Calling all fuel canister engineers!

[Gary Dunckel]

Yup, David, the eyes of all “Moulder groupies” are upon you. Please do what Bob said–start with a 4 oz. MSR IsoPro canister, cooled to ambient on the roof of your vehicle (or, set it outside for an hour while you sip a toddy in the warm vehicle). Actually, it might be better to just set it hidden outside the hotel somewhere overnight. Maybe the Holiday Inn has an outdoor patio table where you could do the test in the dark morning (heck, it’s dark 24/7 these days, right?). Bundle up and take an insulated mug of coffee with you. It should just take 5-6 minutes to determine whether the copper strip system will work in those temperatures. Will you have a cozy and an insulating base for the canister? We anxiously await your “trip report.”

[David Thomas]

I’ve been giving the project manager crap for sending me to Fairbanks (1) on Solstice – the shortest day of the year with 3 hours 50 minutes between sunrise and sunset and (2) during a cold snap.

Yeah, I’m hoping for a patio outside my hotel room, but I’ll bring a folding table as well so I could sit in my running car at a highway pull-off and fiddle with things from relative comfort.

Makes me wonder about my 2005 RAV4 – this might be its coldest trip.  I know it’s okay to -20F and I’ve had to max out the heater.  I once drove a Camry up the Alcan in January and got into some -40 to -44F.  Turns out that Camry could maintain 100F above ambient which at 0F is more than enough (you could make 100F inside).  At -44, +56F in the cabin isn’t comfortable for hours on end, even in my insulated coveralls.  Because those windows right next to your face are COLD!  And there’s a wind chill due to the “heater” blowing cool air at you.  But I bought the RAV in Alaska and all the dealers here order whatever “arctic” options there are, including the bigger heater core.

I’ll top off the coolant reservoir.  I’ve experienced poor heating due to low coolant volume in extreme temps because the liquid in the radiator contracts so much, it doesn’t completely fill the heater core.

I’ll bring aluminum foil for better IR feedback and a square of plywood as an insulating base.

[Gary Dunckel]

It sounds like you have everything pretty well dialed in, David. But you are making me cringe here. The coldest I’ve ever experienced was a week at Christmas in my little Montana home town back in 1968. The temperatures never got above -50* F for 6 straight days. The sparrows don’t fly south for the winter like most smart birds do, and on the 3rd morning there were maybe 20 of them hanging upside down on the power line out back. They apparently locked their little feet onto the power line to sleep, froze to death, and a slight breeze must have spun them upside down. I made a mental note to myself–never, ever consider living in Montana once I graduated from Dental school.

I will be thinking of ways for you to get even with your boss for messing with your holidays, David. Be safe up there.

[Jerry Adams]

I’ve been out when it was 20 F.  -29 F seems pretty cold.

“I’ll bring aluminum foil for better IR feedback and a square of plywood as an insulating base”

Eventually someone will have sympathy, if nothing else just to get me to quit talking about it : )

Try it with just the aluminum foil to see how well that works.  The IR has to get to the bottom of the canister where the liquid is – leave a 1 inch space between foil and canister there.  Top edge of foil should be about vertical so the IR reflects down to the canister.  It should reflect off the foil at about a 45 degree angle.

[Gary Dunckel]

OK, Jerry, next time it gets down around zero here, I’ll give your aluminum thingy a try. But that means that I shouldn’t use a canister cozy, right? That goes against the basic principles that all Moulder Groupies try to adhere to.

[Jerry Adams]

great!  two people are willing to humor me even if just to get me to shut up : )

Yeah, cozy will get in the way, don’t use it

Although if you boiled some water which heats up the canister, you could put cozy on to conserve heat while you’re drinking your beverage, then take cozy off to boil the next pint of water,…   But that’s going beyond any test I’m pitifully asking you to do : )

You see how the foil is near perpendicular at the top?  So the IR is reflected back to the canister?

And there’s a big air space between canister and foil at the bottom so the IR gets to the canister where the fuel is at the bottom of the canister?

[Gary Dunckel]

Then again, Jerry, could it not be done like this? Or does it require greater air space around the canister?

[Ross L]

David… You may already know this, but stuff a piece of cardboard in front of your Rav4 radiator. Makes a world of difference. Looking forward to your trip report.

