Respectfully, simply not true for any canister stove Sierra...or maybe I just go higher.longri wrote: I have never needed to invert the canister while traveling in the Sierra. I'm sure there are some really cold nights in mid-winter but they must not be all that common. Most of the time it's 10 degrees F or warmer. And in the summer there is never any need to invert.
Canisters typically contain propane mixed with either isobutane or "plain" butane (n-butane). The boiling points (vaporization point) of each of those gases are as follows:
n-butane -0.5C 31F
isobutane -12C 11F
propane -42C -44F
Propane has the lowest boiling point and therefore the highest vapor pressure. Because of its high vapor pressure, the propane boils off at a faster rate than either n-butane or isobutane. Toward the end of a canister, you have no propane left, and you're running on just isobutane or n-butane. N-butane will not vaporize below 31F/-0.5C, so it's a poor choice for an upright canister stove in cold weather.
So, with that little fuel lesson out of the way, here's the answer: If you take a typical upright canister stove out in cold weather, you can run it on good fuel (no n-butane) to the point where the fuel temperature is about 20F/-7C at sea level throughout the life of the canister. Yes, isobutane vaporizes at 11F/-12C, but you need a certain amount of pressure in the canister in order to properly drive the stove. If your vaporization point is 11F/-12C, and your fuel temperature is, say, 12F/-11C, then the pressure in your canister will be so insipid that you can't run a stove off of it. Generally, about 10F/5C above the vaporization point will give you good operating pressure. So, if your fuel vaporization point is 11F/-12C, you generally want to shoot for about 21F/-6C in order to have good operating pressure. 20F/-7C is easier for me to remember, so I usually just say 20F/-7C fuel temperature for upright canister stoves using a propane/isobutane blend at sea level.