[T2] Re: LPG as BusFuel

[Robt Mann <robtm@xxxxxxxxxx>]

>A propane depot ignited.. http://www.youtube.com/watch?v=__1Ym_F94CE

	Thanx.  My morbid interest in dangerous technologies is not 
hard to re-ignite  ;-)
	Since it's Friday, and anyhow most T2 drivers visit fuel 
stations with LPG tanks c.2 - 4 ton where they are at some risk even 
if not buying the stuff themselves, let me point out that this 
classic BLEVE (boiling liquid expanding vapour explosion) emits heat 
felt by those making the video  -  a km or so away.  The blast is 
minimal, compared with what can be produced by delayed ignition after 
mixing the LPG vapour with air.
	After my paper (with Brian Williamson) in Combust. Sc. Tech. 
on LPG fireball theory, I visited the previous leading theorist, at 
Sandia Corp (nr Albuquerque N.M.).  He showed me slow-motion films of 
their earlier expts which had contributed to the class of weapon 
called fuel-air explosives, which the USAF had then dropped in 
Vietnamese jungles, to blow down an acre or so of forest (preparatory 
to landing helicopters).  A flimsy canister bomb bursts on hitting 
the ground; the LPG vapour, 300 times the volume of the liquid it 
evaporated from, is denser than air and spreads like a pancake, 
mixing with air.  Then small bomblets which departed from the mother 
bomb on the way down explode in the periphery of the gas/air cloud 
where (with luck) the mixture is within the (rather narrow) 
combustible range.  A wide-area gas explosion then occurs, and the 
pressure wave from it goes further than that from an ordinary solid 
explosive.  In practice, a flash fire often occurs instead; that is 
the greater practical worry to the LPG industry, as burns are a much 
more effective way of killing than explosions (just ask Hitler who 
was badly affected but did survive von Stauffenberg's solid 
explosive).
	I plead with those not familiar with this science to accept 
my word for it: LPG vapour can cause drastic fire/explosion damage 
over a far, far wider distance than any ordinary mind would intuit. 
Treat the stuff as much more dangerous than petrol, and do not be shy 
if you see anyone mishandling it.
	The same awareness is also needed away from filling stations 
or mobile tankers  -  e.g campsites where 1/100 ton bottles abound, 
potentially capable of severely injuring a dozen or so people within 
a range of several campsites.  Check couplings with soap solution; do 
not allow untrained personnel to make such unions.

R

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