Double Sterno Stove Power For Free

Well that was fun…

Made lunch. Tuna sandwich. Was thinking about how the Sterno Stove is just TOO underpowered to really boil water fast and how it was the size of the can top / opening. Had thought about using a can opener to remove the top at the outer edge. Was looking at the tuna can… Isn’t it just about the same diameter?…

Now the height is about 1/2 that of the 6 oz Sterno can, so would be lower from the pot, but the fuel in the Sterno can burns down that low too… And the test I did with Sterno spooned on top of an upside down can worked really well, but really too well in that the support wires got to glowing dull red… Maybe a bit further down would be better.

So I washed the Tuna can and removed the paper lable (Starkist brand – some cans are different and this one is all metal one piece on the bottom, no separate bottom lid with seal). Put “butt to butt” with the Sterno can, it’s just about identical diameter.

Put it in the bottom of the Sterno Stove (pot holder / pot support / windscreen thing) and added 2 tablespoons of roughly heaped methanol based cheap slow chaffing dish fuel as a worst case test. Lit it up with my tea kettle test of 8 ounces cold tap water in a standard home tea kettle of about 1.5 L capacity. Waited.

The prior Sterno tests are in comments here:

https://chiefio.wordpress.com/2018/03/22/60-120-per-gallon-camp-stove-fuel/

Along with a test where I ran 1/2 & 1/2 isopropanol / methanol in a Trangia stove and it worked well. So, after waiting.

At the 5 minute mark it was simmering and making steam, at the 6 minute mark (almost exactly) it began to whistle.

There was about 1/2 tablespoon of fuel left over. I used a meat cleaver to snuff it by laying the big flat metal surface on top (there not being a lid to snap in place … maybe something else needed when camping ;-)

So that’s roughly double the speed of the regular Sterno brand big cans of fuel; but using the cheap poor fuel crap. At no time did the stove over heat (no wires glowed red) and looking in through the vent holes it was a nice blue flame well distributed.

This Tuna Can Burner is now going to be a standard component of my Sterno Stove kit. Now I can choose a more normal full cooking / boiling rate using it, or a “simmer and don’t fry” speed using the regular fuel cans.

Only negatives I can see is that a bit of soot formed inner liner inside the tuna can on the top 1/2 of the can darkened (though I didn’t see any soot on the tea kettle) and it isn’t as easy to snuff (doesn’t come with a properly sized cap for snuffing, so eat 2 tuna sandwiches 8-). Then you have to spoon fuel in / spoon left over fuel back out if it’s enough to save. Guessing how much fuel is “right” requires paying some attention over time. I’m not going to lose sleep over it.

So by having a Tuna Sandwich and washing the can, you can convert the normally anemic Sterno Stove into a nice large platform (easily supports several pot and cup sizes) stove that can cook fast or slow.

IMHO, it’s a very big improvement for almost free.

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About E.M.Smith

A technical managerial sort interested in things from Stonehenge to computer science. My present "hot buttons' are the mythology of Climate Change and ancient metrology; but things change...
This entry was posted in Emergency Preparation and Risks, Food and tagged , , , . Bookmark the permalink.

20 Responses to Double Sterno Stove Power For Free

  1. Larry Ledwick says:

    Cool deal, proof that heat output is roughly proportional to fuel surface area.

    On snuffing the tuna can might I suggest you take a sheet of heavy duty aluminum foil fold it 2x (to form a roughly square 1/4 sheet sized 4 layer foil and form fit it to the top of the tuna can before you light it, then set aside until time to snuff the flame.

    I do that for several similar applications and a 4 layer quarter sheet like that is quite durable, especially if you take the time to put a small roll seam around the edges that is how I make a lid for a spam can I use for drippings.

  2. Larry Ledwick says:

    That also makes it possible for you to ration total fuel burned, as it would auto extinguish when all the available fuel was used up. Just have to work out how much fuel was needed for a given task.

    What is the condition of any remaining fuel after you snuffed the flame, is it largely still an ash free lump of the gel that can be re-ignited later?

