[PmbPhy (OP)]

Here's a cool question I thunk up.

At Lisa's Fuel and Eats gas station the there is a no smoking sign. A man is driving along in his car minding his own bees wax, having a smoke, when he realizes that he needs gas. So when he gets to Lisa's he stops, gets out of the car with smoke in hand, and starts pumping gas with the lit smoke in his pumping hand. Lisa sees this and activates the halogen fire suppression system. The man is startled, stumbles, falls down and hits his head on the pavement and is dazed. Before he can recover he is asphyxiated by the halogen and dies.

Who is most responsible for his death? The smoker or Lisa? Nobody can be accused of manslaughter here of course.

[geordief]

It was Karma.

[Colin2B]

The person who failed to train Lisa properly.
And over here and in France they could face manslaughter charges.

[chris]

Shouldn't this be in "Just Chat" - it's more a legal debate than a science question surely?

[PmbPhy (OP)]

Shouldn't this be in "Just Chat" - it's more a legal debate than a science question surely?

Wrong. It's Lisa's fault. Her ignorance to be exact. The possibility of a lit smoke infighting gas fuse is highly unlikely if not impossible. The heat of the smoke is below the heat of ignition of the gas fumes. The no smoking sign is to make sure that no fire is started by any means while a smoke is being lit since the heat of the flame itself can ignite the fumes. Also there's a small chance that a good toke on the smoke will heat it up enough to cause ignition. But in any case the fumes are almost always too dilute to ignite.

When I was a teen I dropped my smoke into a puddle of gas, intentionally. I think I wanted to see what happened. It was put out. I remember it made a strong, lasting memory. People don't do things like that. At least non-pyromaniacs and non-scientists. Those were my experimental years.

Try it and see what happens. You can also learn this online at reliable sources. Mythbusters also addresses it. Hollywood has to ignore it to make exciting movies. And let's face it. Almost all of us have visions of exploding gas stations from watching movies and TV. And we all know that they lie. We just don't know how much. They had a very hard time getting an apartment to ignite when it was filled with natural gas too. The natural gas replaces the oxygen and both are needed for ignition. The result?

Hollywood: KABLAMM.. BOOOOMMM . KAPOWWW!!!

Reality: Pop.

It's a cool thing to watch. I loved that show. Too bad its no longer running new episodes. ;(

[PmbPhy (OP)]

The person who failed to train Lisa properly.
And over here and in France they could face manslaughter charges.

Remind me never to go to France. How could they do that? Lisa was acting in good faith. Its to her understanding that a fire or explosion was impending and indented to extinguish the flame. What happened to the smoker could never have been foreseen. In fact its ignored when they install such devices. Manslaughter applies to negligence or as the result of an act such as assault (e.g. pushing a man in a hallway but he falls over a railing and falls two floors and dies.)

[Petrochemicals]

You are for being concious. If you where not there would be no concept of responsibility as there would be no basis for blame

[PmbPhy (OP)]

You are for being concious. If you where not there would be no concept of responsibility as there would be no basis for blame

Please rephrase. I don't understand what that means.

I made a boo boo here. I was curious to about how widespread the notion that a smoke could ignite fumes and gas was. If I just asked then I was certain some would do a search and post what they found. So I phrased it in a way to get the info I wanted. Unfortunately this thread resulted in conversation I was not aiming at.

My bad.

[Bored chemist]

The person who failed to train Lisa properly.
And over here and in France they could face manslaughter charges.

Remind me never to go to France. How could they do that? Lisa was acting in good faith. Its to her understanding that a fire or explosion was impending and indented to extinguish the flame. What happened to the smoker could never have been foreseen. In fact its ignored when they install such devices. Manslaughter applies to negligence or as the result of an act such as assault (e.g. pushing a man in a hallway but he falls over a railing and falls two floors and dies.)

Lisa was acting in good faith.
That's why the person who failed to train her might  face manslaughter charges.
(Did you actually read the post?)

[Colin2B]

Remind me never to go to France. How could they do that? Lisa was acting in good faith.

Lisa acted according to how she was trained. The French view, and some other countries, is that whoever trained her is resonsible for putting procedures in place to avoid mistakes, they should have explained to her what the sign meant, what the dangers really are, and under what circumstances she should operate the system. Not to train her would be considered negligent.
Of course, if she had been trained and ignored the proceedure .......

Whoops, sorry @Bored chemist you replied while i was typing.

[Bill S]

Whatever the science behind it, or the legal responsibility, in my opinion, anyone who smokes in that situation is someone I would avoid. 

One night I was called to a hospital to interview someone who had been brought in by the Police under the MHA as he was in process of hanging himself.  During the interview he went to light a cigarette; I pointed out that he was standing next to a rack of O₂ cylinders and said that he might wish to kill himself, but I would rather he didn't take me with him.  (I met that man on several occasions and that was the only time I saw him smile).  Possibly there would have been no danger, but I am always inclined to go for the safe option.

