclosure is panel, wall and surface mountable. Programming is simple using two push buttons and logical prompts in English on the LCD display. The replaceable battery life is estimated to be well in excess of 5 years for a totaliser. With rate readings the life of the Pulsite Solo will depend on the duty cycle but is still expected to be several years. The Pulsite Solo can also be externally dc powered if required. The meter will take frequencies from dc through to 2 KHz and scale them to display rate or total. The scaling factors are adjustable from 0.01 to 9999 and the time base is selectable as seconds, minutes or hours.

To be sent a launch data sheet on the Pulsite Solo please 'Further Information' below.



Q: What did the snowman say to the angry carrot?
A: Get out of my face!


Q: What do you get if you cross a snowman with a shark?
A: Frost bite!


Q: What says ‘Oh-Oh-Oh’ ?
A: Santa Claus walking backwards!


Q: What Christmas carol is a favourite of parents ?
A: Silent night!



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 news from Titan Enterprises.

Expansion at Titan Enterprises

Following a period of steady growth, and to provide extra capacity for expansion in the future, the management of Titan have purchased a further 235m2 of space and now completely own their HQ / production facility in Sherbourne, UK.

Click here for a printable version of Flowdown.

Top of page


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