Fighting Fire Using Sound Waves

Fighting Fire Using Sound Waves

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Every year fires cause devastation in people’s homes, workplaces and in the countryside. Thousands of square miles of forests are destroyed, while people and animals lose their homes and their lives. It can be very difficult and incredibly expensive to put out fires and so we are constantly looking for cheaper and more efficient ways to do this.


Prevention is better than cure…

Of course, it is best to prevent fires from getting out of control in the first place but accidents happen and even the weather can play a part. Wildfires can be started by lightning strikes and hot dry weather makes it very easy for fires to spread quickly.

At the moment, most small fires are put out using equipment like fire extinguishers while bigger fires like wildfires require large amounts of water to extinguish them. But now a new invention that uses sound waves to put out fires has been built by two engineering students in the US. This method of putting out fires doesn’t use any chemicals like the ones found in fire extinguishers nor does it use water.

While the idea of using sound waves to extinguish flames is not new, no one has been successful up until now. Seth Robertson and Viet Tran – both studying at George Mason University in Virginia, US – decided to explore the idea and developed a series of prototype sonic extinguishers for a research project.



All about that bass

The science behind the new type of extinguisher is simple: for a fire to burn it must have air, fuel and heat. Without air (or oxygen), the fire cannot burn. Without fuel, there is nothing to catch fire, and if there is not enough heat then the fire will not start in the first place. The new extinguisher uses mechanical pressure waves that cause vibrations which manipulate both burning material and the oxygen that surrounds it. The inventors knew that if sound could be used to separate the two, the fire would be starved of oxygen and, as a result, would go out.

Tran and Robertson explored the impact of different frequencies of sound on small fires. While ultra-high frequencies had little effect, the duo found that lower, bass frequencies (between 30 and 60 hertz) produced the desired extinguishing effect. Consisting of an amplifier and cardboard collimator to focus the sound, the final extinguisher prototype is a hand-held, 9 kg, the mains-powered device that can quickly put out small fires.

Robertson and Tran didn’t just come up with the extinguisher overnight. The current prototype has been the result of many trials and experiments.

Originally, Robertson and Tran thought their device would work well on small fires in the home but they are now investigating the possibility of other uses.


Inquiry – Digging Deeper


Develop your understanding of sound waves by watching the following videos.