Optimus International - Spirit Fuel Problem Solving

Discussion in 'Stove Forum' started by pipenfly, Nov 28, 2021.

  1. pipenfly

    pipenfly Subscriber

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    Please excuse me. I am not sure if I should call this fuel spirit or meths.

    My story begins with an attempt to burn alky in an Optimus International I recently acquired. This stove came to me with a bag of spares. Spirit jet and two air restrictor tubes were included in the package. I fitted the sprit jet, put one of the air restrictors in the burner, filled the tank with 90% or better ethanol, pumped, primed, added fire and ended up with this..

    20211128_035428.jpg
    ... a poor excuse for a cooking flame.
    I let the stove cool and then added another one of the air restrictor tubes into the throat of the burner. The second attempt was just as pathetic as the first. I flipped the double sided restictor tube around and got no better result burning alcohol from any of the three included restrictor tubes.

    I noticed that the holes on the tubes are drilled very low. When installed, the openings sat far below the collar in which the jet nipple screws into.

    20211128_040430.jpg

    The middle tube and the tube on the right are the restrictors that came with the stove. The brass tube on the left is one I made out of brass tube purchased from a hardware store. I measured and drilled my holes 1 cm up from the end of the tube. Now the holes sit in line with the nipple so air can get to where it is supposed to.

    20211128_011159.jpg

    Here it is burning alky after some trial and error figuring out the proper drill bit size to use for the holes.

    20211127_231804.jpg

    When I made the fuel / air mix any more lean, my cap would begin to glow red while simmering. The orange flame seemed to be the best I could do in order to balance heat output for cooking while running a bit rich so to have some "raw" fuel cooling the burner. Therefore, preserving my 111 cap.

    I learned a lot from reading through this forum. I thank you all for helping me rescue some of these stoves :)
     
  2. snwcmpr

    snwcmpr SotM Winner Subscriber

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    Does the stove run blue with other fuels, and the correct jet?
     
  3. itchy

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    Burning alcohol in these does seem to require a bit of trial and error. Finding the right combination of restrictor and fuel seems to be the key. So you are not alone.

    Q about the 90% ethanol. What is the other 10%?

    If it could be water you may want to try some denatured alcohol (or what ever it is called where you are) where there should be no water in a fresh container. You might even try a couple different brands if you find from their MSDS that the composition is different.
     
  4. pipenfly

    pipenfly Subscriber

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    The stove does run well on other fuels with the correct size jet and, of course, minus any air restrictors. I did made sure to get it sorted out and running well on kerosene and then white gas before experimenting with alcohol.

    The fuel I am using is Kleen Strip Denatured Alcohol Clean Burning Fuel, as per the label on the container. I believe the other 10% is the poison "they" add in order to denature it.

    Also, the stove has a steel burner cap and steel inner cap. Both parts react to a magnet. I think this is another one of the two Norwegian military 111's I ended up with. This stove was purchased in Norway and sent to me.
    I did notice that the steel cap did glow orange on other fuels. Flame pattern and heat output were otherwise good. Putting more pressure into the tank while running kero or white gas mitigated the orange glow of the burner cap on these fuels.
     
  5. Scrambler

    Scrambler Australia Subscriber

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    Most of the 10% will be water. If you have methanol in your denatured alcohol this may be present, but I couldn't tell you what % they would use. Locally we don't have any.

    At one time I had reason to acquire 'pure' ethanol at work. That was 99% and stored in sealed glass tubes. I was advised the alcohol would absorb further atmospheric humidity. In short, nothing in the stove world is over 95% ethanol, unavoidably.
     
  6. pipenfly

    pipenfly Subscriber

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    @Scrambler
    I am not a chemist and almost everything I've learned about ethanol has been a result of burning it as fuel (either pressurized or non pressurized) in camp stoves.
    I understand that it naturally absorbs water from the air. Your sealed glass tubes of 99% certainly make sense. I suppose that as soon as the tubes are opened and exposed to air in a non controlled environment, the percentage of ethanol would decrease due to evaporation and its natural tendency to take water from the air.


