Two students at George Mason University have come up with a remarkable invention, which could be a game-changer in the eternal war of hippies vs ravers. You want us to turn the music off? Well maybe we’ll just turn your fire off!
By blasting a fire with low frequencies between 30 and 60 hertz range, the extinguisher separates oxygen from fuel, explains inventor Viet Tran, who built the device with fellow student Seth Robertson. “The pressure wave is going back and forth, and that agitates where the air is. That specific space is enough to keep the fire from reigniting.”
The pair faced plenty of opposition to their project initially because they’re electrical engineers, not chemical – several faculty members refused to act as advisers on the project. Eventually their professor Brian Mark agreed to oversee their work and not fail them if the whole thing flopped, said Tran.
Some further details from the Washington Post:
They weren’t at all sure that it would work
“I honestly didn’t think it would work as well as it did,” Tran said.
And neither did their professor
“My initial impression was that it wouldn’t work,” Mark, their adviser, said. “Some students take the safe path, but Viet and Seth took the higher-risk option.”
They MacGyver’d it
the goal was to create something portable and affordable like a fire extinguisher that would generate the sound wave at the correct frequency, which they were able to do with the help of an oscilloscope that measured the waves. They connected their frequency generator to a small amplifier and linked the amplifier to a small electric power source. These are hooked up to a collimator that they made out of a large cardboard tube with a hole at the end, which narrows the sound waves to a smaller area.
They tried ultra-high frequencies, such as 20,000 or 30,000 hertz, and could see the flames vibrating but not going out. They took it down low, and at the range of 30 to 60 hertz, the fires began to extinguish…the trial-and-error began. They placed flaming rubbing alcohol next to a large subwoofer and found that it wasn’t necessarily all about that bass, musically speaking, at least. “Music isn’t really good,” Robertson said, “because it doesn’t stay consistent.”
The next level of testing will determine if it can put out large structure fires.
So how does it work?
The basic concept, Tran said, is that sound waves are also “pressure waves, and they displace some of the oxygen” as they travel through the air. Oxygen, we all recall from high school chemistry, fuels fire. At a certain frequency, the sound waves “separate the oxygen [in the fire] from the fuel. The pressure wave is going back and forth, and that agitates where the air is. That specific space is enough to keep the fire from reigniting.”
In 2012, the Defense Advanced Research Projects Agency conducted a project on “acoustic suppression of flame” and found that it worked on small levels but could not determine if it would work at “the levels required for defense applications,” the agency said.
One of the students works for the Defense Department…coincidence?
Robertson has been working at the Defense Department and has been offered a job with the Air Force. Tran has interned at a Dulles, Va.-area aerospace firm with a promise of a job after graduation.
This could be a great solution for fire-fighting in dry areas, like Nevada, drought-stricken California, or the new frontier of space:
Although the students originally envisioned their device as a tool to attack kitchen fires and to eliminate the toxic monoammonium phosphate used in commercial fire extinguishers, they can see more uses: in confined areas in space, or wide areas outdoors, such as forest fires. Not having to use water or foam would be a bonus in many situations.
Read the full story at the Washington Post.