[Jerry Adams]

Beggars can’t be choosers, that would work some, but

If the foil is sloped away from canister, IR photons will reflect away from the canister:

If the foil is vertical at the top, IR photons will reflect to the canister where they get absorbed and heat it:

[Gary Dunckel]

Do you like this one better, Jerry? The walls are 1.75″ tall, and I tried to round the corners a bit to maybe better reflect your IR waves. It’s up to +55* F today, so there’s no way to do a proper test. But I did place a tiny thermometer next to the canister, to try to see if any extra heat was imparted to the base.

[David Thomas]

“stuff a piece of cardboard in front of your radiator.”

Ross, thanks.  I knew that once.  I used it a lot with a POS step van with a bad thermostat while installing solar systems in Western MA through the winter, 30 years ago.  We had a medium-sized piece and a big piece for cold and very-cold weather.

I’m a big fan of the waxed cardboard boxes found behind grocery stores that some vegetables come in.  I also snag it sometimes out of the cardboard recycling bin.  I use 1-inch squares as a fire starter and 4×4″ or 5×5″ squares as a stabilizing and insulating base for a canister stove while snow camping (and which can be more fire starter in a pinch).  So I always keep some pieces in my garage.  I’ll trim one to size in my warmth of my garage and have it ready.

I’m not happy about it, but you guys probably will be.  The forecast keeps calling for colder weather.  Yesterday, Thursday was forecast -18F/-29F and today is forecast for -20F/-30F.

[Jerry Adams]

perfect Gary, thanks

55 F?  It’s only 50 F here

[Gary Dunckel]

Jerry, I just now did my little preliminary test with the “Adams reflective aluminum canister warmer thingy.” It is +55* F here today, like I’d mentioned, but I figured that I could at least see if my thermometer registered any additional warmth at the bottom edge of the canister.

I placed a Titan kettle nearly full of 45* F water atop my trusty BRS-3000T stove, and I fired it up on a medium setting. After 3-4 minutes the thermometer went from +55* F to +70* F, so things were looking good. It took a total of about 6 minutes to bring the water to a boil, and the temperature was about +79* F at that point. I removed the pot and let the stove continue to run. After 9-10 minutes, the thermometer said it was now +65* F. So the pot had a significant effect in warming the base of the canister. What is that, convection? I cooled the pot in a snow bank and poured the water into a different container. I then filled the pot back up with ~ 2.5 C of that 45* F water and repeated the test. Once again, the thermometer registered +80* F at boiling. I again removed the pot and let the stove continue to run. After 10 minutes, it again said it was +65* F.

So it looks like your IR photons do help to warm the canister, but the real deal seems to be the heat that bounces off the bottom of the pot. I should also mention that it was quite breezy on my patio, and I needed to block the wind. I used 3 pieces of aluminum angle flashing that I placed on end. I tried to keep them at least 6″ away from the stove, but I expect that they still had some affect on the test. Mainly by trapping any heat and preventing its escape.

I am wondering if titanium foil will work in a similar fashion as the aluminum foil. I can envision a full circle of ti foil, maybe 2″ tall, with a circular titanium base plate. This is what I do with my caldera “clones,” and it really creates an oven. On a very cold day, I doubt that a “wind screen” that short would allow the canister to heat up much, certainly not to the “Caffin is going berserk” point.

If we get another arctic blast (with 0* F temps) in the next few weeks, I do the test for real. But I kinda think I already know what my go-to plan will be in the future–the Moulder Strip, baby!

David, do you feel like you’re at a party where 4 of us are standing off to the side? You are trying to have a conversation with the guy across from you, while I’m talking loudly to the guy across from me, and nobody can hear what anyone else is saying. But hey, it’s my thread. So I can do thread drift all I want, and I can also orchestrate others to do the same.

Happy solstice, Dave! You too, Jerry.

 

[Jerry Adams]

Aluminum is pretty good because it is highly reflective in IR.  Aluminum foil has an emissivity of 0.04, about as good as it gets.  0 is perfect.  1.0 is the worst.  Polished Titanium foil is 0.19 which is pretty good.

http://www.engineeringtoolbox.com/emissivity-coefficients-d_447.html

A lot of windscreens would be good.  A Caldera Cone would be pretty good.  It actually angles inward so some IR would be reflected to the ground next to the canister, but that would heat up the canister eventually.  Better for the IR to directly hit the canister though.

