It’s one of the stereotypical aspects of action movies (and terrorist alert warnings ): evildoers detonate an explosive whatjamahoosit at a gasoline tanker truck, and it explodes with an ear-shattering BA-BOOM and impressive fireball pyrotechnics.
But, of course, that’s Hollywood. What would really happen if Boris Badenov tried to detonate a gasoline tanker truck? I seem to recall that gasoline, by itself, is not particularly flammable; it’s supposed to be the combination of gasoline mist and air vapor that does the job. Since the gasoline in the tanker truck isn’t in mist/aerosol form, would it still give a Hollywood-style explosion? Or would it simply peter out damply, and then someone would have to hose up all the gasoline that’s now in the street?
Good point; I think there would probably be a big fire that would quickly get out of control, but a large volume of petroleum is going to need a large quantity of oxygen in order to burn all at once. A collision between a petrol tanker and another filled with liquid oxygen (wherein they perhaps implausibly both broke open and the loads became mixed) would be one to watch.
It’s not a detonation but a deflagration… an intense fireball without a supersonic shockwave. Certainly not a trivial event… this happened in Atlanta a couple of years ago. A fully loaded tanker truck caught fire in a collision and the resulting fireball burned right through the overpass.
Liquid gasoline by itself isn’t explosive but it IS very flammable, or more precisely it gives off a very flammable vapour at normal ambient temperatures. I doubt you’d ever get the monster-fireball-from-a-single-handgun-shot seen in e.g. Thelma and Louise. An actual bomb-in-gas-tanker however will get an added “fireball” from the gasoline; in fact most movie special effect explosions are gasoline-based precisely for the photogenic fireball.
What will NOT happen once the gasoline is on fire is for it to peter out damply. The vapour above the gasoline pool will burn fiercely, and the heat of the flames radiating downwards can make the pool boil to produce more vapour at an accelerating rate, and you can end up with an awfully big hot fire very fast. If the tanker is sitting in its own pool of burning gasoline, the remaining gasoline in the tanker could also be brought to the boil.
A mixture of gasoline vapour and air can itself detonate, but is extremely unlikely to in the open air. It is barely possible for it to happen in a nearly empty tanker of gasoline with air in it, but probably not from a bullet impact or low-energy ignition source. A small bomb on a nearly empty tanker might just give a bigger blast than the bomb alone would, although it would be the exception rather than the rule.
A gasoline tanker blew up on I-5 just north of Seattle last summer. (driver fell asleep and cuddled up to the guard rail.)
My firefighter husband says the reason he went boom was not because it was full but because it was not full.
Liquid gasoline is much safer than aerosolized gasoline. Only the surface burns, so when the surface-area is increased 10,000 fold, the potential is higher.
For combustion to occur, three elements must be present. 1. Fuel 2. Oxygen 3. An ignition source.
The gaseous gasoline was a large fuel source. The hole where the guard rail penetrated the tank allowed the fuel to contact Oxygen. The sparks generated by metal against metal provided the ignition. BOOM.
If the tank had been full, the same elements are present, but since the gasoline is liquid, it provides less fuel, immediately. The tank might still catch fire, but it would take longer.
Oxygen, itself isn’t flamable. The tank is very thick and strong. Bullets probably wouldn’t pierce it. They are designed to handle a roll-over at full speed. Liquid oxygen is cryogenic, if by some strange series of events, the tank was punctured, a small hole would self seal by filling with ice. A large hole might roll the truck, but other than freeze-drying anyone too close, it would eventually turn from liquid to gas and disipate.
Now, if the flaming fuel truck or a truck full of dried cow dung were passing the oxygen truck, while the driver was smoking, would be another scene all together.
remember Fuel, oxygen, ignition. miss one, miss the BOOM.
Many years ago, when I was still at school, I did a week’s work experience in a local college. It was pretty boring for the most part, except I got to sit in on a one-day awareness course for hazardous goods truckers, whcih was basically an excuse for a lecturer to play with fire and dangerous chemicals.
Among the demonstrations were ignition and detonation of ethanol and gasoline vapours, the difficulty of extinguishing burning pools of the same, the spontaneous ignition of various substances (e.g. cotton and sawdust) in fuming nitric acid, the instant freezing effects of liquid nitrogen, and finally, the effects of liquid oxygen on tarmac, tyre rubber and steel. Tarmac and tyre rubber burnt fiercely with liquid oxygen, steel took a while to get going but eventually it lit up as well. Not filings or wire wool, but bulk steel. A liquid oxygen spill is potentially a very nasty accident if there is a source of ignition - the road surface itself could go up like a torch. I’m not even sure if it’s legal for road transport in the UK anymore - you may have to make it on site if you need it.
It happened earlier this year near Baltimore. This article has some pictures. In this case, the driver apparently had a heart attack while driving on an overpass ramp above I95, and the tanker fell off the ramp and landed on vehicles below, then exploded.
None of the pictures show it, but the scrubby wooded area off to the side of the highway was blackened for a long time afterwards.
): evildoers detonate an explosive whatjamahoosit at a gasoline tanker truck, and it explodes with an ear-shattering BA-BOOM and impressive fireball pyrotechnics.