All of our fuel is oxygenated (ethanol). I've never heard of anyone having a gas tank explode due to fuel lines or in-tank pumps.Originally Posted by JT56
Question of safety
If submerging the pump in liquid gasoline is safe because the liquid does not explode, what if your tank is getting empty? Is it not as safe then?
My question exactly. I recently took an electric fuel pump apart because it wasnt working. The fuel actually flows through the windings and brushes of the pump which is actually just a tiny motor. I cannot believe anyone would invent such a device. When the tank is almost empty it is full of explosive vapors. The tiny fuel pump itself is sealed on each end by crimping the outer casing against o-rings. If the top o-ring were to fail and the fuel was at a level below thw top of the pump, the pump motor would spark when turned on. I am going to go read up on intank fuel pump explosions and see just how common it is.
The almost empty tank is not technically full of explosive vapor - the air, or oxygen supply, is probably far too low to create an appropriate mixture. In fact, if the cap has not been removed, the fumes should all be gasoline and no air/oxygen at all, due to modern sealed fuel systems developed to reduce emissions of volatiles. Still, I agree that it seems scary, especially when you have to work in an opened fuel tank to replace or repair the pump! human 20:08, 19 November 2006 (UTC)
Most flames can't travel through a gap of less than 1/4 inch wide between surfaces unless they are already really hot. I've done experiments on this. You have to have the fuel to air mixture just right. Considering how small the hole in the o-ring would be, it's highly unlikely that the flame could travel beyond the insides of the pump. Plus, the voltage going through the motor is on the order of 1,000 times less than the voltage going through your spark plug. You're not going to get a strong spark. You're more likely to have this happen if you had someone smoking while trying to fill up a tank. The filler stem might be big enough to allow a flame to backflash into the tank. Smilla0 04:33, 18 August 2007 (UTC)
I designed fuel pumps at Ford for 10 years. The explosive nature of a fuel tank is not a fact due to the low amount of 0xygen in the tank. All cars have the same "design" fuel pump (a small motor turning a device - usually a turbine or gerotor). However, this is one reason why you turn off your vehicle when filling it and DO NOT go back into your car until the fill is complete. The likelyhood of generating a spark (from the interior of your car) goes up dramatically. A static spark at the fillerneck is NOT something you want to happen. I have seen gas station videos - believe me.... I am an auto mechanic who also has a chemistry background. The reason electric, tank- mounted fuel pumps do not cause explosions is that the concentration of fuel vapors is too high to allow an explosive mixture. The volatile (which in this context refers to a tendency to evaporate) nature of gasoline causes fuel vapors to take up any empty space as the fuel tank is emptied. Even if you completely empty a tank, open its access ports, and allow it to sit open, the concentration of vapors INSIDE the tank will still be too high to explode. Now, OUTSIDE the tank is a different story, and for this reason, one must use caution when performing any sort of repair or maintenance to a fuel tank, regardless of the type of pump used on the vehicle.
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