On a recent trip I was using an isobutane canister (Brunton) in temperatures around 50 degrees give or take several degrees. That is not what I would call cold conditions, but maybe it is considered cold.

At that temperature I had very poor performance (about simmer when on full) when the level in the canister dropped to about 1/4 full. Moving it closer to the campfire quickly improved the performance. Simply “cupping” the canister in my hands while it was operating also improved the performance somewhat. I also noticed that the performance dropped when I used it for an extended period (15 minutes?) when making a batch of pancakes. The canister got VERY cold.

I thought isobutane performed better than this. Or am I just expecting too much?

Edited by Hitech on 11/04/2009 13:44:22 MST.

I've had great successs with full isobutane cannisters in 35-40 degree weather - but have only run them for 5-7 minutes (the time it takes to make a lipton / knorr side dish like alfredo).

My guess is that the 20-30% isobutane had burned off during previous trips, and your partially full canister was just butane. (Butane doesn't vaporize below 40 degrees). Also, opening the valve and letting gas escape automatically cools the valve (and eventually the rest of the tank). Sometimes the valve even gets ice on the outside if you run it for long periods in the summer. Also, the farther you open the valve, the faster it ices. My guess is the 1/4 full tank (& resulting wide open valve) + long run times (pancakes) combined with butane's 40 degree limits are what caused the effect you noticed.

My solution would have been to use a windscreen. It would have sealed in enough heat to keep your "only butane left" canister running, even at wide open valve settings. Roger Caffin's BPL report indicates this is safe as long as the canister doesn't get too hot for you to hold you hand on it for a while.

If it's an isobutane / propane mixture, you're supposed to briefly invert, and possibly shake, the canister a bit before every use. The propane separates from the butane, significantly impeding cold weather performance.

Some misconceptions here guys.

First of all, the Brunton canister has a 70% Isobutane / 30% Propane blend. This should be good to a nice low temperature of at least -20 C (-4 F). If you had trouble at 50 F then you must have been running the stove hard for a long time - which I think you said was so.

You need a bit of thermal feedback. The windshield idea is excellent. Just make very sure you can hold the canister in your hands and it will be safe enough.

> My guess is that the 20-30% isobutane had burned off during previous trips, and
> your partially full canister was just butane.
Not applicable here: no butane according to the specs. I suspect you are thinking of the propane content?

> (Butane doesn't vaporize below 40 degrees).
Butane boils at -0.5 C or about 31 F. At 40 F it should be boiling nicely.

> The propane separates from the butane, significantly impeding cold weather performance.
Pure myth, and false. What probably happens is that when someone picks the canister up to shake it they are heating it with their hand.

Cheers

Listen to Roger, he knows his stuff. I've been battling the cold canister for years. This year, I plan to make everything work a little better with this little creation.

www.suluk46.com/RandD

Just need to the temps to drop now.

Edited by Steve_Evans on 11/03/2009 22:02:42 MST.

This year, I plan to make everything work a little better with this little creation.

www.suluk46.com/RandD

Ummmm, I don't think so (unless I missed some important bit of info)

True, it will slow heat conduction from the canister if you start out with it warm (like sleeping with it).

However, the fuel sucks energy when it evaporates (a LOT of energy). The contents of the canister will become cold as you use the stove unless you can provide an external source of energy. Air colder than the boiling point of the fuel does not provide that energy at a high enough temperature ... even if the air is warm, insulating the canister will slow energy flow into the canister, slowing evaporation.

Now if you have an energy source next to the canister and inside the insulation then it's a different story ... just don't make it too hot.

Edited by jcolten on 11/03/2009 22:23:19 MST.

Steve,

Sorry mate, it's ALMOST a really good idea. But what will happen is that it will chill down the gas in the canister even faster, since it can't draw in heat from the air around it.

BUTTTT...... I've been thinking along exactly the same lines as you, and want to try moulding the insulation with a canister hard up against a beer can. This should chill the beer, and heat the gas, as the heat from the beer transfers into the canister. Maybe wrap the beer in a wet bandana for better heat transfer.

What I have done that works great though, is mould a 2cm dish from foam, that I can stand the canister in, and fill with water. Works great in the snow to keep the canister working and ULW. (Roger learned me that one)

OK, if my canister is warm to begin with (from inside my jacket), will the cozy not keep it warmer longer? Or will the insulation actually speed the cooling like Rod mentions. In the past few winters, I have struggled to get my stove to work in temps below -20*C (0*F). I bought the Coleman Xtreme last year and still have problems.

All my research, and I thought I had done enough :), pointed towards insulating the canister from both the ground and the outside air temps. I do agree that having an external heat source such as the flame itself is superior but that's why I pour a bit of hot water on the canister every once in a while.

Gonna need some clarification here so I can save myself some embarrassment...:)

Edited by Steve_Evans on 11/04/2009 06:02:15 MST.

I am sure you are right Steve. At temperatures like that a warm canister is only a temporary solution. An external heat source such as your warm/hot water is needed. At 0 degree F the environment has nothing to give the canister and needs insulating away. Of course liquid feed reduces the heat sucked out of the canister dramatically.

