What is the ultimate cause of "underburning"?? My 111 Hiker was re-built by A&H for alcohol-only burning; I never use any other type of fuel. The jet, or "nipple" is unusual, but I never had to use a restrictor sleeve with it- it burned so clean I could use it inside my tent while winter camping/backcountry skiing. In the Spring of 2013, this fact saved my life. Then, the sudden "underburning" malfunction very nearly killed me, and would have, had I not been rescued. The symptoms were the typical orange-red burner cap and the overpowering stench of metal oxides. Once I got it dis-assembled, I found a damaged inner burner cap, but so far nothing else. It seems like it HAS to be a blockage problem somewhere! The fuel tank, filter, needle, jet and all other parts were just fine; with alcohol there is little of the typical carbon build-up that might obviously cause a blockage...... I have to determine what exactly is happening here, my life literally depends on it. No other stove/fuel combination does what my 111 will do for my "Arctic" stuff.
Hi, Difficult question to answer as there are many variables. 1. The simple answer is the under-burn is caused by the fuel/air mixture under the cap being ignited. The burner then behaves as a roarer burner, but the silent caps are in the way and they get cooked, and can melt. 2. The easiest way to get under-burner is to pressurise the tank whilst the priming fuel is still burning. Fuel exiting the jet mixes with air and is ignited under the silent caps. 3. If you have have delayed igniting the fuel mixture (say with a match or igniter applied to the outside of the cap) until the priming fuel is fully extinguished, the flame should establish itself and stay on the outside of the silent cap. 4. If, later, the pressure under the cap reduces below a critical level, the flame speed can exceed the speed of the flammable mixture coming out of the multiple apertures in the outer cap, and the flame "jumps" under the cap. You then have under-burn. 5. If the inner cap has been omitted when the burner was assembled this can also cause flow instability in the flammable mixture and result in under-burn. 6. If the outer cap is not properly seated on top of the burner, the resulting gap allows leakage of fuel vapour and the flame again can "jump" under the caps. 7. Side-winds and draughts can cause instability in gas flow through the burner and result in under-burn. 8. Cleanliness of the inner and outer caps is very important. These caps get very hot in operation, to the extent that carbon or rust particles can "glow" and ignite the fuel mixture under the cap. You then have under-burn. So many possibilities! Best Regards, Kerophile.
Hello Rattinox, I hope you do get it sorted out. Regrettably I'm not part of your solution but here's input that may stir thought in those more alcohol knowledgable. Generally: "Life depends on it"? is extreme (no pressure guys!). I wonder if there is something about the bigger picture of these outings that might be reconsidered? RE 111 to clarify A&H rebuilt it w/an unusual jet, the stove was working after that for some time. Then suddenly this underburn occurred. You suspect blockage but of the items George mentioned, "reduced pressure" (vs blockage) IS something that can be sudden if a failure occurred and it leaks. Blockage typically develops over time, no? unless you have debris in fuel? IF it's debris it is easier fix than all-coked-up? I would be interested to hear if others are pleased w/the removal of orig Optimus parts and the use of this unusual alcohol jet? (and why?). Rattinox might you share your experience re A&H's service and did stove performance meet expectation?, or better? That said, it was working and you are an alcohol- only user so the A&H fix, imo, seems a least likely source of current trouble. fwiw and a reason I posted, I have an unfettled 111 the inner cap looks very much like yours, half dozen other inner caps I have are all bare metal, the 111 looks like hi-heat silver paint flaking off in chunks. Is that how it looked when A&H returned it, do you think they painted the inner cap? thx omc
Good Morning, All, I had to give long thought to whether I should toss my two 'pence into this thread, but decided to go ahead and post my thoughts. I have had some of those different Meths jets for a few years, and have tested them on different types of stoves, to see how they work. I hate to say it, but at least in my experience, they do not work well at all. I compared it to a real Meths jet from Optimus and from SVEA, and a variety of proper air restrictors, from Optimus, and SVEA, and found that all of the older systems out-performed the new high rise/restrictor jet, hands down!! I think that those newer jets "may" work in certain special Meths burners, but if so, I have not found that burner, so far. They do not work well at all in regular burners, like the 111T used by the OP. I'll continue to stick to the old tried and true 111T burners, or SVEA M1915 burners, with the proper jets for either multifuel, Coleman Fuel, kerosene, or Meths, and any necessary restrictors. Just my two 'pence..... It's very possible that the mileage of others will vary, and if so, I sincerely hope they will share that info here. Take care, and God bless! Every Good Wish, Doc
I know you are using alcohol, but did you happen to change brands about the time you noticed the difference? Denatured alcohols come in a variety of formulations and the diffence in ratios of ingredients can vary dramatically.
I thank you all for the wisdom!! I can see some experimentation is in order!! A few things I did rule out were bad fuel, fuel contamination (water or particles), broken parts (other than blockage). Once I got the stove back from A&H, it performed flawlessly. True, fuel consumption was a bit higher, but reliability was the main consideration in low temps, anyway. I have no problem with packing a few more Sigg bottles on my sled (ahkio/pullka/whatzit). I had a fixed ritual in starting the stove which never varied, yet the malfunction took place literally in an instant. I could have missed some subtle point of technique, but I just doubt it. I knew my stove, or thought I did! You can see from the end-on pic that the aperture is a good bit larger than what I remember being "normal". I haven't gaged it yet, but I'm betting it's a good .015 inches diameter. In any case, I will get started putzing with it. If I can't nail down the problem I'll just have to grit my teeth and buy a spare 111 on EBay- 'prox $150+ these days. One last thing: I suppose the inner burner ring is now useless?? If smooth fuel flow is critical, then it most certainly is!!
Hey, Rattinox, Seek out and purchase a new inner and new outer camp, preferably made by Optimus, and if you want new jet, like the one you have, I will be happy to send you a brand new one, free of charge. Let me know, if that's what you want to do. You most certainly do NOT have to buy another 111T, unless you just want to!! That burner can be fettled back to life, guaranteed, unless you have horribly mistreated it, which I very much doubt!! Take care, and God Bless! Every Good Wish, Doc
G,,day . another generous offer Doc . I agree try genuine silent caps . but it may then be worth looking at the stainless steel ones that were commented on a while ago . cheers, kerry
https://classiccampstoves.com/posts/282419 http://www.fettlebox.co.uk/stove-parts.html Best Regards, Kerophile.
Hi, here is a link to some photos of the same silent burner caps operating on an Optimus No. 48 stove that I recently restored: https://classiccampstoves.com/posts/287646 Best Regards, Kerophile.
No new info. I'm going to do plenty of testing once I get new stainless steel outer and inner burner caps. That will eliminate any problems due to the flakey burnt caps. I'm a machinist, and this problem just begs for experimentation........ I'll keep you all updated if I learn anything new, which is unlikely. All the ground has been covered, I think.
