Hi Jim
The MSR IsoPro is 80/20 isobutane. I am not sure what is available in the USA better than that. It sometimes seems the availability of gas blends varies by country.
For that matter, it also seems to vary by year as well!
Cheers
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Coleman Fyrestorm Ti Stove REVIEW
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Looking at Fig 4 from The Effect of Cold on Gas Canisters, when the canisters are at 100% full, 80/20 isobutane/propane (blue line) is at about the same height (temperature) on the graph as a 70/30 n-butane/propane mix (pink line).
In inverted canister use the mixture of gases should remain relatively constant. It would seem that a 70/30 n-butane/propane mix would work just as well as an 80/20 isobutane/propane when used with the canister inverted.
And, if I'm understanding things correctly, a 15/85 propane/n-butane mix would only be good to at the lowest -15C/+5F, yes?
HJ
Hi Jim
> a 70/30 n-butane/propane mix would work just as well as an 80/20 isobutane/propane when
> used with the canister inverted.
Only while the canister is full if upright. A huge difference develops once you start to use fuel out of an upright canister.
However, for an inverted canister as you asked, you do use the 100% figure right to the end. Well, better use the 90% one, as one sometimes starts the stove with the canister upright.
Why do we have these mixtures – or why can't we have better (more propane-rich) ones? Because there is a limit to the pressure rating of the canister, and that limits the ratio of gases possible. The large diameter of the canister is a problem.
> a 15/85 propane/n-butane mix would only be good to at the lowest -15C/+5F, yes?
Correct!
Cheers
Excellent. Thank you for bearing with me, Roger. Slow learner, but the light bulb does eventually come on.
HJ
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