Jetboil In Frigid Temps At Altitude - The Pros Do It (?)

[jniehof]

Are MSR/Jetboil fuel canisters interchangeable?

Short answer is yes. (Note "UNEF standard" is sometimes misused. I can't recall if it's supposed to refer to the canister construction or the valve/threading, but it's often used to apply to the other.)

 

[DayTrip]

Short answer is yes. (Note "UNEF standard" is sometimes misused. I can't recall if it's supposed to refer to the canister construction or the valve/threading, but it's often used to apply to the other.)

It's the threads. Universal National Extra Fine. (I work for a machinist). Thanks for the link.

 

[alexmtn]

I thought about this a bit more. (Had to think about something while shoveling... ) The expansion temperature drop occurs in the control valve (where the pressure drop occurs) and would have little if any effect on the fuel temp in the canister but will cool the downstream plumbing possibly resulting in frost as noted by peakbagger. Doug

OK, one more slug of geekiness . . .

While experimenting with my Reactor a few years ago, I thought the same thing: how much difference could gas expansion (from draining) in the canister possibly make while running a stove at an 80-minute drain rate? Not much, right? On a rare minus 5-degree F night in the Boston burbs, I put the stove outside, turned off and with the canister lightly insulated, with a temperature sensor against the canister behind the insulation, and measured the cooling rate. I then re-warmed the canister, fired up the stove, and measured the cooling rate with the stove running. Much faster. The unexpected conclusion I came to is that in winter operation, the heat drain from expansion cooling of the canister under moderately adiabatic conditions (wind protection and light insulation) is a more significant factor than the ambient cold air -- at least at slightly below zero F.

Re: cooling whatever there is in the way of downstream plumbing, yes no doubt, but that effect never gets the opportunity to come into play in the context of the overwhelming heat from combustion once the stove is running.

Alex

 

[hikerbrian]

If people are willing to take it on Everest I have to assume warming the canisters allows for reliable operation and reasonable performance even in pretty cold weather so it should certainly be fine for anything I'd ever do. I guess I'll have to retry some tests at the lower temps to see how much the heated canister improves performance.

Couple things:
First, if you translate DP's post earlier in the thread (and I checked the numbers elsewhere), here's what it means: a Jetboil's performance depends not only on temperature, but also on what altitude you're using it at. The key take away is this:
At sea level, isobutane will vaporize and your stove will work down to a temperature of 11 degrees F.
At 20,000 feet elevation, isobutane will vaporize and your stove will work down to a temperature of -19 degrees F (nineteen degrees below zero). Elevation REALLY matters.

Because Everest is relatively close to the equator, basecamp (elevation 18,000') is generally in the 20's during climbing season, and the summit usually averages between -15 and -5 degrees F. The combination of elevation and relatively warm temperatures actually makes Everest uniquely well-suited to use of a canister stove.

But even on Denali, I think canister stoves are starting to take over. This American Alpine Institute blog post from 2011 gives a really good perspective on Jetboil vs. Reactor vs white gas.

Pre-warming your canister and/or using a water bath and figuring out its limitations, as you plan to do, is definitely the right path for our mountain elevations. As I've mentioned several times, I'm VERY happy with my Reactor's winter performace (while keeping the canister warm).