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Speaker 1: Welcome to brain Stuff from house stuff Works dot com

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Speaker 1: where smart Happens Hi Immercial Brain with today's question, how

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Speaker 1: do dry chemical fire extinguishers work? If you ask any

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Speaker 1: firefighter what it takes to create a fire, you will

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Speaker 1: learn that you have to have three things. First, you

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Speaker 1: need a fuel. You need some sort of combustible solid

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Speaker 1: liquid or gas. Next, you need oxygen to react with

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Speaker 1: the fuel, and finally, you need heat. There must be

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Speaker 1: enough heat to get the fuel above its flashpoint. If

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Speaker 1: there is paper on your desk right now, that's a

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Speaker 1: fuel and it's surrounded by oxygen, but it does not

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Speaker 1: burn unless you get the paper hot enough. If you

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Speaker 1: want to put out a fire, you need to remove

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Speaker 1: one of those three elements. When you watch firefighters battling

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Speaker 1: a forest fire, they generally try to remove fuel or heat.

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Speaker 1: Either they pour water on the fire to reduce the temperature,

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Speaker 1: or they try to bulldoze strips of bare earth to

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Speaker 1: eliminate the fuel. A carbon dioxide fire extinguisher works by

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Speaker 1: eliminating oxygen and replacing it with carbon dioxide. You can

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Speaker 1: do the same thing with just about any non oxidizing

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Speaker 1: gas nitrogen, for example, but carbon dioxide is inexpensive and

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Speaker 1: easy to store. Another way to cut off oxygen is

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Speaker 1: to throw a blanket over the fire. Covering the fire

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Speaker 1: with dirt or sand does the same thing as a blanket.

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Speaker 1: You might have heard that you can put out a

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Speaker 1: kitchen fire by throwing baking soda or salt on the fire.

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Speaker 1: Throwing sand would do the same thing, but most people

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Speaker 1: have more salt in their kitchens than they have sand.

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Speaker 1: Baking soda also releases carbon dioxide when it gets hot,

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Speaker 1: so that makes it even more effective. A dry chemical

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Speaker 1: fire extinguisher is essentially just a fancy way of throwing

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Speaker 1: baking soda on a fire. Dry chemical fire extinguishers are

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Speaker 1: by far the most common fire extinguishers in the home.

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Speaker 1: They can handle all three types of fires that you

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Speaker 1: would find in a kitchen or workshop, combustible solids like water, paper,

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Speaker 1: combustible liquids like gasoline or grease, and electrical fires. The

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Speaker 1: idea behind a dry chemical fire extinguisher is to blanket

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Speaker 1: the fuel with baking soda. A dry chemical extinguisher sprays

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Speaker 1: a very fine powder of sodium bicarbonate, which is baking soda,

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Speaker 1: or potassium bicarbonate, which is nearly identical to baking soda

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Speaker 1: or mono ammonium phosphate, and these solids coat the fuel

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Speaker 1: to smother the fire. Do you have any ideas or

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Speaker 1: suggestions for this podcast? If so, please send me an

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Speaker 1: email at podcast at how stuff works dot com. For

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Speaker 1: more on this and thousands of other topics, go to

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Speaker 1: how stuff works dot com and be sure to check

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Speaker 1: out the brain stuff blog on the house stuff works

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