>>There's no possibility a static inside the vent tubing. Fuel vapor flow
>>does not cause static. Any fuel flowing in the vent line requires
>>bubbling or sufficient velocity for turbulent flow to cause any static
>>at all.
>
> However, the metal tube will conduct any stored energy, and the flow of air
> and eventually fuel is very rapid. You can hear the hiss as it comes out,
> also see the convection of the dense vapour.
> I can't remember where the energy is stored in a capacitor, is it the metal
> or is it in the dielectric? I am looking for an understanding of what was
> observed, not trying to prove it can't happen. It did happen.
>
> Bonding the tube to the filler cap flange may well be a very good thing to do.
>
> Graham
In a capacitor, the charge sits on the surface of the metal, just like
static. esdjournal.com (as in electrostatic discharge) has a excellent
explanation of how static charges are produced, and there's much which
is not intuitive and even contrary to folklore. For example, it's
rubbing unlike things against each other which produces static, right?
Nope. As to vapor, in natural gas mains, it's not the flowing gas
molecules which produce the static, it's the dirt particles in the gas
bouncing off the walls of the pipe.
I think the only important question is whether there's any protection
method in a plastic airplane which will allow one to relax the rules for
safe fueling practices. There's no harm in bonding only these two
together, but if they are also tied the aircraft's electrical ground,
it's back to the lightning-protection problem of flying an incendiary bomb.
Regards,
Fred F.
|