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Discussion Starter #1
I plan on adding a fuel pack later this spring...i was wondering what happens when they get hot from the sun or hot day....reason I ask is my gas jugs swell like a beach ball in the heat ....now will the packs do the same ..if so ever had a problem of them bursting
 

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Can't remember the # I read. But the kolpins can take like 2x the psi that a reg can is capable of which they claim is far more then gas is capable of producing. I barely notice any swelling. These cans a VERY stout
 

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It's the air that expands. Keep them full and nothing to worry about. It's always recommended to never keep a fuel can half full, especially in hot climates.
 

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It's the air that expands. Keep them full and nothing to worry about. It's always recommended to never keep a fuel can half full, especially in hot climates.
:stupid: Agreed 100%, Keep them full = less air to expand. Which also equates to less off gas vapor, which is the flammable part of gasoline.

I got a Kolpin from the kids for Christmas.... just trying to figure out where to mount it!!
 

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Discussion Starter #5
thanks..that clears up alot...I just heard the Koplins got recalled for some reason....some CARB issue..not being compliant....was on thier site...
 

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Rotopax are very resistant to swelling. They are rotary flow molded rather than blown so they are thicker and more robust.
 

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^ any idea what the actually is? I've never heard of flow molding.

I'm curious as I do injection molding for work. I've never done blow molding. I'm attempting to go back to school for plastics.
 

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Discussion Starter #8
I am getting roto pax when I get one....I heard they are so much better....no issue with the nozzle either
 

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^ any idea what the actually is? I've never heard of flow molding.

I'm curious as I do injection molding for work. I've never done blow molding. I'm attempting to go back to school for plastics.
The mold is spun at high speed so the plastic flows due to centrifugal force. We actually cast very large nickel alloys parts in a similar fashion at my work. Link below gives some info. Actually the name Rotopaxs is coined after this moulding process.

http://www.hedstromplastics.com/blog/2012/09/04/rotational-molding-vs-injection-molding-understanding-plastic-molding
 

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Rotopax are the only way to go. Yes, they do swell to the point that it can be difficult to turn the handles to take them off of their mounts, and you would swear that they would explode. I will stop and bleed off the pressure when they get too big. Heat and altitude changes will cause this. Keep an eye on them and back off the handles a turn or two as they swell and this won't be a problem. Full or empty, they will swell. I've tried filling them to where you can't get another drop in them, and the result was gas blowing everywhere when I relieved the pressure from them. All that being said, they have yet to leak a drop regardless of how much pressure has built up in them. I wouldn't buy anything but Rotopax.
 

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Discussion Starter #14
thanks bobx2 that explains a lot to me...just burp them a few times on a hot day....thats what I was afraid of..a face full of gas when expanded....I just want them so when i travel and hit some ATV parks near me..where I ride local I have some 2 gallon jugs stashed if i need gas....they are not in the sun..I usally top off when near them and when close to empty I take them to refill....all gas stabililized ....but from reading roto pax is the way to go..not one bad report on them....Thanks
 

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Completely filling them with gas will have little effect on expansion. The vapor pressure of gasoline is a function of temperature. So it will expand when it gets hot, simply because of the gasoline vapor pressure.

Plus, as Bob says.. if its completely full it will blow gasoline out when you open it.
 

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Plus, as Bob says.. if its completely full it will blow gasoline out when you open it.
Or as my father always taught me, in a case like that, you need to learn how to...... "Feather the Controls" :D

But a good point none the less.... gas vapor will expand in the heat, but having less area for the vapor to expand from the start is a big advantage! It is the nature of the beast!
 

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Plus, as Bob says.. if its completely full it will blow gasoline out when you open it.
Or as my father always taught me, in a case like that, you need to learn how to...... "Feather the Controls" :D

But a good point none the less.... gas vapor will expand in the heat, but having less area for the vapor to expand from the start is a big advantage! It is the nature of the beast!
Easier said than done sometimes. Ever tried to open a full bottle of soda after it has been shaken up real good? That point kind of applies to your second statement as well. Opening up a well shaken, not full to the top, bottle of soda is easier to do without making a mess as well. No need for the fuel cans to be topped completely off. Makes no difference in how much they will swell up, so make it easy on yourself to open them without getting gas all over.
 

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PV=nRT
 

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My neighbor had a 2 gal Roto Pac and it blew the seam when it was left sitting on his quad in the sun. He now has a 3 gal roto pac.
 

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I have the 2+2 rotopax mounted on my front box. They swell up like crazy but never leaked. Love them. The nozzles are garbage easier to just pour it without the nozzle.
 
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