Eurotunnel engineers have installed the first part of a new anti-fire system that has been shown in testing to quench fires in minutes.
The system incorporates a series of ‘safe stations’ equipped with novel water-mist pumps.
‘There are fibre-optic heat detectors that localise exactly where the seat of the fire is and within seconds the water-mist system is set off to target it,’ said Eurotunnel spokesman John Keefe.
The specially designed nozzles achieve a dispersal rate of around of 200m3 of water per hour, all in micro-droplet form.
‘There is so much water in the air that it stifles the access of any oxygen from the rest of the tunnel, so any sort of chimney effect that might have happened in the past is prevented,’ added Keefe. ’It has this double-dampening effect.’
Research and development on a new system started around four years ago, before a fire broke out on a Folkestone-to-Calais train about seven miles from the French end in September 2008.
Based on that experience, engineers built a prototype in 2009 and then took it to a rail-testing tunnel in Spain the following year. They created a very significant palette-based fire reaching temperatures of up to 1,000oC in an identical array to the Channel Tunnel itself. Analysis revealed that the system was able to reduce the temperature of the fire from around 900°C to 250°C in less than three minutes, leaving only embers and minimal damage to equipment.
‘The main problem in… 2008 was that, because the train was left static and burning for several hours, the damage to the catenary, to the water pipes, cooling pipes and signalling equipment was extensive over several hundred metres,’ said Keefe.
Talking about the new system, he added: ’We would probably have a section out of operation for a matter of hours, rather than a matter of months, as was the case with the fire in 2008.’
Part of the strength of the system lies in the infrastructure. There are four emergency safe stations comprising sidings of 830m equipped with the heat sensors and water-mist pumps. The first of these has now been fully installed and work is ongoing on the other three.
In the event of a fire, trains will be able to drive into one of the emergency sidings, which are never more than 10 minutes away at 100km per hour.
‘In testing, we found that there is a perfect speed that prevents the fire from getting too much oxygenation and growing and spreading backwards along the train, and also prevents it from growing in situ — the balance between a wind that is fanning it and a wind that is putting it out.
‘At 100km an hour, we can drive it in a contained manner to the safe station,’ said Keefe. ’Then, before it starts to expand, the water mist is released and puts it out very quickly.’
It is expected that all four safe stations will be completed and in place by the end of the year, incurring a cost of £17m.