Speaker 1: Welcome to brain Stuff from house stuff Works dot com
Speaker 1: where smart Happens Hi Immercial Brain with today's question, how
Speaker 1: do dry chemical fire extinguishers work? If you ask any
Speaker 1: firefighter what it takes to create a fire, you will
Speaker 1: learn that you have to have three things. First, you
Speaker 1: need a fuel. You need some sort of combustible solid
Speaker 1: liquid or gas. Next, you need oxygen to react with
Speaker 1: the fuel, and finally, you need heat. There must be
Speaker 1: enough heat to get the fuel above its flashpoint. If
Speaker 1: there is paper on your desk right now, that's a
Speaker 1: fuel and it's surrounded by oxygen, but it does not
Speaker 1: burn unless you get the paper hot enough. If you
Speaker 1: want to put out a fire, you need to remove
Speaker 1: one of those three elements. When you watch firefighters battling
Speaker 1: a forest fire, they generally try to remove fuel or heat.
Speaker 1: Either they pour water on the fire to reduce the temperature,
Speaker 1: or they try to bulldoze strips of bare earth to
Speaker 1: eliminate the fuel. A carbon dioxide fire extinguisher works by
Speaker 1: eliminating oxygen and replacing it with carbon dioxide. You can
Speaker 1: do the same thing with just about any non oxidizing
Speaker 1: gas nitrogen, for example, but carbon dioxide is inexpensive and
Speaker 1: easy to store. Another way to cut off oxygen is
Speaker 1: to throw a blanket over the fire. Covering the fire
Speaker 1: with dirt or sand does the same thing as a blanket.
Speaker 1: You might have heard that you can put out a
Speaker 1: kitchen fire by throwing baking soda or salt on the fire.
Speaker 1: Throwing sand would do the same thing, but most people
Speaker 1: have more salt in their kitchens than they have sand.
Speaker 1: Baking soda also releases carbon dioxide when it gets hot,
Speaker 1: so that makes it even more effective. A dry chemical
Speaker 1: fire extinguisher is essentially just a fancy way of throwing
Speaker 1: baking soda on a fire. Dry chemical fire extinguishers are
Speaker 1: by far the most common fire extinguishers in the home.
Speaker 1: They can handle all three types of fires that you
Speaker 1: would find in a kitchen or workshop, combustible solids like water, paper,
Speaker 1: combustible liquids like gasoline or grease, and electrical fires. The
Speaker 1: idea behind a dry chemical fire extinguisher is to blanket
Speaker 1: the fuel with baking soda. A dry chemical extinguisher sprays
Speaker 1: a very fine powder of sodium bicarbonate, which is baking soda,
Speaker 1: or potassium bicarbonate, which is nearly identical to baking soda
Speaker 1: or mono ammonium phosphate, and these solids coat the fuel
Speaker 1: to smother the fire. Do you have any ideas or
Speaker 1: suggestions for this podcast? If so, please send me an
Speaker 1: email at podcast at how stuff works dot com. For
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