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Subject: Re: Magnesium, formerly The Feel of Aluminium
From: (Jonathan M. Elson)
Date: 29 Mar 1995 20:36:52 GMT

Mark Kinsler ( wrote:
: I think that K-mart or Wal-mart or somebody else with a sporting goods 
: department sells a block of magnesium for kindling purposes.  I think you 
: shave off some magnesium shavings with pappy's old Barlow knife and light 
: them somehow.  Sez it'll start a fire in the rain.  Which was my usual 

Sunce several people mention the combination of Magnesium and water, I
should let you know - if magnesium ignites, DON'T add water.  Perhaps
water will put out fires in magnesium dust and fine turnings, but it
will cause multiple explosions with heavier material.  The burning Mg
extracts the Oxygen from the air, leaving Hydrogen!  The Hydrogen can then
either accumulate and cause a secondary hydrogen explosion or combine with
atmospheric Nitrogen to make ammonia.  The hydrogen explosions are well
documented in Mg fires when people attempt to extinguish with water.
Use sand instead.  I have seen the effect of adding water to Mg fires
done for test purposes (a few grams of granular Mg) and a burning VW
Microbus The Fire Dept. didn't have enough Brominated Foam to put the
engine block (or is it the transaxle) out, so they knocked it down with the
foam, and then hit it with three hoses from 50 feet.  It was a fabulous
explosion!  Looked like the grand finale of the 4th of July fireworks!
It wasn't a Hydrogen explosion, just the Mg getting hit with lots of Oxygen.
The worst in recent memory was in the late 70's in San Jose, CA., at an
IBM disk drive plant, a dumpster full of Mg shavings caught fire.  The
inept fire department was warned it was Mg, don't use water, but they
always fight fires with water.  It blew several walls down and killed
several fireman.

From: Dave Baker
Subject: Re: Magnesium doesn't burn unless...
Date: 18 Oct 1998

>From: "Josh" <gunner1@(NOSPAM)>
>The grindings will burn with a spark, i had a survival tool that started a
>fire with flint and magnesium. You shaved the magnesium off with your knife,
>then struck the flint at the pile of shavings. (don't look at the light)
>John Willis wrote in message ...
>>All I know is after cutting off a bell housing to attach the starter
>>side to an engine sitting on the test stand, we put a sliver of the
>>remains in a propane torch flame, and after a minute or so, sure
>>enough, it burned.  I rather think that a grinder would not get the
>>metal near hot enough to generate enough heat to do the same, as a lot
>>of the cutting was done with a die grinder and the rest with a
>>reciprocating saw.

Magnesium fires are not uncommon during high speed machining on lathes, mills
etc. You need plenty of coolant and keep an eye on cutting speeds and feeds.
Once started the burn temperature is so high that putting water on the fire
makes things worse as the water is split into hydrogen and oxygen and fuels the
flame. Eventually you end up with a warm pile of melted slag where the lathe
used to be. Normal working with hand tools would be unlikely to cause too many
problems though.

Dave Baker at Puma Race Engines (London - England)  - specialist flow
development and engine work.

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