16 November 2017 by Steve Eminton

WISH fire tests ‘positive’ over use of foam and vortex focus

Recent fire tests organised by the waste sector appear to have found new ways to better tackle waste fires, a conference in London heard yesterday.

Speaking at the conference on Fire prevention and control in the waste and recycling industry, Chris Jones, chairman of the Waste Industry Health & Safety Forum (WISH) revealed that the tests had found that the use of foam and targeted pointing of hoses at specific parts of the fire could more quickly control fires.

Mr Jones explained that the latest trials finished two weeks ago at the fire services site at Moreton-in-the-Marsh, Gloucestershire and formed phase three of WISH’s testing.

During the conference at the Queen Elizabeth II Centre in Westminster, the WISH chairman recalled how the organisation had been carrying out a lot of work on fire prevention.

“We have run phases one and two, and gained a recognition that the reality is that you are never going to exclude fire causing components. Phase two found and the phase three tests confirmed that wastes are much more resistant to sustained combustion than had been thought.

Chris Jones, chairman of the Waste Industry Health & Safety Forum (WISH)

“In phase three we have been evaluating a number of different fire-fighting agents.”

Fire vortex

In particular the research looked at the use of foams (surfactants) and tackling the fire vortex which is created in waste fires which also sees tongues of flame going over walls.

Mr Jones said that “we had the idea that a fire vortex is causing the problem. In petrochemical fires you knock down the vortex so we wanted to give that a try. Bunkers of RDF were created and we knew that fire vortices would give angular momentum to the plume.”

And, he added that potentially if “every waste site had a drum of surfactant and a trained team available to mix it and use it, and aim it at the base of the pile and fire chimney vortices, fires would be out before the fire brigade got there”.

He explained further to letsrecycle.com: “Across the UK the fire and rescue services have used a wide range of additives and foam types on waste fires, with outcomes varying from total success to complete failure.

“To understand why one needs to know (at least) four things: the waste type involved; the circumstances (pile, bunker, in a building or whatever); the additive used (and the concentration used); and the technique used to attack the fire.

Referring to a film of the experiments at Moreton-in-the-Marsh he said that these showed particular combinations of a waste type; additive type and application technique.

“One test was of 27 tonnes of bales of plastics fully alight “in a free standing stack :

    • 1. Using water and a “normal” type of ‘top-down’ application the stack could not be extinguished
    • 2. Using water and the attack technique that has been developed that exploits the vortices and air flows in a bale stack the fire could be brought to a minimal level but it was difficult to fully extinguish after 20 minutes
    • 3. Using CAFF (foam) and the technique above the stack was fully extinguished in 6 minutes
    • 4. Using a Type A additive, and the same technique extinguished the stack in around 2 minutes and 20 seconds

Mr Jones continued: “We only finished the actual experiments a couple of weeks ago and there is literally terabytes of information to be analysed, hours of video and thermal imagery to be examined… and all sorts of other sensor outputs.

“We need to look at all of that and, in time, with some further work (which will almost certainly now be picked up by others) we will be able to define combinations of waste types/circumstances/additives/fire fighting techniques that optimise this still further.”

He added: “For now we have a combination of additive and technique which looks to be broadly effective in most circumstances for most wastes and it’s a combination that’s deployable by on site teams with relatively inexpensive equipment and training.

“This is not the complete answer to fighting waste fires, but a really good start, and is a much better place to be and one of the things that we set out to achieve when we started along this road four years ago.”

Related links
WISH Forum

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