In another thread https://classiccampstoves.com/threa...ow-to-remove-a-burner-from-optimus-157.38097/ I had asked how to remove the burner on my Optimus 157 for unblocking them and I received very useful hints. I started to plan for a de-coking apparatus, as proposed by @Afterburner https://classiccampstoves.com/threads/ab-dcs.31915/, and connect it to my compressor at low pressure But then @Radler pointed out an interesting fact: one actually does not want a lot of air flow which cools down the burner. Since I am still a bit leery of taking off the burner (in addition the warning by Nigel Calder, I read from others on this site that they had problems getting the connection pressure tight again), this got me first thinking about disconnecting the bottom of the burner and blow some air threw it, WITHOUT taking off the burner. The next lightbulb then went off: there is actually a perfectly good pump built right into the stove: the one that pressures the tank. So, is the following a crazy idea? --empty the kerosene tank --pump it up to moderate pressure. --take the jet off the burner --heat the burner with a propane torch --open it up a bit and let air flow through it --if needed, pump more. Anything wrong with this? Will the graphite packing burn up? (it is easy to replace). Does the temperature of the burner need to be so high, to be effective, that it will be harmful to the stove? I have had other harebrained ideas before. Please let me know if this is one of them. Thank you!
@OldMariner Only (significant) hitch I could foresee would be that with the jet removed the fuel tank would depressurise virtually instantaneously and no amount of pumping could keep up with the pressure loss. It’s the jet that’s the restrictor to prevent rapid depressurisation. John
1. Decocking with low pressure means you need a much larger pump to produce the air stream. 2. To heath a burner in a controlled way, you need free sight and access to it from all sides. 3. If your burner is a regulated burner, this makes things more difficult. 4. If you want to repair your burner, take it off.
1) So, do you think the built-in pump will not provide enough air? I thought that not much air is needed, just some oxygen to allow combustion? 2) I heated the burner with a propane torch and I think I have pretty good access. 3) Yes, I have a regulated burner. After I wrote my posting yesterday, I actually thought about this a bit more. Perhaps it would be better to remove the spindle, graphite packing and everything, just keep the burner itself to be heated? 4) If I have to, I will. But if I can avoid it (mainly the possible problems with getting it pressure tight when putting it back on), wouldn't that be a good thing?
Sorry to being 'out' for some time... Summer is here and there is so much to do since here is not snow now. I have newer had a problems to get 155 burners pressure tight after disconnecting them (even some of them have worked ok with old fiber gaskets). You would need constant air flow through the burner during coke burning so I think that amount of air in tank may not be sufficient for coke burning. Also control spindle might/would restrict too much air flow so it's better to remove it. I would recommend to disconnect burners from the stove then you have full access to them. Burners have a M14,5x0.75mm (or that is best current approximation...) thread so fitting for standard piping parts would need to be done with a lathe. Control spindle has a UNC 5/16" 18 tpi thread (or that works ok) so if/when you remove control spindle (together with packing and packing nut) from the burner you can close air route out through control spindle hole with a 'standard (US)' screw. If you cannot get fitting for burner to piping parts just mount the burner from it's nut to a bench wise. Heat the burner with a propane torch and blow pressurized air though the burner with this kind of pressurized air gun/handle with constant flow (it doesn't need VERY strong flow) Time to time full flow could be applied to get loose stuff/dirt out from the burner: Some air could be blew though the jet hole backwards direction.
Thank you for your detailed response! It is good to know that re-seating the burners for this style of stove does not seem to be a big problem. And in particular thanks for the thread specs. I don't have a lathe so fabricating custom fittings will not be possible for me. The air gun solution sounds like a good one, or the steel pipe suggested by @Radler in the other thread on the Optimus 157. And I agree that replacing the control spindle with a screw is the best solution. Finding a 5/6 18TPI should not be hard. Overall, it seems there is not a lot of enthusiasm for my in situ de-coking idea. So I guess I should defer to the experts and take off the burner.
In-situ de-coking would work if you blow pressurized air through the tank to get sufficient air flow. Pump in tank would not produce enough air for easy de-coking (work would need to be stopped time to time to pump more air to tank). Also stove body might bend/deform if you heat one portion of it with propane torch. SS body also might discolor from area that gets heated.
I had thought about attaching a compressor through the tank but it seems like a bit too much of McGivering (or is that fettling? ) The second paragraph of your posting is what I am most concerned about. I did heat the burner with a propane torch (see post #17 in https://classiccampstoves.com/threa...how-to-remove-a-burner-from-optimus-157.38097 ) and it was not a problem. But that was just for more intense priming, I suppose for de-coking I would need much higher temperatures and longer heating. I don't think I want to try it out. This is my only kerosene stove, and I need it if I want to have dinner on the boat...
You need to get burner to glow to burn off the coke so temperature will be much more that priming needs.
I have used a tank lid with air screw from a kerosen stove (type Optimus 00 etc). Removed the air screw and holding the compressor piston against the hole in the tank lid. That way I have successed in blowing clean a Optimus 8 burner that I didn't managed to dissasamble.
