Another relatively simple measure would be to install temperature sensors in the central fuel tank. More expensive preventive actions include pumping nitrogen into the tank as the fuel is consumed, and increasing the diameter of the fuel lines, Marsden says. Jet fuel normally is not explosive at temperatures below 100 degrees Fahrenheit. When the aircraft is flying, the energy given off by the heat exchangers is effectively dissipated to the outside air. Aircraft fuel tanks are designed with the assumption that the fuel they carry is explosive.
Safety is provided by eliminating possible ignition sources.
According to Marsden, aircraft designers may have not have fully appreciated the dangers of flow electrification. Hydrocarbon fuels often carry small, electrically charged particles. When the fuel moves through a metal pipe, some of these charges stick to the inside of the pipe while others continue to move with the liquid. When combined with the fact that hydrocarbon fuels are poor conductors of electricity, this separation causes an electrostatic charge to build up. Petroleum industry studies have shown that it is possible to build up electrical potentials of thousands of volts within a matter of minutes by pumping fuel at velocities above one meter per second, Marsden says.