Ahh, I see what happened here. OP stated a temp of 50*F and I went and posted a solution to a problem that occurs at a much lower temperature then that. My apologies - just got a little excited about my new little invention ;)

I forgot to mention that the overnight temp was down around 40 plus or minus a few degrees. The canister had not likely warmed up much past that as it was sitting on the cold rocks. Combined with long run times and the canister was really cold.

I'll have to take this into consideration next time. Anyone think a simple heat reflector from tin foil would work? There is no wind to speak of. Or maybe that heavy duty foil wind screen that comes with the MSR whisperlite?

Hi Larry,
I think the best thing is to warm the canister in your sleeping bag or such. Then for long cooking keep it warm with a relector.

Even warming the canister for 15 minutes under my jacket helps considerably. A piece of insulation under the canister helps when the ground is really cold.

On a recent trip where it got down to 18*F, I also had to warm up my mini-Bic lighter under my jacket before it would work.

What kind of stove is it? If it has a preheating tube, you can invert the canister. This has been approved by at least my stove (primus omnifuel) manufacturers literature.

Hi Steve

Jim and Rod (and Mary) have already said what I would say. The guy who designed that cozy is simply totally ignorant of the science. I would guess that 95% of the energy loss is through evaporation of the fuel inside the canister. Loss to the atmosphere can be ignored.

Sitting the canister on a bit of foam might help a little - bit probably not much. Letting the bare canister absorb some heat from the stove (radiation or from the hot gases) will help significantly, but *monitor the canister temperature*. Sitting it in a dish of *cool* water really WILL help a lot and is completely safe.

Pouring some hot water over the canister will also work - but why not sit the canister in a bowl to collect the water as well. Just don't immerse the canister in hot water - a bit too exciting! Cool water is great.

Cheers

Edited by rcaffin on 11/04/2009 13:22:44 MST.

The guy who designed that cozy is simply totally ignorant of the science

Perhaps, but he's still a good guy so let's not hold that against him. :)

I'm totally thrown off here. I actually thought you were the guy who recommended I wrap my canister for winter use. Are you saying (like Rod mentioned) it will actually perform worse with the CCF cozy?

Edited by Steve_Evans on 11/04/2009 19:33:21 MST.

Hi Steve

> I actually thought you were the guy who recommended I wrap my canister for winter use
NOT guilty!

> Are you saying (like Rod mentioned) it will actually perform worse with the CCF cozy?
Most likely. Without the cozy it may at least get some radiation warming it.

Cheers

Steve,

SOMEWHERE (!) on BPL there's a thread with a really great photo of a canister frozen into a block of ice burning away merrily (Roger may know where, I know he's also seen it)

It's not the outside cold that gets you, it's the inside cold. Actually that's not really true, but the outside cold is controllable.

Think of it this way. A fridge works by releasing pressurised gas. It stays colder when you insulate it. It doesn't work so well when you leave the door open, and especially if you put a big pot of luke warm water in it.

Just imagine if we could get a beer can shaped to fit outside/around a canister. Think man, think!! There's money to be made here.

Rod

First off, thanks for the info. Here is where I get confused.

A fridge works by releasing pressurised gas. It stays colder when you insulate it. It doesn't work so well when you leave the door open

But this is assuming that the outside temperature is warmer then the inside temperature. Imagine you want the fridge to be 40*F and no lower so you set the temperature and close the door to insulate it. The outside temperature is 0*F and if you open the door or remove the insulation, the fridge will get colder inside because the outside air is colder then inside the fridge. You want to isolate it from this lower temperature (ie. canister cozy). Leaving the door open would only WARM the inside of the fridge if the temperature inside the fridge dropped lower then 0*F outside temperature, in which case you would open the door and actually warm the inside of the fridge with the 0*F outside temperature.

This is my logic for making a canister cozy. At warm temps, the cozy would do nothing because the canister would be colder then the outside air which means simply exposing the canister to this warmer air would be better then isolating it. But if I had the canister in my jacket and put the cozy on it to expose it to -5*F temps would it not benefit from the isolation?

I hope this is making sense. :)

So, let me try and sum up a question here.

At what temperature will it be beneficial to isolate the canister from the environment and what temperature will the environment warm an uninsulated canister?

Or.

I assume that since the fuel mixture will stop boiling at roughly 0*F that the act of burning the fuel does not create this temperature or else an insulated canister run at full would eventually stop working? What temperature is created by burning the fuel?

With both you guys from Australia, I'm going to have to wait until tomorrow morning to get an answer. ;)'

p.s. Rod, I'll start working on a canister shaped beer can.

Edited by Steve_Evans on 11/05/2009 08:31:45 MST.

I guess it depends on how much "futz" tolerance you have. Using 80/20 cartridges I regularly have performance problems with canister stoves in 40*F weather, especially if I'm boiling air temp water or 1000ml instead of 500ml. Personally I'm not willing to sleep with a cold canister, keep it under my jacket, bathe it in water, and otherwise baby it just to try to make it work. Too much trouble for me. Using the windscreen isn't too bad, I guess, but I'd just as soon use something that works without fuss in cooler temps. Even my Ti-Tri, whether w/wood or alcohol, is preferable to me. If I were consistently in cooler temps, you could run an inverted canister as so many espouse on this site, or use a Simmerlite, the lightest white gas stove I'm aware of. To each their own.