[Roger Caffin]

We have several articles on foil windscreens here at BPL, eg:
https://backpackinglight.com/taming_those_large_flexible_foil_windshields/
https://backpackinglight.com/wind_dynamics_and_windscreen_design_part_2/

One of the other effects you get with a foil windscreen, apart from blocking the wind, is a warming of the canister by both reflected radiation (as discussed above) and by trapping of hot air around the canister. The photos below illustrate this:

(These are from the first of the URLs.)
You can see the opportunity for reflection in these photos. It works well.

Cheers

[Hikin’ Jim]

Fascinating post.

David, bring a catalytic heater and a canister of 100% propane.  And some wood, a steel tub (not galvanized; I seem to recall that would be bad), and a can of gasoline.  Sheesh that’s cold.

The Moulder Strip is awfully tempting.  I mean who wants to carry extra water and an extra container on a trip?  But on the other hand, there is the possibility, however remote, of heating the canister to the point of failure.

Water, albeit messy, is pretty safe.  It’s not going to get hotter than the temperature it starts at when you pour it into whatever container you intend to use.

HJ

 

[Bob Moulder]

Jim, if you were to test the copper strip setup — using enough thermometer probes placed around the canister to make you comfortable — you would see that canister temperatures remain in an extremely comfortable range.

When I did my first tests I was extremely paranoid and monitored every test until I had done perhaps 30-40 burns up to an ambient temperature of about 55°F. Even 1″ away from the copper strip on the side of the canister, the metal was very comfortable to the touch and the thermometer confirmed this time and time again. All who have replicated this setup have had the same results.

And the best part is, it renders moot the whole fuel composition issue. I now run straight N-butane all the time, down to -5°F so far.

Here is a photo showing a temperature probe in contact with the canister less than an inch from the copper strip… it’s 74°F, and that’s inside the cozy. This is VERY safe.

 

[Roger Caffin]

Hi Bob

I am not disagreeing with you, but please remember that society does have some teenagers who will mindlessly throw a nearly-empty canister in a fire ‘just to see what happens’. Let’s keep preaching some caution?

Cheers

[Bob Moulder]

Roger, I was thinking last summer about the number of Darwin Award contestants ‘out there’ so I intentionally abused this setup (Cu strip and cozy) by running the BRS and JB at full power, at 75°F ambient, pots on top of the stoves, for 30 minutes straight, with 2 thermometers monitoring canister temperature and frequent ‘touch tests’ of the tops of the canisters. You probably remember this as I have mentioned it a couple of times, but I’m mentioning it again for those new to the topic.

In those tests — which I was monitoring like a dynamite factory manager — the canisters got pretty warm (110-115°F) but obviously didn’t blow up then, so somebody would have to do something ridiculously reckless to create a problem.

I have no problem mentioning again the caveat not to use the setup above 45°F ambient (which is VERY conservative) and to be extremely cautious when using it in concert with a windscreen (better to use natural wind blocks such as stacked rocks or snow walls, anyway), never to fully enclose with a windscreen (which caveat should accompany your photos above, one might argue… “Gee it works great with the screen slightly open, so it’ll be even better with it closed!”) And also, don’t operate it on the Long Island Railroad tracks at rush hour.

However, recognizing that there’s no limit to the creative genius of morons, I am open to a boilerplate, catch-all disclaimer to display any time the topic of stoves comes up.

It is interesting that the MSR Disclaimer for the Pocket Rocket instructs users NEVER to employ a windscreen, and to use ONLY MSR cookware!

 

 

[Roger Caffin]

Hi Bob

Let’s keep it really simple?  By pass all the rules about windscreen openings etc, and focus on the real danger: the temperature of the canister. How about

‘Always monitor the canister with a finger to make sure it never gets hotter than you can touch.’

Cheers

[Hikin’ Jim]

Ha, ha, yes.  You must use MSR cookware.  Oh, and MSR butane, because their butane is, well, different than the other guys.  lol.

Bob, those are super rigorous tests, and you probably used very specific materials arranged in a very specific way.  I’m more worried about some yahoo out there who sees a photo, doesn’t read the text, and tries it with a “more is better” philosophy.

