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Rebuilding a marine stove regulating burner, a tutorial

Discussion in 'Fettlers Master Class' started by Manul, Aug 21, 2016.

  1. Manul Canada

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  2. z1ulike

    z1ulike United States Subscriber

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    You obviously put a lot of work into that tutorial. Wonderful job!

    Ben
     
  3. Manul Canada

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    I'm posting the whole tutorial here:
     
  4. Manul Canada

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    Most commonly found in marine kerosene stoves, regulating burners are without doubt one of the most wonderful pieces of gimmicky engineering in the world of European Primus style stoves. These are basically silent burners with built-in control spindles and cleaning needles, which allows for convenient adjustment of the flame and the ability to easily clean a clogged jet. Even though these burners are still made today, they are rare and expensive, making rebuilding an old one an especially good idea. Did I also mention that restoring old things reduces waste and is all kinds of eco-friendly and responsible?

    These burners also need regular heavy maintenance, which basically involves totally dismantling and cleaning them, so this tutorial would be useful for any everyday user as well.

    This is what a kerosene regulating burner looks like when complete:
    Pic01.jpg


    If you found an old one, it may be missing its burner caps, the inner and outer one. They are found on top of the burner, and this is what they look like (on many burners the inner cap may not have any of those 9 holes on top of it, which is perfectly fine – more about it later) :
    Pic02.jpg
    So if your burner has the caps in place, remove them and put them aside, we’ll come back to them later.

    Here is a stove enthusiast forum thread (I can’t recommend this forum enough!) which shows cutaway pictures of a burner like that. This would help you understand how it all comes together. Don’t just look at the first ones, there are more complete ones towards the bottom.

    http://classiccampstoves.com/threads/regulated-burner-cutaway.15697/

    Disassembly, Inspection and Cleaning
    Taking Apart the Control Mechanism
    To begin disassembling the regulating/cleaning mechanism, unscrew the packing nut (which is also called the “stuffing box” in British English):
    Pic03.jpg


    To remove the cleaning needle, you need to unscrew the jet first. The same key as the one used for removal of NRVs (Check valves) on stoves is required to do this, none of the jet keys for non-regulating burners would fit these bigger jets. Just reach the jet from the top of the burner and unscrew it.
    Pic04.jpg


    After the jet is gone, turn the control spindle to the left and you’ll see the needle on its toothed rack come out of where the jet was. Keep turning until the rack is fully released. If the needle is in good condition, not broken, you can reuse it, so in this case take it out carefully with tweezers and put in some safe place for the time being.

    To complete the disassembly, keep turning the spindle to the left until it comes off the threads and just pull it out. It should come out together with the old graphite packing and a brass washer. If the old packing is holding things in place, apply some heat to the burner (no need to make it red hot, this can cause the brazing that holds it all together to melt, just hot enough for you to not want to touch it with bare hands). This should soften the packing and let you remove the spindle.

    In the end you should get something like this:
    Pic05.jpg


    Examine the parts carefully. If the control spindle is not bent, the needle is intact and everything looks good, you may just need a new graphite packing and everything can be reassembled after a good cleaning. If you need a new spindle/brass washer, or a new packing nut, you need to get one of these rebuild kits available online:

    http://www.tilleylampsandstoves.com/#!product/prd1/4486376161/primus-stove-regulating-burner-repair-kit

    http://www.tilleylampsandstoves.com/#!product/prd1/3941650751/regulating-burner-jet-and-needle

    These bits can also be found separately here:

    http://www.base-camp.co.uk/optimus.html

    While it may be tempting to only replace one of the items in the spindle/brass washer/packing nut assembly, unfortunately they may differ in sizes: some spindles are bigger than others in diameter, which implies bigger hole in the washer/packing nut. So if your spindle is bent, replace the packing nut and the washer together with it to ensure proper match. This is why I’m advocating for buying the bits together as kits. Graphite packing will be compressed to fit any of the spindles when you reassemble the burner, so no need to worry about it. The cleaning needles can also be reused, because they all have the same general size – even if they look different. Here are the pictures showing how different the replacement parts may be from the original ones, note how in this case the original control spindle is bent:
    pic06.jpg


    Pic07.jpg


    Pic08.jpg


    Pic09.jpg


    Cleaning the Parts
    General Cleaning

    Now that everything is taken apart and inspected, you need to clean everything you are going to reuse. There are many ways to do this. I use the POR15 cleaner/degreaser myself.

    http://www.por15.com/POR-15-Cleaner-Degreaser_p_14.html

    I just put the burner parts into 1:1 mixture of this stuff and hot water, let them sit there for an hour, then rinse it with water while removing the loosened dirt with a rag and steel wool. This is a fairly aggressive and caustic detergent, so safety glasses and rubber gloves are recommended.