  3. E.M.Smith says:

    The left over fuel is mostly just gel as from the can. The surface has a small amount of ash lumps where significant gel has had the alcohol evaporate. At times, I’ve added alcohol back into partially used Sterno and the ash has reformed some gel. Most of it seems to stay CaAcetate and only when burned hot enough to breakdown the acetate does the ash finally become real ash.

    For this batch, I “picked off” about three pea sized bits of ash (with some gel sticking to them- from earlier burns with this can of fuel); but that isn’t really needed. It works even if you leave the ashy bits there.

    Yes, IF you work out how much fuel for a task, you can ration it that way. The only issue is the gel tends to stick to a spoon (or your fingers if you use them to scrape it from the spoon…) I don’t know which loss is greater – the stuff sticking to spoon and fingers or the stuff lost to evaporation as the fuel lump cools. In either case it isn’t much.

    Oh, and I need to check the tuna can ( I’ve taken a dinner break…). In retrospect I think the “soot” might just be the plastic inner liner charring in the heat. I just looked at a dark layer and thought “soot” without testing it.

    It is quite satisfying to have turned the Sterno Stove from “Feh, if all else fails it is better than nothing at all…” into “very workable with 3 levels of flame control (Tuna -high, open can – simmer, lid 1/2 closing hole – just barely warming) As a pot stand the big square with narrow wire spacing works better on very small and larger pots than the Trangia stands (that have a preferred size pot. Too small they sit on the burner, too big they get ‘tippy’).

    It is also well known that you can just squirt liquid alcohols into the empty Sterno can and go. You lose the ‘safety’ against spilling of the gel, but it works OK. Now the tuna can would give a higher power version of that too. Turns a “Feh” stove into a flexible field item. Ought to even burn twigs in the tuna can well too. (Twigs in a Sterno can don’t get enough air to burn well. You must add vent holes). I’d be quite willing to use a church-key to make a tuna burner with vents for wood. Could likely also get the larger salmon cans and do the same with them, too. Yes, I’m hooked. ;-)

    The aluminum foil idea is a ‘keeper’, thanks. I was thinking old can lid… but they have sharp edges…

    Don’t know of you saw on the $60 – $120 link, but 50/50 isopropanol / methanol has slightly visible flame in daylight. I’ve christened it “Spirit Stove Daylight Safety Fuel” ;-) Acetone / methanol at 50/50 is about the same (though acetone is harder on paints and rubbers – more for ’emergency knowledge’ than daily use).

  4. Larry Ledwick says:

    Yes I have been watching your stove test series.

    I was thinking the same thing about adding some vent holes to the top of the sterno can to see what happened.

    An interesting thought would be to use the tuna can and borrow a page from the boy scouts. They used to have us make little cooking candles by rolling up a 1 inch wide strip of cardboard and putting it in a tuna can with a candle wick in the center and then pouring the can full of paraffin.

    The cardboard might work as a surrogate for the gel and a large wick for use with liquid fuel.

    I see more testing coming soon.

  5. E.M.Smith says:

    I’m less than keen on the tuna / cardboard / wax burners. (Be careful with “paraffin’ unadorned. In the UK it is kerosene… so “paraffin wax” or just “wax” to assure someone in the British Empire isn’t thinking mineral oil / cardboard / tuna can…)

    They work, but are very sooty. Not enough air can get to the vaporized wax vapors.

    That’s a generic problem for all long chain hydrocarbons without a vaporizer / air mixer jet, and burner head.

    I’m just not keen on cleaning soot from pots, or the inside of my pack.

    I can see the utility for a last ditch emergency heater / stove. Or for entertainment as a portable campfire. Cooking? I’d rather use gas or alcohol ;-)

    FWIW, I found that the Sterno can sits nicely on top of the tuna can. Has prevented the residual Sterno fuel from evaporating over a few hours now.

    Wood has a similar problem. That’s why you must have air mixing holes in the can to get the sooting down to an acceptable level. I’m a bit more interested in charcoal as it doesn’t soot.

    What I’m thinking is a soup can or ‘whatever’ is the same diameter as the Sterno can. Put a few nails crossways at about the 1 inch height, with church key vent holes in the bottom sides. Now you have a nice “chimney” charcoal burner. (Maybe add some more holes 1/2 way up if more air is needed – see a Webber charcoal starter can for design ideas…). That ought to let me use a couple of ‘self lighting’ charcoal briquettes for cooking in a nice compact stove burner. “Ash pit” in the bottom, a couple of briquettes in the top. Good to go.

