Innovation: Optical fibre hot tip for industrial safety

AFTER its successful role in the telecommunications revolution, optical fibre is poised to cut costs and improve safety in other industries, such as power transmission and petrochemicals, which rely on temperature sensing to ensure the safe and efficient operation of factories and equipment.

The technique works by sending a laser pulse of light down an optical fibre and measuring changes in its properties when it is reflected back. Variations in the reflected light translate into temperature readings, while the time between injecting the pulse and receiving the reflected signal pinpoints the location of the temperature reading.

Traditional temperature sensing relies on discrete sensors, such as thermocouples, which provide information only from their own location. They must be linked to a data acquisition unit, which often causes complex wiring problems.

When there is a need for multiple-point or shifting monitoring, discrete sensors are inflexible and expensive. Optical fibre sensors can discriminate between temperature readings only a metre apart for distances of up to 40km - long enough to reach across the English Channel.

Users can monitor thousands of points without needing to decide where to take the measurements.

Adopting optical fibre to monitor temperatures is the work of York Sensors, a Southampton company with close links to Southampton University, which has pioneered many developments in optical fibres. Peter Orrell, sales and marketing manager of York Sensors, says it might cost around pounds 10 per point to install discrete sensors, whereas an optical fibre system costing pounds 50,000 could measure up to 10,000 points.

'Not only can an optical fibre system provide information from thousands of points, it can respond to temperature changes in less than a second and continues to measure even if the fibre is broken,' Mr Orrell says.

This makes the technique very powerful in fire detection. It also has an advantage over infra-red fire detection systems, which cannot distinguish between smoke and fire, in being able to pinpoint the seat of a fire.

York Sensors is working with companies to develop new applications. In the chemical industry, the method is being used for surface monitoring of vessels that operate under high temperature and pressure. Such vessels have refractory linings that can fail. By winding the optical fibre on to the outside of the vessel, any hot spots, indicating lining failure, can be detected.

Mr Orrell says companies using the technology do not want to be named, as they believe the ability it gives them to operate safely with fewer maintenance shutdowns provides an advantage over competitors.

Optical fibre is flexible and easy to install, and is now so cheap (a few pence per metre) that it can economically be used to monitor long lengths of pipeline.

The fibre can be sheathed in different coatings, allowing it to operate at temperatures between minus 190C and 460C.

One low-temperature application, being tested by Gaz de France, is monitoring gas pipelines. Gas is moved as a liquid at low temperatures. Any leak - which could cause an explosion - is registered as a cold spot.

Oil pipelines could also be monitored to ensure that the water in unrefined oil did not freeze, blocking the pipeline.

'Because the fibre does not depend on electrical current to transmit its measurements, it is an ideal monitoring technique for oil pipelines and refineries, where electric sparks can cause explosions,' Mr Orrell explains.

The National Grid, in collaboration with Electricite de France, is currently assessing the sensors for monitoring underground cables, which must operate below a certain temperature to avoid burn-out.

National Grid has 600 route kilometres of underground cable and its safe capacity varies, depending on the time of the year and ambient temperature.

The difficulty of monitoring underground cables has led electricity companies to specify a higher capacity than they need (at a significantly higher cost). According to Mr Orrell, York Sensors has now given electricity companies the confidence to specify lower-capacity cables.

Start your day with The Independent, sign up for daily news emails
election 2015The 10 best quotes of the campaign
A caravan being used as a polling station in Ford near Salisbury, during the 2010 election
election 2015The Independent's guide to get you through polling day
David Blunkett joins the Labour candidate for Redcar Anna Turley on a campaigning visit last month
voicesWhat I learnt from my years in government, by the former Home Secretary David Blunkett
ebooksA celebration of British elections
  • Get to the point
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs Money & Business

Ashdown Group: Editor-in-chief - Financial Services - City, London

£60000 - £70000 per annum + benefits : Ashdown Group: A highly successful, glo...

