Høvik Verk Standard No. 37 - strange flame behaviour

Discussion in 'Fettling Forum' started by HaakonJ, Aug 18, 2019.

  1. HaakonJ

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    Hi

    So far I have only used 1-pint versions of the classical 3-legged brass stove. The ones I have are: Høvik Verk No. 41, Optimus 00 and a Radius 21. I recently bought the stove mentioned in the title, my first 2-pinter. I changed the nrv pip and lead seal. Pump only needed a bit of oil and was in great condition. I suspect the previous owner must have replaced it in an attempt to bring the stove back to life, because the rubber gaskets were hard as a rock, with no indication of being functional for the last couple of decades. After I replaced the tank lid gasket and flushed the tank thoroughly, I tried firing it up, and it went straight into underburn. A loose jet was tightened, and it burned perfectly... at least for now.

    IMG_20190815_163219.jpg

    I used it to prepare some lunch in the backyard, and suddenly noticed a lot of yellow flames. No underburn, but all yellow flames. Pots were all sooty after cooking. Took it back to the workbench and gave the burner caps and burner a good cleaning. No sign of damage from underburn, so I replaced the fuel and fired it up again. Now the burner behaves strangely. The flame is pulsating at a very slow pace (around 0.2-0.5 Hz), and goes from small, simmer-like blue flame, to rather big bursts of yellow flame.
    IMG_20190818_142422.jpg

    At first, while cooking, I thought the jet was worn out, but the pulsating behaviour I saw later isn't really typical for a worn jet. Could the burner be dirty inside the tubes, restricting proper fuel flow? Do I need a brass mesh in the riser tube to control the fuel flow better?

    When I tried replacing the nipple, I assumed the replacement nippples I have for my other stoves would fit, but I don't think the threads are the same. Had to reinsert the old one. Do these larger stoves (or this one in particular) use different nipples?

    Hope someone could give me some tips here. I have not seen this type of behaviour on any of my other stoves :-k

    Cheers,
    Håkon
     
  2. Afterburner

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    1 & 2 pint stoves (at least Optimus & Primus) have same jet thread. No brass mesh in the riser tube needed. Maybe burner tubes a filled with residue and/or coke?

    Remove jet and pump pressure to tank to see that fuel flows freely.
     
  3. Lennart F Norway

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    Most 2 pint stoves use one number bigger size of jet and burner than is usual on 1 pint stoves resulting in approximately double power - there are some 1 pint Høvik stoves using larger burners.
    It sounds like you have some coke inside the burner and I suspect the very popular "grønn guffe" leave more residues - the cure for the problem is to heat the burner until slightly red while blowing air through it. It can be done just by removing burner cap and nipple, empty the tank and blowing low pressure air through the filler hole with a rag around while heating the burner with a blowlamp ar gas burner - take care to direct the outlet where the flames and sparks can't damage anything.
     
  4. Tony Press

    Tony Press United Kingdom Subscriber

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    Before taking the burner off, try taking the nipple (jet) off and re-seating it using a smear of copper grease, and making sure it’s snug tight.

    Tony
     
  5. HaakonJ

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    @Afterburner

    Thanks for the tip. Fuel flow is not much restricted it seems. Liquid kerosene flows freely.

    I tried cleaning the burner like you suggested, @Lennart F . Used a butane/propane torch, heated the burner until slightly red and blew hard (with my mouth) through a tube I fitted against the filler hole. Repeated this quite a few times. Some sparks were flying out, but not as much as expected. I managed to find a replacement nipple that fitted, with the same size jet hole.

    Still burns the same way, maybe pulsating slightly faster, and does not reduce to a simmer-like flame. Could it be that the burning gas is too rich with fuel? Is it possible I need a nipple with a smaller size jet hole?

    I have a video of the burner in action after cleaning and replacing the jet:
     
  6. HercL4D2

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  7. Lennart F Norway

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    That is what it use to look when burning the first half tank filling of a similar Primus 5 that had residues of dried out kerosene/paraffin in the tank.
    I would let it burn for 30 minutes or something and see if it works better - if not, shift to fresh fuel and test again.
     
  8. HaakonJ

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    @HercL4D2
    Those were quite cheap! How is the quality of those? Also, it doesn't seem to have any threads, but the picture quality was not the best. Are you supposed to machine your own threads?

    @Lennart F
    Thanks, I'll try that. Any good way to clean out old/dried kerosene from a tank? Just let it sit with kerosene and wait for it to dissolve?
     
  9. HercL4D2

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    @HaakonJ The Silent burner has threads and should fit your stove. Carburetor cleaner will clean out the kerosene. Kerosene is just refined Gasoline. Coleman fuel is refined gasoline called drip gas.
     
  10. HaakonJ

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    Okay, I'll see if I need to pick up those burners. I'll first try restoring the stove as is. I think the burner itself is good, and that a dirty tank might be the issue.