It goes something like this:

Well, shoot, I can do better than that little itty bitty strip of metal that guy has!  Why here’s a big ol’ strip of copper right here!  I can just go set this up in my (heated) garage for a test.  There!  It’s all set up and running.  This may take a while.  I’d better run back inside and get a beer, and besides, I hear the phone ringing.  It’s probably Aunt Mildred.  Wow!  She can talk for hours…

You laugh, but…

Anyway, not a criticism on my part.  Just a musing about the relative merits of the Moulder strip vs. water.  Water too can be misused.  Again, our friend with the “bigger is better” mentality may think that if warm water is good, then boiling water, lots of it, will be better.

Roger’s admonition, if it’s too hot to touch, then it’s too hot, is a good one.

HJ

[Roger Caffin]

and MSR butane, because their butane is, well, different than the other guys
It has more ‘butaneness’ maybe?
I will add that we have had associated rows with the MSR lawyers in the past.

 I’m more worried about some yahoo out there who sees a photo, doesn’t read the text, and tries it with a “more is better” philosophy.
Ah well, perhaps one should see it more as ‘selective evolution’ ? With Darwin Awards.

Cheers

[Hikin’ Jim]

Eh?  What have the lawyers been complaining about?  Surely not about butane??

Perhaps it was windscreens with their upright canister stoves?

HJ

[Roger Caffin]

It was over the CO emissions from the Reactor, the use of a canister stove inside a tent, and the matter of windscreens.

They were hugely embarrassed by the extremely high levels of CO I measured, especially when seen against the table of effects of CO concentrations. The stove was withdrawn from the market for several months while they tried (not very successfully, mind you) to reduce the levels of CO emitted.

They were adamant that you should never use a stove inside a tent even if there was a howling snowstorm with 100 kph winds outside. The idea that someone could die from the cold at 8 pm outside at 3,000 m in a storm was utterly irrelevant compared to the legal risk MSR might face from acknowledging the use of a stove inside a tent.

The same applied to the use of windscreens , in all senses.

MSR has gone WAY downhill since the founder, Larry Penberthy, died. Larry was an engineer and a mountaineer; the lawyers are not.

Cheers

[Gary Dunckel]

To get back to Jerry’s aluminum IR reflector concept, This morning I modified my reflector design a bit. Thinking that a circular version might more efficiently focus the IR photons to the canister base, I made it 2 inches tall, with a circumference that was 1.5 inches from the sides of the canister. Here’s what it looks like. Note that there is a tiny thermometer hacked from one of those compass/thermometer zipper pulls sitting next to the base of the canister. Also, I needed to thwart a mild breeze, so I used a piece of aluminum roofing angle flashing, which was positioned a full 6″ away from the reflector (to hopefully eliminate any effect on the test). There also is a full titanium disk for use as a base plate.

I once again used a MSR Titan kettle, which was near full with ~2.5 C of 33* F water. I wasn’t interested in boil times or fuel consumption for this test. The ambient temperature this time was +30* F, which is what the mini thermometer said and which was confirmed with another thermometer.

After 6 minutes of burning with the BRS-3000T set at medium flame output, the mini thermometer registered +75* F, and the water was about to boil. I removed the pot from the stove to see how things went without it. In 7-8 minutes, the mini thermometer said +55* F, so the pot did have a big effect on the warming of the canister base. I then poured the hot water into a different container, and I refilled it with more 33* water and placed it back on the stove. In about 7 minutes the mini thermometer registered nearly +80* F. I noted at the time that ambient had risen up to 34* F as the day was beginning to warm up a bit.

Now it became time to see how things would work without the aluminum reflector. I left the titanium foil disk in place. After 7 more minutes, the mini thermometer showed +45* F. I didn’t want to waste too much fuel, so at this point I replaced the aluminum reflector and I set another fresh pot of cold water on the stove. When the water nearly came to a boil after 7+ minutes, the mini thermometer registered 75* F.

So there’s no doubt to me that Jerry’s concept has merit. The only question I have is what are the optimal ambient temperatures in which this will work. I have a sneaking suspicion that at 0* F it likely won’t be able to keep up (to keep the canister base at say, +35* F). But I could easily be wrong here. If we have another of those Arctic blasts, I’ll give it a try. But for the time being I will remain a Moulder Strip fan boy, because I know what it will do.

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