Ashdown Group: Junior Application Support Analyst - Fluent German Speaker

£25000 - £30000 per annum + benefits: Ashdown Group: A global leader operating...

Guru Careers: Management Accountant

£27 - 35k + Bonus + Benefits: Guru Careers: A Management Accountant is needed ...

Guru Careers: Project Manager / Business Analyst

£40-50k + Benefits.: Guru Careers: A Project Manager / Business Analyst is nee...

Day In a Page

General Election 2015: ‘We will not sit down with Nicola Sturgeon’, says Ed Balls

'We will not sit down with Nicola Sturgeon'

In an exclusive interview, Ed Balls says he won't negotiate his first Budget with SNP MPs - even if Labour need their votes to secure its passage
VE Day 70th anniversary: How ordinary Britons celebrated the end of war in Europe

How ordinary Britons celebrated VE Day

Our perception of VE Day usually involves crowds of giddy Britons casting off the shackles of war with gay abandon. The truth was more nuanced
They came in with William Caxton's printing press, but typefaces still matter in the digital age

Typefaces still matter in the digital age

A new typeface once took years to create, now thousands are available at the click of a drop-down menu. So why do most of us still rely on the old classics, asks Meg Carter?
Discovery of 'missing link' between the two main life-forms on Earth could explain evolution of animals, say scientists

'Missing link' between Earth's two life-forms found

New microbial species tells us something about our dark past, say scientists
The Pan Am Experience is a 'flight' back to the 1970s that never takes off - at least, not literally

Pan Am Experience: A 'flight' back to the 70s

Tim Walker checks in and checks out a four-hour journey with a difference
Humans aren't alone in indulging in politics - it's everywhere in the animal world

Humans aren't alone in indulging in politics

Voting, mutual back-scratching, coups and charismatic leaders - it's everywhere in the animal world
Crisp sales are in decline - but this tasty trivia might tempt back the turncoats

Crisp sales are in decline

As a nation we're filling up on popcorn and pitta chips and forsaking their potato-based predecessors
Ronald McDonald the muse? Why Banksy, Ron English and Keith Coventry are lovin' Maccy D's

Ronald McDonald the muse

A new wave of artists is taking inspiration from the fast food chain
13 best picnic blankets

13 best picnic blankets

Dine al fresco without the grass stains and damp bottoms with something from our pick of picnic rugs
Barcelona 3 Bayern Munich 0 player ratings: Lionel Messi scores twice - but does he score highest in our ratings?

Barcelona vs Bayern Munich player ratings

Lionel Messi scores twice - but does he score highest in our ratings?
Martin Guptill: Explosive New Zealand batsman who sets the range for Kiwis' big guns

Explosive batsman who sets the range for Kiwis' big guns

Martin Guptill has smashed early runs for Derbyshire and tells Richard Edwards to expect more from the 'freakish' Brendon McCullum and his buoyant team during their tour of England
General Election 2015: Ed Miliband's unlikely journey from hapless geek to heart-throb

Miliband's unlikely journey from hapless geek to heart-throb

He was meant to be Labour's biggest handicap - but has become almost an asset
General Election 2015: A guide to the smaller parties, from the the National Health Action Party to the Church of the Militant Elvis Party

On the margins

From Militant Elvis to Women's Equality: a guide to the underdogs standing in the election
Amr Darrag: Ex-Muslim Brotherhood minister in exile still believes Egypt's military regime can be replaced with 'moderate' Islamic rule

'This is the battle of young Egypt for the future of our country'

Ex-Muslim Brotherhood minister Amr Darrag still believes the opposition can rid Egypt of its military regime and replace it with 'moderate' Islamic rule, he tells Robert Fisk
Why patients must rely less on doctors: Improving our own health is the 'blockbuster drug of the century'

Why patients must rely less on doctors

Improving our own health is the 'blockbuster drug of the century'