I have a Trangia Mini Alcohol Stove that I love. I’ve had it for several years without incident.
I’m fairly certain this incident was entirely a result of the way I operated the stove, and it is unlikely to be something you would ever encounter in normal camping use.
That said, it is a “mode” that anyone using such a stove needs to be aware can exist.
This is a Trangia Mini:
The “pot holder” is the scallop topped bit of aluminum under the pot on the right. Inside of it, you can barely see the alcohol burner. The brass lid and control ring are in front of that.
Image From article here:
I’d noticed before that it starts slow, then “blooms” when the fuel is warm enough to pressurize the gas holes around the rim to make a more normal flame / burner effect. I’d also noticed that sometimes it seems to “bloom” again into a larger stronger flame. Rarely have I run it much longer than that, or if I did, I’d toss the control ring on it to keep from burning the stuff I was cooking or having the pot boil over.
Clearly over time, as the heat built up, the alcohol gets hotter and the “speed” of the stove increases until it limits on high. For this particular stove, this is helped along by the aluminum pot holder legs that end up IN the flame, and conduct heat to the body of the pot holder. This can result in a warm area under the stove.
To assure this didn’t hurt the table top, I’ve run it in a tin pie pan, or on top of a “lab book” without incident. I think this matters. This time I used a cork pad about the diameter of a pie tin and about 1/3 inch thick. Cork is a great insulator.
I had a 2 quart / 1.5 L (per the bottom of the pan, I know they are not the same) pot with a steamer basket in it and broccoli in the basket. The water level was to the bottom of the basket, about 1.5 inches. It started cold. This was set on an absolutely full near to the rim Trangia. I think this matters too.
I started it running while I went to get the rest of dinner underway, knowing it would take about 5 minutes for the water to reach a boil.
Time passes. The stove eventually “blooms”… then later “blooms” again to a size of flame the is starting to extend around the edges of the pot. I decide that, at about 8 minutes all told, maybe headed to 10, I need to put the control ring on the pot. So I’m inspecting the flame size and have the ring in hand, deciding on a setting…
POOF!!! The stove uber-‘Blooms’ again and spits alcohol into the pot holder and splatters some outside the pot holder onto the cork pad. I’ve now got a nice fire about 8 inches in diameter and a foot tall. The part on the cork is just small spatters, but the pot holder is now acting as stove with about 1 mm or maybe 2 of liquid in the bottom. I set the pot over on the other counter.
I’m not particularly excited at this point as:
a) I just don’t do that much any more. Jump out of an airplane a few times and everything else seems kind of tame.
b) It isn’t very big, there’s not much flammable near, and it has clearance to the ceiling. It is slowly diminishing anyway.
c) I kind of like playing with fire ;-)
At this point, thinking maybe the part on the cork can just evaporate off and burn out, I notice the cork is charring under the wet spots. So that’s not going to work. They are down to about 3 inch flames and the center is still running about 8 inches and not slowing down much.
I just carefully pick the whole thing up by the rim and carry it to the sink, set it down, and run water on it. Problem goes away… Nice thing about alcohol, water puts it out.
I think this particular stove is balanced for a narrower range of ambient temperatures and heat loss context than my other larger one. Same burner, but a larger steel ring that holds the burner up off the surface. I’ve run it under similar conditions without issue.
Used in cooler air, or without a superb insulator under this pot holder / stove, I have not had any event like this happen. I think it expects cool dirt or a heavy wooden table under it for heat loss.
I’m fairly sure that running it for about 8 to 10 minutes, on full, with the top covered for a goodly radius by a pot, and the bottom very insulated, caused excess heat build up.
Had it NOT been filled “to the brim”, there likely would not have been enough alcohol left after 8 to 10 minutes to have a “spit up” happen.
Had I been less slothful about putting the burner control ring on, it would not have gotten to this state. Being interested in getting a LOT of water to boil fast, and then spending time marveling at how large the flame had gotten were not good decisions.
