Slightly off topic-Fuel Cell rollover valve question

I have a kind of silly question. I have a fuel cell with a roll-over valve on top of the fuel cell. The rollover valve has a #8an fitting on it. Whats the proper way to plumb/run the vent line? I'm not sure where the vent line needs to be routed(above or below the fuel cell?), and what to terminate the vent line with(if anything).

I know fuel cells are not a "traditional" approach, but I figured somebody must know the right way to plumb it. Thanks in advance for the help guys!
Dan

 

Run the line up as high as you can above the tank then do a 180 and run it as low as you can below the tank, this way if the valve were to fail it really lessens the odds of fuel leaking.

 

You can also get a ping pong ball check valve.

 

the roll over valve is a steel ball in a cage that seals off when upside down, when right side up the ball is down and it vents properly, just run the vent tube above the cell at keast 3 ir 4 inches and then make a 180 down and out side of vehicle..

 

I had the same thing and could smell fumes in the garage, not strong, but noticeable.

Cured by:
Getting a Japanese pickup (Toyota I think) steel charcoal cannister - they're small and have a built in bracket, paint it black and it disappears from view.
(Mine is somewhat exposed, but in 13 years only one guy noticed it.)
(The cannister I got was in the left front corner under the hood.)

Plumb the vent line up high as you can in the trunk then go down and connect it to the charcoal cannister.

Go forward with another line.
Somewhere in this line install an Earls screen type inline filter. (Mine's about middle of frame equi-distant between wheels fwiw.)
Use the one with stainless screen (looks like window screen) and not the one with the ceramic filter.
What you're doing here is imitating the anti-flashback deal that goes in the acetylene hose of a gas welding rig.

From there, go forward with another line and plumb it into the base of the air cleaner.

The fumes don't seem to reach the carb area and if they did and if there was an engine backfire - done a few of those - the flame would not travel back to the fuel cell.

Overkill perhaps, using both the charcoal cannister and inline filter, but I worry about fires and inside the fuel cell is not the place to have one....

 

On Power Tour, I saw a guy who didn't run the vent high enough before making the bend to go down.
Say your vent tube is at the front (engine) end of the car, and comes off the top of the tank and goes straight up for a couple inches. Then it makes the bend. If you're sitting on a hill or filling your gas tank, and the rear (back bumper) side of the tank is higher than the bend, you'll drain your gas until you lose enough that the fluid is no longer touching the top of the tank. This could be a gallon or more. The car I saw dump gas wasn't on much of a hill. Remember, if you've got a big cell, you only have to tip the back of the tank up a few degrees for it to be an inch or two higher than the front of the tank.

Doesn't come close to answering the original question, but I thought it was good advice to add to a fuel cell post.
-Brad

 

I talked to a guy with a keg gas tank. He said he used a PCV valve on the vent tube for rollover protection. We didn't get into detail. Anybody heard of that?

 

I'd run a loop in the line as well.

 

Up to the cage then down beside the cell and hang a small fuel filter on the end to act as an air filter (I race dirt track and sucking dirt in everything is always a possibility....)

That said - the charcoal canister is a great idea and really saves the ozone from the evaporative emissions of an 'open' fuel container...

 

i have vented caps.....no vents, got a cell and the vent filter is mounted to the vent/ check valve fitting. high test smells best...

 

was wondering on updates on this from anyone? didn't want to start a brand new thread when one existed. using the canister too, with fuel prices as high as they are gas evaporating out of the bowl or tank is money blowing in the wind basically . i'm figuring out a way to use the vaccume type fuel shut off valves for minibikes to vent the carbs,close when the engine is off. open when it's running and a canister to catch and reburn the fuel vapors, fuel is fuel and i hate wasting money on it evaporating

 

x2 for the loop works like a champ

 

Tingler I've never seen it happen. I know alot of the roundy round guys belch flames out the exhaust.

As for terminateing the vent line I've always used one of those cheap in-line fuel filters. All it does is keep you from sucking dust back up when the cell cools off.

 

For terminating, lot of different ways.
-Cheapest and easiest is a Chevy Valvecover PCV valve in the end of the hose for a one way vent.
-Vented Catchcan
-Into a fuelfilter (used like a catchcan) like the FRAM G6567




For routing I use #1 below in my race car if that helps.


1. Route the line three sides then down.


2. Route the line following the FATS system (Fuel Air Trap System)
From the vent/valve the hose extends to the left past the left side of the fuel tank on a slight angle past horizontal (See reference to horizontal and vertical reference lines.).
Once past the end of the tank, the fuel line is routed upward, again not quite vertical, but angled slightly.
Again the hose is routed to the right, completely over and past the right end of the fuel tank (Not quite horizontally).
And then lastly the hose is routed downward to a level close to (or below) the bottom of the fuel tank.
Hose routing is vital, for this routing is what makes the FATS design work.
Again, hose routing attributes are:
· Left-to-Right or Right-to-Left hose routing must always extend Past the Sides of the Fuel Tank.
· Vertical and Horizontal hose routing must not be square, but rather sloped so as to allow any fuel in the lines to drain back to the tank.
· Hose should terminate as close to the bottom of (or below) the fuel tank