It is amazing to think that dust can be explosive! But, there are many documented cases of explosions being caused by coal dust floating in mines and by grain dust floating around in silos. This science demonstration helps show how dust can cause an explosion!
How can dust cause an explosion?
First, let's talk about the fire triangle which outlines the requirements for a fire to start and to be sustained. For a fire to occur - oxygen, heat, and fuel must be present. If you take any part of the fire triangle away, a fire will not occur.
Then, let's examine a grain bin explosion as an example of a dust explosion. Wheat, for example, is a seed that is ground down to make flour for bread, pastas and many other things. Wheat has calories - meaning it stores energy in the form of carbohydrates and fats. In a grain bin, it is possible that wheat dust (small pieces of wheat that break off during transport) would mix with air in the grain bin as dust. At this point we have two sides of our fire triangle: fuel (grain dust), and oxygen (in the air). All we need is the third part which is heat. This heat could come from the sun as the steel of the bin heats up or from an electrical connection used in the equipment that transports the wheat through the facility where the grain bin is located. If all three sides of the fire triangle are present then a fire can occur. And, if a fire occurs in a confined space, the pressure can build up and a violent explosion can occur (for examples visit: https://en.wikipedia.org/wiki/Dust_explosion).
That violent dust explosion is what we are modeling in this demonstration!
Dust Explosion Demonstration
Supplies:
Lycopodium (recommended) or Cornstarch
Instructions:
Drill a hole into the side of the paint can so that the funnel will fit tightly.
Fit the laboratory funnel into hole so that the opening of the funnel is inside the paint can.
Attach the hose to the portion of the funnel that is sticking outside of the psint can.
Set a candle inside the paint can so it is very close to the opening of the funnel.
Fill the funnel with a small amount of lycopodium or corn starch.
Light the candle and securely attach the lid of the paint can with a hammer or mallet.
Blow into the rubber tubing.
Boom!
Precautions / Disclaimer:
Do not try this. These instructions are provided for trained science professionals so that they can safely perform this demonstration for science education purposes. Beals Science and Craig Beals can take no responsibility for any accidents or injuries. Perform the demonstration at your own risk.
Keep on Learning! ~Craig Beals
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Flame Thrower Made from Moss Spores
Holding Fire in my Hand
Exploding Eggs
