Fuel fumes and air, at the atmospheric pressure of flight. Not a favorable mix to support combustion.
Many sensors for fuel do not have the electrical elements in the tank.
Most large aircraft do not measure volume in the tank. They meter the volume that has been consumed in a fashion similar the way fuel is metered when you purchase it for your car; and, that is mechanically subtracted from the amount of fuel that was loaded.
Another matter: TWA 800 was fueled with JP4, which is not a particularly volatile fluid.
Do you people actually believe that the engineers never thought of these problems when designing the instruments?
So was the CWT explosion on Thai Airways 114 also a missile or bomb or something other than nearly the exact same thing as the official explanation of TWO 800?
PS there are a lot of things engineers don’t think about or think about incorrectly when designing their products, including instrumentation. I mean, just look at the 737 Max disasters. A single stuck AoA sensor (among other things) led to the planes driving themselves right into the ground.
Boeing and Airbus aircraft measure volume inside the fuel tanks. Google “Aircraft FQMS”