> what influence has the amount of fuel inside the canister on the temperature at which the bottom of the canister pops out? You used 33 grams of the gasmixture
Yeah, this bit gets technical.
If there is liquid fuel in the canister, the pressure of the vapour is set by the laws of physics - the so-called 'vapour pressure'. The vapour pressure of the liquid is set by the temperature, as shown by the graph in the article. The key thing here is that it does NOT matter how much liquid is in the canister, just that there still is some liquid. I know some people have written otherwise, but they are wrong.
Of course, once your canister gets very low you can't be sure what the remaining liquid fuel is: 30% propane, or maybe just 10% propane, so there is some uncertainty about the pressure. Under most any circumstances I can think of, the concentration of propane will not be greater than the initial concentration, so the pressure may be a little lower than predicted.
In the case of the experiments described, the liquid in the canister would have been very close to 30% propane and 70 % isobutane, because I refilled some empty canisters from a new canister of known mix. However, refilling canisters is complex and something I strongly recommend you do NOT try. I only did it for this article; I do NOT do it for normal use.
If the amount of fuel in the canister is small, such that it all turns to vapour as it heats up, then the pressure will be different - lower in fact. Then and only then does the PV=nKT equation come into play.
Hope this helps.