Earthing of plastic fuel tanks.

4 years 7 months ago #26555 by Trickie Dickie
Trickie Dickie created the topic: Earthing of plastic fuel tanks.
Normal practice with outboard fuel tanks is to set them on the ground when filling, thereby earthing them. Risk in not doing this is a build up in static electricity and a spark, fires/explosion risk etc. Apparently there has been an upsurge in these incidents with people filling plastic fuel jerries since they started fitting plastic liners in utility (pick up) vehicles; it tended not to happen when plastic containers were filled in a steel floored tray.

We've recently removed the stainless steel tank from our club grp hulled RHIB; the damned thing had rusted internally and particles clogged the fuel filter causing us some embarrassing loss of performance.

The tank was fitted in a compartment under the cockpit deck; we've now replaced it with several HDPE tanks which also considerably increases our potential range.

Only trouble with this is that fitting them in there is a bit of a squeeze; once in, they're in but getting them in requires a fair bit of manipulation and general buggering about. When doing this with full tanks, it gets very difficult for 2 people, almost impossible for 1.

I've been trying to figure a way of earthing the tanks whilst in the hull compartment to avoid the need to lift them in and out every time we fill them.

Ideas I've had include:

1. Making up an earthing strap, clamp at one end to temporarily connect to the brass fuel tank spigot, a wedge of copper at the other to stick between the tyre and the concrete forecourt surface to earth it whilst filling.

or

2. Have an earthing strap permanently connected to earth on the boat's electrical system, and a clamp on the free end to connect to the spigot of whichever tank is being filled.

or

3. Simplest of the lot, just douse the hold and fuel tanks with water using the forecourt watering can to wet everything and hopefully suppress any static buildup.

As (3) is the simplest, I much prefer it; or perhaps a combination of (3) and one of the other two solutions.

Anyone else got any ideas on this?

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4 years 7 months ago #297372 by spiro
spiro replied the topic: Earthing of plastic fuel tanks.
Most servos that I've been to lately have an earthing cable on a reel near the bowser.. Is this of any help?

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4 years 7 months ago #297373 by Trickie Dickie
Trickie Dickie replied the topic: Earthing of plastic fuel tanks.
No never seen such a thing...... but this is Tasmania after all; however, maybe they are there and I just haven't noticed, although I suspect it isn't, probably differences in Dangerous Goods Regs between NSW and Tas.

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4 years 7 months ago #297374 by spiro
spiro replied the topic: Earthing of plastic fuel tanks.
I would consider some how fastening a cable to the fuel tanks ant then to a spigot, and have an aligator clamp leed in the car for when you fuel up.

Basically the servos here have a reel about 150mm in diameter with a thin cable that is earthed to the awning structure of the building. It just has an aligator clip on the end. I think it is there mainly for the supply tankers to use when delivering fuel.

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4 years 7 months ago #297387 by burna
burna replied the topic: Earthing of plastic fuel tanks.
I have seen earth cables at only a few service stations, they are normally used at aircraft fuelling points. I think it is more prevalent in aircraft bc they build up a large static charge flying through the air at speed.

The idea is to get the fuel tank and the fuel nozzle at the same potential. If there is somewhere to earth a plastic fuel tank you could run a short earth lead connected to the fuel tank with a large alligator clip on the other which you could connect to the handle of the fuel nozzle, then you don't need to remove it, but, I would have thought there'd be a very low chance of getting a spark between a plastic fuel tank and the fuel nozzle on an approved tank.

If you were really worried you could tap the fuel nozzle or nozzle handle on the trailer or some other metal part of the boat before opening the fuel tank.

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4 years 7 months ago #297394 by Trickie Dickie
Trickie Dickie replied the topic: Earthing of plastic fuel tanks.
quote:

Originally posted by burna

The idea is to get the fuel tank and the fuel nozzle at the same potential. If there is somewhere to earth a plastic fuel tank you could run a short earth lead connected to the fuel tank with a large alligator clip on the other which you could connect to the handle of the fuel nozzle, then you don't need to remove it...



Same thing was suggested to me by an ex-aircraft refueler, so will probably go with that idea as it's certainly the simplest.


quote:

Originally posted by burna


but, I would have thought there'd be a very low chance of getting a spark between a plastic fuel tank and the fuel nozzle on an approved tank.




Apparently, it does happen though:

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4 years 7 months ago #297427 by Hornet
Hornet replied the topic: Earthing of plastic fuel tanks.
Static is the biggest risk in the petrochem industry. Personally I would not be relying on earthing and bonding at the service stations as you have no idea if it complies, meets current standards or if it has been tested. Splash filing (generates static) is a major risk especially with distillates (diesels etc), as well as switch loading (WorkCover had a ball with audits last year after 2 people were killed in Parkes 2008). Far safer to place (approved) containers on the ground.

Bec (Oil Industry Engineer)

Other references:

- AS 3000 - crimping of lugs on static leads
- ACTDG Part 10: Bulk transfer of dangerous goods; Para 10.1.2.2.3 Electrical Continuity Testing
- AS 1020 - The control of undesirable static

Resistivity of less than 10megohms for the 'system' rings a bell...

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4 years 7 months ago #297428 by AB
AB replied the topic: Earthing of plastic fuel tanks.
"Apparently, it does happen though:
"

That did look more like a steel boat fuel tank. And the customer pulled the nozzle out with the petrol still running and directed it under his car. So many mistakes one after another it looked like either a training video or an insurance job!

Not being an electrically talented person, I thought the plastic of fuel tanks was an insulator, so if there was any static, it would have to be in the fuel itself???? Like I said, I have very little knowledge in this area, but thought a dry plastic tank would be safe.

Alan

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