– How exactly does water put out a fire? Is it a smothering thing, or a chemical reaction?
In: Chemistry
Certified but retired firefighter here.
Fires have to have four things to exist, we call this the fire tetrahedron.
1. Fuel
2. Oxidizer
3. Heat
4. Chemical Reaction
It’s the 4th one that most people don’t know or remember and is missing in the fire triangle.
Water works in different ways for different fires. A simple wood fire the water cools the wood (heat) and penetrates into it creating a barrier between the wood (fuel) and the air (oxidizer). Water is very effective here.
It is important to remember that when water is used lots of steam is created. This is because water expands over 1700 times when converted to steam.
Fire fighters plan for different scenarios where things like the fuel sources or oxidizer change for example. Additives to the water (detergents) help create foam and increase the penetration of the water so it soaks in. Ever have water sit on the surface of your clothes or couch, we want it to soak in immediately.
For more learning look at chemical fire suppression agents like fm220 and fm200. They work by preventing the chemical reaction. A common misconception is that they remove oxygen from the area. Additionally,Take a look at steam converting a room.
Fire science was so interesting to me and many of you may find it interesting as well. Contact your local fire department and see if they have a citizens fire academy type class. You might get to experience several aspects of fire fighter life including:
Protective equipment – bunker gear, SCBA
Fire apparatuses – tankers, engines, ladder.
Fire fighting tools – nozzles, hoses, hand tools, foams, saws, ladders.
Fire science – How and why it exists. How to “kill” it.
Rescue – Cut up automobiles! Rappel!
Communications – radios and 911 dispatch
Fire command – scene control, public relations, incident command
Safety – man down alarms, strobes
Emergency Medical – cpr, triage, etc
Firefighting history – fire insurance, fire fighting around the world.
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