OT. Hypothetical explosive related legal question

Ignore this if you don't feel happy with the subject, but I know that we have one or two people that have relevant knowledge or views.

This is one that has been causing me some considerable disquiet of late.
This is purely hypothetical but...
If a person put a retail butane or propane cylinder in a vehicle, surrounded it with rags, soaked in petrol and possibly surrounded some or all of it with nails, then set fire to it. How could they possibly be charged with "Doing an act with intent to cause an explosion likely to endanger life or injure property"?
Unless the safety valve on the cylinder were disabled or plugged, surely the offence must be arson, since no explosive substance or device is involved in the assembly otherwise. and the laws are quite clear that a conflagration is not an explosion.
Or is it that if you hope to kill someone by tickling them to death with a hypoallergenic feather, that it is still attempted murder?
Puzzled Mark Rand RTFM
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On Fri, 17 Oct 2008 22:53:56 +0100, Mark Rand

Because Fuel/air mixtures are explosive.

Propane/air, flour/air, petrol/air are all explosives in the right mixture. Buncefield was just a bit of petrol and a spark or two. For a "conflagration" it looked, sounded and felt very much like an explosion to me. I don't think all the buildings got redesigned in a "conflagration" either.
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wrote:

If you'd been on 'ground zero' at Buncefield ( I have been), you would be fairly certain that there was an explosion; the sight of the crushed cars in our (former) building's car park and the collapsed remains of my former workplace would tend to indicate that it wasn't just a coflagration, despite the fact that it was 'only' an uncontained ignition of petrol vapour. Martin
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martin<dot here>whybrow<at here>ntlworld<dot here>com



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On Sat, 18 Oct 2008 00:37:08 +0100, "Martin Whybrow"

In my miss spent youf, before such things were regarded as terrorist events, I made fuel-air explosions along with other honest-to-goodness explosions. I would submit that the volume of air inside a motor car is insufficient to create a meaningful explosion except under carefully controlled conditions. Those could not possibly have pertained with the equipment in the "hypothetical" case (especially with bloody open windows!)
I have no problem with locking people up specifically for being stupid. But I am deeply worried about potentially locking people up for something they could not possibly have achieved.
(Hypothetically :-) Mark Rand RTFM
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On Sat, 18 Oct 2008 02:14:23 +0100, Mark Rand

It doesn't have to be a big explosion to count, even a small one would do.

I think a safe presumption would be that the intention of piling petrol soaked rags around propane container and igniting it was to cause an explosion. That built in safety features would minimise (but not eliminate) that explosion isn't much of a defence.

If someone started shooting at me from 100m with a shotgun I'd be a bit peeved if PC Plod declined to arrest them because they were not close enough (yet) to cause injury.
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Mark Rand wrote:

"with intent to" - it doesn't mean what they did could successfully cause an explosion, just means they intended it to.
Their incompetence does not change their intent, only the outcome.
-- Peter Fairbrother
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As I understand it the definition of an explosion is that the chemical reaction "front" travels outwards at subsonic speeds (as opposed to a detonation in which the velocity is supersonic and a conflagration which is localised, however intense). Gas/air mixtures have complicated flame behaviour. There are composition ranges giving stable flames and others giving explosions.
I'm no engineer in these matters but my guess is that any safety device on a gas cylinder is designed to cope with moderate overpressures due to heat. If the cylinder is heated to a high enough temperature by an external conflagration my guess is that the safety device will simply not be able to "blow off" fast enough, pressure will build and the cylinder will rupture violently. Under those conditions there will not be enough oxygen to burn the rapidly expanding fuel (small volumes of liquid make lots of gas) so there will be a rapidly expanding "ball" of fuel which travels faster than the flame can and dilutes with air until it reaches the explosion limit, at which point the core flame can suddenly propagate and you have a proper explosion. Look up thermobaric weapons for more detail.
Just my guess for what its worth - I'll leave it to the experts to tell me what is wrong with the argument.
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On Sat, 18 Oct 2008 10:56:42 +0100, "Norman Billingham" <norman.at.tumulus.org.uk> wrote:>

I've seen propane cylinders which had been in a fire, some of them had ruptured very thoroughly.
Tim
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Norman Billingham wrote:

The term "explosion" is ill-defined. "An explosion may be defined as a loud noise accompanied by the sudden going. away of things from the places where they were before."
When an energetic flame front travels through a material at less than the speed of sound it is known as a deflagration. If the velocity is supersonic, then as you say it is a detonation.
A conflagration is just a large fire.