Next time I’m going back to the pie tin. a) The Splatter Spit did not extend beyond the rim of a pie tin. b) The pie tin conducts heat away. I’ve done a similar cook on a pie tin without issue. c) Pie tins do not burn at normal fire temperatures / conditions.
I need to buy a new cork hot pot pad.
Having a pint of water near the stove might have simplified things and saved the cork pad.
Be wary of running this stove a long time, full, in very hot weather. You have a control ring, monitor the flame size and use it.
Dinner was fine. Cork pad tossed on the damp lawn; I moved the (basically done) steamer to an electric hot plate, fried the fish over a propane burner, and microwaved the side vegetable. Didn’t really even break stride in the prep of dinner.
Maybe it is growing up as a restaurant brat. If you get a kitchen fire (say a pan of grease spits and catches) you don’t panic and shut the place down. Just deal with it quickly and don’t forget you are still cooking… Besides, you are surrounded by big gas burners all the time anyway. The Wolfe range we had had 6 burners about a foot diameter each (for the flaming bit!) and you could have all of them going at once. Fire, it’s part of the job.
I still love my Trangia Mini. I’m just going to marry it to a pie tin and respect its limits…
What’s the approximate capacity of the pot in the picture?
You were using a 2 quart pan and I know the size of one of those. I’m just asking to get a feel for the scale of the setup you were using as opposed to the kit shown with an unknown size little pot.
If it were me, I’d have squirted some chocolate syrup on the whole mess and dumped a few cherries on top. Then I’d announce, “Surprise, honey! I made a special flaming dessert for tonight!” The only kink that I see is you’d have to somehow fast-talk your way past the chocolate covered broccoli ;o)
The Pot Support is about 4 inches and the pot I was using extended about an inch or inch and a half in all directions around it.
Basically, the bit above the square holes in the pot support gets heated by the flame. The bottom is insulated. Inside has radiant heat from the fire. That leaves just the ring of the square holes and below to dump excess heat.
That’s why I think blocking conductive heat flow out the bottom of that aluminum bucket matters.
The kit specs say the pot on the stove is 0.8 L and it has a diameter of 150 mm at the widest part of the lid and is 65 mm tall.
My pot measures 6 1/2 inches diameter at the bottom / 165 mm more or less if I can still read my ruler right ;-)
Their pot measures 120 mm at the bottom with the same ruler.
Pot Support / stove measures 3 7/8 inch or 97 mm peak to peak.
Burner measures 55 mm burner diameter (but flames come out from it to eventually touch the pot support ends.)
I probably also ought to add that I’ve run the Trangia burner with similar pots / loads / durations sitting in a tuna can in the Sterno Stove and without the heat build up. This IMHO confirms that heat loss through the bottom prevents the issue from developing and only extended burn time when highly insulated on the bottom can make it happen.
Though 110 F in the shade and thar ain’t no shade in the desert might also cause issues…
Thanks for the additional dimensions, E.M.
I’ve mentioned before that all of our customers’ drawings were in mm, our drawings to our machine shops were in decimal inches, and a lot of our fixtures and tooling were in fractional inches.
Anyhow, I have a good feel for what your setup was versus the kit picture shown and it seems there really isn’t enough difference in pot size to blame the fire on anything other than not having something to bleed off the excess heat or restrict the flame via that control ring.
I keep a quart spray bottle full of water with the spray nozzle set for a fine mist near the stove.
It works as a dandy emergency cooling tool, and won’t ruin food if you use it to deal with something that got too close to the stove burner.
Wondering if you could tame that behavior by adding just a bit of water to the alcohol?
Filled pot to bottom of the steamer (so same volume): 500 ml.
Measured my usual almost full coffee mug of water: 400 ml.
That’s what Ive heated to whisling in the tea kettle, larger diameter than the steamer pot, daily for weeks.
