Pyro Patent c1912

Discussion in 'AB Pyro' started by igh371, Aug 29, 2015.

  1. igh371

    igh371 SotM Winner Subscriber

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    DSC03165.JPG

    This is one of the original pattern Pyros with the innovative combined filler and pressure pump assembly, and a modern top plate to make it usable. Patent Pyro stoves do keep surfacing, but relatively few seem to be operational, these original design examples especially seem to be viewed more often as museum piece curios.

    So what problems did we start with? First there were the disintegrated elements in the pump and NRV systems. All the bits were there, either in the bottom of the pump tube or amongst the debris inside the tank, but not all recoverable from a practical point of view:

    DSC03140.JPG DSC03141.JPG DSC03142.JPG

    The leather cup carrier was reusable, but the rod end 'nut' had no thread anymore; with a little rework of the rod end thread a modern nut had to be substituted. As can be seen from the photo even the remains of the NRV carrier took some extracting, the spring, cup and broken fragment were recovered later from the tank bottom. A replacement NRV carrier was made by butchering and then counter sinking a modern NRV to get a base fit on the pump tube end:

    DSC03144.JPG DSC03145.JPG
    The whole NRV is all tank side, the photo above just shows the first step in the modification process.

    Secondly, the burner unit was in a mess. Someone in the past had tried to solder the whole riser to burner joint, rather than just replace the washer :doh:. In the process significant damage had been done to the unique horse-shoe spirit cup. Once again the problem was one of trying to salvage as much as possible, one of the perils of dealing with irreplaceable non-standard components.

    And, thirdly, the flame spreader was missing as usual, but of course as SMolson explained in his excellent posting this is not your usual burner/spreader arrangement. Luckily, although this is a '00' size burner, some (but not all) No.1 size burner spreaders can be found to fit:

    Before - DSC03148.JPG After - DSC03149.JPG

    Finally with all of these bits and pieces dealt with, and a suitable automotive rubber 'O' ring sourced to fit the pump/filler cap joint; the first attempt at a firing up in decades [-o<:

    DSC03146.JPG

    OK, no leaks [​IMG], but a new jet might be in order ...

    DSC03161.JPG Better!

    So what do we have now:

    DSC03150.JPG DSC03152.JPG DSC03153.JPG DSC03154.JPG DSC03159.JPG

    The modern pan ring is a functional substitute for the exceptionally rare, massive, original. The relative heights of the burner and leg tops makes a ring essential.

    All in all though, a reasonably presentable and usable classic.

    DSC03147.JPG This was it in use for a coffee even mid-way through the renovation.

    Meanwhile those few old components that were not able to be actively used are being retained for posterity.
     
  2. jbf

    jbf Subscriber

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    :thumbup::thumbup::thumbup:wow
    john :clap:
     
  3. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    Hi Ian, a masterful and well documentd re-build.
    Best Regards,
    Kerophile.
     
  4. z1ulike

    z1ulike United States SotM Winner Subscriber

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    Were you able to get your Pyro going with the self pressurizing auto lighting feature? It's supposed to self pressurize during the meths preheat then auto ignite without having to do any pumping or relighting. I'm curious to know if it works.
     
  5. igh371

    igh371 SotM Winner Subscriber

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    Short answer to your question @z1ulike is 'yes'; both of my Pyro stoves will self-light just from the pre-heat alone as long as the pressure release is closed from the start. But there is a big 'BUT' to this - the self-lit flame takes so long to build up any meaningful power that scientific tests done in 1912 to evaluate Pyro's claims concluded:

    "The third claim: 'Pyro burns with an adequate and just right flame without any pumping', however, is clearly false and contradicts itself by the fact that the manufacturer also provides the Pyro with a pump. According to the investigation made by the Chemical-technical bureau, it took more than half an hour to boil 1,5 litres of water on a Pyro stove using only self-pressurizing ... The flame from an unpumped Pyro stove is only adequate if it shall keep an already boiling liquid still boiling." (my emphasis).

    The whole paper on the comparative evaluation of the Pyro stove and its makers claims is well worth a read!.
     
    Last edited: Aug 30, 2015
  6. z1ulike

    z1ulike United States SotM Winner Subscriber

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    Wow...that article debunking Pyro's puffed up claims is amazing! Still, I kind of like the self-lighting feature. I can't count the number of times I've had to pre-heat a burner twice because I got distracted and the burner cooled after the meths ran out. Then lighting a cooled burner with liquid fuel spewing out and ending up with a sooty mess. With the Pyro you can light the meths, get distracted, come back in half an hour, give it a few pumps, and Bob's your uncle Fanny's your aunt!

