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I'm raising these two questions based upon something I read on Backpackinglight.com - see link #1 - having to do with the internal pressure of fuel canisters filled at sea level and used at 6,000 feet.
The first question has to do with the boiling point of n-butane used in the test - see link #2
In link #2 it states:
Temperature: 31F/-0.5C as measured on a digital probe type cook's thermometer. No calibration was employed on the thermometer.
Boiling point of n-butane at sea level: 31F/-0.5C
Boiling point of n-butane at 6,000'/1800m: About 19F/-7C
Question 1 - What was the boiling point of n-butane the canister?Question 2 - Can anyone explain the canister pressure equalization disussed below? My gut tells me that the effects of altitude would have little effect on the internal pressure of the canister because of the rigid nature of the canister.
Paul Mason wrote: > What about the issue of the n-butane being in a canister? For the inside pressure of the canister to equal the outside pressure; wouldn't the volume/size of the canister have to increase while the amount of the fuel inside remained the same?
If my understanding is correct there is a 23% decrease in air pressure from sea level to 6,000ft.
http://www.endmemo.com/physics/pressurealtitude.php
If, I'm correct that means that the n-butane was below or at the borderline of its boiling temperature during the test.
Paul, the key difference in pressures is the relative difference between the inside (the canister) pressure and the outside. As gas is drawn off, pressure starts to equalize between the inside and the outside. At the point no more gas issues forth, the pressures are equal. Ultimately, it is the ambient air pressure and canister temperature that determines how much flow you'll get from a canister.
Link #1 - the bottom video is long but shows everything
http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=73386
Line #2
http://adventuresinstoving.blogspot.com/2013/02/advantages-of-regulator-valved-stoves.htmlThis is what a fuel caniste looks like - not used in the tests.
http://www.rei.com/product/643061/snow-peak-giga-power-fuel-canister
Here is more on canisters and the effects of cold.
http://zenstoves.net/Canister.htm
The first question has to do with the boiling point of n-butane used in the test - see link #2
In link #2 it states:
Temperature: 31F/-0.5C as measured on a digital probe type cook's thermometer. No calibration was employed on the thermometer.
Boiling point of n-butane at sea level: 31F/-0.5C
Boiling point of n-butane at 6,000'/1800m: About 19F/-7C
Question 1 - What was the boiling point of n-butane the canister?Question 2 - Can anyone explain the canister pressure equalization disussed below? My gut tells me that the effects of altitude would have little effect on the internal pressure of the canister because of the rigid nature of the canister.
Paul Mason wrote: > What about the issue of the n-butane being in a canister? For the inside pressure of the canister to equal the outside pressure; wouldn't the volume/size of the canister have to increase while the amount of the fuel inside remained the same?
If my understanding is correct there is a 23% decrease in air pressure from sea level to 6,000ft.
http://www.endmemo.com/physics/pressurealtitude.php
If, I'm correct that means that the n-butane was below or at the borderline of its boiling temperature during the test.
Paul, the key difference in pressures is the relative difference between the inside (the canister) pressure and the outside. As gas is drawn off, pressure starts to equalize between the inside and the outside. At the point no more gas issues forth, the pressures are equal. Ultimately, it is the ambient air pressure and canister temperature that determines how much flow you'll get from a canister.
Link #1 - the bottom video is long but shows everything
http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=73386
Line #2
http://adventuresinstoving.blogspot.com/2013/02/advantages-of-regulator-valved-stoves.htmlThis is what a fuel caniste looks like - not used in the tests.
http://www.rei.com/product/643061/snow-peak-giga-power-fuel-canister
Here is more on canisters and the effects of cold.
http://zenstoves.net/Canister.htm
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