MSR Windboiler – Completed Review

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Re: MSR Windboiler – Completed Review

Post by markskor » Fri Dec 05, 2014 1:40 pm

HJ -
Figured that you would pick up on your own blog...a homage?
Especially liked:
30F - 40F Regular Gas, Liquid Feed Gas, or Liquid Fuel will all still work, but you're going to start to notice degraded performance on gas.
20F - 30F Regular Gas, Liquid Feed Gas, or Liquid Fuel will all still work, but you're going to notice degraded performance and you're going to have to use tricks on gas with many gas brands toward the low end of the temperature range.
10F - 20F You're getting below where regular gas stoves operate. If you're headed out in this kind of weather, do your self a favor and upgrade to a different type of stove. Yeah, if you fiddle with it enough, you can get your regular gas stove to work, but basic tricks don't work well down this low, and more advanced tricks can be dangerous. Dangerous as in severe injury or death...


Reinforces my observations about temperatures found Sierra and always using a stove with the canister inverted. A canister upright, the more volatile gas vaporizes first - burns off first, leaving increasingly poorer performance as the canister empties over time.
Inverted, (all liquid), solves this problem.
Thanks,
Mark


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Re: MSR Windboiler – Completed Review

Post by rlown » Fri Dec 05, 2014 2:36 pm

my coleman apollo also states it burns unleaded. haven't tested that out yet. kind of afraid to.

Got a free MSR stove sitting around here somewhere deeper in the gear box. dunno what it does as I haven't really started it up.

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Re: MSR Windboiler – Completed Review

Post by longri » Fri Dec 05, 2014 3:51 pm

It's usually reassuring to have your opinions buttressed by others.

I don't use any special tricks. I put the stove in a snow pit, often inside the vestibule. I surround it with a partial windscreen. And I melt snow. A monkey could do it.

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Re: MSR Windboiler – Completed Review

Post by longri » Fri Dec 05, 2014 4:10 pm

Hiking Jim,

Where did you get this grainy chart that you included in your blog?
Elevation_vs_Boiling-Point_Chart.gif
It's wrong. Look at the value it gives for the boiling point of isobutane at 10,000 feet. It's hard to read but it looks like about -9°F. It should be -5°F.

Assuming you need between 5 and 10 psi gauge pressure for acceptable stove operation, the minimum isobutane fuel temperature at a given elevation is the region between the blue and green lines below.
isobutane_vs_elevation.jpg
I haven't been doing much winter camping in the last few years. The drought has taken the joy out of it for me. But the last time I camped above 13,000 feet in the Sierra in mid-winter it never got below 20°F.
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Re: MSR Windboiler – Completed Review

Post by hikin_jim » Fri Dec 05, 2014 8:21 pm

longri wrote:Where did you get this grainy chart that you included in your blog?
That's from an old climbing magazine from the 70's called "On Belay". I had seen a lot of talk about how the vaporization (boiling) points of gasses are affected by temperature, but I hadn't seen a lot of talk about the effect of elevation. My "How Cold Can I Go?" post was written in part to emphasize the affects of altitude. It probably doesn't matter much if one is living in Florida (the highest point in Florida, Britton Hill, is only 345' above sea level!) :eek: but for us Californians who regularly travel above 10,000', it's a significant difference -- as in 20 degrees Fahrenheit. In other words, if you can operate a particular stove with a propane/isobutane fuel mix at 20 degrees Fahrenheit at sea level, you can operate that same set up at 0 degrees Fahrenheit at 10,000 feet. THAT'S COOL! \:D/ No one was talking about it, so I did. And that graphic was illustrative albeit old. In a way, I chose that graphic on purpose, just to illustrate that the concept had been around for a long time. We just need to reincorporate it into our thinking. It's not just a matter of temperature and fuel type. Elevation (really air pressure, but that's highly correlated to elevation) must also be considered. Now, is the graphic, precise? No. But it communicates the idea very effectively.
longri wrote:Assuming you need between 5 and 10 psi gauge pressure for acceptable stove operation...
Actually only about 3 psig is required for decent pressure on an upright canister stove. Keeping the fuel temperature about 10 Fahrenheit degrees above the boiling point of the fuel mix should be sufficient to generate that pressure. Your stove won't necessarily be screaming at maximum, but it'll be decent. For an inverted canister stove, you can get by on as little as 1 psig. You just need enough to get liquified gas to the generator (i.e the "pre heat loop").
longri wrote:the last time I camped above 13,000 feet in the Sierra in mid-winter it never got below 20°F.
Wow, that's warm. I've camped in the teens in lower elevations than that. If you're not getting below 20F, then bringing an inverted canister stove isn't absolutely necessary, but God help you if the temperature drops unexpectedly low. Of course at 13,000', you've got a lot of "slack" because of the low pressure which depresses the vaporization temperature of your fuel. And you'll do better with a fresh canister with an upright canister stove since the propane content is still fairly high when the canister is full.

