I just returned from a camping trip with our scouts and even in the summer heat they wanted a campfire to toast some marshmallows. But the kids often struggle to get a fire going. Understanding the science of fire makes building a fire easier and is an important part of fire safety.
The Science of Fire – The Fire Triangle
First, you must understand that a fire requires three elements, which are known as the fire triangle:
The first thing to consider in the science of fire is fuel. Fuel is the part of the fire triangle which you are burning. For a campfire, this would usually be wood. The wood has cellulose (the stuff which makes up plant cells) and some moisture.
When you are starting a fire, you are heating the wood up and getting rid of the moisture. Only after you get rid of the moisture will the wood give off burnable gasses and really start to ignite.
So drier wood is better for starting a fire. This is also why you must be extra careful when using fire in dry, drought-like conditions. In this setting a fire can start quickly and rapidly become out of control.
Heat is also an essential part of the science of fire. When a fire burns, a chemical reaction takes place and the energy stored in the chemical components of the fuel is released. But heat is also what starts that process. So basically, you need some heat to start the fire in order to burn off the moisture and to cause the carbon in the fuel to burn.
The larger your fuel, the more heat you will need to start the reaction. This is why you need to start with paper and tinder. Holding a lit match under a log will not make it catch on fire. Holding the lit match under your paper and tinder will start the ignition process.
Oxygen is the third part of the fire triangle and is required for the chemical reaction. More oxygen will cause the fire to burn hotter and restricting oxygen will slow the reaction down or even stop it. This can be seen when you get a little flame going and then add a big pile of fuel on top, smothering it. The excess fuel restricted the flow of oxygen to the flame and stopped the reaction.
Gently forcing air toward a fire can help it grow. But if you blow on the fire with two much force, you blow away the flammable gasses, which also puts out the fire. The simplest example of this is blowing out a candle. Safety is always a concern when blowing oxygen on a fire also. It is better to fan it with a flat object or blow through a tube rather than putting your face close to the fire.
Since oxygen is required for the reaction, removing oxygen can be a very effective way to control fire. So if you have a campfire, it is a good idea to have a shovel and some dirt or sand nearby in addition to buckets of water. Adding dirt or sand to your fire will restrict the flow of oxygen and is a very fast way to make it smaller or extinguish it all together.
So understanding the science of fire and the fire triangle can help you light a campfire quickly and also know how to safely control it.