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Showing posts with label tips. Show all posts
Showing posts with label tips. Show all posts

Monday, March 19, 2012

Canisters, Cold, and Altitude: Gas in a Nutshell

OK, so here's the deal on canisters in cold weather and at higher elevations, in step-by-step form:

1.  Choose good gas.  For weather below 50°F/10°C, avoid butane mixes. Get an isobutane mix.  I've got all the major US brands sized up on my blog in What's the Best Brand of Gas for Cold Weather?  Above 50°F/10°C, it typically doesn't matter what brand or blend you buy.

2.  Know your limits.  Canisters containing isobutane mixes work reasonably well down to about 20F/-7C at sea level throughout the life of the canister if you use good gas (see item #1, above) and good technique (see item #4, below).  Now, that's just a number, which isn't a bad number if you just want the short version, but if you want to know more about that number, how I came up with it, and how to plan using it, see Gas Stoves: How Cold Can I Go?  Canisters get colder as you use them (canister "chilling") which can negatively impact performance.  See item #4, below, for how to compensate for canister chilling.

3.  Adjust for Altitude.  The higher you go, the lower the outside pressure.  The lower the outside pressure, the colder you can operate a canister gas stove.  You receive approximately a 1F per 1000' of gain colder advantage (about 0.5°C per 300m gain).  The idea that canister gas stoves don't work well at altitude is a myth.

4.  Use good technique.  Basically, start with a warm canister and keep the canister warm.  For "best practices," see Cold Weather Tips for Gas Stoves.

Now, in the above, I'm speaking primarily about "regular" gas stoves, the kind that screw right on to the top of a canister.  If you have a remote canister stove that is capable of inverted operation (see my Stoves for Cold Weather II article in Seattle Backpacker's Magazine for more information), then the limit in item #2, above, changes from about 20°F/-7°C to about 0°F/-18°C.  All of the other items still typically apply.  If you want to go out in weather that is that cold, I strongly suggest you do your homework, part of which should be to read Gas Stoves: How Cold Can I Go?

There, in the proverbial "nutshell," is how to deal with cold weather and adjust for altitude for canister gas stoves.

HJ

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