what is the principal behind the coil burner ? has anyone tried to build one ? I thought of making one from a coleman lantern fount, but have never seen one ,other than pictures.
Umm her goes rough and ready veiw on the matter. A wick extends into each arm of the coil burner up to roughly the first bend. This wicks up fule for the tubes that are pre heated by a match and later the jet flame that hits the top of the coils. The coil heats up and vaporises the fuel to the nipple/oriface. The extra heat and pressure caused by this burning process heats the tank and fuel in the tank and the presure pushes the fuel out till a stable flame and temperature is reached. Hopefully at safe levels!!! Sort of a coil heat /verses oriface size/presuure relationship somewhere but don't ask me how to figure it out. Most tanks are apparently silver soldered togher. To withstand heat and pressure. Specially if you are dealing with petrol. Thats all I knows. Something that could go off into a screaming uncontrollable bomb if done wrong ..me thinks anyway. Good luck see you in the burns unit. Like to make one myself but still thinking... I was hoping copper would be good for a coil as you could bend it easier ..ish than brass.If it will take the use. About the same melting point and pressure I think but un sure. Bit soft and would bend easily out of shape though. Barra
Hey guys, I was a member of this forum several years ago, before the forum was updated. Drifted away about that time. Back then I built a little coil burner stove I call the Pocket Rocket. Yes, that name's been taken, but hey, what can a guy do. This is a proof of concept stove, and to keep the risks down, I kept it small. The whole stove is about 6" tall, 2" diameter, with the legs folded in. It burns for about 10 minutes on a tank, long enough to boil about 3 cups of water. I take it with me for a lark on dayhikes for some hot chocolate on the way. Not a tea drinker, I. This is a compilation of 2 emails I sent to a couple of forum members back then. I'll get a couple photos for ya hopefully tomorrow. First is a brief summary of the stove, and second is a how-to. NOT RESPONSIBLE, NOT RESPONSIBLE, NOT RESPONSIBLE!!! Jason Summary: It's constructed using a 1.5" copper pipe cap for the fount. The bottom of it is another 1.5" cap with the walls cut off leaving only the round top. The coil is 3/16" copper tubing, as used in auto fuel lines with a 0.3mm orfice. The coil diameter is such that it fits within the 1" pipe cap I used to make a funnel. It is self pressurizing, petrol fuelled. All the soldering is done with silver solder for thermal resistance (melts at about 230 C) (except the legs, which use the usual 60/40 bunk). The fill cap is a copper pipe compression fitting, complete with pricker inside for the orfice. Total weight is about 240g, fuel included. Burn times of approx. 11 minutes, 2 cups boil in about 5 minutes, 1 cup in about 3. I've never tried boiling a liter, it would be close on fuel. There is no relief valve. I've done some testing, temperature only, not pressure, with a piece of lead solder (melts at 165 C). The only points on the stove that ever get hot enough to melt it are above the bottom of the coil. The tank never seems to exceed about 60C, at which temperature the petrol should still be only under 5 or 10 pounds of pressure. The size of the orfice and the quantity of fuel keeps things from getting too excited. There is some wicking within the coil. Some small diameter oil lamp wick goes up the risers to the first bend in the coil. The coil is empty. Really, so far as construction goes, the coil is the hard part. First you gotta drill a stupid small hole. Princess Auto here in canada carries drill bits this small, and a dremel will turn 'em down to .3mm. Thus my choice of jet size. After that, you have to keep a piece of wire in the orifce while you bend the loop, or it compresses shut. Bummer. Make sure you pressure test the stove before lighting it. Lots of solder joint to leak. Don't kill yourself I ain't responsible. Howto instructions: I'll give you a couple of pointers.... the hardest thing for you to do is probably drill the jet hole in the tubing. It's .3mm in mine, and that's a hair bit too big, burns with yellow tips till it's really going. 0.25mm would be better, but my dremel chuck won't grip'em. I got the drill bits at Princess Auto, a canadian surplus/oddity of construction store. It was called a Miniture Drill Index, had sizes from 0.2mm to 2mm and cost about 10 dollars. www.princessauto.com Once the hole is drilled in the tubing (3/16" flexible copper tubing, auto parts store (canadian tire for me)), you have to bend the coil. I left the drill bit in the hole while doing this, so it wouldn't pinch shut. The second time, anyway . Start with a big loop and gradually make it shrink to avoid kinks. Maybe 3/4" inside diameter. It is important that the jet be at the bottom of the coil pointing directly up. This can take some tries. I used 3 whole feet of tubing in the attempt before I got one I liked. Cut the "legs" of the coil to the desired length. Closer heats the tank more, so not too short. Mine are about 2" long, I guess. Some small oil lamp wicks are shoved up the legs to the bottom of the coil. Any cotton yarn would work (think mop). They extend about �" from the end of the tubing into the fount. The tank is made from two 1.5" copper pipe caps. I cut the "skirt" off