    Some people use an ultrasonic cleaner:

    http://classiccampstoves.com/threads/ultrasonic-cleaning-of-stove-burners.27409/

    Cleaning the Burner Flange

    Now one of the most tedious and unpleasant parts of the restoration: removing the remnants of the old gaskets on the burner flange. If your burner is old, most likely its flange looks like this, with extremely stubborn multilayer mess of compacted and petrified old seals all over it:
    Pic10.jpg


    This is what it is supposed to look like, free of all of the garbage, and showing a nice groove machined into it for better sealing (most burners have this groove, some don’t):
    Pic11.jpg


    Pic12.jpg


    Squeaky clean flange and groove are essential for proper sealing of the burner/fuel tube joint, so this is a crucial step. If your burner is already clean there, skip this step.

    A word of warning: back in the “good old days”, high temperature seals for stoves were made of asbestos, now a widely known carcinogen. Its airborne fibers were determined to cause lung cancer and mesothelioma when inhaled, so avoid creating dust. One of the easiest ways to do it is to perform all the operation while the burner is submerged under water.

    Use a sharp knife to meticulously scrape off the old gaskets from the flange until it’s all shiny. Try to avoid scratching the brass too much. Then use something like a sewing needle to reach into the groove and remove all the junk from there. The point of a knife can be used to finish this job. I highly recommend wearing cut resistant gloves while doing all of this to protect yourself from slipping sharp tools.

    Unclogging the Burner: Removing Carbon Deposits

    Some of the burners may be clogged inside with carbon that forms in the tubes as kerosene is turned into gas by the heat. Sometimes such deposits can completely plug the tubes.

    If your burner has this problem, there are two possible solutions. The simplest, but potentially more damaging one is to heat it (Until very hot, but not red hot), then quench it in cold water multiple times. This causes metal to expand and contract fast, making the crust of carbon covering it to break up and flake off. A lot of black powder can come out of the burner this way! Here is a good illustrated description of this method:

    http://classiccampstoves.com/threads/old-roarer-burner-heads.6479/

    A small wire brush can be used to further clean the tubes.

    While this is a simple and accessible way to get rid of the carbon, sometimes metal can crack from thermal shock, too, so the original method used by the manufacturer to rehabilitate the burners was more complicated: feed the air through them while heating with a torch from the outside, until the carbon ignites and burns off entirely.

    Some stove enthusiasts have actually successfully tried it. If you are a handy and adventurous type, here is the description:

    http://classiccampstoves.com/threads/air-powered-burner-cleaner.10978/#post-104661
     
  5. Manul Canada

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    Reassembly
    Now that everything is thoroughly cleaned and inspected, it’s time to finally put things back together! Put the brass washer back onto the spindle with its flat side facing away from the treads, followed by the new graphite packing and the packing nut:
    Pic01.jpg


    Pic02.jpg
    Screw the whole assembly into the burner, tighten the nut so that it’s tight, but the spindle can still turn.

    Now comes the time to reinstall the cleaning needle. This is a somewhat tricky operation that may take some time to get a feel for.

    Turn the spindle as far right as possible, then insert the needle through the top into the jet opening. To do this, you can either hold it with tweezers (by the rack only!), or gently push it into the end of a wooden stick like a kitchen match. Wiggle it in there till it engages with the spindle by its first tooth (it will abruptly “drop” a little deeper down the hole when that happens), then, while gently pressing down on it, turn the spindle to the left until you hear and feel 3-4 clicks as it jumps on its gear. After that turn the spindle right all the way again, it should engage the needle and make it disappear down the hole.

    To check if you put the needle in the right way, you can reinstall the burner on the stove filled with fuel, and pressurize the tank while the spindle is in the closed position (all the way to the right). If everything worked out well, no kerosene should appear in the jet hole. If you see fuel there, remove the needle and try again.

    Finally, with the control/cleaning mechanism in place, you can install the jet. Just screw is back in with the key and tighten it.

    Take a deep breath, we’re almost ready to fire up the burner!

