Tanks for the memories--Grounding issues

[Bearh]

News from the bloomin'Bay country--got my new tanks in, and today trundled "Snowdon" out in afternoon traffic for a stroll to the gas station. $90 dollars later, I have 21 gallons in my new port tank, and 22 in my starboard tank, plus six gallons in a portable tank between them, with a line to connect it to my new Racor 320 in the engine well where I can see it. So far nothing leaks, and nothing has blown up.
C-Bill and I have similar questions--what constitutes grounding the fuel tanks? I used the ground wires left attached when I took the old 18 gallon tanks out, and laid the circle connectors over my elbow fuel feed line nipples, then tried to plastic-tie them firmly into contact. Is that enuf? The instructions from the factory didn't mention grounding wires, and the pictures I have seen of 20 gallon tank installations don't seem to have white wires dangling about, so any help here would be appreciated.
I am kind of excited about what figures to be a 200+ mile range with these babies--I kinda feel like an oil tanker.

[C-Bill]

When I start thinking about the static electricity potential in those plastic tanks with all that gasoline slushing around, I get concerned.

I look at rubber hoses as insulators.

A big question for me is, "Is the ground on the fuel gauge sender adequate to deal with any static build-up in those plastic tanks?"

I realize that all metal components which the gasoline passes through on the way to the outboard motor should be grounded (fuel filters & valve to switch tanks, etc.).

I have seen the vivid results of poor grounding.

I have looked & looked for written instructions.


Bill

[Bearh]

Bill, one of us needs to call the factory--I'll let you know what I learn. You do the same, yes?

[Sea Wolf]

Bearh- You're sure right about there not being much info around about grounding issues, especially regarding plastic tanks. Perhaps some of the reluctance to put anything in writing is due to the consideration of liability for any erroneous information that might be construed as contributory to any subsequent disaster. (Pat Anderson could comment here on the legal issues).

The above having been said, let me say forthwith, that this is my reasoned opinion for your consideration and should not be taken as necessary final truth or any recommended plan of action.


I may be wrong, but I'm going to give you my thoughts on this subject, as I feel the thinking on this issue is bordering on having a touch of hysteria(!).

To begin with, we all know that the grounding of the tanks as well as the gas delivery nozzle is done to prevent the build up of static electrical charges in the tanks and the delivery system, such that similarly grounded components will have no charge relative to each other and no spark will occur setting off the dreaded explosion and/or fire. The grounding system in the boat works two ways, first to keep the tank grounded at all times, and, secondly, is especially important when filling of the tank(s) takes place, as the transfer to fuel is considered to be a operation that can generate a static charge.

The delivery nozzle is grounded through the wire in the hose to the electrical ground in the pump system and electrical supply. This is understood and accepted.

The gas tank and fuel system in the boat are all grounded together and to the boat's ground system, including motor, drive mechanism, and electrical and electronic components. If this fuel supply system is all metal, the chances that the grounding system will do it's job are generally felt to be very good. The great questions arise when using plastic tanks (and Neoprene hoses).

Typically, the ground system on plastic tanks connects the deck fills, top rings around the tank inlets, and fuel tank level sender units to the boat's ground system. This is just about all that can be done reasonably without adding special grounding plates , and apparently is considered adequate. I have seen some commercial specifications for this for very large storage tanks (on land) that have a surface area to gallonage ratio specified, but never on a boat related basis. We'll have to assume the standard connection/grounding set up is adequate, and in practice it must be or the number of fires and explosions would dictate a change in the status quo.

Now think about the filling process. If you wanted to minimize the danger, what procedures would you take? The boat and the delivery nozzle should be without differential charge when we begin fueling. To be sure, touch the nozzle to some other grounded part of the boat other than the deck fill, or to the deck fill before opening the screw cap. As an added precaution, be sure the motor and all electrical units are off. Most important: Be sure the nozzle stays in contact with the metal components in the deck fill (some boats have fills made of plastic with metal inserts) throughout the filling process to insure the ground in the nozzle will pick up and drain off any developing charge as the tank(s) is/are filled.

That's about it, what else can be done? Call Dave S and have him stand by with the fire boat? The fact that we don't have more problems in this area indicates that the grounding systems currently employed work. My guess is that most gasoline fires on boats come from faulty lines, leaky carburetors, and inadequate blower usage (on inboard boats).

Gas sloshing around in plastic tanks is probably not an issue, since the gas and vapors are in a closed system and are grounded and self-neutralizing.

Filling a tank by hand from a portable tank of some sort is probably not an issue if both are plastic, or if a siphon (slow transfer) is used. A rapid fill from a metal can to a plastic reciever could result in a charged transfer. Connect a ground wire from the metal can to the gas tank ground for safety's sake.

I'm sure there are more possibilities, but we can discuss them as they arise. Hope this helps us all think this through! Joe.

[C-Bill]

Sea Wolf...

Your post is very informative!!! Well done. This is an important subject and I look forward to getting as much information as possible. You're very correct in the liability issue. It's unfortunate that there are layman who make a very good living from the judicial system (I hope I said that right as I don't want to offend anyone such as lawyers etc.).

I left out an important detail in my above post when referencing the electric fuel sender. With regards to the gasket between the mounting plate and the plastic tank, I have seen a staple in this gasket. Do not remove this staple as it has a grounding function with the tank! I mention this as it's too easy to see this staple and assume someone has been playing with a stapler. That was my first impression.

As Sea Wolf pointed out, when refueling at the service station, your tanks may have a static charge from known or unknown sources and will be insulated from the normal ground which the water provides. I'm sure most everyone has seen the signs at the service station warning you to put gas cans on the ground before filling them. This warning is in a way applicable to tanks in your boat. Touching the nozzle to a ground on your boat has a similar affect as setting your tanks on the ground.

I'm sure readers of this thread didn't need my 2 cents. I feel this subject is very important when considering the explosive force from the fumes in an empty gasoline tank. Protect your investment!!!!

Bill

[C-Bill]

Sorry Bearh...

I may have been the kiss-of-death to your thread.

Bill

PS - I didn't call C-Dory. I was just there and they are swamped. The technical people are all very busy.

[Bearh]

Bill--
A worthwhile discussion. I searched the C-Dog site, and apparently they have already had a similar discussion, because of a similar lack of clear guidance. Interesting. In the end, I think I did the right thing, and maybe I should figure out a better way to ensure maximum grounding wire contact to the metal fuel feed nipples than simply plastic suturing them as tight against each other as I can.
The factory is probably swamped because they've finally gotten tanks in to install in a bunch of boats in the pipeline.