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Learn me on Fuel Vent Valves Plz


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I don't know how much force it takes to submerge the ping pong ball, that would be interesting to figure out what that number is. That is the question.

 

Anything sub-90 degrees (car on it's side or partially sitting on another car at an angle), the steel ball probably will not seal BUT the ping pong balls should still float and move with the direction of flow and seal. 

 

Anything over 90 degrees (car approaching upside down), the steel ball SHOULD seal, thus negating the discriminator valve. I could be wrong but I am on the same assumption as @okkustom that with a full or near full fuel load, the flow/weight of the fuel would force the ping-pong balls to seal. With almost no fuel (no flow/no weight coming down the vent line) then the fuel would leak past the discriminator valve.

 

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If my ho-made discriminator valve is in need of help, I'll probably just buy the ATL unit as well.

 

If I do, I'll rig up a unit with a 5 gallon bucket, some -10 vent line, and the discriminator valve and see what happens in various simulated roll over angles. 

 

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Chris I ended up with a discriminator valve and roll over valve. The roll over is for safety, and the discriminator is for fast fueling and keeping the fuel in the tank. It worked really well for me once I figured it all out. I fuel 15 gallons in 30-45 seconds and no fuel loss during race conditions. 

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On 5/12/2018 at 12:34 PM, Huggy said:

 

 

 

Im not sure I understand.  The idea of the pingpong ball or whatever is in there as a “float” is that it is buoyant.  The weight of the gas doesn’t come into play?  

 

Im gonna order the ATL valve and play around with it before installing on the car.  I can always add another device, but I am limited on my vertical space to mount these things, and for each additional device the flow will be reduced.

Just think of them as two completely separate issues. Discriminator valve is to keep fuel from running straight through the vent line when fueling and rollover check valve is for just what it sounds like, ROLLOVERS. We have had to run Discriminators for a few years now in Off Road to keep from dumping fuel on the ground and killing ants, snakes, spiders, etc but Off Road as a whole is pretty sloppy with fueling. I wouldn't spend the dough on one for a Champcar because if you just run your vent from one side of the tank up the cage to the other side of the tank and vent out the back you will never spill a drop.

On 5/12/2018 at 12:34 PM, Huggy said:

 

 

 

Im not sure I understand.  The idea of the pingpong ball or whatever is in there as a “float” is that it is buoyant.  The weight of the gas doesn’t come into play?  

 

Im gonna order the ATL valve and play around with it before installing on the car.  I can always add another device, but I am limited on my vertical space to mount these things, and for each additional device the flow will be reduced.

Just think of them as two completely separate issues. Discriminator valve is to keep fuel from running straight through the vent line when fueling and rollover check valve is for just what it sounds like, ROLLOVERS. We have had to run Discriminators for a few years now in Off Road to keep from dumping fuel on the ground and killing ants, snakes, spiders, etc but Off Road as a whole is pretty sloppy with fueling. I wouldn't spend the dough on one for a Champcar because if you just run your vent from one side of the tank up the cage to the other side of the tank and vent out the back you will never spill a drop.

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  • 2 years later...

I have been trying to resolve this venting of a fuel cell tank as well. Started due to fumes in my garage. I have researched the web for weeks and consulted some top racer friends on safe ways to do it. What I am going to do is similar to what others have mentioned for my twin 15 gallon fuel cells. I am installing a roll over valve on both tanks. Coiling a hose several times above the valves and above the tanks. I am then going to try installing some sort of an fuel separator catch can with a removable bowl that I can fill with activated carbon pellets that can be changed out easily similar to a water/oil separator on an air compressor but with carbon in it to eliminate fumes. Poor man's EVAC system. From there I was going to run the hoses under the vehicle to small air filter. But I am liking the idea of a discriminator valve in there somewhere after reading this thread. Just not sure where to put it in that sequence. Hope these images help.   spacer.pngspacer.png

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Peewee

I did exactly what you described from my fuel cell. It passes but, Jay noted it needed to come from the top of the tank and straight out the back for me to pass inspection next year. That will be a total of 1 ft 4" from the AN fitting center of the cell to the rear of the car. I dont think it will not spill during driving. Any suggestions. 

 

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Try Googling this phrase and click on the images tabs to see only pictures: "racing fuel cell venting tube".  There are a lot of images about everything we are discussing. Also I have read that everything in the venting process has to be higher than your fuel cell filler neck if you added one of those. I think I am going to even move my roll over valve higher than the top of the tank including the coiled hose and fuel canister etc. But the final end of the hose with the vent filter on it from what I have read goes down under the vehicle far enough that it would be higher than the tank if it was upside down and as far to the side of the vehicle away from the side of the tank if the vehicle rolled onto it's side. Venting it out the back would seem to be even better than just underneath I would think so if by some chance fuel did make it out it would not be under you.

Scroll down on the Google search to you find this picspacer.pngture and click on it. There scroll through those images.

Edited by Harley
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Radium makes a discriminator/rollover for fuel cells OR you can use it alone with AN fittings. We have one, @E. Tyler Pedersen, has one, and @hcsi99 that i know of now.

Steel Ball is below the floating ball. When full, floating ball seals, when rolled over steel ball pushes on floating ball and it seals.

 

We all run cells but i could see using one on an altered vent line as well. 

 

I will say we had our floating ball swell and stick, we contacted radium and the overnighted us 2 spares so we can keep an eye on it.

 

We can pack our fuel cell as full as possible all the way to filler neck if we want and will not spill a drop on track.

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On 11/17/2020 at 11:30 AM, Gkuhn41 said:

Radium makes a discriminator/rollover for fuel cells OR you can use it alone with AN fittings. We have one, @E. Tyler Pedersen, has one, and @hcsi99 that i know of now.

Steel Ball is below the floating ball. When full, floating ball seals, when rolled over steel ball pushes on floating ball and it seals.

 

We all run cells but i could see using one on an altered vent line as well. 

 

I will say we had our floating ball swell and stick, we contacted radium and the overnighted us 2 spares so we can keep an eye on it.

 

We can pack our fuel cell as full as possible all the way to filler neck if we want and will not spill a drop on track.

Radium is not immune to this hollow ball sticking.  It happened on our Fuel Safe as well.  We had the car ready to go before April for Daytona, the car sat for 3 months with (non-ethylated) fuel in it (should have been fine). When we eventually did run Daytona, we ended up with fuel coming out of the vents during fueling.  We initially though it was because of the position of where ours was mounted and possibly thought it was due to us also having the stock filler neck vent connected.  We changed that but had a similar issue at PBIR so we took it apart after PBIR and found that the hollow ball had stuck.  It didn't swell as we immediately compared the ball diameter to the inner diameter of the venting "shaft", there was an excess of .050" clearance, so it was just stuck.  We have since made modifications to our setup to allow easier access for service, and we will do a test fill as part of the car prep to make sure the discriminator is working as advertised. 

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