Could a gas station blow up if a car was on fire next to a pump?
I’m writing a novel and want it to be realistic – not cheap Hollywood theatrics. I’m assuming the station wouldn’t blow up because of some kind of protective equipment between the pump & the tank in the ground, plus an explosion would be caused by fumes, which would probably be isolated by a valve or something.
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Good thinking.
Gas pumps have several safety features to prevent this kind of thing.
The simplest is to have the gas tanks underground. and a flame trap in the feed pipe. This is a thin screen that does not let flames pass down the pipe.
Even if a flame got down there, the tank would not explode. The explosive range for gasoline vapors is in the range of 1.4% and 7.6% or so.
The percent of vapors in a gasoline tank will be much higher than this.
Sure it could… gas needs a source of ignition.
It could blow up. That’s why they don’t let you smoke at the pump. That’s also why they have emergency shut off buttons on the outside.
With ideal circumstances, you might get a pretty good sized fireball, but the likely hood of an explosion is very, very small. The gasoline is not stored in the pumps, and there is not an oxygen rich pathway to the tanks. The most likely scenario would be that the spilled gas would ignite under a car, boil the gas in the cars tank, would would cause pressure to blow out the filler tube which would ignite.
By that point, someone has hit the emergency button and all gas to the pumps is shut off.
Edict the truth is No, even if the pump is knocked off, it is a one way valve system like when your gas welding with acetylene. Even though you have a burning torch the fire doesn’t go in the tank. With the triangle of fire, you need all 3 parts of the equation, oxygen, fuel, and spark. A one way valve system prohibits oxygen from entering the tank eliminating explosion. An example of this is if a welder is welding a leak on the gas tank of a car, it is more safe to fill the tank completely up with gas before welding. Even if gas spewed out of the hole, it is still only one way with no oxygen comming out of the tank. So you may get a little fire on the outside of the tank but you will not get one on the inside as any air would be at the top of the fuel level and not comming out of the hole. Now if the tank thats on the car is empty you would have all 3 components as there would still be fumes, the oxygen would be present and the spark thus explosion. With a gas station tank this is not possible as the main valves are one way valves and are also below the surface of the ground. You may have an external fire but never internal to cause an explosion.
Hope that sums it up for you.
It’s called the triangle of fire. Without all 3 components, there will be no explosion.
Yep, I watched it happen about 25 years ago.
Realistic? No, not happening.
Johnny’s cousin Ted is a firefighter, apparently.
Someone didn’t tell the other the full story.
The heat from the fire at the car would set off the fire suppression system above the pumps.
It’s similar to the range hood systems in restaurants but much bigger.
Look up sometime and see the nozzles.
Edit: I’m not here to disagree with people, but the guy below aint quite right either. The statement about all the things we do to make it burn is, but that’s all. The rest is plain not the way it works. I’ve repeatedly thrown lit cigarettes and matches into pools of gasoline as demonstrations.
Getting gasoline to explode is actually quite tricky. To be able to do it reliably in engines we use carburators, injectors, air mass meters and all sorts of things to ensure that we get the right ratio of fuel to air for an explosion to occur. Either too little or too much and "nothing" will happen.
Your best bet for a realistic scenario IMO would be a leaky pump or a pump that doesn’t shut off when the tank is filled. A torn hose would be detected by the pump and causing it to shut down , but if it’s only a leak the pump would keep running. Or maybe a rusted off/dislodged filler pipe in the car?
Any of these would allow for a sizeable puddle of gasoline to gather on the ground around the pumps, and if the ground is wet from rain it won’t be immediately visible.
Introduce an open flame to that scenario and you’re likely to get big nice fireball, probably with a bit of a shock wave as well.
There are one way valves between the pump and the tank that act as safety features.
When I was a kid in the 70s, I can remember smelling the gas as it was pumped into the car. That doesn’t happen anymore.
Also, keep in mind that only gasoline vapors are flammable, not the liquid.
To explode, the fuel must be vaporized. Liquid fuel is not explosive, it will just burn. Only when the fuel is sprayed into a mist, and ignited is it explosive. The fuel in the underground tanks is liquid. There are several safeguards to prevent flames from reaching these tanks, but even if it did, they would not explode like in the movies.
A car on fire could cause the gas in the pumps to burn, but there are standard fuel cut off switches to prevent fuel from continuing to flow, and prevent fire from following the line back to the tanks. There would be lots of burning, but small if any explosions. The fuel tanks of modern cars are built to prevent explosions also.
I hope this helps.