Primus Winter Gas Review

Roger,

Is there any chance that there is a paper chromatography effect going on where butane is wicked more readily than propane in the liquid phase?  That would further explain the propane lasting longer.

Cliff

Thought this sounded familiar Forum thread from 2014

Ah, bloody hell, finally an article worth reading!! Very nice, very very nice!

Is there any chance that there is a paper chromatography effect going on where butane is wicked more readily than propane in the liquid phase?

I really doubt it. No, I have not tested this (I do not have those sorts of facilities), but somehow I cannot see it.

EDIT: as a butane molecule is bigger and heavier than a propane molecule, it is even less likely.

John A – thanks. :-)

Cheers

nice article Rog, thanks

the Gosystems canister has N-butane?  That shouldn’t even be considered for cold weather because of higher boiling temp

you judged IR absorption based on the color in visible wavelength.  That is very misleading.  A dark color in visible does not necessarily absorb better at IR than a light color in visible.  A better rule would be all colors are about the same, emissivity of about 0.9.  If it’s shiny aluminum, then emissivity of about 0.  But an aluminum canister may have a coating on it which actually makes it closer to 0.9.  According to engineeringtoolbox.

18 F?  That’s pretty cold.  I can’t get an upright canister to work at that low a temp.  But I usually experiment with mostly empty canisters

another thing about fuller canisters working better, is there’s more heat in it, because there’s more butane, so it will take longer for the temp to drop from evaporative cooling.

that sounds like a good theory though, that the paper helps transfer heat so it maintains a higher propane ratio

I can’t believe they wouldn’t have technical people involved with the design of this product, amazing!

Hi Jerry

you judged IR absorption based on the color in visible wavelength.  That is very misleading.  A dark color in visible does not necessarily absorb better at IR than a light color in visible.

True of course. But the GoSystems coating looked as though it might have metallic flakes in it, while the dark Primus coating looked a bit like a mineral oxide to me.

Cheers

Thanks for writing this up in a cohesive manner Roger. I’m glad to see us snapped back to the reality that trying to save grams at the margins comes with some seriously diminishing returns. In this case, paying for fancy gas. I’m with the inverted canister camp for winter, turning it upside down makes it a moot point.

Bob Moulder’s strip of copper

except a strip of aluminum is lighter

“Bob Moulder’s strip of copper. . . except a strip of aluminum is lighter”

+1

When there is a 25-gram, $11 upright canister stove AND there is a proven way for a strip of Cu, Al, or 10 inches of Al or Cu wire bent in a loop to keep a canister going to temps that no one but I am likely to encounter, why incur the cost and weight penalties of inverted stoves?

And if you get really stuck, in a cold environment?  Be a man about it and just rewarm your canister with the Bic lighter you just pulled out of some body orifice.

Overcoming any hesitation to direct a flame against a compressed gas container is what separates the women from the girls (or “men from the boys”, if you prefer).

arm pit would work : )

and the other problem with inverted is stuff gets into the valve and gums it up.  Not that big a deal if you know how to take it apart and clean it

Thanks, Roger. There are several points that I think you missed here.

1. The insulation effect of the paper in the canister. From the picture reprinted from Morkel’s site it appears that the stove is operating a bit warmer, based on the size of the melted hole. I suspect that the retained heat resulted in a higher canister temp/pressure than without the paper, delivering more BTU’s from the stove, overall.However the heat got there, it is more efficiently maintained IN there.
2. The increased surface area for evaporation will not effect your pressure nor temp, but at these low temps, it will effect the volume of gas available to the output. Similar to spreading a sleeping bag out to dry it quicker in the sun, we maintain a constant temp, constant pressure but allow larger volumes to be evaporated off. Important when opening the valve at cold temps drops the pressure to what can be maintained by liquefied gas. Of course, this would only show up later, as the tank fuel is utilized. The trick of shaking a lit stove at these low temps will often increase the volume of flame as another example pointing out this effect (just ignore any sputtering from raw liquid fuel.) The blotter paper simply increases this effect.
3. In any case, at around 32F/0C, it is time to switch to an inverted stove.

>>and the other problem with inverted is stuff gets into the valve and gums it up.  Not that big a deal if you know how to take it apart and clean it

This, and the weight, as David mentioned.

Maybe it was just bad luck, but I got a Kovea Spider for experimenting with an inverted canister and experienced this problem almost immediately. I used some of that compressed-gas cleaner to back blow it onto a paper towel, and although I didn’t see anything on the paper towel the stove worked again afterward. I don’t remember if it was an MSR or a Primus canister.

However that is not something I’d want to deal with coming back to a cold base camp after dark at -20°F expecting a hot drink and dinner.

Great article, Roger- thank you!  It was a fascinating read.

+ 1 on this being a very worthy article.  Nice to see this type of critical investigation in BPL.  Thank you!!

