Greetings everyone, I am new to this forum, so let me start by introducing myself. My name is Richard and I live in the Northern part of Sweden. For Christmas I have acquired a Petromax HK500 Bundeswehr Pressure Lamp from around the 1960’s. My family is really happy with the lamp and the light it produces. I am hoping however that this fine community might be able to help me out with a problem that we have run into. Since Christmas we have acquired the cooking grill for on top and the radiator, for we would like to utilize the lamp a bit more. The cooking grill is easy enough to install as was the radiator. The lamp works fine with just the mantle and glass and works fine with just the radiator (with or without glass). However we would like to utilize the lamp in combination with the mantle and the radiator so that it can provide more heat (mostly for cooking and it will radiate heat a bit more) and we like the dampened light by the radiator. Also we do not want to replace the mantle every time we feel like using the radiator. According to Petromax the mantle and the radiator can be used in conjunction (link to radiator: Radiator for HK500 | Petromax. This is however where we run into trouble. Every time I try to use the two in conjunction after a few minutes the mantle will “extinguish” (not sure if that is the proper term here) and will be engulfed in a blue flame as the radiator then heats up and after that the mixing tube start to glow red as well. If I remove the glass the result is the same albeit a few minutes later. Which leads me to think that heat buildup is the problem here which might result in not a proper gasification of the lamp oil. I have fastened the mixing tube to the maximum height as that was a problem before. I hope that someone might be able to tell me what the issue is. I have recorded a video of the issue. I first light up the lamp, but to skip immediately to the issue go to 4:05 on the timeline. Thank you upfront for any information and help. Richard P.S. I know I have to change the leather from the pump, it is quite worn.
Hello Richard and welcome. When the lamp starts to "back burn" (burns inside the mixng tube), is there still plenty of pressure in the tank ? Have you tried turning the wheel to clean the jet ? With or without a mantle or radiator / heater, the lantern is burning the same amount of fuel so in theory, it should give the same amount of heat. Perhaps a long shot but have you tried removing the hood to see if it makes a difference ?
Hello Richard, Welcome to the forum. Its quite clear from the video that you're having a 'backburn' or burning inside the mixer J-tube. The lamp will dim out eventually. Sometimes it'll happen suddenly, sometimes gradually. These things can happen on these lanterns, with or without the heater. Firstly, would you get this problem if you light up with only the mantle(without the heater)? If not, then its quite certain that this was due to excessive heat build-up within the lantern, especially around the inner hood where the mixer tube is located. There are a number of reasons on why this could happen, for instance, a slightly worn jet. You'd be getting more fuel burning in such cases and thus, extra heat. If the mixer tube becomes too hot(above the autoignition temperature of kerosene), then the fuel-air mix inside it would auto-ignite and deplete whatever burning outside the burner cap. If the above wasn't the case, then its just that the mixer tube is 'worn out'. That'd reduce the velocity of the fuel-air mix flowing inside and chances are it'd ignite inside it instead of outside the ceramic burner. Its also possible that a speck of dirt or carbon might partially block the jet orifice and initiate such a scenario but this that wouldn't be a sustained problem if you operate the cleaning needle. Do check that the ceramic burner cap is not broken or loose. Sometimes the holes get enlarged or hairline cracks expand with heat, causing the flame to propagate from the burner back into the mixer tube. Check also' that there are no leakages at the jet(gas tip) around where its screwed onto the vaporizer. If there is a slight leak, then you'd get excessive fuel throughput that you might not notice. Inspect the vaporizer that its in good condition and not having a tiny pin hole or a micro crack that opens up only when things are hot. There are more reasons these things can happen but I'll leave those for later discussions. It'd be helpful that you flush or clean out the internals, retry the light up and feedback on any progress.
Well to be honest I don't think you can use a mantle and the radiator at the same time. I think that was a biggest issue with the (real) Petromax 1500 too. The Petromax 500cp even the matt BW version of Graetz was not intended of being used with the radiator. The radiator was designed for the Petromax 1500 from Graetz. The heat of the mantle is shielded of by the radiator and while there is not enough heat left for heating up the vaporoser the flame will die after burning inside the J-tube.
@Richard K, Just for a trial if you suspect overheating to be an issue, remove the hood and try lighting it up. If overheating was the issue, the J-tube wouldn't glow without the hood as it did in your video.