    Yes, more testing ;-)

    Update: Checked the tuna can. It isn’t soot. Some kind of inner coating darkened in the tuna can. Not even a full black, really. I’ve updated the posting.

  6. ossqss says:

    Just curious, a buddy swears by a white gas 2 burner coleman stove he has. Expensive, but the fuel seems to be stable for a long time. Is it worth it for a non-small space need?

  7. Larry Ledwick says:

    Conventional gasoline from the pump is a mixture of something like 350-400 hydrocarbons, where white gas (as sold for camp stoves by coleman) is a much narrower range consisting of essentially only these hydrocarbons.

    Coleman fuel is a mixture of cyclohexane, nonane, octane, heptane, and pentane.(from wiki)

    As such it is not as prone to complex chemical reactions if stored for a long time and formation of varnish like deposits due to evaporation of the light ends of the fuel as is the case with conventional gasoline.

    I have one of the 2 burner dual fuel camp stoves that will take both white gas camping stove fuel and non-leaded motor fuel. If you are going to store the fuel for emergencies I would store the sealed factory 1 gallon cans of the stove fuel and only use motor fuel unleaded gasoline when you can be reasonably sure you won’t leave fuel in it for a long time (like over the winter).

    The only issues I have seen with those stoves and similar gasoline fuel camping stoves is they need occasional service for the pump which you use to pressurize the fuel tank and maybe a leaky O ring seal, otherwise they seem to work for decades without much attention.

    Just run the fuel tank dry when you store them over the winter.

  8. E.M.Smith says:

    @Ossqss:

    The “Coleman” type gasoline stoves work very well, but are a bit of bother to pump up and get warmed up (the ‘generator’ pipe in the flame must get hot enough to boil the gasoline). They work very well, once you are comfortable doing the start-up dance.

    The “wings” on the lid make a decent wind screen outdoors, but you need to turn the stove the right direction (back to the wind, more or less).

    With the fuel drained from it, it will store for years and start right up. Eventually the ‘seal’ on the pump gives out and needs replacing. Cheap and easy.

    THE major feature is the fuel is dirt cheap.

    MUCH easier to use is the equivalent Propane stove. Just turn the knob and light it (many have built in ‘clickers’ to light via piezo electric spark).

    Only issue with them is the fuel canisters are more expensive. You can get an adapter to run directly from the 20 lb. BBQ bottles / tanks. Then the fuel cost is much closer to gasoline (varies by area). Propane in a closed tank keeps forever, near as I can tell. ( I’ve personally stored it for over a decade. Maybe two.)

    White Gas is more stable than gasoline. Most gasoline stores for about 6 months to a year for stove use. Then the stuff it’s made from reacts (polymerizes slowly, faster in sunlight or heat) and forms “varnish”. White gas takes a LOT longer to go off (and I’ve never kept any that long) We’re talking years. White gas also burns more smoothly and cleanly (though Unleaded gasoline never offended me enough to care).

    Propane is about $3.50 / lb in canisters. About $3 to $5 / gallon in larger tanks.

    Your “use case” matters.

    IF you intend to regularly go camping or making hot dogs at the little league a lot, and fuel cost will be a big issue, get the gasoline stove. IF you intend to put it in a closet for “someday” and worry about how to make it go then: Get the propane stove and some canisters.

    If your use case will be both, undefined, or variable, get the gas stove and buy the replacement Propane “generator” for it. In about 2 minutes you can take the gas tank off and put the propane tank on (or vice versa) and use both fuels (all three fuels…)

    Here’s what the adapter looks like:

    https://www.amazon.com/Stansport-185-Propane-Converter/dp/B004RDQT92

    I have the 2 burner “Powerhouse” and the propane adapter and have used both. Works fine. You can cook for a whole family as on a regular stove with 2 burners. IF you need a third burner, it’s usually for ‘simmer’ or warming something and any small stove will do.

  9. ossqss says:

    Thank you all for the feedback and coaching! It is appreciated and welcome. After dealing with Irma last year, I had to think about gaps in my planning. On the same subject, I would offer some experience based observation on disaster recovery.

