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.

peopleFrankie Boyle responds to referendum result in characteristically offensive style
Arts and Entertainment
Highs and lows of the cast's careers since 2004
New Articles
i100... with this review
ebooksAn unforgettable anthology of contemporary reportage
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

Senior BA - Motor and Home Insurance

£400 - £450 Per Day: Clearwater People Solutions Ltd: **URGENT CONTRACT ROLE**...

Market Risk & Control Manager

Up to £100k or £450p/d: Saxton Leigh: My client is a leading commodities tradi...

SQL Developer - Watford/NW London - £320 - £330 p/d - 6 months

£320 - £330 per day: Ashdown Group: The Ashdown Group have been engaged by a l...

Head of Audit

To £75,000 + Pension + Benefits + Bonus: Saxton Leigh: My client is looking f...

Day In a Page

Scottish referendum: The Yes vote was the love that dared speak its name, but it was not to be

Despite the result, this is the end of the status quo

Boyd Tonkin on the fall-out from the Scottish referendum
Manolo Blahnik: The high priest of heels talks flats, Englishness, and why he loves Mary Beard

Manolo Blahnik: Flats, Englishness, and Mary Beard

The shoe designer who has been dubbed 'the patron saint of the stiletto'
The Beatles biographer reveals exclusive original manuscripts of some of the best pop songs ever written

Scrambled eggs and LSD

Behind The Beatles' lyrics - thanks to Hunter Davis's original manuscript copies
'Normcore' fashion: Blending in is the new standing out in latest catwalk non-trend

'Normcore': Blending in is the new standing out

Just when fashion was in grave danger of running out of trends, it only went and invented the non-trend. Rebecca Gonsalves investigates
Dance’s new leading ladies fight back: How female vocalists are now writing their own hits

New leading ladies of dance fight back

How female vocalists are now writing their own hits
Mystery of the Ground Zero wedding photo

A shot in the dark

Mystery of the wedding photo from Ground Zero
His life, the universe and everything

His life, the universe and everything

New biography sheds light on comic genius of Douglas Adams
Save us from small screen superheroes

Save us from small screen superheroes

Shows like Agents of S.H.I.E.L.D are little more than marketing tools
Reach for the skies

Reach for the skies

From pools to football pitches, rooftop living is looking up
These are the 12 best hotel spas in the UK

12 best hotel spas in the UK

Some hotels go all out on facilities; others stand out for the sheer quality of treatments
These Iranian-controlled Shia militias used to specialise in killing American soldiers. Now they are fighting Isis, backed up by US airstrikes

Widespread fear of Isis is producing strange bedfellows

Iranian-controlled Shia militias that used to kill American soldiers are now fighting Isis, helped by US airstrikes
Topshop goes part Athena poster, part last spring Prada

Topshop goes part Athena poster, part last spring Prada

Shoppers don't come to Topshop for the unique
How to make a Lego masterpiece

How to make a Lego masterpiece

Toy breaks out of the nursery and heads for the gallery
Meet the ‘Endies’ – city dwellers who are too poor to have fun

Meet the ‘Endies’ – city dwellers who are too poor to have fun

Urbanites are cursed with an acronym pointing to Employed but No Disposable Income or Savings
Paisley’s decision to make peace with IRA enemies might remind the Arabs of Sadat

Ian Paisley’s decision to make peace with his IRA enemies

His Save Ulster from Sodomy campaign would surely have been supported by many a Sunni imam