Have you used a chemical hand warmer?

>Have you used a chemical hand warmer?

I'm not sure who you're asking, but that would really do the trick, especially with a coozy (or your hands) to hold it onto the canister. With a max temp ranging from 45-65C (110-150F) * it might be a bit on the hot side, but that's easily remedied in cold air. However, as the article mentioned, 0C (32F) or better is sufficient, and a water or snow bath is a zero-carried-weight item.

* http://www.wemjournal.org/article/S1080-6032(09)70081-X/abstract
( http://download.journals.elsevierhealth.com/pdfs/journals/1080-6032/PIIS108060320970081X.pdf )

Edited by Otter on 11/08/2010 11:16:38 MST.

I can remember years back Primus designed a chemical canister warmer that you would place in the void beneath their fuel canister stoves. These hand warmers needed to be boiled in water to gain the energy and by pushing a metal “plate” in the hand warmer activated the chemical agent absorbed the water energy, and thus releasing their energy. I think you can see the down side to this device as there is a downside to the “one shot" chemical hand warmers.

Water bath is still the best way to go OR use an external inverted fuel canister with a heat rod design to vaporize the liquid fuel as has been explained in the following article:

http://www.backpackinglight.com/cgi-bin/backpackinglight/myog_winter_stove_summer_upright_stove_brunton_stnd.html

Ken, you refer to a sodium acetate phase change hand warmer. I have a couple, and they work fine.

Often, I don't have as much liquid water sitting around as you describe, so I simply warm the canister with a candle flame.

--B.G.--

I'd forgot about those (sodium acetate warmers); my EZ Heat (Pristech Products, Inc.) weighs 3.8oz. One drawback is that it must be boiled for about 10 minutes to ensure all the crystals melt, which requires more fuel than I'm willing to spend. And, worst, the one time I carried it, I found that I had accidentally snapped the metal plate or shocked it sufficiently to activate it, and when I needed it, it was hard and cold. Now it doesn't leave the house.

Edited by Otter on 11/08/2010 12:00:40 MST.

"Often, I don't have as much liquid water sitting around as you describe, so I simply warm the canister with a candle flame."

I would consider this advice Very carefully. Past performance is no guarantee of future longevity.

IMHO.

Oh, the candle flame is tried and true. First of all, we don't use a big candle, and we don't put the flame on a seam. Instead we warm the large metal surface initially, then save the candle for next time. We generally only need to do this when it is a very cold morning in snow country, and the fuel canister is cold.

As for the sodium acetate hand warmer, I carry mine in a durable plastic container, so it never gets set off accidentally. Boiling water will recharge mine in six minutes.

--B.G.--

.......and fuel to recharge that can be use for other uses.

When cold out i put my upright canister stove in a cup of warm water while using the stove. this works best if using small canister for they fit tight and it needs just a little bit of water. jet boil bottom cup or snow peak solo set has a cup also. Having this extra cup is still lighter than buying a remote canister stove. I tend to use a insulated cup for winter use.

So I have the Primus Spider remote can stove. I used it at around 10-15 deg F last week and it worked great upright, but when I inverted it, the fuel leaving the can made the valve freeze and it went out. I had to leave the can upright. The Jetboil Helios and others have an inversion canstand. Wouldn't they all freeze? I thought it was a winter stove designed to be inverted...

Thoughts?

It worked great upright, even at 15 deg, so I'm not worried, just wondering...

PS: the Caldera cone for a 1300mL upside down is THE BEST wind screen.

> when I inverted it, the fuel leaving the can made the valve freeze

This is possible, but rather hard to do deliberately. Normally the fuel goes down the hose as a liquid and vaporises in the preheat tube near the burner. For it to be vaporising at the valve on the canister is odd.

What to do if this happens? I'm not entirely sure as I have not had this problem more than once or twice. I THINK what I did was to open the valve up for a moment, to overload the system and force liquid fuel down the hose, then shut it down to a gentle flow again quite quickly. Once the hose is full of liquid fuel all seemed to be well.

But I am not recommending that you should do this, just saying what worked for me. Experimenting like this has a few hazards... big ones.

If the stove continues to behave like you described, I would return it for exchange, as it just may be that the hose is missing the filler cord which is meant to be inside it. Once again, I am not sure about this.

Cheers

Interesting...

It only took a few minute from when I first inverted it to when it started freezing. I held the valve in my hands and chemical warmers but it would still freeze (my chem warmers are horrible though). I tilted it back and forth changing whether or not liquid or gas was going in and it would make the stove roar then subside. I kinda lost the feel of when to have it be liquid or gas and it went out. Finally I just turned it upright and kept it going.

Weird. Dunno. Did not happen with mine. Sorry.

Cheers

Stuart Robb said> For a liquid fuel stove, the iso-butane is not neccessary. It will work just as well with regular butane. What is required is 25% or more propane.

Edited by hikin_jim on 03/20/2011 13:30:04 MDT.

Jim - did not say isobutane did not matter, I said that it was not neccessary, and this was in response to the comment:
"For temps above -25C (-13F) you can use any of the mixtures that contain both propane and iso-butane with a stove designed to burn canister fuel fed to it as liquid (connected to an inverted canister)."

Isobutane has a vapour pressure ~50% greater than n-butane. With an inverted canister stove, 30% propane / 70% isobutane will work at approx 4C lower than 30% propane / 70% n-butane (look at Fig 4 with 100% remaining).

Stuart,

Ah. That makes sense. Thank you.

And that's a good point about Figure 4. Thank you for that as well.

HJ

So, another question, if I may: Does the following statement (referring to Fig. 4) apply for inverted canister use as well?

"you should be able to use the canister so long as its temperature is approximately 5 C above the relevant line"

HJ

Hi Jim

Yes.

Cheers

Yes

Fig 4 shows the boiling point of the mixture, ie. the temp at which the vapour pressure equals atmospheric pressure. The gas pressure has to be a little more than atmospheric to get thru' the jet and based on experience, 5C above boiling point is sufficient.
There are no graphs shown for inverted use because the gas mixture does not change, so the graphs would be simple horizontal lines aligned with the 100% remaining point in Fig 4.

Gentlemen:

Thank you very much. I think I've got it. Your first comment yesterday, Stuart, (about looking at the values at the 100% mark for inverted mode) made the proverbial light bulb come on for me. When I re-looked at Fig 4 and that section of the article with that in mind, everything fell into place. This all makes a great deal of sense.

Thank you both very much,

HJ