internally vented fuel tanks ??

[Home Cookin']

A guy on another forum was talking about internally vented fuel tanks, that don't release fumes into the atmosphere (or bilge!) nor do they have an overflow vent. They don't let water in, either.
This came up while discussing boats with tanks that don't appear to have a vent anywhere.
I can't find anything on them but I know they have to let air in somehow and address expansion/contraction. I know that many fuel caps are "internally vented" but they are nonetheless vented to the atmoshere, adn he said this was not what he was referring to.
Anyone know anything about these?

 

[Bifflefan]

Re: internally vented fuel tanks ??

That would be a neat trick.

 

[180shabah]

Re: internally vented fuel tanks ??

I'm thinking the dude, doesn't have a clue.

Where I come from, a container that is internally vented into ITSELF, is called sealed.

 

[Home Cookin']

Re: internally vented fuel tanks ??

Me too. First, I think the guy was confused with an internally vented fill cap, which may reduce the release of fumes into the air but I doubt it eliminates completely--without fans, if air migrates in, fumes migrate out. The best I can conceive is a second chamber to trap fumes and somehow route back to the tank chamber, almost like a circulating moonshine still.

 

[Chris1956]

Re: internally vented fuel tanks ??

Modern automobiles have sealed gas caps, and semi-sealed fuel tanks. When pressure builds up in the gas tank, the pressure is released into a charcoal filled canister which can be vented into the engine's air intake stream if necessary. Therefore, the fumes in the charcoal canister are either drawn back to the tank as the fuel is consumed, or burnt in the combustion chambers, if the charcoal canister capacity is inadequate.

I would guess that a system of this type "might" be adapted for marine use. however, I would think it would need to have a positive seal, when the motor is off, to keep fumes out of the bilge, but could function a lot like the automotive version, as long as the engine is running.

 

[Bondo]

Re: internally vented fuel tanks ??

I'm thinking the dude, doesn't have a clue.

Ayuh,.... Me too,.... There's Always alotta Bullship posted on forums that's Just Plain Wrong......

 

[Home Cookin']

Re: internally vented fuel tanks ??

but I read it on the internet! It has to be true!

 

[Paradise David]

Re: internally vented fuel tanks ??

I am working on a gas tank problem myself and was searching here for some infor.
Years ago, I used to delievery gasoline/diesel to gas stations. You all seen the tanker trucks doing this. These tanker trailer that haul the fuel have a "closed venting system" (it the law). Dropping a fuel line from the tanker trailer to the inground tank, open a valve, and gasoline flows into the inground tank.

The inground tank MUST be vented or gas would not flow into it.
Another hose (from the tanker trailer) is plugged into the vent of the inground tank which is a spring loaded check valve. Now when gas is dumped into the ground tank the air inside the ground tank is vented back into the tanker trailer. I could unload 8000 gallons and never smell gas until I diconnected the hoses.

Maybe a system like this was what this guy was talking about. I dont know how you would setup sure a system on a boat.

I just realized this post is over a year old......oh well, this might help someone