Fibreglass Body and Static Electricity. 1

[scrimshaw]

HI

On a fibreglass (epoxy) body with a stainless fuel tank are there any issues regarding buildup of static that I should be aware of? The tank will be connected to the stainless filler with non-conductive fuel hose.

I am not sure wether it is best to bond everything or leave some parts isolated.

Thanks for the help.

 

[Compositepro]

The only problem I see is the non-conductive fuel hose. If it is indeed an "fuel hose", however, it is probably made to be conductive enough to be anti-static.

 

[MintJulep]

You need to look at the whole system - tank, mounting, level senders, venting, whatever and all the possible failure modes.

You might be building a capacitor.

 

[swall]

Ground every individual piece of the body. There was an article in the SAE magazine about 3 issues ago about a BMW Formula 1 mechanic getting shocked while he was pushing a car in the pits. It was severe enough to knock him down.

 

[scrimshaw]

Thanks for the replies. I will bond all metal parts that are connected with the fuel system including the filler cap.

With my truck I get a major static shock almost every time I get out of it sometimes even when it is raining. My passengers don't seem to be affected. Not sure if it is the clothes I wear but it makes me very nervous when refueling. It will be interesting to see if it happens with the fibreglass car.

 

[patprimmer]

It is very likely the combination of your cloths and the seat upholstery.

If you connect yourself to the body and stay firmly connected until you touch the ground you will not get zapped as there will be no gap to create a spark as you discharge to ground.

Certainly you should ensure you are fully discharged before removing the fuel cap.

Regards
Pat
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[waross]

I had a car with upholstery that didn't like my favorite trousers. I learned to hold the top of the door or the roof as I exited the car to avoid building up a charge.
Many years ago cars used static straps dragging on the ground to discharge the static buildup on the car body. Car tires are now formulated to have enough conductivity to avoid static charges building up on the body.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[patprimmer]

As Bill says, tyres ground the body. The zap comes from your cloths discharging. If you have a contact with the car body that discharges your cloths without a spark nd therefore no zap. It is the spark jumping that zaps you.

Regards
Pat
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[swall]

But don't tires also generate static electricity under dry conditions? I have driven past tractor trailers numerous times and observed that I got "static" on my AM radio just as I passed the tires.

 

[waross]

Although the tires are conductive, they do have a high resistance. I suspect that if airflow past the body of a large truck is generating a lot of static, the tires may be arcing to the road a little as well as conducting. This would be at the bottom where the gap between the tire and the road is almost zero. There may also be a discharge as the tires transfer the static charge to the pavement. Myself, I have not experienced this effect.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[thruthefence]

Many years ago, working offshore as a helicopter mechanic, part of my duties was refueling 'transient' helicopters that stopped at our platform taking oil field workers further off shore. A large Bell 205 ( UH-1 Huey ) on fixed floats landed for fuel, and as I attempted to attach the grounding clip to the airframe, a large blue spark jumped (at least 6 inches) from the aircraft to the clip. There was supposed to be a small chain that grounded the aircraft, but it had broken off at some point. The large rubber floats had picked up quite a charge. I have also heard stories of ground personnel attempting to wrangle external loads into place, and being knocked down by the static. ( normal procedures are to 'touch' the load to earth before final positioning)

 

[patprimmer]

I now remember exactly how it worked on my car that kept zapping me. I had to ground my cloths before I grounded myself. I normally did this by touching y shirt sleeve on the door frame.

The problem went away when I installed a genuine leather covered steering wheel in place of the synthetic covered wheel.

Regards
Pat
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[drwebb]

I think the F1 incident was related to the KERS system. Unless you have regenerative braking it may not be germaine.

 

[bentwings2]

I have fiberglass bodied streetrod. I just gave it a power buffing and it was loaded with static however after towing and driving it for and afternoon it was dissapated.

I got a heck of a jolt when I climbed up on the trailer to fill it with gas. The trailer has a wood deck so I suppose that going down the road is like an aircraft flying with no ground. Possibly the charge was lost when I touched it and unscrewing the gas tank cap probably finished it off. I've not heard of any problems with other guys doing the same thing so I think it is ok.

Some of the boat marinas have ground wires so I think it would be a good idea to clip a ground to the tank and pump before you fill up.