How does the stuff in a fire extinguisher stop a fire?

fire extinguisher

Let’s talk about fire! Also, fire extinguishers.

To start a fire, you’ll need three things: fuel (such as wood or gasoline), oxygen, and heat.

Fire is the result of a chemical reaction between oxygen and the fuel. Simply remove one of those three elements — fuel, oxygen, or heat – to put out a fire. When the fire is under control, removing the fuel is simple. When you turn off the gas on a propane grill, for example, the fuel stops flowing and the fire goes out.

I teach chemistry and have seen firsthand how difficult it is to remove the heat or spark from a reaction. Once the fire is lit, it gives heat and continues to burn. That is why putting water on a fire extinguishes it. When water comes into contact with fire, it boils, turns to steam, and floats away, absorbing some of the heat. It also keeps oxygen away from the fuel.

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The majority of fire extinguishers work by separating the fuel from the oxygen in the air. Air is the source of oxygen. It is the same oxygen that humans take in. Because oxygen must come into contact with the fuel, the fire will die out if the fuel is coated with something that keeps the oxygen out.

Gas that is cool to the touch

Water isn’t the only chemical capable of extinguishing fires. You’ll need something that won’t burn, is light, and spreads easily. Carbon dioxide is a popular option.

Carbon dioxide is a colorless, odorless gas found in the atmosphere. People and animals inhale oxygen and exhale carbon dioxide from the air.

When wood burns, this is exactly what happens. The fire consumes oxygen while emitting carbon dioxide. So carbon dioxide has already been burned; if you toss it on a fire, it will not ignite.

Carbon dioxide is easy to store and distribute because it is a gas. When a steel canister is squeezed, the gas escapes when the nozzle is opened.

Carbon dioxide has a greater density than oxygen. As a result, when you spray carbon dioxide on a fire, it sinks beneath the oxygen and separates the fire from the oxygen. There is no fire if there is no oxygen.

Danger lurks at every corner

Carbon dioxide provides a number of significant advantages. Because the gas is squished into a canister, it is extremely cold when it emerges – at least minus 100 degrees Fahrenheit – and thus removes heat from the fire.

Carbon dioxide simply floats away when sprayed on a fire. That means there will be no cleanup. Water will flow along the floor if thrown on a fire. This means that if the fuel is light enough to be carried, water can spread the fire. As a result, carbon dioxide eliminates two of the three elements required for a fire.

Carbon dioxide, unlike water, does not conduct electricity, making it ideal for electrical fires.

In enclosed environments, the greatest danger of employing carbon dioxide is suffocation. Carbon dioxide may extinguish a fire by depriving it of oxygen, just as it can extinguish a human.

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