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Re: Europa-List: Static when Refuelling re Braid

Subject: Re: Europa-List: Static when Refuelling re Braid
From: Brian Rauchfuss - PCD <brauchfu@pcocd2.intel.com>
Date: Wed, 14 May 2003 09:29:30

> That would be braid dangling inside the tank, wired to electrical
> ground?  It won't do anything during refueling to suppress static 
> charges, since fuel is essentially nonconductive.

It is because fuel has a low conductivity that the braid is required!  A
great deal of the static created in a nonconductive tank is due to the 
turbulence of the non-conductive fluid as it flows down the refill pipe.
There is a very interesting experiment where distilled water is flowed 
between two tanks that are insulated from each other.  A spark gap between
the tanks will start sparking as the charge builds.

The braid bleeds off the charge as the fuel flows around it - the close 
contact between the two is required due to the low conductivity of fuel.
The main goal is to prevent any sparks from occuring near the filling point,
where the mixture can be low enough to support combustion - the center of the
tank has too rich a mixture.

> FAA is clear about the lightning hazard problem with composite A/C.  The

Perhaps making the braid removable would solve the lightning problem?  
Lightning is such bad news (as well as icing and severe turbulence which tend 
to go along with it) that I plan to stay far away from thunderstorms and 
associated weather.

Brian




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