    I will do so tomorrow as it is very late here, but here is a sampler. Ridgid 18v cordless tools and batteries and compatible accessory products (most with lifetime warranty, in particular the batteries), inverters, and multiple size generators for different tasks. It is quite eye opening what a Hurricane can teach you and your neighborhood about needs!

  10. Larry Ledwick says:

    Looking forward to your observations! Each experience teaches lessons if you are willing to learn.

  11. E.M.Smith says:

    “Coleman fuel is a mixture of cyclohexane, nonane, octane, heptane, and pentane.(from wiki)”

    That’s basically the 5-9 carbon long gasoline ‘cut’ run through a hyrdotreater so all the bonds are saturated. Winter gasoline in the frozen areas can have a bit of 4 carbon butane and in august in Phoenix you can get some 10 to 12 long bits; but usually gasoline is the 5 to 9 range, kerosene 10-16 (or so) and Diesel 8 to 21 (so #1 Diesel overlaps with kerosene)

    Prior to lots of EPA rulings on gasoline, high octane gasoline had a lot of cyclic aromatics (benzene, xylene, toluene – basically benzene rings with one or more methyl groups stuck on it). Extremely good ‘octane’ rating ( like 110 ) but prone to making soot at rich mixtures full throttle and some carcinogenic properties, so now mostly banned.

    Branched chains are better gasoline than straight chains and shorter chains are better than longer (for anti-knock properties).

    The stuff in gasoline that boils in the gasoline temperature range is a mix of all sorts of cyclic, straight chain, and branched compounds with saturated (full of hydrogen) or unsaturated (multiple bonds between the same two carbons) carbon chains.

    Take that ‘cut’ and running over a catalyst with high temperature, pressure, and excess hydrogen, the hydrogen gets added to the multiple bonds “saturating” them. A saturated chain is much less reactive than an unsaturated one, so much more stable in storage. As there is no need for easy starting of your engine at 20 below zero (it’s just a stove, after all) none of the 4 carbon “cut” goes into Coleman fuel. Similarly, as you want it to evaporate and burn well and it won’t be subject to carburetor vapor lock in Phoenix in August, there’s no need to include the heavier 10 and up chains that would be harder to vaporize in the generator of the stove. Finally, taking the aromatic benzine and hydrotreating it saturates the ring and makes it cyclo-hexane.

    So that’s the chemistry of it that’s summed up in that list of chemical names in white gas / coleman fuel. “Middle cut gasoline” saturated in a catalytic hydrotreater.

    FWIW, I doubt they go to the trouble of removing branched chain gasoline molecules and think the wiki is just being “economical” in their precision. It is possible to run things through reformers and make it all straight chains, but that’s a lot of work for not much gain.The difference between 2-methyl-butane (or iso-pentane) and n-pentane (normal or straight) is “not much”. 28 C boiling point for the iso and 36 C for the n-pentane. I suspect the wiki is just collapsing all that into “pentane”. Similarly, I suspect that with cyclohexane called out, someone forgot to include n-hexane and just figured it was “the same”… even though it isn’t.

    But the reality is it doesn’t really matter. As long as it’s all saturated bonds it is relatively inactive chemically, and as long as the boiling range is where you want it, you’re good to go.

  12. Pingback: Open Discussion of Aw Shit Lessons Learned | Musings from the Chiefio

  13. Graeme No.# says:

    I hope there isn’t too much n-hexane in your fuel; it is subject to a carcinogen rating. Given the regulations in Calfornia I hope they did remove it.

  14. jim2 says:

    I’ve viewed a few videos on stoves and such and have one observation. When different fuels are used in the simpler stoves, the higher molecular weight fuels tend to burn orange, meaning incomplete combustion. An improvement on the simple stoves that use heat from the flame to vaporize the fuel would be a means to control the air in the fuel mixture. The picture in my head is of a Bunsen burner. It has adjustable air vents at the bottom. It would just be a matter of enclosing the primary burner pipe in a larger vertical pipe with the adjustable vents, but the devil would be in the details.

