IIRR they are safe precisely because the petrol tank is full of vapour
- to get a dangerous mixture of petrol vapour and air you need an empty petrol tank, because the saturation concentration of inflammable gases above liquid petrol/gasoline at room temperature is too high to sustain combustion (the fuel-air mix is too rich).
That is, the fuel concentration is above the Upper Explosive Limit
------------ Bill Sloman, Nijmegen
I had a friend who tried to solder a leaky, assumed-empty car gas tank with a propane torch. It came out sort of spherical.
John
Ignition also needs the correct proportion of oxygen, and (afaik) there is never enough oxygen in there.
Years ago, helping a friend respray a car, we had a steel dustbin that gradually got filled up with old rags soaked in cellulose thinners. At the end of the day we decided to burn the rags, so we lit them through a small hole in the bottom of the bin.
We never found the dustbin lid, and I have no idea how high it went.
dPearce Consulting
Paul! Paul! Paul! Paul!
Get real. Everyone in the industry knows the failure mechanism was in the tank-to-tank pump.
Sheeesh!
...Jim Thompson
That was a surface to air missile.
Right, and the limits are pretty narrow as well. I remember playing with a cork gun, a piece of steel tube with a spark plug at one end and a cork at the other. Three drops of petrol popped the cork 20m high. Two or four drops did nothing.
Jeroen Belleman
I saw a guy at a car shop who had taken the gas tank off some car, and poured the leftover gasoline into a 5-gallon bucket. Not very much gasoline, there was about 1" - 2" of gasoline in the bottom of the bucket. We were all smoking, (back in those days, almost everybody smoked) and I said to the guy, "Hey, I've heard that a lit cigarette won't ignite gasoline. Do you know if that's true?" He didn't say anything, just took his cigarette and flicked it into the bucket. It went "SSst" as if it had been flicked into water.
Cheers! Rich
I heard it was somebody smoking in the bathroom.
Yep, Blew his ass off ;-)
...Jim Thompson
One day Franc Zabkar got dressed and committed to text
I imagine the current levels would preclude any arcing. Certainly they have stood the test of time Franc :-)
Nonsense. The pilot wasn't wearing his tinfoil hat when he was hit with an Illudium PU36 Explosive Space Mudulator beam.
Remember, shiny side out!
Could someone please explain why rheostat type fuel level senders as used in automotive petrol tanks are considered safe? Intuition would suggest that an intermitent contact could pose an ignition problem, especially when the tank is full of vapour.
- Franc Zabkar
Wrong. From
"The National Transportation Safety Board determines that the probable cause of the TWA flight 800 accident was an explosion of the center wing fuel tank (CWT), resulting from ignition of the flammable fuel/air mixture in the tank. The source of ignition energy for the explosion could not be determined with certainty, but, of the sources evaluated by the investigation, the most likely was a short circuit outside of the CWT that allowed excessive voltage to enter it through electrical wiring associated with the fuel quantity indication system."
They don't really know what caused the CWT to blow, but they are pinning the problem on the FQIS. So much for the theory that fuel level senders are safe. Cars should be blowing up right and left on the freeway from the senders, not to mention immersed electric fuel pumps.
What I wonder about is: Following the accident, the FAA attempted to identify and interview the crew of every aircraft operating in the area. One aircraft, shown on radar flying in circles nearby, was never found and no crew ever came forward. There is one type of aircraft that exhibits this behavior. A target drone.
This is what is alleged to be what went wrong on TWA 800 ( the fuel air mix that is ).
Graham
I see you use the past tense ' *had* a friend ' !
Graham
They (and the electric pump) are usually submursed under the fuel. It's never a good idea to run the tank dry because the fuel also lubricates the pump bearings.
Shiny side out! How many times do you need to be told. Sheesh!
keith said
Actually, it's recommended you do both.
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A Note About The Shiny Side:
It can't be stressed enough how important it is to have the shiny side pointing out. This is needed because the shiny side is most reflective to psychotronic radiation, while the dull side can actually, in certain environmental conditions, absorb it. However, as is illustrated in the instructions above, it is also wise to complement this with a layer of foil pointing shiny side in. This will keep your brain waves, which are also reflected by the shiny side, from being picked up by mind-reading equipment. There is a small number of aluminum foil researchers who believe that this may cause an alpha-wave harmonic to build up in the skull resulting in memory loss or pseudo-religious visions, but their findings have never been replicated by the aluminum foil research community at large. Even if their findings are validated, the risk involved is small compared to the potential of mind-intrusion.
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It is many years since I pulled open a fuel level sender but I do remember the resistive element was fully enclosed. Also, since the moving contact is tied directly to one end of the resistive element then the circuit is always maintained even if the moving contact becomes open circuit momentarily. Since there is always a circuit maintained then all that can happen is the full resistance applies and there is no risk of arcing.
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