one, leaving a shallow saucer for the bottom of the tank. I chamfered the edges of the other (dremel or file) so the two would mate with a bit of a "lap joint" so as to increase the joint's strength. This is the joint you really don't wanna blow apart. I cut 3 holes in the pipe cap that will make the body of the tank. 2 to fit the coil ends, and one to fit the tank filler nipple. I used a tubing compression fitting to make the tank's filler neck and cap, but any threaded fitting of suitable size would work. A small threaded brass nipple and cap would work nicely too. Mine has an o-ring to ensure a good seal, and I've encorporated a pricker under the cap for the jet. That part's up to you. The legs are 3/16" solid brass rod, mounted in 1/4" copper tubing as lugs. I made and attached these a couple days after I made the burner. More in a moment on this. So now we have all the parts, unassembled. It's important that you use Silver solder for the assembly of the burner and tank. It is available from plumbing supplies stores for use in potable water systems. It has a rather higher melting point than 60/40 lead solder, making it a bit safer. It's also stronger. Make sure you use silver solder flux with it too. So anyway, insert the burner coil into the tank top holes you drilled. The legs should stop about 1/4" short of where the bottom of the fount will be. Test fit with the bottom in place before you solder. Put in the fill assembly too. Note that all mating surfaces should be sanded or the solder may not stick easily. Solder the coil and fill assembly. Allow to cool. Now solder the base of the tank on. Make sure you leave the fill cap open when soldering the bottom, to allow expanding gases to escape. You may find it easier to "tin" the surfaces to be joined, then assemble them and re-heat. I didn't do that, but it may make a neater job. After this, I tested the burner. Mine leaked a bit at he bottom of the tank after the first day, I guess flux was sealing it and dissolved. I resoldered it. The legs I atached with regular lead/tin solder, since it's lower melting point allowed me to attach them without compromising the integrity of the "real" burner solder joints. Anyway, hope this helps. Let me know how you make out, and feel free to ask any questions you might have. Happy fettling, J
Well, I got around to taking some photos... Here ya go! The Pocket Rocket Stove See the tiny jet hole? The pricker under the cap... No pricking while lit, unfortunately.... Bottom seam.... Not the neatest soldering.... Fill funnel... The Kit Folded for packing Packed up. Truely a pocket stove. Just lit... Some yellow in the flame Long exposures make the flame look cool! Burn baby Burn! Pretty blue! Not as pretty as the stove posted above, and certainly no primus, but it has a certain appeal.... Hope you enjoy, Jason
Thanks guys for all the info , I'll definately giv this one a go as soon as time permits .I can't wait to try it.
Yup, nicely done indeed! I must confess to a certain fascination for coil burners, no moving parts and a neat noise, I sometimes fire up my Handy-Camper just to listen to it Just a thought, if you added a couple more loops for better preheating, could you run kero?
Great stove that you made there! I guess all coil stoves use petrol as fuel? I have a small Primus blowtorch that also uses the same principe, but unfortunately the hole where the vapours should go out, is too big so I can't use it anymore. It worked for about 20 minutes only because there was so much "gunk" around the hole, that it had the right size, but when that burned away it stopped working as it should. Anyone know how to fix that one (or any other coilburner that has a too big "nipple")?. Anders
Got love it!!! Thanks Jason From the desciption I had a different idea of what it looked like. Cheers barra
Coil burners are petrol only, unless you add a pump. Even with extra coils, Kero isn't volatile enough to pressurize the stove. Thanks for the nice comments, all. It's one of my favorite stoves, tho I may be a bit biased, and it is, of course, pretty close to fundamentally useless. No wind resistance (should make a shield for it like the one above, I suppose). With carefully piled rocks, tho, it does work! J
There's a few ways to fix an oversized nipple. None are perfect. If the nipple's removable, do that. Thread it into a nut or something to protect the threads. Peen it on top to close up the orfice. Re-drill to the correct size. If you have the technology, braze it over and re-drill. If the nipple's not removeable, you can try to peen it closed in place, but this is more doubtful. Also, you could try to braze it in place. Hopefully you can remove it.... J
Unfortunately, on this one it is not removable, it is just a hole in the coil. But I'll see what I'll find out, maybe it is possible somehow. Thank you anyway! Anders
NZMike, you read my mind. Hmmmm, not exactly 100% true. I have a Primus 96 Kero burning stove that self pressurises with considerable success From this ... ... to this .. .. to this The tricky part might be including a priming cup into the design and keeping the jet/flame close enough to the tank to continue the pressurising process ... without any risks ? Q. How do you turn off a coil burner ?
Try replacing the Jet nipple with a motor cycle Carburator Idle jet nipple. Thay are fire resistant and small in size. Only available from Alibaba or your local motorcycle repair shop
