Disappearing gas mixture ratios

[Tony]

Hi Orion,,

Interesting graphs, Tony, thanks for that link.

It's worth noting that in calculating these graphs he assumed that butane and propane form ideal gases, which is not true. Taking into account their true nature would bias the loss of propane somewhat, in favor of keeping the propane percentage somewhat higher. But the overall picture is the same: You lose the more volatile fuel(s), and at about the same rate regardless of operating temperature.

Also worth mentioning is that actual canisters are not the exact mixtures that their labels suggest. They contain other components, in particular higher volatile fuels in small amounts. This results in an initial canister pressure that is much higher than one would expect from the calculations.

Here is a graph produced from actual canister pressure data (please excuse the non-metric units). As with that guy's calculated graphs, you can see quite clearly that choosing a canister with isobutane as the base fuel is more important than the amount of propane in the mix.

Thanks for the chart and for the information about other additives in fuels, it is very informative, along with Rogers FAQ mix/T-P charts, your charts are very helpfull.

I have done some research about fuel mixtures on the fuels you have used, with the JetBoil and Campingaz fuel mixes I was unable to trace the actual mix ratios but found some reference to the fuels used, from your chart I have made a guess at what ratios are in the JetBoil and Campingaz canisters, please correct me if you wish. ( all of the mix and or ratios are from the manufacturers web site)



Jet Boil: propane / isobutane stated but ratios unknown, from chart would guess 30% propane/70% isobutane

Snow peak gigapower Contents:15% Propane, 85% Iso Butane mixture

Brunton Bruntane canisters performance mix contains 20% propane/80% isobutane

Power gas 25% Propane/25% Isobutane/50%butane

CV 270 Plus mix 230 g Butane/Propane stated butmix ratios unknown, from chart would guess 20% Propane/80% butane.

Tony

[Orion]

Tony, I don't really know what the mixtures are. I wanted to get time on a GC but it didn't happen!

Primus: At one point on their website they said the Power Gas mixture was 20/10/70 (pro/iso/n-but).
Brunton: Both Brunton and MSR used to claim 20/80 (pro/iso) on their websites. Brunton canisters produced the same curve as MSR.
Jetboil: At one point on their website they also claimed 20/80 (pro/iso).
I've read unsubstantiated claims that Snowpeak used 30/70 (pro/iso) and Campinggaz was 20/80 (pro/n-but).

Another disclaimer: these data were taken about five years ago and the mixes could have changed.

Cheers.

[Ent]

Hi All

Thanks for information and feedback. It appears the butane versus ISO is a big point so back to reading labels again, assuming that the information is published Given what I have read it appears by not putting the ratios or the various fuels you are not going to have much hope of selecting the right mixture for the season. Labels such as Winter/Premium blend appear to be nothing more than shallow markerting designed to gloss over "cheap" ingredients. In all enough for me to avoid Primus and Kovea brands as buying them rewards bad behaviour

Cheers Brett

[Tony]

Hi Orion,

Tony, I don't really know what the mixtures are. I wanted to get time on a GC but it didn't happen!

Primus: At one point on their website they said the Power Gas mixture was 20/10/70 (pro/iso/n-but).
Brunton: Both Brunton and MSR used to claim 20/80 (pro/iso) on their websites. Brunton canisters produced the same curve as MSR.
Jetboil: At one point on their website they also claimed 20/80 (pro/iso).
I've read unsubstantiated claims that Snowpeak used 30/70 (pro/iso) and Campinggaz was 20/80 (pro/n-but).

Another disclaimer: these data were taken about five years ago and the mixes could have changed.

Cheers.

Thanks for that information.

It is interesting it looks like that the mixes change with time, Kovea who make MSR and Brunton canisters and probably many more, have dropped the mix ratios from their 230g canisters, but still have them on the 450g canisters.

In winter I use Coleman Max fuel which for a long time was thought to be 40%/60% Propane/nButane but as you can see from the MSDShttp://www.coleman.com/coleman/msds/peak1.pdf it is 35%/65%.

Tony

Last edited by Tony on Thu 01 Jul, 2010 11:25 am, edited 1 time in total.

[Orion]

It appears the butane versus ISO is a big point so back to reading labels again, assuming that the information is published Given what I have read it appears by not putting the ratios or the various fuels you are not going to have much hope of selecting the right mixture for the season.

Find a stove that you can remove the burner from and use hose clamps to attach some tubing and a decent tire pressure gauge. Now stick the canister in a water bath for ten minutes or so, note the temperature, then open the valve and measure the pressure. Do this when the canister is about 5-10% full.

Compare the value to the expected gauge pressures for pure isobutane and pure normal butane and you will have your answer.

If you're a fan of inverted canister stoves, the pressure of a full canister is more relevant.

[timmy_pete]

I took my gas trange for a quick flit up Mt Bogong two weekends back and was happy with the performance in cold conditions. I ended up not taking the apparatus previously pictured in this thread, but did take the disc I cut from a CD spindle to insulate the can when starting up as well as a Brunton remote adapter (also mentioned previously).

The remote adapter gave a second valve which helped regulate output when the canister was inverted, not to mention making the task easier in gloves (the trange valve is finicky). Once the preheating loop was warm, a boot served the purpose well to flip the stove. It cooked easily in what I'd predict were approximately -10 and windy conditions. Brief blowouts quickly restarted owing to the heat of the loop (you might also note that the final shot shows it still cooking off the residual fuel a minute after the fuel was disconnected), and the food cooked pretty quickly too.

Liquid fuelled gas Trangia (Primus made) operating in cold conditions

GasTrangeLF1.jpg (104.29 KiB) Viewed 3968 times

GasTrangeLF2.jpg (77.34 KiB) Viewed 3968 times

Still burning, sans canister.

GasTrangeLF3.jpg (41.71 KiB) Viewed 3968 times

[Ent]

The residual fuel suggest to me that the gas was in fact a liquid so ok for the Trangia setup but not so promising for the more common stove on cylinder type.

Cheers Brett