    Burner Caps and Testing
    Now we can come back to the burner caps. If your burner had them in place, just reinstall them (The inner cap slips onto the burner upstand like an inverted salad bowl, largest opening down) and scroll down to “Testing”, if not, or also if you are curious why these uninteresting things require a whole paragraph, read on.
    Pic03.jpg
    The Mysterious Inner Caps

    These silent burners are actually very finicky precision devices. The proper match between the shape of the burner and BOTH of its caps are required for correct operation. Because none of these parts are made with precision, matching them up is more of an art than a science.

    To further complicate things, there are two kinds of inner caps, a solid doughnut-like one, and a perforated one. The perforated caps were made for burners with holes in their upstand (the tube that sticks up vertically from the centre of the bowl). Here are the pictures, you can see how the burner with holes in that tube has a perforated cap while the one with a solid tube has a solid cap:
    Pic04.jpg


    Pic05.jpg
    Here’s a nice forum thread talking about what inner caps are for and differences between them:

    http://classiccampstoves.com/threads/what-does-the-inner-burner-cap-do-in-a-silent-burner.6699/

    It is a lot easier to find a reproduction solid inner cap than the perforated one, and in my experience they work perfectly well on all of the burners, regardless of holes in the upstand of lack of thereof. If you are a purist, you can easily perforate your new cap.

    Here are the measurements of the holes on the one I have:

    9 holes, 3 groups of 3

    Inner diameter: 3mm

    Distance between the edges within the groups: 4mm

    Distance between the edges of holes in different groups: 10.5mm

    Outer Caps and Testing

    As if the inner caps weren’t confusing enough, things aren’t quite straightforward with the outer ones, either! Though they all appear to look roughly the same, slight differences in dimensions and hole placement can have dramatic effects on the flame.

    Oh yes, now that you’re firing up the burner, if you see a flame appear at the packing nut, no need to panic. Simply tighten the nut with a wrench to get rid of the leak. Graphite packing softens in the heat, and it may happen. If a stray flame appears at the jet, tighten it, too.

    If all goes well, you will get a sustained beautiful hissing blue/purple flame right away, which means everything is running just right. Having some red particles flying through is perfectly fine, especially at first since your freshly refurbished burner may contain loose pieces of carbon.
    Pic06.jpg
    If, however, the flame burns sooty, orange, or flashes into a roaring underburn (a condition when the flame burns below the outer cap with loud sound and lots of heat, this can easily damage the burner, turn if off if this happens!), your caps are mismatched. Either with each other, or with the burner.
    Pic07.jpg

    Pic08.jpg
    Unfortunately, the only way to fix this is to try different combinations of inner and outer caps till it works.

    Some people on forums say that brassed steel outer caps from the UK seem to work the best, this is where you can get them:

    http://www.tilleylampsandstoves.com/#!primus-spares/cjg9

    http://www.base-camp.co.uk/optimus.html

    Now that you spent the whole day (or a few days!) making your burner work, fire it up, take a moment to appreciate its beautiful flame, make yourself some tea or coffee on it, or cook a tasty meal. You definitely deserved it.

    Smilie.jpg
     
  6. Manul Canada

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  7. shueilung.2008 Uruguay

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    Great, Handy Flame-Keepers gide. :clap:
     
  8. BradB

    BradB United States Subscriber

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    Thanks so much Manul. This is very timely for me as I am awaiting parts from Fettlebox to rebuild my newly acquired Optimus 1s, which has the regulating burner. This will be my most involved fettle, so wish me luck.
     
  9. BradB

    BradB United States Subscriber

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    I am currently taking apart my regulating burner from an Optimus 1S. It looks identical to the one you have posted, Manul. But when I try to turn the spindle to the left, it lowers the cleaning needle. Turning it right (clockwise) raises the needle. It has about 120° of rotation and stops. I am afraid to force it since I am wondering if it could be a left hand thread! Thoughts?
     
  10. BradB

    BradB United States Subscriber

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    So I looked really closely at the burner and it appears to be a whole different animal in there. I turned the spindle all the way to the left and see what dropped out! Then I noticed that above the toothed spindle there is a rectangular cut out. Thoughts?

    Pic1.jpg

    IMG_0228.jpg
     
  11. BradB

    BradB United States Subscriber

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    And the spindle still won't turn any farther left or right beyond the 120°.
     
  12. BradB

    BradB United States Subscriber

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    So watching carefully I could see that as I rotated the spindle through its 120° rotation that it was indeed a normal right hand thread. So as per Manul's directions I lightly heated the burner body and it allowed the spindle to unthread by turning left. I just don't know what the little u shaped pin is.
     
  13. ROBBO55

    ROBBO55 Subscriber

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    Nice tutorial Manul :thumbup::thumbup:
     

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