Fire Extinguisher via Sound Waves

[Hashi Lebwohl]

Viet Tran and Seth Robertson, engineering students at George Mason University, have invented a fire extinguisher that uses sound waves to put out fires. The based their research on one DARPA project called Prometheus, whose goal is to address the problem of fighting fires not from a chemical perspective (foams or other chemical retardants, many of which surpass water in efficacy) but from a physical perspective. The primary considerations were fires in enclosed locations (such as on a naval vessel, an enclosed workspace underground/underwater, or in space)--it is a bad idea to try and use a typical extinguisher in zero-g. The basic principle is to use sound waves to push the oxygen away from the flames, by which I presume they are creating small pockets of relative vacuum sufficient to stop the rapid oxidation process which causes flames.

If this device can be made commercially available it will see practical application in all sorts of places where fighting fires without using possibly destructive chemicals is necessary, such as hospitals or even personal homes.

[Cord Hurn]

Wonder what those sound waves would do to a human body that got in the way of the fire? Would ribs be bruised, or would one just feel the need to belch? This new fire extinguisher is a great idea for putting out fire in space, sounds like. It's "all about that bass, 'bout that bass, no treble".

[Hashi Lebwohl]

With sound waves it all depends upon the frequency and intensity. 140 dB at 440 Hz will make the hair on your head fly around wildly and probably make you feel as if you are sitting in one of those vibrating massage chairs. 80dB at 10 Hz won't sound like anything at all but it could potentially rupture capillaries or vibrate the vitreous humor inside your eyeball, making you hallucinate. Some research indicates that 7 Hz could cause damage to major organs, induce nausea, or even be fatal. I do know that current non-lethal weapons actually in use at this time include "screechers" which use 2 panels, one producing 16 kHz and another at 16002 Hz to create coinciding overlaps of 2 Hz and 32002 Hz, to induce painful headaches.

I do not know what intensity and/or frequency(ies) they are using but I suspect they can't be harmful or the device wouldn't be useful in any circumstance.