HJ
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Re: MSR Windboiler – Completed Review

Post by rlown » Fri Dec 05, 2014 8:35 pm

canister cozy.. can already see a market for it. :) most pics on line show them soaking a can in hot water.. umm. Just sleep with the can and then slip some neoprene sleeve over the thing.

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Re: MSR Windboiler – Completed Review

Post by markskor » Fri Dec 05, 2014 10:10 pm

Interesting thread this...
HJ -
Your chart seems to show that increasing altitude affecting the lowering of the temperature window for "decent" canister gas ignition, (you called this slack?). IE - the higher you go, the less pressure, "depressing the vaporization temperature of the fuel." - gas canisters should then "burn" easier at somewhat lower temps at altitude.

Concerning this altitude/ lowering of pressure/vaporization hypothesis...As the isopropane/butane mix is in a liquid state and under pressure inside of a metal canister at constant temperature, (remote from the vaporization area), why would any (slight) external pressure change outside (at the stovehead) matter? The gas is still a liquid while inside the can?

Temperature of the canister and/ or if your stove has a generator?...just wondering?
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Re: MSR Windboiler – Completed Review

Post by freestone » Sat Dec 06, 2014 7:30 am

HJ,
On some of the images I could see you were writing something on the canisters. I assume you were measuring and recording how many grams of fuel you were using with each test? It boiled 500cc of water in just over 2 minutes, how many grams of fuel did it use on that test?
Fram...

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Re: MSR Windboiler – Completed Review

Post by hikin_jim » Sat Dec 06, 2014 8:55 am

markskor wrote:Interesting thread this...
HJ -
Your chart seems to show that increasing altitude affecting the lowering of the temperature window for "decent" canister gas ignition, (you called this slack?). IE - the higher you go, the less pressure, "depressing the vaporization temperature of the fuel." - gas canisters should then "burn" easier at somewhat lower temps at altitude.

Concerning this altitude/ lowering of pressure/vaporization hypothesis...As the isopropane/butane mix is in a liquid state and under pressure inside of a metal canister at constant temperature, (remote from the vaporization area), why would any (slight) external pressure change outside (at the stovehead) matter? The gas is still a liquid while inside the can?

Temperature of the canister and/ or if your stove has a generator?...just wondering?
Great question.

OK, so why is the "gas" inside a canister in liquid form? Because it's under very high pressure, pressure so high that the gas changes state into a liquid.

What does the valve on a stove do? It in essence releases pressure. As the pressure is released, the fuel changes state from a liquid to a gas through a process commonly called boiling. Now boiling water is quite hot, 212 F at sea level, but something can boil at a much colder temperature. Butane for example boils at 31F. Break open one of those clear plastic butane lighters some time on a cold day (below 40F), and you can literally watch the butane boil, but put your finger in it and it will be cold.

So the issue with an upright canister stove in cold weather is to keep the gas boiling (turning into a vapor). Just as with water, the boiling point of the fuel in your canister drops as the atmospheric pressure drops, therefore you can operate a canister gas stove in colder temperatures at higher elevations. The Lindal valve in your canister is really nothing more than a sophisticated hole. Whether you break open a little plastic hand held butane lighter (unsophisticated) or open the Lindal valve (sophisticated), the principle is the same: You're releasing the internal pressure. That internal pressure will continue to be released so long as the hole remains open.

It is the difference between internal canister pressure and the outside atmospheric pressure that causes gas to flow out. Reduce the outside pressure, and more gas flows.

This matters less with a stove with a generator/pre-heat loop, but you still need enough pressure inside the canister to drive fuel into the generator.

HJ
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Re: MSR Windboiler – Completed Review

Post by longri » Sat Dec 06, 2014 9:08 am

hikin_jim wrote:In other words, if you can operate a particular stove with a propane/isobutane fuel mix at 20 degrees Fahrenheit at sea level, you can operate that same set up at 0 degrees Fahrenheit at 10,000 feet....Now, is the graphic, precise? No. But it communicates the idea very effectively.
It communicates the idea, but imprecisely. At 10,000 feet your hypothetical fuel mix would only work down to 5°F on average, not zero. And since the barometric pressure changes not only with elevation but also with time of day, season, latitude and weather, you really have to speak about a range.

hikin_jim wrote:Actually only about 3 psig is required for decent pressure on an upright canister stove.
How did you determine that? I don't believe it's true, at least not in general.
hikin_jim wrote:Wow, that's warm. I've camped in the teens in lower elevations than that. If you're not getting below 20F, then bringing an inverted canister stove isn't absolutely necessary, but God help you if the temperature drops unexpectedly low. Of course at 13,000', you've got a lot of "slack" because of the low pressure which depresses the vaporization temperature of your fuel. And you'll do better with a fresh canister with an upright canister stove since the propane content is still fairly high when the canister is full.
Often there is an inversion and it's colder at lower elevations. I don't know what you mean by "slack". Except for when there are inversions the typical winter lapse rate exceeds the rate that elevation lowers the boiling point.

I've had a pretty easy time down to about 10°F. Below that it takes more time to get the stove primed. Bootstrapping a near empty canister on a cold, windy morning is the worst case. But there are ways to deal with it that don't require any heroics.

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