The classic petrol flame chase problem

[Rubycon]

Was this ever on mythbusters?

You see it in movies where a car/truck with a holed gas tank pissing everywhere is getting away and someone lights up the trail and the flame chases the car, catches up and it blows up. Can they out run it? Decreased rolling resistance from having tires at 150% of sidewall give them an advantage? :biggrin:

 

[Bignate603]

Yes, they tested it and no the flame doesn't move that fast. If I remember right you can almost walk faster than the flame advances.

 

[Rubycon]

Yes, they tested it and no the flame doesn't move that fast. If I remember right you can almost walk faster than the flame advances.

Sounds about right. Of course in Hollywood gas on the ground is like detonating cord.

 

[PottedMeat]

Yes, they tested it and no the flame doesn't move that fast. If I remember right you can almost walk faster than the flame advances.

yep. jamie had a little RC tank - 'firebug' with a squeeze bottle full of gas running around. the fire was pretty damn slow.

 

[Rubycon]

yep. jamie had a little RC tank - 'firebug' with a squeeze bottle full of gas running around. the fire was pretty damn slow.

That's kind of disappointing for those guys. I figured they'd try it with a garden tractor, at least.

 

[Iron Woode]

they also did it with gun powder like you see in those old Bugs Bunny cartoons.

 

[Bignate603]

That's kind of disappointing for those guys. I figured they'd try it with a garden tractor, at least.

If I remember right they did a full scale test with a pickup. It wasn't that impressive.

 

[Rubycon]

If I remember right they did a full scale test with a pickup. It wasn't that impressive.

Did they at least stop, get out of the truck and let it catch up to see what happens next?

 

[coldmeat]

Ya, the tank doesn't explode.

 

[Mark R]

I think they should try it with a tanker.

You know, just to be sure.

 

[sjwaste]

Rubycon, I'm sorry we cannot help, but this is the kind of question we'd normally post then wait for you to answer.

If you don't know it, there's no backup plan.

 

[Rubycon]

Rubycon, I'm sorry we cannot help, but this is the kind of question we'd normally post then wait for you to answer.

If you don't know it, there's no backup plan.

What I had in mind was a large LPG tanker and ended with a BLEVE.

 

[DrPizza]

I'd think that it would depend on how rapidly the gasoline was exiting the vehicle, the amount of breeze at ground level, etc.

 

[CallMeJoe]

What I had in mind was a large LPG tanker and ended with a BLEVE.

Even with LPG you'd need to rupture the tank significantly before ignition if you want a big boom; the fuel has to have time to mix with atmospheric oxygen before it's sparked or all you get is a Whoosh.

 

[Rubycon]

Even with LPG you'd need to rupture the tank significantly before ignition if you want a big boom; the fuel has to have time to mix with atmospheric oxygen before it's sparked or all you get is a Whoosh.

BLEVE implies that a fire would be already burning beneath the tank heating up the liquid, raising the pressure until the tank burst. This also implies no safeguards in place or (required) ones effectively disabled.

 

[TheNoblePlatypus]

You mean Die Hard 2 wasn't realistic?

 

[BUTCH1]

I saw one of those scenes on "Die hard 2" where the jet fuel (which is basically kerosene) get ignited and catches the 747 going 100+ mph on a takeoff roll, even if you used gasoline it's not gonna travel anywhere that fast..http://www.youtube.com/watch?v=e34hLQYFqpA here, take a look..

 

[Gibsons]

Well, if gas doesn't work, what about gunpowder? Yosemite Sam was never fast enough.

 

[darkswordsman17]

Clarkson outran a flame in a ZO6 Corvette.

 

[Rubycon]

Pyrodex would be very susceptible to breezy conditions if out in the open. Once you enclose it though it will move fast!

 

[JoeBleed]

From someone who has personally thrown a 5 gallon, plastic, gas can onto a camp fire, it doesn't explode, it just burns bright, fast, and spreads out once the can melts away.

I'm sure someones wants to know why i did that, because i was trying to sleep earlier that evening by the fire in the dead of winter. Then my camping buddies thought it would be fun to toss small cups of gas on the fire to make a large flame ball. With me trying to sleep, i was not amused.

So i waited until about 4 am when they were asleep, grabbed the can which still had at least 3 gallons of gas or more, and just tossed it on the fire and yelled, "What the fuck!!!".

They woke up, gas started burning and they scattered fast while falling all over the place because they couldn't get out of their sleeping bags fast enough.

Like was said earlier, if it doesn't have time to vaporise, you don't get much of a "explosion". Which is why when a car's gas tank burns, it usually doesn't make any kind of explosion. You have a the potential if it is around 1/4 tank. You can also pour some gas in a tin can, lite it and it burns like a torch. (i do not advise doing this for a torch or cooking)

 

[Rubycon]

Throwing the can on the fire is actually pretty lax.

I was at a party and watched a (fool!) run down a hill with a cooler filled with gas (5 gallons easy) and did a rolling dump into a tree stump fire. The resulting fireball was so hot it made us sweat on top of the hill! He looked like a lobster and was lucky. No explosion...

If you want an explosion strike an arc in an empty tank!

 

[vshah]

extremely scientific video:

http://www.youtube.com/watch?v=HzPv9lUXpoI

jump to 1 minute in

 

[Rubycon]

I really enjoyed his video where he dropped the red Porsche on a piano and a trailer!

In this one they just talked about boring stuff.

 

[Squisher]

extremely scientific video:

http://www.youtube.com/watch?v=HzPv9lUXpoI

jump to 1 minute in

http://www.youtube.com/watch?v=HzPv9lUXpoI + #t=1m


http://www.youtube.com/watch?v=HzPv9lUXpoI#t=1m