[PmbPhy (OP)]

Whatever the science behind it, or the legal responsibility, in my opinion, anyone who smokes in that situation is someone I would avoid. 

In any case its wise to know what's real and what's exaggerated. Otherwise how would I know when to yell profanities at the movie screen about the director.

But I'm dead serious here. It could mean life or death to know what happens. Suppose a sicko or terrorist takes a woman hostage and pours gasoline on her and threatens to drop his lit cigarette on her and thus burn her his demands aren't met? Is it important to know at that time?

What about one of those people who do smoke around a gas pump? Suppose they get arrested and go to court. Is it important for the judge to know whether it was possible under those circumstances to cause a fire? Its illegal but the judge determines the fine.

I should add that no cigarette can ignite gas vapor which is in the open when its a distance away, e.g. 3 or more inches. So when gas is pumping and the cigarette is in his mouth I don't believe its possible to ignite any vapor. The vapor and oxygen concentrations have to be in certain ranges. You can always watch the MythBusters show on it and see what happens in real life.

This one is exactly what I did about 40 years ago.

I wish I thought to record it.

Remember folks. Science is all about knowing the exact nature of nature. The video which follows that one has is about a guy who is doing an experiment in response to a video of a man in a gas station who refused to put his smoke out. The guy who challenged him said he'd give him a cookie if he was right. Since he likes cookies he went ahead with it. See the exciting result!

[syhprum]

Once I was sitting in a car park eating some fish and ships when along comes a young girl about 14 years old who removes the cap on my petrol tank andI lights a match intending to drop it in.
Leap out and ran after her for about half a mile but abandoned the chase not knowing how to proceed if I caught her!.
what would the result have been if she dropped the lighted match in ?

[wolfekeeper]

The fuel tank wouldn't explode. Often she would fail to light the vapour, but it's quite possible that it would catch. Then you'd have a flame coming out of the filler. To put it out, you just have to smother it, for example, a wet rag should work.

[CliffordK]

The fuel tank wouldn't explode. Often she would fail to light the vapour, but it's quite possible that it would catch. Then you'd have a flame coming out of the filler. To put it out, you just have to smother it, for example, a wet rag should work.

It depends on when the person last filled the fuel tank.  If the tank is full to the filling tube, then there may be a relatively small amount of oxygen/gas vapor in the filling tube exposed to air.

If the tank is say  1/4 full of gas, and 3/4 full of an air/gas mix, then it could have a vigorous reaction.  The tank itself being open to the outside may not explode, but could certainly shoot flames. 

I still woudn't watn to be standing near it.

[Bored chemist]

For some strange reason, nobody does the experiment where they take a drag on a lit cigarette in an atmosphere containing a flammable concentration of  petrol vapour.
Or maybe they did- we'd probably never find out.
And that's why smoking is banned in filling stations.

When you draw air thorough the glowing end of a cig, it gets a whole lot hotter.

If anyone plans to do this experiment, get a long pipe.

Re the cig in a fuel tank, uit's perfectly possible that the vapour pressure of gasoline is high enough to ensure that there's not enough air in the tank for it to burn.
I'd not want to rely on it.
 

[CliffordK]

As far as the OP's question.

Spraying someone with a fire extinguisher may seem like a good joke, but is entirely inappropriate when one can simply ask for an activity to be ceased.  The only reason to release the fire extinguisher would be if an imminent threat was determined.

Nonetheless, a person would be required to safeguard others that were impacted by one's actions. 

So, spray someone with a gas that knocks them out, one should get them to safety. 

Asphyxiation generally would occur over a couple of minutes, rather than seconds.  So, dragging the person to clean air should be more than adequate. 

It would have to be quite a calm day for the gases to remain in one place long enough to incapacitate a person.  A confined space, of course, is a much different issue.

Anyway, if a death occurred, I'd blame the death on the person using the fire extinguisher as a toy.

[Bill S]

….abandoned the chase not knowing how to proceed if I caught her!.

Wise move.  If you had caught her, she might have accused you of all kinds of unpleasant things. 

[PmbPhy (OP)]

Once I was sitting in a car park eating some fish and ships when along comes a young girl about 14 years old who removes the cap on my petrol tank andI lights a match intending to drop it in.
Leap out and ran after her for about half a mile but abandoned the chase not knowing how to proceed if I caught her!.
what would the result have been if she dropped the lighted match in ?

You'd see a flame a the tank intake.

Ever wonder how a propane torch works? Such a torch is a tank of propane with a exit pipe where there's a control on the exit pipe. To light the torch you place a spark or flame where the fumes are escaping. Did you think your car would explode? Why? Why don't propane torch explode when used as designed?

[Bill S]

Why don't propane torch explode when used as designed?

Could it have something to do with the control on the exit pipe, or the design of the torch?