That's correct - further, the released liquid can then turn to gas, in the process expanding violently, in a BLEVE (boiling liquid expanding vapour explosion).
[1] the gas pressure breaks the container, an explosion - [2] the released liquid vaporises almost instantly in a second explosion, a BLEVE - [3] the gas from the released liquid burns or .. see below
However the fire would have to be very hot indeed, like a blowtorch - containers are designed to fail gracefully in ordinary fires.
Under those conditions there will not be enough oxygen to burn

The expanding ball of gas will most likely burn at the edges where it meets the air. It's quite hard to make a thermobaric (fuel/air explosive) detonation, except in enclosed spaces and when the gas and air have a long time to mix thoroughly.
But whether it would have exploded doesn't matter, what matters is that they *thought* it would explode.
Some other examples - the "liquid bomb" plotters explosive would probably have worked, but they didn't get to the stage of actually making bombs - nevertheless they were guilty of "Doing an act with intent to cause an explosion likely to endanger life or injure property".
The Police swapped dummy explosives for some semtex, which was later made into a "bomb" by an Irish bomber, can't remember what flavour. Again he has guilty, even though it couldn't have exploded.
The failed tube bombers explosive obviously didn't work, but they thought it would - again, guilty.
The gas doctors? Seems they thought it would go bang. Guilty.
Chemist makes a mistake and blows up his lab - not guilty.
What is slightly worrying about the offence is that there is no exception for your own property - suppose you blow up a tree stump in your garden, you aren't just guilty of the lesser EA offences, but of the greater offence, which carries a maximum life sentence. Also, the damage to property might be very small, but you'd still be guilty.
In practice however, I only know of one case where this charge was misused, and that was for a different purpose and they were open about it - they weren't seeking to send the guy to jail, just to get his explosives license revoked (long complex story).
-- Peter Fairbrother
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On Sat, 18 Oct 2008 12:14:55 +0100, Peter Fairbrother

Ah - so a cat when you stand on its tail becomes an explosion? Seems reasonable :-)
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wrote:

I guess I'd better start being very careful what I hope when I fart in the Boss's office :-|
Mark Rand RTFM
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Mark Rand wrote:

This is pretty simple I think: the person intended their actions to cause an explosion, even if safety features meant that they would not.
Chris
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Mark Rand wrote:

I think the operative word is "intent"
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I won't go into detail, but if metal gets hot it doesn't have as much strength as it does cold. If it gets hot enough then it will not contain the pressure even if the pressure relief valve is doing its job. If this happens you can get a sudden rupture and the result is a BLEVE, a boiling liquid expanding vapour explosion. Look it up...so its not the sizing of the pressure relief, its the weakening of the metal. Plenty on u-tube, but of course the industrial scale ones tend to make better pictures.
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On Sat, 18 Oct 2008 16:21:03 -0700 (PDT), Cheshire Steve

This is part of the problem. How do you think that the metal could get that hot in a simple distributed fire without raising the temperature and pressure of the contents to the point of causing the safety valve to lift? These are the circumstances for which the safety valve is designed! Arson is simple to prove. Explosions require more thought. I would have such difficulty sitting on a jury in such a case and living with my conscience that I would probably be forced to ask to be excused and face the contempt of court and retrial issues that went with it.
Oh well. Not my problem. I'm sure that such a quandary couldn't occur in the real world...
Mark Rand RTFM
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Mark Rand wrote:

Different people see cases in different ways, and consequently so do different juries. Ultimately some things are a matter of opinion, so different jurors can have different opinions without either of them being wrong. What is reasonable doubt is a matter of opinion.
If you sit on a jury and have an honest and considered view which is different to that of the other jurors, that's allowed. Besides, in England a jury split 11-1 or 10-2 won't result in a mistrial. That only happens in the US.
Personally I think I would have had problems voting to convict O.J. Simpson in this latest trial in Las Vegas, had I been on the jury. It just looked like a disturbance of the peace to me. I'm probably in the minority, I know. But different people have different opinions. That's life.
Best wishes,
Chris
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Which bit of "even if the safety relief valve is doing its job " did you interpret as the safety valve not lifting ? When I say it is "doing its job" I mean it is maintaining pressure exactly as designed. I can't make it simpler .. please someone tell me how can I make it plainer that if the metal turn to cheese cos its bright red, then it won't hold the pressure - EVEN IF THE FRIGGIN PRV IS WORKING PERFECTLY.
This is such hard work. I give up - figure it our for yourselves.
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On Fri, 24 Oct 2008 16:07:50 -0700 (PDT), Cheshire Steve

A conflagration with a fireball is not and never will be an explosion. Arson could be proved in a morning of court time. Conspiracy to cause an explosion could not be reliably proved at all. Vehicle fires involving small retail propane and butane bottles do not commonly cause explosions because those safety valves do lift well before the temperature at which the steel loses any strength (critical temperature of butane is 152C).
The whole point of this hypothetical question is that simple undefendable offence has been prosecuted as something that could be thrown out by any half competent lawyer or engineer.
There is a vast difference between a 3000gallon tank and an 11kg cylinder.
Law should not be decided by calm decision, not by hysterical imagination.
Mark Rand RTFM
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Few too many nots in there :-(
Mark Rand RTFM
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