>>1916928butane condenses to liquid earlier than porpane. So if it's cold enough ( ~ <32F) the butane will become liquid while propane remains gas
with upright stoves, the propane gas is used first and once you use up the propane gas you're left with useless butane liquid.
with inverted canister stoves, the propane gas is used last and maintains pressure on the butane liquid. The inverted stove has a preheat tube that then boils the liquid butane, so it can be burned like normal butane gas.
this vid has a nice demonstration:
https://www.youtube.com/watch?v=vbuhwHfhR18Of course if it's really cold < -40F then the propane stops vaporizing and the inverted canister stove will also fail.