    I would think that even plain old hardware store denatured alcohol would behave in the same way. To me, this makes it interesting as a stove fuel because there is a lot going on in the tank of a camp stove when it is being used as a fuel. Especially pressurized fuel. Pressure change, heat, opening and closing the tank lid must have some sort of affect on evaporation and water content. Ultimately, would these inevitable changes have some affect on combustion and heat efficiency? These are the types of questions that go on in my mind when fettling a stove. Maybe this is my Asperger Syndrome talking but I may have to begin taking notes on all this.

    I do plan on burning plain hardware store denatured in this stove. I am wondering if I will have to make another air restrictor with different sized holes to accommodate the fuel/ air mix of the hardware store denatured.

    I love these stoves. They keep my mind busy and out of trouble :D
     
  7. hikerduane

    hikerduane Subscriber

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    I've only been able to get the green label denatured alcohol to burn correctly in my alky, pressurized stoves, but the issue only seems to be the flame blowing itself out.
    Duane
     
  8. itchy

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    @pipenfly

    Kleen strip should have minimal water before you opened it. Its a crap shoot as to what the denaturant might be. Worth trying another brand when you find some. Some of the brands of denatured alcohol sold in the US have as much as 50% methanol in them. That can be good or bad.
     
  9. pipenfly

    pipenfly Subscriber

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    Kleen Strip with the green label. This is exactly what I am using. I read somewhere that the stuff is 90% ethanol or better when the container is first opened. I have good luck with this brand in my Radius 43 when it is set up for alcohol.
    Is anyone running a silent 111 with a steel outer burner cap on alcohol with good results?
    I'd love to get this stove sorted out and running well with the three fuel option and then put it in a Trangia set up. The big picture with this thing is to use the burner in a triple fuel Kap Arctic kind of clone.
     
  10. snwcmpr

    snwcmpr SotM Winner Subscriber

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    Kleen Strip with the green label
    SDS link
    https://production-s3.wmbarrhub.com/assets/559/f5e80de1-8a6b-424b-ae6a-26f9c39b691b.pdf

    %%%%%%%%%%%%

    Kleen Strip Denatured Alcohol
    SDS link
    https://production-s3.wmbarrhub.com/assets/sds/1625_6_Klean_Strip_Denatured_Alcohol_EN.pdf
     
  11. itchy

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    Good information there @snwc

    Is is just me or does the green-label stuff appears to be less "green". Must be the ethanol to methanol ratio.

    @pipenfly

    Just curious. With your current set up, do you know if the bottom of the pot gets sooty? If you have not checked, but a pot of cold water on it and bring it to a boil. If your suspicions about the steel caps are correct the color may not reflect a rich fuel mixture.
     
  12. snwcmpr

    snwcmpr SotM Winner Subscriber

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    Yes, I thought the same thing.
    Beancounter & marketing department version of green. It is greener though..... lol. And costs more.

    My Regal Flame fireplace fuel was $5 per qt free shipping.
     
  13. hikerduane

    hikerduane Subscriber

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    I had two of my pressurized alky stoves refuse to stay lit with "normal" denatured alcohol, Keith @Majicwrench, said he had no issue. I was trying to use my Optimus 45A and I think my Homestrand Mariner stove, seems it was those two, I have since sold my Homestrand. I had even located a set of new burner caps for my 45A, thinking the remaining rust on the originals was hindering correct burning. Maybe my 3800' elevation effected performance.
    Funny though, while camping in a windy location in Nevada, the only stoves I could keep lit were my alcohol stoves.
    Duane
     
  14. theyellowdog

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    I haven't ever tried this so I am probably wrong. I thought the restrictors help you burn alcohol with the standard jet. My new 111t came with restrictor pipes but not with a alky jet.
     
  15. pipenfly

    pipenfly Subscriber

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    Thank you all for the very helpful information. I will have to go a bit deeper into this stove. I read in another recent thread that the boil time on a silent 111 is about 4 minutes with the stove running on white gas. When I have this thing set up for white gas, it is boiling a liter of water in about eight to nine minutes. I am thinking there must be something blocking fuel flow. I'm going back to the beginning on this stove for a more thorough step by step.
     
  16. snwcmpr

    snwcmpr SotM Winner Subscriber

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    I thought the alcohol jet was .04 inch.