+1  On Jerry’s comment on being cautiousness about judging IR absorption based on color in visible light wavelengths.

+1 On what Jerry alluded to … that finish has an effect on IR adsorption

I appreciate BPL Myth Buster  efforts

Hi James

From the picture reprinted from Morkel’s site it appears that the stove is operating a bit warmer, based on the size of the melted hole.

I am not game to try to draw conclusions from the size of the melted hole. Far too many variables for me.

The increased surface area for evaporation will not effect your pressure nor temp, but at these low temps, it will effect the volume of gas available to the output.

I will have to respectfully disagree here. The rate the gas is being used in normal stove operation is not that high. Pressure and temperature will suffice imho. Now if you want a 10 kW flame thrower, yes, then it might matter.

Cheers

Hi Jerry

and the other problem with inverted is stuff gets into the valve and gums it up.  Not that big a deal if you know how to take it apart and clean it

This is true, but … in practice I have seldom had this problem. I do clean my stove at home either before or after any big trip, which helps. I had unholy trouble with a Chinese canister, but that was dust. The shopkeeper took one look at my face when I returned the canisters and hastily shoved a full refund into my hands.

More on this subject in a forthcoming article.

Cheers

Hi Bob

I got a Kovea Spider for experimenting with an inverted canister and experienced this problem almost immediately. I used some of that compressed-gas cleaner to back blow it onto a paper towel, and although I didn’t see anything on the paper towel the stove worked again afterward.

It is possible that what you had here was not stuff out of the canister but swarf or similar rubbish from the machining. I have to go to some lengths to clean all that stuff out of the stoves I make.

Cheers

Bob, the weight of inverted stoves is around 87-92gm (around 3 or 3-1/4 oz.)  This is close to the lightest toppers.Weight is not really an issue.

But canisters can be a bit dirty inside. As others have noted, a fully upright canister can allow dust, dirt, metal bits, etc into your stove potentially plugging it up. Roger mentioned some filters before the valve. Alternatively, unless the can is very low, ie less than 10% left, simply setting it down provides a sump for the debris. Unfortunately, the large sized cans don’t set that way, only the smaller 110gm and 240gm cans do.

yeah, but with an upright, the dust and metal bits and waxy stuff tends to stay in the canister.  Most people have uprights so there’s no huge reason for canister manufacturers to keep that stuff out of the canister

yeah, Roger’s stove in particular is so light that’s not a factor

and with an upright, the burner is higher in the air where there’s more wind.  And it’s less stable, more likely to tip over.  You could run Roger’s stove upright.  I suspect Roger’s stove is a bit higher quality so less likely to fail.

I think other inverted stoves are heavier and less quality.

I think upright or inverted (or white gas or alcohol or esbit) all can be good depending on conditions and the people.

looking at the primus cutaway one gets the impression that the vapors are actually rising between the corrugated paper and the interior metal housing wall and exiting through the slots at the top, this volume between housing and paper would likely be the warmest and subjected to a quickened vapor flow to produce a steady flow for a flame….and this volume increases with use promoting the continuity of a sustained flame….fyi

>>this volume between housing and paper would likely be the warmest and subjected to a quickened vapor flow to produce a steady flow for a flame….and this volume increases with use promoting the continuity of a sustained flame….fyi

That actually makes a lot of sense.

It also implies that there is external heat coming from somewhere, but there is almost always some stray radiant/convective in most setups.

Excellent work!  Best article I’ve read on BPL in a very long time.

Thank you Roger and BPL for a great article and for all the work and research that went into it.  What an antidote to the pedestrian drivel and spew that passes for journalism in outdoor magazines, with their bullet points, sound-bites, and sensationalism.  “10 Ways to Keep from Dying In a ___/On a____/From a___________.”  “The 8 Best Places to_______.”  “I Survived a ________!”

My question is more about n-butane, and sorry for going off-piste: Every year I do a long-distance hike where I have to resupply via mail or at trail towns where canister fuel may be unavailable or out of stock. I’ve often wondered if I could use a can of butane, the kind with a needle used to refill lighters, to top off my fuel canister. I know that resealable does not mean “refillable,” but would it even work? If so, butane would seem less risky for accidentally exceeding the safe pressure than iso-butane or propane. I wonder if it’s even possible to overfill my canister since a steady-state would be achieved between the butane lighter fuel can and my canister, unless the butane can was built to tolerate greater pressures.  If, for liability reasons, you’re reluctant to answer this publicly, feel free to email me directly. Thanks!

Hi, Maxine:

I just asked this same question in another thread and our answer is HERE.

And if you decide to go this route, I’ll save you some searching for the adapter, which is THIS ONE.

I googled quite a bit to find a better price but was not successful. It is not now available on eBay as it was when Hikin’ Jim bought his.