Grounding of a Gas Tank

[Patrick Shannon]

I am installing a plastic below deck gas tank in a wood epoxy encapsulate boat. I will place neoprene under the tank. According to the Coast Guard web site plastic tanks are not required to be grounded. In addition, I have one of those Perko fuel fills that do not require grounding. Being good at following directions, but unwise in the ways of electricity I am unsure of the wisdom of not grounding. Could someone offer an opinion, please. Thanks.

[Tom Robb]

Plastic is a pretty lousy conductor. What's to ground?

[Ray Frechette Jr]

Be aware however that plastic will;

A.) swell a bit upon first filling, so ensure ther is enough room around the tank for swelling.

B.) Plastic is gas permeable to a small extent meaning vapors can pass through the plastic walls, meaning the compartment the gas tank is stored in should be ventilated.

[Gary E]

Learn about STATIC ELECTRICITY... then maybe you'l change your mind...

[Bob Cleek]

We have plastic carpets in the office... well, they're some sort of synthetic like maybe nylon. They are over wooden floors. The soles of all my shoes are leather or else some sort of plastic, too. There's nothing to conduct electricity so I didn't think there was any need to ground the carpet. Still, on a dry day when the atmospheric conditions are just right, I can touch a metal file cabinet and get knocked on my ass. Do you think there's any need to ground the file cabinets. They don't have any gasoline in them.

[Spokaloo]

There is a screw on the filler neck that will need to have a wire run out from it to a grounding bus bar on your boat. However you wire it, this is a pretty easy little task and worth its weight when you consider that fuel running across plastic is an efficient electricity generator. You see your best buildup at fill time through the filler hose and across the gaps at the neck. I have a stainless filler neck which has a ground wire run from it, along the fill tube, down to the tank ground, and across to the neg bus bar.

A little safety goes a long way.

E

[pcford]

I was once filling a client's boat...when I removed the nozzle simultaneously a couple drops of gas spilled on the deck and a spark ignited it. I slapped out the flames....and the attendant and I just stared at each other for a few seconds.

[Tom Robb]

While I'm all for avoiding stupid behavior, especially if it involves lost cash, fire, explosions, maiming or death, I also find myself wondering about the reasonableness of some of the things we worry about.
Is there any evidence from what may be thought of as experts in electrical engineering and fire prevention that a plastic gas tank needs grounded? If so, I'd be all for it. (argument by analogy doesn't cut it - scuffing along on a dry carpet is not the same thing as a boat in the water)
Or is it the equivalant of HEAD-ON - a placibo designed to remove your cash?
It seems that the whole bonding argumant we've witnessed here over the years has not been settled. Or has it and I didn't notice?

[Gary E]

scuffing along on a dry carpet is not the same

Ok, so you may not think it's the same, but the fuel is scuffing along while flowing through the pump hose and into the tank...all the while creating static electricity....

If it's not a problem, why do those who fuel jet aircraft which is sorta non volitile kerosene ground the airplane ??

"was it 5 or was it 6 shots, I sorta lost count....
this is a .44 Mag, the most powerfull handgun..
and can blow your head clean off with one shot...
so, do you feel lucky"

[PaulC]

Couldn't you make a metal cage (foil with galvanized strapping or some such) to draw the charge off the tank? You may want to add a metallic ring around the fill point to alleviate any accumulation of electrons there too. This connected to the rest of the cage assembly.

This is more the theory and not so much the application. For the application I would want to sit and contemplate the metallic materials a bit more.

You need to be sure everything is bonded together otherwise you will have made a capacitor which will give you a much bigger spark. That you would want to avoid especially with a fuel tank.

[Tom Robb]

They ground aircraft which develop a different voltage potential than the ground they sit upon is insulated by the rubber tires. You wouldn't want the Jet A to complete that circuit.
Actual empirical evidence supporting some reasonable theory would be somewhat more persuasive. Argument by analogy still doesn't cut it.
The Coast Guard which loves rules doesn't require it. Why, one might ask? Beacuse it isn't a problem?

[pcford]

They ground aircraft which develop a different voltage potential than the ground they sit upon is insulated by the rubber tires. You wouldn't want the Jet A to complete that circuit.
Actual empirical evidence supporting some reasonable theory would be somewhat more persuasive. Argument by analogy still doesn't cut it.

See my post above.

(?)

[tomlarkin]

I will place neoprene under the tank.

I'm at this same point in my build. Where did you see to put neoprene under the tank? Are you holding it down with nylon straps?

[Patrick Shannon]

Thank you for all the comments. They certainly helped to decrease my electrical naivety somewhat and/or make me aware of how naive I really am. At present, I plan to go with the, as advertised, groundless fill/vent cap and ground the fill pipe from the tank screw. I figure since it is no trouble it is better to be somewhat safe than the alternative. As to the neoprene: Somewhere on this site I saw it suggested. Figured, given the tank bottom is flat and it will expand, pieces of neoprene might be a way to get some air under the tank and allow some room for expansion. Once again thanks for the comments.