Free Radicals

Free radicals form the basis of fire. When a material warms, molecules vibrate from side to side. As they do so, some break away from the main body of material. These are what is known as Free Radicals.

Due to now increased surface area of the material, sufficient oxygen can reach the free radical for combustion. Providing the temperature is high enough, an exothermic reaction ensues which emits radiation in the visible light band. This is what we call flame.

This exothermic reaction further increases the heat in the area, causing the molecules in the body of material to vibrate even more, thereby emitting more free radicals. It is due to this that fires are seen to grow in heat and violence.

Free Radicals also are the basis of fire extinguishing systems:

• Cooling material down via liquid-based agents (e.g. Water Extinguishers) reduces the amount of free radicals being emmitted
• Reducing the concentration of oxygen via gaseous suppression agents means that the chemical reaction is cut short
• Attacking and changing the chemical composition of the free radicals via aerosol suppression agents effectively eliminates the material’s ability to burn.