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[Possible SPAM] Re: Static Dischargers

 
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harley(at)AgelessWings.co
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PostPosted: Tue Feb 28, 2006 6:13 am    Post subject: [Possible SPAM] Re: Static Dischargers Reply with quote

Morning, David (and everyone)...

In my prior life as an engineer at a pharmaceutical company, I spent
years trying to convince management how to solve static buildup problems
with dry powder transfer systems (Desenex Foot Powder, and Caldesene
Baby Powder, among others). Of course, being budget conscious, they
didn't want to change out the plastic tubing for conductive tubing. And
I couldn't just do it, as every change required extensive documentation
and testing followed by FDA approval before it could be implemented.

Understandably, the line operators and mechanics would complain every
time the air was dry, and they got zapped when they came too near a
transfer line (whether it was a vacuum cleaner hose or the main product
flex line). During the summer, when the air was warm and more humid,
there was no problem. The humidity in the air was the conductor.

But, every winter, after the first dry, cold day, I would get a
call...fix it....

Of course, they wouldn't listen to my suggestion...spend the money and
replace the plastic with conductive tubing...so, the managers came up
with many methods they thought would cure it. The mechanics wasted
hours hooking up all kind of crazy gadgets the managers thought of or
heard about that never worked. When they finally used conductive plastic
and ss line, they solved the problems.

As you all know, static buildup occurs on NON-CONDUCTIVE surfaces. So,
if you attach a grounded, conductive wire or braid to such a surface, it
will keep THAT SPOT discharged. Being non-conductive, the rest of the
object can't discharge as the current can't "flow".

An inch away, on the non-conductive surface, the charge will build just
as it always has, looking for a place to jump to when the voltage gets
sufficient. Like your finger, or eventually the wire you hooked up if
it's not too far away (or your radio antenna lead). It can't traverse
along the non-conductive surface to the wire until the voltage is high
enough to make the jump. And that creates noise and/or sparks.

A single wire or braid attached to a single point cannot discharge the
entire plastic surface. As was mentioned already, creating a conducting
surface that contacts every point of the plastic to allow bleeding at
that point, and within a reasonable distance either side of it, will.
Like a fine mesh wire screen. Or a conductive surface.

Or, a metal airplane....<G>

Harley Dixon
Long EZ N28EZ
David Carter wrote:

[quote]

I believe p-static is principally the noise created by static electricity
jumping from skin panel to skin panel on the way aft and finally off of the
plane in elevator and rudders. I think fiberglass stuff up front is a big
source of buildup. You could try running a wire from nose to tail, with good
electrical connection at each end - this might let the static build up on
fiberglass cowl (I'm thinking RV series aircraft) bleed off by going from
front to back without jumping a lot of little skin gaps along the way (don't
ask me why the fore-aft longerons wouldn't do the same).

David

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