    By the way, it's nice to know we're not alone. There were stovies back a hundred years ago worrying about boil times!
     
  7. igh371

    igh371 SotM Winner Subscriber

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    Spot on @z1ulike - treat the Pyro system simply as a very good auto-lighter and you're on to a winner! The perfect stove to have lying around the garage ready for a brew while busy and your attention is on other jobs ...
     
  8. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    A really enjoyable thread Ian, bravo, and I admire your ingenuity and tenacity getting the old stove working.

    John
     
  9. z1ulike

    z1ulike United States SotM Winner Subscriber

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    I just purchased this PYRO but have not yet received it. As you can see the pan ring has pot supports to increase the distance between the pot and the burner. The pan ring also seems designed to capture any boil over and divert it out the three slots well away from the burner.

    Pyro.jpg
     
  10. igh371

    igh371 SotM Winner Subscriber

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    Wow @z1ulike that is one absolutely superb Pyro you've got there, looks as good as new!!! That unique pan ring really is incredibly rare, and is that the original documentation I see too!!! Well done indeed, that will make one incredible new addition to the gallery once you've got it sorted out :thumbup: Isn't it amazing the stuff that is still out there to be found!
     
  11. shagratork

    shagratork United Kingdom Moderator, R.I.P. Subscriber

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    Great stove and an absolutely amazing (rare) pan ring!
     
  12. igh371

    igh371 SotM Winner Subscriber

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    An update on the original stove in this thread. Here are the pieces of the original Pyro NRV now reassembled and restored to functionality with the help of a brass reinforcement ring and some surprisingly delicate, but not pretty, soldering. Before, after, and in comparison with the homemade temporary substitute which is now relegated to status of an emergency reserve (just in case):
    DSC03142.JPG DSC03193.JPG DSC03192.JPG
     
  13. z1ulike

    z1ulike United States SotM Winner Subscriber

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    Ingenious repair. "Pretty" is a matter of function with NRV's especially when hidden inside the tank. Well done.
     
  14. igh371

    igh371 SotM Winner Subscriber

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    Well the 'debunking' of Pyros claims commissioned by C.R.Nyberg (Svea) certainly questioned this assertion. But maybe there was more to it. Here is a time-lapse sequence of this Pyro started up and used to boil a kettle without any use of the pressure pump:

    DSC03512.JPG DSC03513.JPG DSC03514.JPG
    Pressure release closed; Methanol alight. Paraffin flame started, primer burning. Paraffin flame gaining, primer dying.
    DSC03515.JPG DSC03516.JPG DSC03518.JPG
    Primer almost out, main burner on. Main burner securely lit. Burner flame increasing, pan ring on ready for kettle.

    DSC03522.JPG
    Burn more than adequate to bring a kettle to the boil without pumping as long as not in a hurry;
    perfectly good in a garage/workshop situation.

    And what about the much vaunted exhaust combustion idea of directing the blow-off from the pressure release towards the burner flame when finishing. This was a little trickier to photograph and again the pan rest and kettle are removed for clarity:

    DSC03519.JPG

    Here is the pressure release just opened, and the exhaust gas alight
    and over-enriching the main burner flame.

    And finally the burner flame about to die, but the exhaust release still
    burning:
    DSC03520.JPG

    Needless to say these last 2 photos are within barely a second of each other. Interestingly the visibility of the exhaust burn off varies. It is most apparent when self-pressurised with a fairly full tank. At other times it will just go off with an invisible but audible 'pop'!

    And just a random thought - is it pure coincidence that both Primus and Optimus offered optional variants of their main domestic stoves with priming cups placed at the base of the riser tubes at about the same time as the Pyros were introduced?
     
    Last edited: Dec 16, 2015
  15. z1ulike

    z1ulike United States SotM Winner Subscriber

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    Thank you very much for posting those photos. I fired up my PYRO and really liked the self lighting feature. Light the priming alcohol, walk away, and forget it. The flame starts out small but increases as the tank heats up. I didn't try boiling water but I suspect having a pot on top helps direct the heat downward to the tank. I too was impressed with the way the fumes burn off when the pressure is released. I can't believe you got photos of it. It happens so fast, a whoosh, the flame increases, and then goes out in a flash. Fast fingers on the shutter for sure. Thanks for going to the trouble so I don't have to!

    Ben