    I would disagree that kerosene is refined gasoline, as kerosene is a heavier oil fraction than gasoline. Gasoline typically has hydrocarbon chains of length 4-12, while kerosene has 12-15, or somewhere along those lines. Kerosene is more similar to diesel than gasoline.
     
  11. HercL4D2

    HercL4D2 Subscriber

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    @HaakonJ I have been wrong before considering my age. You can probably follow this flow chart better than I. It don't matter Gas, Kerosene, Naphtha all come from crude oil and so does paraffin wax. Carb cleaner first then kerosene, that is my suggestion.



    [​IMG]
     
  12. igh371

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    Silent burners can be more sensitive to having a worn jet than roarers are. It might be worth changing the jet for a new one, that certainly won't do any harm.
    Also, in trying to work through eliminating one potential cause after another, it is always worth trying a temporary swap with a different burner to see if that behaves the same way.
    But in either case definitely empty and refill the tank with fresh fuel too.
    Hilsen,
    Ian:thumbup:
     
  13. janders

    janders Subscriber

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    Re cleaning tank:
    I use some small stainless steel bits the wife bought to tumble polish silver. Works very well.
     
  14. HaakonJ

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    The flame in the video above is with a newly installed, unused nipple. I will try running it for a longer period of time tonight. Carb cleaner will be my next try.

    @janders
    Thanks, I'll look into that!
     
  15. HercL4D2

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    @HaakonJ The reason I suggested a new silent burner is because of the difficulty of cleaning and removing the carbon inside the burner. Old roarer burner heads
    And this quote: Old roarer burner heads which is correct. Especially if you don't have spares. The link for the new burner I gave you also has a spares kit for these burners and stoves fairly cheap.

    If you are a married working man the better half can have difficulty understanding why you are paying more attention to that cursed stove hobby instead of Her!!! Unless you have a lot of free time on your hands and love fixing up stuff with no interference.

    I am in my senior years and enjoy getting off the couch and messing about in my workshop. I also enjoy getting it all done as conveniently as possible. Take the time to read through the link on Old-roarer-burner-heads. Some good info there.

    I have no experience with your stove but they all use the same principals in creating that perfect flame. So some of my own thoughts here. Your video looks to me like your fuel is surging or burping like there is not enough air in the tank, burner is not hot enough to sustain a blue flame, carbon obstruction of the burner piping or a restriction of the fuel feed pipe that the burner mounts into; as if there is a cotton wick installed in the pipe and it is partially blocked with some carbon forming coke buildup.
     
  16. HaakonJ

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    I am indeed a married, working man, so it is tempting to just buy a new burner! However, this hobby is also about the fun of actually restoring the stove parts I get, so buying my way out of the problem feels a bit like cheating :lol:

    I believe the tank is now pretty clean inside, after using @janders method. At least clean enough not to be the cause of the strange behaviour seen in the video clip. While testing, I noticed the pressure seems to drop quite rapidly while in use. Had to pump every 5 minutes or so. I sealed the jet with candle wax and did a dunk test. Saw no bubbles, and it held pressure over a long period of time. I have restored quite a few kerosene stoves, but have never been left dumbfounded like I have with this one.

    Could pressurized air be leaking into the riser tube close to the top of the tank (on the inside)? This is almost the only way I can see how it can loose pressure too fast, but only while running?? Doesn't really explain the strange flame behaviour, though. There are no signs of leaks around the burner mount or jet. I have tried holding an open flame around these areas, with no sign of fuel/vapor igniting. It does seem to burp a bit while running also.

    I may retry cleaning the burner, but with a careful heat and quench instead. My last attempt with heating and blowing air through didn't give many sparks at all. Should I use a compressor for best result?
     
  17. janders

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    Did you try to pump it up before the dunk test? A bad seal that doesn't show unless under higher pressure? (Had one of those...)
     
  18. HaakonJ

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    @janders

    1/2-3/4 full tank, and about 20-30 strokes with the pump (before dunking it, of course). Normal operating pressure in my book.
     
  19. HaakonJ

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    Just redid the dunk test with higher pressure, but still no visible leaks. Did 30 pumps, dunked it and waited a few minutes. Took it up and added about 10 pumps, dunked it and waited again. Repeated this until it was pumped about 70-80 strokes in total, and the wax seal started breaking/leaking. No bubbles. At this point I took it up and released the vent screw. The pronounced sound and air blast from the vent screw was to me a good indication of a well sealed tank.
     
  20. Radler Switzerland

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    If the pressure falls during use, how do you know there is a leak?
    Maybe there is something clogging the burner/jet as soon a certain temperature is reached.

    Or something is leaking as soon as a certain temperature is reached. In this case I would suspect first the gaskets between burner and riser tube.

    Radler