What could an electric fire cause?

Targeted electrical fields can influence and extinguish flames - portable extinguishing systems and improved production processes are conceivable


Anaheim (USA) / Cambridge (USA) - simply extinguishing fires like a magic wand - this vision is no longer too far-fetched after the experiments of US researchers. With the help of electric fields, they had specifically extinguished knee-high flames. The main reason for the effect is apparently the soot particles in the fire, which are electrostatically charged and therefore influenced by the field. The researchers expect fires to be fought faster, more environmentally friendly and without damage to the extinguishing water, at least indoors. In addition, the deletion can be done from a safer distance. They presented their findings at the spring meeting of the American Chemical Society in California. The method is also conceivable for portable extinguishing devices that could pave the way for fire fighters into and out of burning buildings, as well as extinguishing systems on ceilings, similar to sprinkler systems. The technology is less suitable for outdoor fires through to forest fires. However, it could help industrial processes with controlled firing - for example in power plants, engines or welding torches - to become more efficient.

"Controlling fire is an extremely difficult challenge," explains Ludovico Cademartiri of Harvard University in Cambridge, "but our research has shown that we can suppress flames very quickly by applying large electric fields." Cademartiri and his team had taken up a principle that had been known for 200 years: electricity can influence the shape of flames. It can make them bend, flicker and even extinguish. The researchers connected a 600-watt amplifier, such as that found in car music systems, to a metal rod and used it to direct electric fields onto a knee-high open flame. In fact, it went out immediately and with all repetitions. Cademartiri estimates that amplifiers with just a tenth of the wattage could suppress the flame. That would pave the way for simple portable systems.

The team is unclear what exactly goes on with electrical extinguishing, because the phenomenon is complex and several effects occur simultaneously. However, carbon particles formed in the flame seem to play a major role, said Cademartiri: "Soot particles can easily become electrically charged. The charged particles react to the electrical field and impair the stability of the flames." With the method, the researchers also succeeded in preventing flames from igniting a combustible gas-air mixture. They are now working to get a more precise picture of the complex chemical - and physical - processes involved in combustion.

Extinguishing methods commonly used today are based on removing heat, oxygen or other fuel from the fire. Systems with water should cool and smother the flames, foam, extinguishing powder or even carbon dioxide should mostly smother them. However, these variants often cause considerable damage through extinguishing water or less environmentally friendly substances.

For the time being, the method does not seem suitable for large outdoor fires because of the large areas involved and the enormous embers. In buildings, vehicles and airplanes or even submarines, however, it should be the extinguishing agent of choice. On a small scale, electromagnetic waves can definitely influence the distribution of flames and heat in a fire, reports Cademartiri. Therefore, the method could also help improve the efficiency of a whole spectrum of specific combustion processes in industry - from blast furnaces and power plants to car engines to cutting and welding torches.