The Fire Triangle
Posted: September 4, 2018
Don’t pull the alarm. Don’t ring the bell. That was not a warning. It was just a fact.
Somewhere in this world, fire is burning grassland or forest. And that’s fine—mostly. In God’s creation, fire has its place. A fire now and then cleans up a forest floor or stops overgrowth of grass and bushes on a prairie. Some trees depend on the heat of a fire to release seeds from their pine cones. Fire in nature only becomes a problem when it harms people and property. Then it needs to be controlled. To control fire, we have to understand it. Start with this: Fire is not a thing. It is an event. And the event continues as long as it has three ingredients. Those are the three sides of the “fire triangle”—oxygen, heat, and fuel. You might say that firefighting is a game of takeaway. Take away one side of the triangle and the fire event ends.
Take away oxygen:
Burying a fire in dirt keeps oxygen from reaching it.
Fire extinguishers spray a cloud of powder that crowds out oxygen-rich air. When water from a fire hose hits fire, it evaporates into a blanket of steam that takes the place of oxygen-rich air. Did you know that firefighters battling a blazing oil well sometimes light sticks of dynamite? The explosion uses up all the oxygen in the air near the fire.
Take away heat:
A sudden heat source can start a fire. It can be tiny, like a spark. It can be huge, like a lightning bolt or lava. A fire spreads by heating nearby fuel enough to burst into flames (about 500 degrees), then heating more nearby fuel, and so on. When water hits fire, it absorbs heat as it expands into steam. A fire starved of heat cannot make nearby fuel hot enough to burst into flames.
Take away fuel:
Hotshots make a fire break. These hardworking firefighters rake, dig, cut, and haul away brush. They light backfires to burn away brush and grass. A wildfire starves from lack of fuel when it reaches the bare ground of a firebreak.
Fuel is the one side of the fire triangle that people can control in advance. That’s where good planning and regular maintenance come in. Send in the goats!