Primus 96, large yellow flame after double priming

Discussion in 'Fettling Forum' started by Sternenlicht, Jul 24, 2021.

  1. Sternenlicht

    Sternenlicht Subscriber

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    Dear all,

    after some time of absence I am back with a question to the only Primus 96 I have:

    It needs at least two times, sometimes more than two, of priming with ethanol to burn with a nice blue flame. As I got that stove the jet hole was little too large, the flame was a little yellow, but only one time priming was needed. I peened the jet hole down to ~0.2mm and changed the inner mesh. From that on, it needs much more time for priming. In between I put in the original mesh, but it did not change anymore.

    What did I wrong?

    Ciao, Bastian

    Primus_96.jpg
     
  2. hikerduane

    hikerduane Subscriber

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    New crack? I've never had my peened lipsticks come close to what you show, even before I peened them tighter. Look closely at the tip maybe. I had to "push" out a crushed tip one time and used too large a diameter bolt to do it, it burned real yellow like you show, so had to silver solder the damage, I am unable to silbraze.
    Duane
     
  3. IvanN

    IvanN United States Subscriber

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    If the only changes were peening the jet and the mesh, I suspect the mesh. I’m not a regular 96 user, certainly not an expert, but the only time I’ve had a flame like that it was a mesh issue. I had to readjust it several times to get the fuel to vaporize properly, once I did it was back to normal.
    Ivan
     
  4. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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  5. hikerduane

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    Most cases I'm sure. I've even fired up one of my 96's w/o putting the mesh back in after cleaning, ran fine, did not run too long, so don't know if it would have kept going. I've never had issues with depth the mesh was placed in, although I try to poke it all the way up. I'd think the flame would turn yellowish if poor thermal feedback thru all the parts after initial preheat.
    Duane
     
  6. Twoberth

    Twoberth United Kingdom Subscriber

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    That flame looks like a large amount of kerosene is escaping, far more than I would expect to escape from a 0.2mm hole, even without the mesh.

    Sometimes when peening the outside around the jet hole (with a mandrel inside the lipstick), the lipstick end can crack. Check to make sure the tip area around the jet hole is still sound.
     
  7. Sternenlicht

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    Thank you all for the reply and the interesting links. I checked the lipstick, no cracks! I also tried some different mesh rolls, bug no success. But I will keep on trying!
    Ciao, Bastian

    IMG_20210725_141417.jpg
     
  8. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    Peening can certainly result in cracks, maybe one not visible.

    Granted, THIS example of a crack produced by peening was visible!

    AD89BFE6-1FF5-4197-988B-0AD6A36D3AD1.jpeg

    John
     
  9. hikerduane

    hikerduane Subscriber

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    I think I would take the stove outside and pump it up to see where the excess fuel is coming from. Should only have the single stream out of the orifice. Correct fuel?
    Duane
     
  10. Sternenlicht

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    I'm using the same fuel as in my other kerosene stoves, I can exclude that.

    Thanks for the good photograph! Mine are much worse, but I hope you can see the quality of the surface:

    IMG_20210725_220037.jpg IMG_20210725_220101.jpg

    Absolutely no cracks! I peened the hole and drilled it with a 0.2mm drill. That was closest to 0.23mm I could reach.

    But I will pump it tomorow!

    Ciao, Bastian
     
  11. Sternenlicht

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    So, my stove is working again. I checked the stream out of the orifice, looks good. Then I put in the fine brass mesh which was in before and primed one time, the stove runs great!
    The only thing I changed was to loose the mesh roll a bit, nothing more... so I think it really was a matter of the mesh.

    Thanks fir the great help!

    Ciao, Bastian

    IMG_20210726_211300.jpg
     
  12. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    Hi @Sternenlicht . I am pleased that you have your Primus No.96 operating well again.
    Best Regards,
    Kerophile.
     
  13. IvanN

    IvanN United States Subscriber

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    Glad you got it, and thanks for posting the result. It’s useful to learn what to he final fix was.
    Ivan
     
  14. Sternenlicht

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  15. Sternenlicht

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    Hey again,
    I thought everything is fine, but today I tried to fire it at little wind (with good wind shield) and I had the same problems again. Directly after, I fired my Ahno lipstick burner, after a short priming it burned perfectly.
    What are the differences between both stoves?
    The Ahno is larger, so I would assume it needs longer priming. The inner mesh is similar. But maybe its the fact, that the burner bell of the Ahno sits quite narrow on the lipstick. The bell of the 96 sits very wobbly on the lipstick. So maybe the thermal conductivity during priming between bell and lipstick is not that good?!

    Ciao, Bastian

    IMG_20210728_121650.jpg
     
  16. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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  17. hikerduane

    hikerduane Subscriber

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    You got it, I've had to shim some of my bells, I even have a bell that the PO cut the bell and squeezed it tighter. Issues are manifested when outside or in a breeze, even with wind protection.
    Duane
     
  18. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    What Duane said.

    A shim works.

    F0624C37-101C-4CD4-8D7E-CBC5167C1C95.jpeg DFDF0025-D5A9-4559-BED1-6C6FFAE5B27C.jpeg

    A more elegant solution is to make a saw cut in the mounting boss, squeeze it to match the taper of the vapouriser …

    C007AE39-173C-4EBE-8BDF-0F4E5CC409F8.jpeg 20D39516-818B-49E8-BCAB-EA2A02AF4585.jpeg

    … and silbraze the join.

    03C9367B-7A8C-449E-8D65-989367700451.jpeg 23300119-F9BA-47A3-8233-F896A59A1F13.jpeg
     
  19. Sternenlicht

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    @kerophile @hikerduane @presscall
    Thanks again for your reply, sometimes it needs some time to reach the aim. I will try the shim, but I think cut and silbraze is the proper way...

    Ciao, Bastian
     
  20. Sternenlicht

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    It's done!
    I cut and silbrazed the burner bell and its running better then ever! A short prime and it is roaring like a beast!

    Thanks for all the help, the interesting links and the good advice regarding the method and the tools! @hikerduane @presscall @kerophile
    @IvanN

    Ciao, Bastian

    IMG_20210729_185515.jpg
    Cutting with a fine saw

    IMG_20210729_185643.jpg
    Pressing

    IMG_20210729_185717.jpg
    Cleaning

    IMG_20210729_190224.jpg
    Preheating with a propane torch to save MAPP gas, then silbrazing with MAPP

    IMG_20210729_190545.jpg
    Directly after

    IMG_20210729_192344.jpg
    Cleaning again

    IMG_20210729_192705.jpg
    The result

    IMG_20210729_193001.jpg
    First priming

    IMG_20210729_193124.jpg
    Nice flame, with a little large orifice it would be more powerful...

    IMG_20210729_190640.jpg
    The tool setup
     
    Last edited: Jul 29, 2021