Fuel container venting?

[Pioneer]

I recently added a cork seal to the cap of my fuel container and now it might be sealing a little TOO well. We recently had a big temperature swing and I just noticed that the tank had enough pressure built up to give it a 6 months pregnant look. I've never had this problem before as my tanks didn't have such a perfect seal. Do you leave the vent cracked slightly to relieve pressure on plastic containers? This is an old one, and there is no way to relieve pressure except manually.

 

[husqORbust]

Id put in the max amount in volume(i.e 5gal in a 5 gal can), seal it 100%, and not be concerned.

For a 90° summer I had 6 5gal jerry cans sitting covered outside. Newer style with no vent. They sure swell up, and were permanently swollen that 5gal at the pump wasnt enough to meet the 5gal line on the jerry can. But, I dont consider it as a hazard.

 

[Bob Hedgecutter]

If they get hot, then you vent them to assume their natural size again- but the fuel is still warm, when it cools overnight that reverse happens and they suck themselves in under vacuum.
A lot depends on the quality of the container as to how far they go, or how many times they can do it without splitting.
If you have a wagon style truck not a pick up and you do a days cutting in the middle of Summer- it is alarming just how rounded those gas cans can become!

 

[KASH]

They shrink alot to.They implode and get some weird shapes doesnt seem to harm the can.
Kash

 

[deye223]

They shrink alot to.They implode and get some weird shapes doesnt seem to harm the can.
Kash

They expand and contract by design you do not vent them if you let air in you are letting moisture in let them expand let them shrink if it worrys you that much keep them full only thing that lets them expand is the air that's in the container the more air they have in them more expansion you will get simple physics .

 

[old CB]

Much of my cutting is done in summer, in high temps, and it's a nuisance managing for the effects of heat. We always keep my fuel can in the shade, carry a folded up tarp to keep sun off the fuel can but the thing still blows up like a balloon. I open the vent only to fuel saws, as otherwise every time you open it you're letting some of the volatile portion of your fuel escape. On a hot day up at 8,000--9,000 feet elevation after I've fueled up late in the day, the next morning my fuel can is shrunk into ridiculous form after it cooled and came home to 6400'.

One day last week, first time cutting in hot temps this season, I forgot and let a saw sit in the sun for about an hour. Did not want to start & run of course. Had to open the fuel tank and let the boil subside, then pull the starter numerous times to clear the air bubbles from the fuel line. Ran like a champ after that of course.

 

[lone wolf]

I recently added a cork seal to the cap of my fuel container and now it might be sealing a little TOO well. We recently had a big temperature swing and I just noticed that the tank had enough pressure built up to give it a 6 months pregnant look. I've never had this problem before as my tanks didn't have such a perfect seal. Do you leave the vent cracked slightly to relieve pressure on plastic containers? This is an old one, and there is no way to relieve pressure except manually.
View attachment 907712

Loosen the cap a bit.

 

[OM617YOTA]

It's not air in the can expanding, it's the vapor pressure of the gasoline itself. Take a look below. Vapor pressure of gasoline is ~9psi at 100F. Doesn't matter how much you vent it, if it's hot and you have gas in the can, it'll keep building pressure. The point at which it stops building pressure is the point at which an important part of your gasoline is gone. Don't vent your gas cans any more than you have to.

 

[deezlfan]

The modern cans that come with no vent and the self sealing spouts are made from a less permeable plastic and are designed to hold the pressure. If you resealed an older can, those were never designed to withstand large internal pressures and could be a significant danger.

 

[Wood Doctor]

I have one of those vintage metal 2-gal cans and all I did was leave the 1/16" dia. hole open in the fill cap after the rubber stopper wore out 20 years ago. I've had no trouble with it or the fuel I fill it with.

 

[lone wolf]

The modern cans that come with no vent and the self sealing spouts are made from a less permeable plastic and are designed to hold the pressure. If you resealed an older can, those were never designed to withstand large internal pressures and could be a significant danger.

Much better now they can blow up in your face and stop all our saws from working well Damn idiots!