  15. E.M.Smith says:

    Yes, any yellow or orange comes from a Carbon atom dropping an energy level emitting a photon. To do that, you must have a carbon unadorned by oxygen at high energy. So combustion must have partially proceeded but not enough to oxidize the carbon. With methanol, the OH oxygen is already single bonded to the carbon so you can’t get carbon unadorned by an oxygen.

    The longer the carbon chain, the more likely you will have a carbon, stripped of the hydrogens, but not yet oxidized. You must have enough oxygen present to burn all the hydrogens AND attach to the carbons to get a blue flame and it must be well enough mixed into the hydrocarbon that no pockets of the gas are under oxidized.

    So heavier hydrocarbons are pressurized and sent through some kind of orifice causing turbulent mixing with air, then the mix goes though a burner head that prevents the flame from propagating back up stream to the mixer.

    For the Trangia / Esbit type spirit stoves, the fuel is evaporated inside a gap in the walls and the slight pressure that generates makes the circle of little flames around the perimeter increasing the surface area of flame (and power) of the stove. This slightly increases the oxygen mixing, but not enough for heavier alcohols or alkanes.

    The Bunsen burner was designed to use light alkanes (methane, ethane, propane) in rough mix natural gas. So has a highly variable air mix port to let you use variable gas AND make anything from a reducing to an oxidizing flame (it is for chemistry after all…)

    Now your idea of adding an oxygen mixing device to the alcohol stove is very interesting, but as you said, the devil in the details… Usually it is done via pressurizing the tank. The pumps on Coleman White Gas stoves or the natural pressure of liquid propane / butane. The Optimus old style gasoline stoves would burn some fuel to self pressurize via heating the tank (thus the very small tank sizes or it would take forever to prime…). In theory one could put a variable air port on such a stove and use it with alcohols. That ups the complexity from the simple alcohol vaporizers, though. You are back in the land of jets, air mixers, valves, pressure tanks, etc. etc.

    So is there a way to keep the simple form of the alcohol vaporizer and add air mixing?

    Maybe. First you need something to hold the flame away from the fuel ports around the top. So a ring of burner mesh / metal. Then you need an air delivery that also prevents flame getting up that way. I’d make it a 3rd wall layer, open at the bottom of the stove well away from priming flames. At that point the initial lighting would be the open pool of alcohol in the center cup. That would warm the stove walls leading to vaporization inside the walls. That vapor would exit the perimeter holes into an air space at the top of the outer air ring-wall and entrain air then impinge on the burner ring and present to the outside for burning. You would need a bit of flame path from the center to the burner perimeter (as on many old gas stoves where the pilot light had a row of gas holes to the burner to deliver the light) but that’s easy.

    The only potential problem I see is that at first start up gas generation, the air column is NOT hot in the outer shell so you don’t have convection moving it upward, and the gas being injected into the space at the top, toward the burner, is not very hot nor very fast but it is heavy being high molecular weight. It might (emphasis on I don’t know…) be heavy enough to sink in the outer air wall space instead of mixing and exiting the burner ring. It might be necessary to have a way of occluding the air intake at the bottom until the stove is hot enough to assure upward air flow. It also might be helpful to make the stove a bit taller and skinnier. Some experimentation required.

    I could see a Bunson Burner like ring around the outside bottom to both adjust the air mix and shut off air flow during start-up. Fabrication would be a bit more tricky as you would have 3 nested walls, a burner head ring to press on, and a complicated bottom ring that must seal well enough to prevent reverse air flow at start up, stay cool enough to adjust in operation, and be easy to move to adjust the mixing. Ought to be doable…

    Essentially it would be a very low pressure self pressurizing Bunsen Burner that is started by the central cup as a priming heat but with a larger ring like burner head.

    Don’t know how well it would work as the fuel in the center cup gets low reducing pressure in the walls, and there would also be the problem of the center cup vapors not being well mixed with air so at some alcohol chain length it will not be well mixed enough. IF you enclose that space, it will over pressurize and pump liquid out the ring holes. If you don’t enclose it, too much unmixed hydrocarbon enters the flame area. I suspect that the ratio of height to diameter of the pool would give you some control of the vaporization … but it’s a worry point.

  16. jim2 says:

    I just had another thought that might make oxygenation simpler. I have a micro torch that has one fitting that consists of a wire mesh. The fuel is basically oxidized at the mesh, which is red hot. Basiclly, this fitting is used as a heat gun.

