This experiment is one of those things that looks too simple but it has been proven by Mythbusters to be true. A large container is filled with sawdust, a road flare is stuck in the top and some compressed air is released in the bottom of the sawdust container. The results are amazing! I would have been one of the skeptics if I didn’t see the recreation by Mythbusters.
"My brother has been working on a way to make large explosions without the inherit danger of real explosives. Sawdust ignites well when mixed with the right ratio of air, so he devised this contraption. I hope to have an example of this at night- which is a truly spectacular effect!"
Sawdust Cannon. from Ben Stone on Vimeo.
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Now there is this voice i my head saying: Do it. Do it, but do it bigger!! 😀
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i dont get it. what’s the point of the high flow valve?
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The high flow valve is so that the compressed air is released into the container of sawdust very quickly. Without it the plume of sawdust would not be very high.
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I like science and engineering and such, but I love these videos purely for the beauty of a big fireball!
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say (i’m not english) what is sawdust? little piece of wood that come out of my chainsaw when i cut a three? in that cas, the saw dust need to be very dry no?
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Hey sliders_alpha
Yes that’s right, but the sawdust can also come from a wood shop where they use dry wood.
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Very coool, but not too interesting. It is quite obvious. Most any substance which is finely divided, i.e. has a high surface are will ignite in air, flour, finely divided metals, saw dust…
There’s not much to think about.
another fun one is potassium manganate 7(rather powerful oxidising agent) and fine dust.throw that trough a fire and it is even more spectacular.
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Reminds me of a trick I used to pull in restaurants. Take an empty 5 gallon bucket, throw in a scoop of flour, put the lid on and swing it around by the handle for a while. Pull of lid, drop in lit match- whoosh! Impressive, brief fireball, scared wait staff, lotsa fun. Of course, this is also why sawmills and grain elevators go up from time to time…
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As Amit says, not terribly interesting, certainly not a myth, but still fun to do. You don’t even need the high-tech approach, a large spoonful of flour, custard powder, or fine sawdust simply thrown through a naked flame will produce a fairly impressive fireball.
sliders_alpha – nope, doesn’t need to be terribly dry. Powder explosions are massively exothermic (hence the big fireball), as soon as you get one going the relative humidity of the powder doesn’t matter overly much as long as it is well mixed with air.
Powder explosions are a very real hazard, to the point where flour mills have *very* specialised electrial switchgear – the flour in the air is quite enough to totally remove the building from the map, and distribute its parts over a fairly wide radius. http://en.wikipedia.org/wiki/Washburn_%22A%22_Mill for example.
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As Amit notes… nothing new, and in my opinion, nothing that would have required Mythbusters (are they some new standard or something). I think of silos etc., which have demonstrated this issue for time emporium.
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I am not so sure that it was obvious. I personally would not have thought that that small volume of compressed air (one old propane cylinder) would have produced enough rush to through the plume of sawdust that high in the air.
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This would be so much easier (and even less dangerous) to do with black powder, instead of the high pressure air setup. Only one pressure sensor has to be faulty, only one pressure fitting damaged, for someone to be seriously hurt around a homebuilt pneumatic system.