Fighting Fire with Sound: Wave Extinguisher
Two U.S. electrical engineering students have discovered a cutting-edge and unconventional way to fight fires: with sound. Specifically, bass frequencies between 30 and 60 Hz. Seth Robertson and Viet Tran – both final-year undergraduates at George Mason University in Virginia – have developed a hand-held device that allows them to aim a sound wave of a specific frequency at a flame and effectively douse the fire without using any chemicals or water.
Though it sounds simple, the road to the sound wave extinguisher solution has not been easy. Previous attempts to use ultrasound as a tool against flames – including efforts by the US Defense Advanced Research Projects Agency (DARPA) – had proven unsuccessful and the two students were met with skepticism from peers and faculty when choosing this as a research project. They explained that they put quite a bit of time and money into exploring ultrasound as the solution, with little success, and even lost most of their student team when a solution seemed unattainable.
However, when they discovered the power of the bass frequency in putting out the flame, their perseverance paid off. Since sound waves can move oxygen and fire through pressure from their vibrations, this specific frequency of sound wave works to separate the flame molecules from the surrounding oxygen, effectively starving the fire and snuffing out the flame. The students’ final hand-held, mains-powered prototype, built for around $600, is making a stir on the Internet and in scholastic circles thanks to its popular YouTube demonstration.
Although sound wave extinguishing does pose a risk of the flame reigniting once the oxygen returns to the space (aka, when the device is turned off), the initial success of the extinguisher is very promising for a potential future deployment of sound technology in firefighting. The duo explained that they originally envisioned the concept being used on smaller-scale settings, like in a kitchen on the stove-top. But they also hope that, in the future, the idea could be developed into an effective firefighting tool utilized by “swarm robotics” and drones on larger-scale fire fields, like forest fires, to prevent putting firefighters in harm’s way when possible.
An additional use case for the sound wave extinguisher could be outer space, where fire poses a huge problem. Since traditional extinguishers used in zero gravity spray contents in all directions, it’s incredibly difficult to target a flame. But since sound waves can be directed without gravity, using the bass frequencies could be an ideal solution.
Robertson and Tran have currently acquired a preliminary patent application and are now hoping to move onto further testing and refinements of their design, with ultimate goal of potential commercial applications.