Himachal students build sound-wave device to douse fire without water

An interesting innovation has come out of the Government Polytechnic College in Sundernagar, in Himachal Pradesh's Mandi district. Final-year electrical engineering students there have built an "automatic sonic fire extinguisher" that puts out fires using sound waves. The device does not need water, foam or any chemical fire-fighting material.

The students say the project was designed to prevent the damage that happens to electrical equipment when fires are put out using conventional methods. Fire extinguishers that use water or chemicals often end up damaging servers, electronic circuits and expensive equipment. With sonic technology, no chemical residue is left behind once the fire is out, so the equipment is not damaged.

The device is fitted with sensors, a microcontroller, a digital logic controller and a high-power amplifier. As soon as the sensor detects fire, the system starts generating sound waves at a set frequency. The students' prototype uses sound waves in the 30 to 60 Hz range.

These waves create vibrations in the air that affect the movement of oxygen around the fire, cutting off the oxygen supply to the flames and helping put out the fire. In simple terms, the sound waves create a kind of "wall of air" around the fire that stops it from spreading.

The device is currently estimated to cost around Rs 7,000 to 8,000. Being lightweight, it can easily be carried to remote areas. The students plan to eventually use it in data centres, server rooms and labs, as well as for dousing forest fires.

For now, it remains a prototype, and work is underway to make it more compact and powerful. The students are also preparing to apply for a patent for the project. They are looking to take the innovation beyond a college project and turn it into a commercial product.