Drehrapid fixing!

Discussion in 'Pressure Lamp Discussion Forum' started by Adolfo, Sep 15, 2025.

  1. Adolfo

    Adolfo Chile Subscriber

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    Hello everyone,

    First of all I would like to apologise if say something wrong.I hope I don't break any rule in this forum but I do need some help with a couple of petromax drehrapid from the 30's .
    If anyone-more skillful than me indeed- can give me a hand with those capilar pipes, please let me know vía P.M

    Thanks in advance.
     
  2. WimVe

    WimVe Subscriber

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    What information do you need?
    Answers may help more people so keep it public, please.
     
  3. Adolfo

    Adolfo Chile Subscriber

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    Hello Winve,

    I was wondering about the threads and metric in this tiny pipe. Are there modern capilar pipes as tiny as this one? . Is there a store where I might get it?
     
  4. MYN

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    @Adolfo
    Which Petromax drehrapid are you referring to?
    Is it this:
    Screenshot_20250916_212737_Adobe Acrobat.jpg
    Or this?:
    Screenshot_20250916_213220_Adobe Acrobat.jpg

    Which parts are your concerns?
    I don't quite understand what you meant by 'capilar' pipes.
    Do you mean capillary pipe or the fuel pick-up pipe/tube?
    Small diametre brass tubes are available from example K&S Metals.
    What about the threads?
     
  5. Adolfo

    Adolfo Chile Subscriber

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    Hello MYN

    Thanks for your información. The one I have is the first picture, 645164. I mean capilar tube to the tiny pipe that reaches the tank.
    I'm trying to figure out how to fix one of these rapids. That's why I ask about threads, pipe providers and metric. I'm learning actually.
    The pipe's thread from the picture atacched is isn't in good condition.
     

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  6. MYN

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    That is a very small pipe and very fine thread at the upper end.
    I do not know the pipe's diametre or thread size/type.
    Petromax usually use metric but I'm not too sure about the older ones.
    You can measure the diameter using a digital vernier caliper.
    A thread gauge can determine the size and type whether metric, UNF, Whitworth, BSF or others.
     
  7. Adolfo

    Adolfo Chile Subscriber

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    It's a very fragile one. I will measure the diameter one of these days. The pipe I have has no threads left. If someone here can provide it, that will be great. At first glance, the pipe's material is brass. Am I right?. By the way the term is capillary, you are right. I misspelt that.
     
  8. MYN

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    From my vague recollections, I guess the tube might be somewhere between 2 to 3mm in diametre?
    Maybe between M2.0...M3.0 × ??-pitch if it is really metric. Could be standard coarse or fine pitch. Hopefully it is not custom-sized.
    Dies are available for standard sizes.
     
  9. WimVe

    WimVe Subscriber

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    Adolfo,
    Is there still a piece of tube stuck in the main body?
    The thread is very fine and I have no measurements of it. Most of those tube are more or less corroded so if they work don't remove it.
    It is very easy to twist the tube while trying to get it out of the main body.
    You may try, I have no idea how much is left or in what condition it is, to solder the remaining part in place after the broken part is removed from the main body part. Or make a sleeve which hold the two parts together.
     
  10. Adolfo

    Adolfo Chile Subscriber

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    Hello Winve,
    There is no section of the tube stuck in the rapid body at first glance. The threads from the pipe I attached in my picture and the upper tube section is not in good shape either.
    This is an old part (whole part) that I'm trying to fix (recover). When a section of the pippe is still there, you can solder a modern one as you said.

    Thanks
     
  11. Sellig33

    Sellig33 France Subscriber

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    Hi @Adolfo ,
    The Rapid is very energy-intensive for pressure, personally I prefer to use the gentle method with the spirit cup, less stressful for the mantle, and so much more pleasant to use.
    On my lamps, when the Rapid is not functional, I secure it waterproof, and I always use the spirit cup for lighting.

    Gilles
     
  12. MYN

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    If you still intend to repair it, perhaps you can first measure the diametre of the capillary tube.
    Then find some threaded fasteners having the nearest diametres and gently try whether they would screw into the threaded hole:-
    Screenshot_20250919_082527_Samsung Internet.jpg

    Do not use force. I'm not sure if the threads in the hole are also worn or damaged as well.
    If the thread is metric, you also need to check whether they are coarse or fine.

    Thread sizes and pitches can be checked with the standard ones here:
    International Thread Standards
     
  13. MYN

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    Or even better, if you happen to have any spare Petromax drehrapids (old or modern). Then you can unscrew the capillary tube to check the (size × pitch) with more precision and certainty.
     
  14. Adolfo

    Adolfo Chile Subscriber

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    Thank you all for your tips and advice.
     
  15. WimVe

    WimVe Subscriber

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    Why do you write that the tube is in bad shape?
    Given the fact that it isn't broken: clean and re use it.
     
  16. Adolfo

    Adolfo Chile Subscriber

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    There is slightly broken (crack/fissure) and it has almost no threads. That's why I ask about metrics and some other technical info. How do you normally call the tools for carving threads on that tube?
     
  17. MYN

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