Brought to the boil in a bit over 5 min in the 2 quart pot, with the burner in the tuna can in the Sterno Stove and poured over coffee, filled again and placed back on stove.
At about 8 minutes had the “2nd bloom” to higher power. At 10 minutes, called it, as the 2nd batch was at the boil and nothing was accelerating that I could see.
So slightly longer time and more mass (not that much cold broccoli :-) and longer to second bloom with no third or spitting.
I may try it again some day with a L of water and 15 minutes, but really, that’s outside my usage profile…
I think it could go to thermal runaway in the tuna can / Sterno Stove combo on a hot day or very long burn as it is almost fully enclosed (air enters a thin zone around the bottom) but the added distance flame to stove and aluminum walls to burner along with heat conducted to the bottom will make it take longer than for my food to burn or boil over…
A water cut ought to work. More latent heat of vaporization.
This is using the 50:50 methanol:ethanol mix , so likely just using straight methanol would do it as fuel value is lower and latent heat of vaporization higher.
Or just don’t run it for 10 minutes straight full power on an insulated surface ;-)
Tomorrow I’ll try a pie pan runaway test…
These look nice…
Those do look quite nice.
Measured the cork circle. 7.5 inch diameter.
Max edge to edge burn marks 7 inches
Diameter of pie pan 9 inches
Pie pan it is.
Some other folks with various degrees of runaway burn. Primarily on ethanol blends. ..(Entirely?)
Assetion that a tsp. of water prevents it.
Assertion their mass spec says all sorts of stuff as denaturant and some can be an issue.
Assertion reduced air flow via windscreen involved.
Assertion never happened on methanol.
Interesting test series. Finds 190 Everclear best. 70% ethanol from drug store also good.
I didn’t see any ethanol at our drug store, maybe it is behind the counter or another California ban… I remember seeing it a few years ago.
The federal government allows several different denaturant mixes, addition of methanol is only one.
Gasoline is also allowed
See page 8
Click to access Industry-Guidelines-Specifications-and-Procedures.pdf
It should also be
noted that while many denaturants are allowed by the TTB, ASTM D4806 specifies the use of
natural gasoline, gasoline blend stocks, or unleaded gasoline, as the denaturant.
Looks like a crap shoot regarding what denaturants are in use in a given sample.
I guess MSDS is your friend on this one.
Click to access MSDS.Fuels_.Denatured%20Ethanol.pdf
Did two more tests.
These were outdoors on top of a redwood 1/2 log table. Fence about a foot away behind the stove, a hydroponic tub on each side. Air temperature maybe 5 F cooler than the indoors run, or maybe the same. At most an occasional waft of breeze, but mostly nothing.
First test: Same 50:50 fuel, stove on tin pan on wood. Heated 9 oz water to the boil at about 5 minutes for a noodle cup, then refilled with about a L more and put back on the still running stove. At about 9 minutes there was a small “poof”: sound of the “second bloom”, but softer than the one indoors. At not time was there a 3rd, and at 20 minutes I stopped the test as the pot was boiling fast and nothing was changing.
At first fire, completely full, I watched from the side and got to see a dribble of alcohol coming out of the burner holes making a small puddle on top of the stove as the first heat tried to pressurize a completely full stove. While this gives a VERY fast time to pre-heat and first bloom, it is showing that “full to the brim” accelerates stove warming with liquid overflow, even if not much.
Conclusions: Leave a 1/4 inch / cm or so headspace. I had fuel left after 20 minutes of burn time. You don’t need it full to the very top.
The Tin Pan had enough heat removal to prevent the problem case under normal room temperatures.
HEET brand methanol. On the SAME cork pad that was a problem before, but turned over to the clean side.
At 5 or 6 minutes had enough boiling water ( 400 ml ) for tea. Refilled the pot with about a L of water and back on the stove. At bout 11 minutes there was a soft “poof” sound that might have been a “second bloom” or could have been the dog burping. Hard to tell if it was ambient noise or not. At about 19 minutes the pot was boiling nicely and at 20 minutes I halted the test.
