Some fire extinguishers work with spraying water under pressure, but I noticed that some seem to spray out some sort of powder. (And if you’ve seen videos of exploding coffee creamer, then you’ll understand my confusion. 🤣) Turns out, many powder substances when blown into the air becomes flammable, such as sawdust, flour, non-dairy coffee creamer, pollen, powdered milk, cocoa, grain, starch, sugar, and even some metals. The worst dust explosion happened in 1942 in China. The coal-dust explosion killed 1,549 people – 34% of the workers in the mine.
Found this poster from World War I in Wikipedia’s creative commons. It was put out after six dust explosions. 😬
A dust explosion happens when something ignites a dispersed flammable substance (fuel) in a confined area.
I do realize that not all powders are combustible, but it made me wonder what is inside a fire extinguisher and why the aerated powder doesn’t combust.
Fires can happen when heat, oxygen, and fuel combine. You get fire as a chain reaction. A fire extinguisher is designed to remove at least one of these three things, which makes the chain reaction stop.
There are three types of fire extinguishers: water-based (removes heat from the fire), dry chemical (usually filled with foam or a mix of monoammonium phosphate and ammonium sulfate powder with a nitrogen propellant – this works by removing oxygen from the fire), and carbon dioxide (a mix of liquid and gaseous carbon dioxide removes oxygen and heat).
It looks like different extinguishers are used for different fires. For example, you don’t want to use a water-based one for an electrical fire because you may get electrocuted, and you don’t want to use the dry chemical extinguisher on a chlorine or oxidizer fire because that could cause it to explode.
So in short… under the right circumstances, a dry chemical extinguisher COULD explode. 😱