Another issue may be that there has been a distinct change in the mixture of gases in the canisters.
Ken, absolutely right. The original mixes were butane only. Butane will not vaporize below 31F, and you need to be at least 10 degrees Fahrenheit above that for your stove to have enough power to work right. In other words, you really can't use butane below 40F, and that's the very lowest you can go. And what happens to a canister after you run it for a while? It gets colder than its surroundings. So even if the outside temperature was 40F, your canister would quickly get colder than the surroundings, and your flame would get smaller and smaller and smaller...
Needless to say, 100% butane went over like a lead balloon and gave canister stoves a bad name for many years. Then people started getting smart. They added propane and made a mix. Propane vaporizes down to -44 F. That's right
minus 44. Brr. Now, the propane as it would vaporize would drive the stove. Problem of course is that propane burns off faster (it's a bit more complicated than this, but this is a good approximation) rate than the butane, so toward the end of the canister's life, all the propane would be gone, and you'd be back to square one with a stove that barely functioned at 40F (which isn't particularly unusual even in summer as any Sierra hiker knows). Then they got really smart. Certain chemical processes can "bend" (not a precise scientific term here folks, but close enough) the butane molecule into what's called an isomer. The isomer has the same chemical formula (C4H10), but it's different geometry gives it different properties, one property is that the point at which it vaporizes goes from 31F to 11F. Huzzah! We're saved.
lol But seriously, that 20 degree Fahrenheit lower vaporization makes a big difference in practical terms out in the field in real world conditions. Even at the very end of the canister, you should still be able to cook even if the temperatures are approaching 20F
if you keep the canister warm. If the canister falls below 20F, you're not going to get much more than a flickering candle flame.
Probably WAY too much physics and chemistry for one day, but hopefully a few will find this interesting.
Told you I was a stove nerd,
HJ
