I have always heard, since the 1960's, that if you put a flash cube in a vehicles' gas tank and it is driven away, the gas will disolve the plastic and cause the gas fumes to explode causing the tank to explode. This is supposedly an old assisins trick as I understand. Could you bust this myth? I would love to help!!

whats a flash cube

The fumes in a gas tank are non-explosive, except possibly in the coldest conditions... in all other cases, the vapour/air mixture is far too rich to support combustion. This is why the Mythbusters haven't been able to explode gasoline tanks in any of their other tests.

the fumes in a gas tank are non explosive? so if i were turn on my gas stove for one hour inside the house and then lite a match would i not be a dead man underneath a ton of rumble. fumes are very volatile.

1) A flash cube is a four sided flashbulb that was used on the popular cameras back in the 60's and 70's, it automatically rotated so that you could take 4 flash pictures in a row. 2) The colder gasoline is, the less likely it is to vaporize, and burn. At about -37 degrees C (or -34 degrees F) Gasoline won't burn which is why those who live in the north country have engine block heaters to let them start their cars.

living in fairbanks alaska we had engine block heaters and it was to deter the oil in the pan from solidifying into a solid and allowing the engine to crank.

The limits for the natural gas are different than the limits for gasoline, but yes, if the mixture was too rich, it would not burn.

With gasoline, if the volume percentage in air is below about 1.5% (lean limit) or above about 7.5% (rich limit), it will not burn or explode. Under normal conditions, the vapour at the top of a closed container is far higher than 7.5% and it is non-flammable.

As I said, this is why they have failed at exploding gasoline tanks in other tests.

Due to the lower volatility at low temperatures, the mixture can be down below 7.5% in very cold conditions.



For the gas in your house, the limits in air are about 5.3% and 14%. If the mixture was above 14% methane it would be too rich to support combustion.

quote:

Originally posted by lannybob:
the fumes in a gas tank are non explosive? so if i were turn on my gas stove for one hour inside the house and then lite a match would i not be a dead man underneath a ton of rumble. fumes are very volatile.

I have never lit a fire with gasoline that did not start with the fumes igniting first! it is my understanding that a full tank of gas will not explode because there are few fumes present. The danger is when the gas level goes down the fume levels rise causing the risk of a spark causing the fumes to light, hence, BOOM! Lets bust it on the show and see. Fumes are the culprit.