28 March 2011

Electrical "wand" extinguishes fires

by Kate Melville

A 200-year-old observation that electricity can affect the shape of flames is being revisited with an experimental device that uses an electric field projected from a probe to rapidly suppress flames. The scientists behind the development, who presented their findings at the 241st National Meeting of the American Chemical Society, say that the discovery could usher in a new genre of fire-fighting devices, including sprinkler systems that suppress fires not with water, but with electric current.

"Controlling fires is an enormously difficult challenge," said Harvard researcher Ludovico Cademartiri. "Our research has shown that by applying large electric fields we can suppress flames very rapidly. We're very excited about the results of this relatively unexplored area of research."

Importantly, the new method would allow fire-fighters to put out fires remotely, without delivering material to the flame. The technology could also save water and avoid the use of fire-fighting materials that could potentially harm the environment.

In the new study, Cademartiri connected a 600-watt electrical amplifier to a wand-like probe and used the device to shoot beams of electricity at an open flame more than a foot high. The flame was snuffed out almost instantly and Cademartiri stressed that it worked repeatedly. The research team believe that a power source with only a tenth of this wattage could have similar flame-suppressing effect. Such a device could be hand-carried or fit into a backpack.

Cademartiri says the extinguishing phenomenon is complex with several effects occurring simultaneously. Primarily, it appears that carbon particles generated in the flame are behind the effect. "Soot particles can easily become charged. The charged particles respond to the electric field, affecting the stability of flames," he explained.

The system shows particular promise for fighting fires in enclosed quarters, according to the researchers, but would not be suitable for forest fires which are spread over much larger areas.

Intriguingly, Cademartiri also reported that electrical waves can control the heat and distribution of flames. As a result, the technology could potentially improve the efficiency of a wide variety of technologies that involve controlled combustion, including automobile engines, power plants and welding torches.

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Source: American Chemical Society