Discussion on custom gas tank setup

[Evan]

I was just watching the History Channel - Engineering Disasters. They featured a BP oil refinery that violently exploded due to an unflared vapor tower. It got me thinking about my gas tank setup and its safety. I imagine I am not the only person running a fuel cell in their rig, so maybe others will be interested in everyones opinion on this.

I have an aluminum fuel cell in the back of my truck with an intank pump. Coming out of the tank is a high pressure feed line, and a return line back into the tank. The return line goes to the bottom of the tank, so fuel is not "dumped" into the tank as it's returned.

The third line attached to the tank is a vapor line. This line comes out of the top of the tank and then goes out through the bottom of the truck near the rear diff. This is what I am a little concerned about. I am wondering what's the best way to design a breather system. My concern is that vapor could maybe pool under the truck and then ignite. Maybe I should run the line all the way back??

 

[Shran]

You could set up something like stock tanks have...a check valve with a line to a charcoal canister somewhere else. If you still have the stock one just extend the vapor line and use it.

 

[Evan]

You could set up something like stock tanks have...a check valve with a line to a charcoal canister somewhere else. If you still have the stock one just extend the vapor line and use it.

A check valve would stop air from going a certain direction though. I need air to go in as the tank gets lower or cools down, and vapor to go out as the tank warms up or I fill it.

 

[racinranger]

You could use a vapor managment valve like a newer obdII car. burn the vapor in the motor. The other system that i have seen used is a 4 line setup. with one vapor line to the intake to put a vaccuum on the tank and another line setup as a purge line. open to atmoshpere. thatway the tank is constantly drawing in fresh air accept under WOT conditions but that isnt all the time.

 

[Evan]

You could use a vapor managment valve like a newer obdII car. burn the vapor in the motor. The other system that i have seen used is a 4 line setup. with one vapor line to the intake to put a vaccuum on the tank and another line setup as a purge line. open to atmoshpere. thatway the tank is constantly drawing in fresh air accept under WOT conditions but that isnt all the time.

What would happen if you had a backfire with that system?

 

[racinranger]

im thinking you use a flame arrester in line with the line to the manifold. I also dont belive the concentration of vapor is going to be heavy enough to back up that tiny tube. altho i could be wrong here. In this case tho a 1 way check valve could serve a purpose. letting vapor in but nothing back to the tank. since the 4th purge line would always be open to atmoshpere

 

[Shran]

A check valve would stop air from going a certain direction though. I need air to go in as the tank gets lower or cools down, and vapor to go out as the tank warms up or I fill it.

How about just running the vapor line directly from the tank into the charcoal canister? You wouldn't have to worry about backfiring then, plus the whole point of the carbon is to absorb fuel vapor. Just an idea

 

[85_Ranger4x4]

What would happen if you had a backfire with that system?

In stock form they collect the fuel vapor in the charcoal, and then during low power settings (cruising on the highway) it feeds back into the intake manifold. I would almost garrentee every vehicle sold new in the US today uses this system or one similar to it, my '85 Ranger had it... I bet your Explorer had it new as well. It is really pretty neat how it all works.

I don't know how they deal with backfires but they are not all that common, especially when you take a distributer out of the mix.

 

[85_Ranger4x4]

How about just running the vapor line directly from the tank into the charcoal canister? You wouldn't have to worry about backfiring then, plus the whole point of the carbon is to absorb fuel vapor. Just an idea

There is a limit as to how much vapor charcoal can hold. You would have to be able to vent it somehow eventually.