A relatively new invention will change the way we douse fires, in particular it will improve our approach to them.
Whenever something huge burns, we think only of a forest or building fire, the risk of sacrificing human lives is truly enormous and finding an alternative way to combat this problem would mean saving many lives.
Water, chemicals, flame inhibitors, fire extinguishers, aerosol suppressors are the most common ways to put out a fire, but still not the best and not usable for every situation.
A revolutionary way to put out a fire is definitely with sound waves. But how? Sound waves move oxygen away from the source of a flame and spread it over a larger surface. In this way the “fire combustion triangle” is broken, consisting of the three elements necessary for the combustion of the fire (heat, fuel and oxygen).
Without relying on other sources such as water and chemicals, the frequencies of these sounds are between 30 and 60 Hz.
The concept of using sound waves had already been studied by teams at West Georgia University and the US Defense Advanced Research Projects Agency, but without any success.
In 2015, two final year students from George Mason University in Virginia, USA, Seth Robertson and Viet Tran, created an acoustic fire extinguisher for their senior design project at George Mason University.
It was originally created to put out small fires in the kitchen, but currently the goal is to fight large fires.
They tested different frequencies of sound on small fires and found that the lowest frequencies, 30-60Hz, produced the desired effect.
The final prototype consists of an amplifier and a cardboard collimator to focus the sound, it is a portable device of only 9 kg, powered by the network, able to quickly extinguish small alcohol-powered fires.
They are currently working to move on to further testing and refinements and studying the feasibility of applying the principles. For example, it could be applied in space, where fire is a big deal, and it is possible to direct sound waves without gravity.
It contains no refrigerant and may not be able to prevent re-ignition after the sound has been turned off, but they are trying to improve it.
Resources:
PhysicsWorld: Dousing flames with low-frequency sound waves. 2015
DellTechnologies: Sound Waves to Fight Wildfires: How Does it Work?. 2020
