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Discussion Starter · #1 ·
After awhile sitting there it seems to be compressing itself. Basically sucking itself in. :) When you open the cap you hear air escaping. What's happening? There's some gas in it (a gallon maybe) when it occured last. It's one of those 5 gallon ones you get at your local auto parts places.
 

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grendels_arm said:
After awhile sitting there it seems to be compressing itself. Basically sucking itself in. :) When you open the cap you hear air escaping. What's happening? There's some gas in it (a gallon maybe) when it occured last. It's one of those 5 gallon ones you get at your local auto parts places.
You're not hearing air escaping, you're hearing it rush into the container! If the container is crushing, it means the air that was inside the container is being absorbed by the liquid. The container is tightly sealed, so the external air pressure is crushing it to take up the space left by the disapearing air.

I don't know why the air in the container is being eaten up, but it's probably some kind of oxidation process of the fuel. The fuel is changing (probably going stale). I've left gas in a container for over a year, but I've never seen the container crush itself. It may be that my container has a valve to allow air in.
 

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The gas fumes/air contract with falling temperature more than just air would.

You probably last opened the gas container with fuel when the ambient temperature was relatively warmer than it was when you observed the container collapsing.

Check out this photo:



Since brake fluid absorbs moisture, I thought it would be a good idea to displace the air in the container with the gas from those canned air dusters (the duster air being dry). There was just enough fluid in the container to flush the clutch system and I thought what the heck, I'll just save it until next time. This was during the summer. With the onset of winter and the colder temperatures, the container collapsed.

Basically, you see the same thing happen to gas containers.
 

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One of the gas laws, P1 * V1/T1= P2 * V2/T2. This means that if the volume of a container is constant and temperature, drops, the pressure will drop also to satisfy this relationship. Opposite occurs if the temp rises, pressure will increase. The drop in pressure causes a flexible container to suck in on inself and will cause air to flow in if the lid is opened.

Mike
 

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ducatimike said:
One of the gas laws, P1 * V1/T1= P2 * V2/T2. This means that if the volume of a container is constant and temperature, drops, the pressure will drop also to satisfy this relationship. Opposite occurs if the temp rises, pressure will increase. The drop in pressure causes a flexible container to suck in on inself and will cause air to flow in if the lid is opened.

Mike
The Ideal Gas Law in action!
 

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Discussion Starter · #7 ·
Now I think I understand. The container I got at the local auto parts store is alot more flexible than the one I got from the motorcycle place, which is harder plastic.

Any harm in letting a container do that?
 

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no, thats why they are plastic. Thicker plastic=less shrincking. Just don't buy more gas then you need or preject to use. motocross racers use very durable canesters. The army uses uses metal because of all the extreme temp changes they go to.
 

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Put uyour kero tin in the sun, about 1.30 pm go screw the lid on it tight and then stick it in the freezer.. You'll soon see your tin collapse,.. oh don't put it above the steak just in case

Mal
 

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Ok, this has got to be one of the most lame threads that I've ever seen posted on a gearhead type of website.

If this is indicative of your handle on physics then please sell the bike and consider taking up scrapbooking or perhaps gardening.

[/sarcasm]

Seriously though, i can't believe that I'm the first person ribbing you about this. When I read your initial post I honestly thought it was a joke.
 

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I didnt read the whole thread but a short _Warning_:

I have seen several photos on this forum of Ducati's who wants were dented or sevearly crushed by the vacume inside the tank. You might want to make sure what you have isnt unusual at your dealer or it could be expensive if not coverd under warranty.
 

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I just skim read this post but...

A drum imploding well then you'll need a new head.
I'd go with a Remo or an Evans you get better sound and they adjust easier.

Drum roll please....tada...
 

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smegtheprez said:
I just skim read this post but...

A drum imploding well then you'll need a new head.
I'd go with a Remo or an Evans you get better sound and they adjust easier.

Drum roll please....tada...
LOL
+1 on the Evans
 

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I would add that gasoline is a highly volitaile fuild, meaning it vaporizes very easily. kerosine is a heavier fluid that is resonably stable, so when you close the container its normally liquid kerosine and air, when you close the gas container much more of the vapor volume in the container is actually vaporized gasoline then as with kerosine. when it gets cold the gasoline condenses much easier and the amount of air in the container is actually smaller then the equivalent setup with kerosine, so the gas container will crush more. gas being more voliatile in terms of vapor pressures also is why it explodes easier, the fumes catch first, if there not a lot of fumes you can actually extinguish a cigarette in gasoline cause the smoldering temp of the cig is lower then the flash point of liquid gas, however the flash point for gasoline in vapor form is much lower, hence the big boom :D

Sorry for the long post; I realize I have officially established myself as a dork, but thats what happens when a kid grows up being a pyro and then goes into aerospace engineering :cool: :p

PS If anyone is dumb enough to actually test that cig thing, I refuse to be held responsible ;)
 
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