Thank you all for the welcome and the quick replies. I will get the obvious questions out of the way: Yes there was still plenty of pressure in the tank, yes I have turned the wheel to clean the jet and also checked if the needle was still in good shape. However did not turn the wheel during operation (I think that is also not what you are talking about). Yea I have been pondering about the amount of heat generation and if it would really make a difference... Yes I tried and removing the hood did not make a difference. I have used the lantern with just the mantle several times without any problems, even now if I remove the heater it functions without problems and have tested it for about consecutive two hours. I have used the lantern with just the radiator (mantle removed) and that as well worked flawless, the radiator heated up nicely and started to glow red without the mixer tube heating up the way it did in the video. If the mixer tube would be worn out than it would not function properly with just the mantle? I do not suspect (nor see blockage at the jet orifice). I inspected the ceramic burner cap upon receiving in December and when I removed the mantle, I did not looked broken or loose, however I did not look with a magnifying glass (so that might be a little possibility). I will check the jet (gas tip) (that is part 152 right?) How do you mean leakage? Fluid should not come out when not pressurized right at the needle when it is up, but is the needle meant to hold back all the pressure when it is up? ...ok as I was writing this I went to check the part and ended up cleaning up the whole jet and vaporizer. There was quite a lot of carbon deposit on it, so I removed the washed and everything (part 104 and 114) and cleaned it, however I can't test it now as it keeps leaking everytime I start pre-heating. The leak seems to be coming from part 107/108. 108 was incredibly hard to loosen and after removing it a second time, retightening it all it is still leaking. Either from there or from the guiding tube that goes into the reservoir that I saw turning when I was tightening part 152 again. I am however more convinced it is part 108, I am almost wondering if there shouldn't be some kind of washer in between. Feeling a bit foolish as I now have a non-functioning lantern So you mean to say that the radiator absorb so much heat that the lamp will "die out" because the light can not sustain itself because too much heat is flowing elsewhere?
On second thought it might be part 90 (dichtungsring) that might be leaking. Yes I had the same result with the glass removed. Sorry what do you mean with the cleaning needle? Part 68 the Düsennadel? I heard you should not try to stop the burn by putting the needle back up again, but by letting the pressure escape, so that is what I do. In the first few times I did it like that, but not anymore no.
Here you can see the leaking part, on the third picture I point at the tube that is going down in the tank that was turning with the retightening.
Quick update: lekage solved, just had to tighten the main shaft properly. Does seem to be an overheating problem, without hood it burns fine, with hood I get the same problems again. Think I have to accept that I should not use them together.
Richard, it was the lower vaporizer part screwed on to the fount leaking? There's a lead washer there and you can't use it over again because it has already deformed from initial tightening. Sometimes, PTFE tape can be used as a temporary substitute but you'd need to check the relative distances of the pricker needle and the jet to make sure its still correct. Anyway, you've got this sorted out already. The cleaning needle is not meant to hold back pressure. That's the job for the footvalve located inside the fount at the end of the fuel pick up tube. If the lantern-heater works fine without the hood, then its overheating. As a quick solution that sometimes works, use a new jet/gas tip that's not worn or a smalleŕ 350cp jet. That'll reduce overheating to some extents. Do check that the heat shield cup located above the ceramic burner is still there. That'll deflect a bit and prevent convected hot gases from 'licking' the J-tube too much. WimVe's right about the design issues regarding the lantern as a lantern-heater combo. You might or might not be able to improvise in order to counteract the problem.
If you ever try to use a 350hk jet, be sure to change the pricker needle to the correct size too, because the 500hk needle would enlarge the orifice. Or the needle would be bent when you operate it.
By swiftly turning the control knob, you operate a cleaning needle. This my be done while the lantern is alight. But indeed shutting down this way is not the best way. Although in my opinion it also can't hurt the technique. Only problem that can arise is that fuel may still escape can then you get a messy shut down. If the main foot valve is working 110% it is a normal way to shut off the lantern. One of the main components of back flash is the lack of pressure. The flame will then follow the fuel back into the J-tube, where you get a kind of bunsen burner, roaring flame. The same thing happens when you run out of air. Best advice: 1) keep one lantern for light. Maybe downsize it to 350cp. 2) get one lantern for heat. 3) get a stove for cooking. Have fun and enjoy !
