Lower limit of UNinverted canister

I used mh Pocket Rocket into the single digits a couple Fall's ago in the Crabtree Meadow area in early Oct. Two nights in a row, temps were into the single digits, my temp gauge showed that and the ice on slow moving water also.
Duane

Did you do anything special besides keep the canister warm when not using it?

I use my Pocket Rocket down to 20F occasionally – gets very slow

When it's full, the lower limit will be ballpark 0F.
BUT, as the propane gets used up, the lower limit will rise rapidly. Then, the lower limit depends on which gas is left.
If this is iso-butane, then the lower limit when near empty will be around 20F.
Otherwise, with regular butane the lower limit when near empty will be around 40F.
These temperatures refer to the temp of the canister, which may not be the same as ambient.

I used a SP GP with a small SP canister on snow this weekend. It was noticeably slower and was a bit finicky when starting. I didn't do much warming of the can' as I was curious to see how it would do. Air temp was mid 20s.

I only placed my canister in my pants or somewhere for a few minutes, then after the stove ran a few minutes, dunked the whole thing in the water, instant higher flames, did that twice on the very cold AM's, worked fine, YMMV.
Duane

"These temperatures refer to the temp of the canister, which may not be the same as ambient."

When it's cool but above freezing, after I boil a couple pints of water the outside of the canister will be cold, water vapor will condense on the outside of the canister and freeze.

This is part of what happens at cold temperatures. You have to figure that the canister is colder than ambient.

And the fact that a full canister will operate a bit better initially as the propane boils off isn't very useful. I need my stove to operate for several days, including after the propane is all gone. I don't know why they bother adding propane, unless it just naturally is part of the mixture and would be difficult to remove.

It does not matter how cold it is outside, the canister is still going to cool down due to the released gas. When I dunked my canister with the PR attached to it still, there may be some thermal transfer from the burner to offset the cooling effect of the escaping gas. If anyone has ever used some vintage Svea 123's or other brands of stoves like a Optimus 111 line that use gas or kerosene, they will notice the thermal feedback from the burner. That helps pressurize the fuel. Maybe not so much using Isobutane.
Duane

Well, It really doesn't happen that all the propane is burned off first. It is just primarily propane. Read this and note that there is still some vapoure pressure even at about -40F (though not much.) Propane has much greater vapoure pressure, but not all will be boiled off, even at -40F.

http://en.wikipedia.org/wiki/Isobutane_(data_page)

This is a graph of gaseous pressure for propane. Note that even at very cold temps it maintains fairly good pressure.
http://encyclopedia.airliquide.com/images_encyclopedie/VaporPressureGraph/Propane_Vapor_Pressure.GIF

Generally, a topper stove is mostly not usable without tricks at around 20F.

> I don't know why they bother adding propane,
Because if they didn't, the stove wouldn't work at cold temperatures at all.

Read our stove articles.

Cheers

Back in the old days forty years ago, I don't think that butane-blend fuel was known. It was pure butane back then.

The only places where pure butane worked well at cold temperatures was at extremely high elevations, like on Mount Everest.

At cold temperatures, the worse butane works, but at high elevations, the better it works. The reduced air pressure makes it easier to exit the canister.

–B.G.–

Generally, operation down to 20F/-7C over the life of an isobutane-propane (no n-butane) canister is a reasonable expectation. As has been noted, the canister temperature will typically fall below the air temperature, so you need to take some steps to keep the canister temperature up. Generally putting the canister in (liquid) water is pretty safe and will keep the canister going. If things get really cold, it can be hard to keep that water liquid.

However, as Bob mentioned, the higher you go, the lower a temperature you can operate a canister stove at. The following graphic may be useful. Sorry it's in English units only. :(

HJ

P.S. Remember that you need about 10F/5C degrees "clearance" above the vaporization (boiling) point in order to have enough pressure to operate a stove. For example, at sea level, isobutane vaporizes (boils) at 11F/-12C, but don't think you can operate a stove that low. You need some "clearance" where the fuel temperature is above the vaporization point. At sea level, about 20F/-7C is about right. At 10,000 feet, the vaporization point is going to drop to around 2F/-17C — but you still need some "clearance" so more realistically at 10,000' you can operate your stove as long as you keep the fuel temperature at about 12F/-12C (pardon my rounding errors).