REFLECTOR: Fw: [Canards] Static discharge

[Al Gietzen]

??Can't this grounding of the fuel pool be accomplished by simply grounding 

the fuel lines??

 

I don't think so.  As I understand it, static charge is primarily a surface
effect, so it isn't going to get to the fuel line.  We get static charge
from two potential sources - air friction on the strake surface during
flight, and friction of the fuel flow through the hose and nozzle when
fueling.  The first is easily removed by wiping the strake surface with a
damp cloth prior to fueling, the second by maintaining a contact from the
nozzle to the fuel surface while fueling.  A lightweight metal chain or
braid that keeps your cap from getting lost, and that hangs into the fuel
while fueling seems like a very good approach.

 

Al

 

At 07:42 PM 8/8/2004, you wrote:

>Does anyone know if the Jeffco 9700 tank coating has any significant 

>electrical conductivity?  I installed a ground wires from my fuel cap 

>rings to the strake-tip tiedown rings and on to the aircraft's electrical 

>system ground.  The idea is that the lineman's ground clip can then be 

>attached to one of the the tiedown rings, which is electrically equivalent 

>to attaching it to both of the fuel cap rings.  However, I have not 

>installed anything to electrically ground the fuel pool itself.  I wonder 

>if it is really necessary?  My hope is that the Jeffco will bleed the 

>charge off the fuel to the grounded vent lines and/or fuel cap rings.

>

>Keith Hallsten

>----- Original Message -----

>From: <mailto:LGallup at mn.rr.com>Lynn Gallup

>To: <mailto:reflector at tvbf.org>Velocity Aircraft Owners and Builders list

>Sent: Friday, August 06, 2004 7:57 AM

>Subject: Re: REFLECTOR: Fw: [Canards] Static discharge

>

>Ron,

>Man! That was a REALLY interesting note about refueling. I have considered 

>myself a fairly well informed engineer but I never knew that in a plastic 

>airplane it was the static electricity building up on the fuel itself 

>which was the source of the spark. I always thought it came off the wing 

>surface.

>

>So, if I am going to carry the aligator clip thing to bond the fuel nozzle 

>to the braid attached to the cap, why can't I just carry a length of braid 

>with a wire and clip attached. I could just drop this in the tank and 

>connect it when I refuel.

>Lynn

>

>

>----- Original Message -----

>From: <mailto:romott at adelphia.net>Ronnie Brown

>To: <mailto:reflector at tvbf.org>reflector at tvbf.org

>Sent: Thursday, August 05, 2004 2:16 PM

>Subject: REFLECTOR: Fw: [Canards] Static discharge

>

>The second note.

>

>----- Original Message -----

>From: <mailto:alex157 at direcway.com>Alex Balic

>To: <mailto:Canards at tnstaafl.net>Canards at tnstaafl.net

>Sent: Thursday, August 05, 2004 1:26 PM

>Subject: [Canards] Static discharge

>

>I am interested in this thread- I am not sure how touching the fuel with a 

>conductor will help any static discharge condition, the fuel is non 

>conductive, the static problem that we are all familiar with is not a 

>charge difference between the fuel and the filler nozzle, it is between 

>the filler nozzle and a conductive part of the aircraft - like an aluminum 

>fuel cap, or filler cap ring, which can store charge, and dissipate it to 

>the nozzel at a very inopportune time. What needs to be done is to ground 

>the cap and filler ring to the aircraft grounding system, not to the 

>fuel.   As far as the screens go, their function is as a flame arrester, 

>they function by not allowing the flame front  to pass through to the main 

>fuel source (your tank) they do this by dissipating the energy from the 

>flame front.  I have seen a demonstration of an osha gas can where the 

>demonstrator held a burning propane torch right at the opening to a full 

>can of gasoline, and no significant combustion occurred (I still think 

>that guy was nuts).  For anyone that is looking for ball chain, home 

>depot, lowes, and ace hardware sell it by the foot- it is the same stuff 

>that is used for turning ceiling fans on and off- get the stainless steel.

>I would instruct and/or placard for the  fueling personnel to "touch here" 

>the fuel nozzle or grounding cable from the truck to the gas cap before 

>opening it to dissipate any built up charge.

>

>

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