What Gives a Fire Life and Keeps It Going?

How does a fire start and keep burning? Just as we need oxygen, so does a fire, and in approximately the same amounts. The air we breathe is 21% oxygen. If the level of oxygen should fall below 16%, there is not enough oxygen to support life, nor is there enough to support combustion. Our barns, usually designed to provide good ventilation, will permit a continuous supply of oxygen to a fire.

And, as we need fuel in the form of food to keep our bodies functioning, so does a fire. Fuels are found in three physical states: gases (natural gas, propane, hydrogen); liquids (gasoline, kerosene, alcohol, paint); and solids (coal, wood, grain, hay, plastics).

Gases in your barn are normally contained in consumer products in aerosol cans, such as grooming sprays or insect repellants. Liquid fuels are more common. Alcohol, alcohol-based liniments and rubs, hoof tars, and stop-chew products can be found in any barn. Of course, solid fuels are available in abundance–hay, straw, loose or baled shavings, grain, and the materials of which the barn is constructed.

Along with oxygen and fuel, there must be a source of heat that raises the fuel to its ignition point. Heat can be provided by sunlight, friction, electrical energy, open flame, compression of gases, and bacterial or chemical reactions. Combining heat with oxygen and fuel will permit a fire to start, but in addition to these factors, fire is maintained by chemical reactions that occur in the flame area itself, reactions which produce additional fuel and heat.

Fire suppression is successful when the tactics employed reduce or remove any of the essential components a fire needs to continue. Water is the most commonly used suppression material because of its ability to quickly lower temperatures below the fuel’s ignition point.