No Problems At All.
Conclusion: The stove is designed for Methanol and is safe and works well on methanol. Using a 50:50 blend of methanol / ethanol with a few percent of Mystery Hydrocarbon Denaturing Agent raises the heat output enough that, especially if insulated on the bottom or very hot environment, the stove can enter a “runaway mode”. It gives ample warning with a strong POOF sound of a second “bloom” and you can just put the control ring on it to slow it down.
In short, it’s the fuel. You can make this worse by abusive heat building practices, or you can make it better with heat removal or fuel dilution.
I’m done with testing unless there some particular thing I’ve missed. I’m pretty sure I can very easily run the stove without issues all the time (use methanol) and run it with a bit of care on methanol / ethanol mixes.
Thanks for the additional info, it is interesting that there is an edge case that can bite people. I wonder if that if the source of those occasional tent fires you hear about where someone is cooking something and next thing you know they are trying to save their sleeping bag before it all goes up in a ball of flame. You are “Not supposed” to cook in most tents but many of us do when the conditions require it.
The pie plate base is a good safety in any case and a very small weight penalty.
Were I packing, I’d likely just use the pan / lid unless it were hot, but if it is hot, you likely don’t need to cook in the tent… in the car, a pie tin is nothing. If outdoors, dirt contact is likely enough to slow it. Hmmmm…. tent floor thermal insulating? Just enough some times?
In the case where it spit up at me, it was litterally instant. One moment I was contemplating “to control ring, or let it boil sooner?” the next POOF and a 7 inch diameter fire a foot tall.
I’d try a test with 10% or 20% water dilutions, but I only had a couple of ounces of the mixed fuel left and an opened HEET botte doesn’t seal all that well, so just dumped it in my fuel bottle together. I’d have to open a new sealed can of the 50:50 mix for any new test. Maybe in a few weeks…
It does seem to be right at the edge of not doing it. Any increased heat removal or insufficient burn time or less energetic fuel, no problem… I think this summer I’ll try some high temp tests… coffee on the patio and all :-)
In any case, knowing the case exists, that the big poof second bloom is your warning, and being aware of the fuel as causal / contributory so you know when it is a risk, it is pretty easy to toss the control ring on or snuff it.
Actually, for packing, a foot of aluminum foil would be protective and weigh nearly nothing.
Tonight, for dinner, same stove. Same pot. Same water. Same broccoli. Same location. Same temperatures. Same time of day. On a pie tin and using the 75% methanol 25% mixed fuel … ran for 15 minutes, not a single problem and nothing to say one was coming. (i.e. no big “second bloom”)
I think this pretty much closes the case on it. You must have things Just Right to get outside spec and have it burp fire at you. Miss any point, it just cooks. A key point is the mixed methanol / ethanol fuel with “mystery hydrocarbons” in it. Another is an insulated stove bottom. A third is a long cook time.
I’m still VERY happy with my Trangia Mini. I’m just going to be careful feeding it mixed ethanol fuels in hot conditions on an insulating surface… and when it does a big POOF second bloom, toss the control ring on it pronto.
For those in cold weather country, if you can keep your core warm, your extremities and you will be warm. One way to do that would be a hand warmer kept near your chest. This one runs on liquid fuel, but there are also lithium battery ones.
And I’m wondering if something like this would work also:
And finally, don’t leave out the woman in your life:
One Christmas, my Sister knitted for her husband a, um, er, “nose cozy”… except it was rather long…
Which lead to speculation that the real purpose was a, ah, “pecker warmer”… to keep it “ready and warm for action”… which lead to ribbing about was he just a “cold ‘fish’ or what?” and more…
Oddly, the gift was never seen nor heard from again…
But it was in bright Christmas colors…
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