    But a mesh wider than the stream of fuel gas could also spread the fuel, forcing it to contact the air around the mesh, thus enhancing the supply of oxygen. Some spreader might be necessary to force the fuel to cover the mesh. The radiant heat from the mesh and the hot gasses rising from it would heat a pot with greater fuel efficiency.

  17. E.M.Smith says:

    @Graham No.3:

    IIRC both benzene and propane also are believed to be carcinogens. The implication being that lots of HC molecules ought not be eaten… But they can’t be very strong carcinogens, since I’ve been exposed to gasoline fumes for decades before any such worries showed up, have breathed propane on and off for decades (about 8 going camping is the first I remember a tank venting while being filled and getting a snoot full) and in my Chemistry classes we used Benzene to wash our labware (organic chem). Nothing like hand washing your dishes in benzene to get a good exposure.

    Yet here I am…

    I don’t doubt there’s some carcinogenic property to the alkanes and related HC compounds, but it can’t be very strong or few gas station attendants, car / truck / train / ship mechanics and repair personnel, nor oil workers would survive…

  18. jim2 says:

    For the metal mesh idea, you wouldn’t want a mesh with too much area, otherwise it will cool the combustion zone. One could have a variety of mesh diameters that would simply sit on top of or around the, let’s say, single loop stove made with the jam jar. So far a beefier carbon fuel like gasoline, one could have a larger area mesh. For methanol or ethanol, a smaller mesh.

    And each mesh assembly would incorporate gas diverters to spread the fuel gas under the mesh.

  19. jim2 says:

    Benzene is (or was maybe) a cheap, multipurpose solvent around the lab. I’ve inhaled and absorbed a lot of it in the lab. And before I was a chemist, washed the lead paint off my hands with leaded gasoline that contained benzene. It’s a wonder I’ve lasted this long without government protection!!!

    It’s hard to see how a non-polar, small molecule like propane would be able to cause cancer, but one never knows I guess.

  20. E.M.Smith says:

    If one turns the empty tuna can upside down (intact bottom up) it is a very nice platform on which to sit a Trangia / Esbit alcohol burner. Even has a bit of ‘lip’ around the edge to reduce slip issues.

    Just made a cup of coffee that way.

    Now there IS something of a spill and cause fire issue in that the open cup of flaming alcohol can be knocked off, and applying the “snuffer” is a bit tricky as there’s a grate above and not much room from the side (but it worked). The flame is hot enough it basically trashes the sort-a chrome finish on the pot support wires (Sterno doesn’t make them nearly so hot).

    Still, this means you can have a large effective pot support that also works with small cups, in a stove combination that can burn any / all of: Gel fuels, Sterno cans, methanol, etthanol, propanol, actone, solid fuel tablets (hexamine and related); and while I’ve not tested it yet, wood twigs, wood pellets, and charcoal.

    The addition of an empty tuna can moves the Sterno Stove from my next to least favorite (the hexamine is my least favorite as it makes noxious smelling fumes, soots pots, and leaves a residue on the burn surface that’s annoying) to my next to most favorite (pressurized gas is my favorite as it’s just so reliable, clean and easy – propane or butane).

    As Sterno keeps well in storage, having this combo in my Car Bag makes a lot more sense. Simple and easy for the spouse to use, flexible in fuel use if it’s me off in the middle of nowhere.

    Glycol fuels typically burn in what looks like a Sterno can with a fat wick. One of those will work in this stove as well, or one could make an expedient wick from some cotton cloth twisted into cord and spiraled in the tuna can bottom (glycol not covering it all the way). This matters as both propylene glycol and ethylene glycol are used as antifreeze. It is likely a jug of cheapest anti-freeze in the car would be a relatively safe and usable fuel too.

    Golly! So much benefit from so simple a thing as an empty tuna can.

    @Jim2:

    Propane was suspected some decades back. Just checked the list at:
    https://www.cancer.org/cancer/cancer-causes/general-info/known-and-probable-human-carcinogens.html

    and propane is not on it, only substituted propanes like with a bromine stuck on it. So I’d guess they tested and found it OK somewhere between then and now.

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