No doubt the fire and other emergency services will tell us eventually, but it's quite possible the initial explosion was caused by sawdust suspended in air, which in the right concentration is highly explosive and can be set off by the tiniest spark. Other dusty substances, flour and even cement, behave in a similar way.
The navy is very paranoid about flash explosions. I seem to remember people having to wear felt overshoes, like big slippers, when they entered naval weapon storage facilities, or magazines as they were called in calling-a-spade-a-spade days. They were supposed to suppress static electricity and prevent sparks being struck by metal heel or toe studs on people's shoes.
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"The navy is very paranoid about flash explosions"
With some justification, when they have rooms full of munitions, and what you have described happens with plain ol' sawdust!
I was involved some years ago with a device for in-situ testing of solid rocket fuel used to propel short-range missiles, and there were a few precautions involved there, I can tell you!
I'm not sure I'd describe it as paranoia, though...
Last edited by: J Bonington Jagworth on Fri 17 Jul 15 at 18:35
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>> I'm not sure I'd describe it as paranoia, though...
Heh heh... I suppose just commonsense really.
But I do remember people's cigarettes, lighters, matches and pipes being solemnly shut in a metal box at various places, not always obviously hazardous ones, and entrusted to the dockyard or admiralty police in their khakis and slouch hats until the inner sanctum was reached, when the box would be opened and the adults would resume their usual chainsmoking.
Regulation drift... have I come up with a new concept? The metal box businesss wasn't entirely rational. It might have been at first but things had moved on. I could see that even as a child.
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Flour yes, cement no. it's non-flammable.
Last edited by: CGNorwich on Fri 17 Jul 15 at 18:49
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>> Flour yes, cement no. it's non-flammable.
So one would think. But I do seem to remember a flash explosion involving cement dust. Perhaps it was just wishful thinking.
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>> So one would think. But I do seem to remember a flash explosion involving cement
>> dust. Perhaps it was just wishful thinking.
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Pure cement yes but add some contaminant or other mix and the risk is there.
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You could of course say that of anything.
Organic materials are the main problem Wood flour, flour, sugar etc. Most mills dealing with these products typically are designed to vent explosions via a light roof. Very specific regulations regarding dust extraction and cleaniinf of ledges etc where dust can accumulate. You still need a flashpoint, which quite often proves to be elecrical.
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The putative culprit was named on Ceefax last night as "wood flour". This is a product manufactured for use as a filler in, for example, lino.
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The culprit was obviously going to be wood flour. It was a wood flour mill. That's what it made.
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Woodmill explosion near Macclesfield - J Bonington Jagworth
