Hello forum members I'd like to welcome you, as this is my first post on this forum. The reason for my visit is a cracked J-tube in my first Petromax 826 pressure lantern. I got it fairly cheaply and it looked good in the photos. It appears to be dated 8 9 (or maybe 6 8?), so probably August 1939. After cleaning, assembling, and lighting the lantern for the first time with a lot of fire from the roof, I started looking for the cause of the problems with this lantern. I believe the problem lies in the distance between the nozzle and the J-tube, which is significantly less than 14.2 mm. So, when I tried to adjust the height of the J-tube, I noticed that the thread on the J-tube was too short. I searched the forum for photos and concluded that the J-tube in my lantern was cracked. I was thinking about buying another lantern, perhaps a new Chinese one for spare parts for this tube, but newer tubes are constructed and mounted differently. Overall, my lantern is complete and in pretty good condition, and I'd like to give it a chance at a new life. I just need to replace the J-tube. I'd appreciate any help I can get, wherever I can find it.
Welcome@Borgi! My solution would be to cut the remaining threads off and silbraze the threaded portion of a Chinese J-tube onto the Petromax component, using the Chinese fixing nuts subsequently and widening the hole in the J-tube support bracket if required to accommodate the Chinese J-tube thread portion. I’d use a 30% silver content silbraze rod to provide plenty of latitude to cope with the high temperatures encountered in use. The Chinese nozzle holder (mixing chamber) might have to be used too if the threads of the Petromax item are not compatible. John
Thank you John for your advices. I think that I have to gather new skills and tools - I mean for brazing. I've been repairing stoves with soft solder using cheap propane torch, soldering paste and solder for copper plumbing pipes. Will a propane torch be suitable for silbraze? Kind regards Borgi
I'd just try to cut off a piece of the straight (short) end of the tube to sufficiently increase the distance between jet and tube, if the remaining threads are enough to hold the threaded nuts and the mixing chamber/ burner in place.
Brilliant idea! Yes, the remaining threads are enough as I've assembled the lantern completly and tried to fire up. I'll try this with careful measurement before how much I need to cut off. I'm wondering what effect will be with shorted pipe. More heat I assume under the roof. I was loosing my hope and thought about selling this lantern and look for better one but regret a bit this old stuff. Thank you Martin!
Pre-WWII, 1930s Petromax are not always easy to find everywhere. If there are other parts donors to be found in your location, perhaps you can find a J-tube that is exactly like the one in your lantern. Otherwise, I'd just repair it. The newer Petromax J-tube might not fit properly in your lantern. Otherwise, perhaps even getting a complete, new Petromax inner hood/sheath with all attached parts?: Buy Petromax Inner housing HK350 HK500 PX-117-500 Wolfswinkel your Petromax specialist New Chinese Petromax-styled "clones" can always be bought. They are inexpensive and plentiful, at least for now. They burn just as brightly as the originals when functioning properly. However, its not the same 'feel' as having a functional, original 1930s Petromax. (Cannot be compared in this manner). They're totally different from a collector's point of view.
You are absolutely right and it's a reason why I'd like to bring new life to this old stuff than replace parts with other models, in addition to quality of new parts. The good news is that the whole new inner hood should fit in case of total destroy. One more additional idea I've got before cutting the J-tube is to lift whole inner hood to get proper distance from jet and try out.
Only for the smallest of components. The J-tube repair and (relatively) low silver content (high melting point) filler rod would require a MAPP blowtorch and fuel.
@Borgi You can also try 150cp jet. Maybe this lamp will run with a smaller jet even with that J-tube and reduced air gap. Anyway, this is an interesting old Petromax with F.Racek label on the site. Congratulations! all the best, Piotrek
Thanks John. Something to consider when I'll find somebody more advanced and prepared better than me in this matter. Regards Borgi
Hi Piotrek Ah, yes. It's F. Racek. I've learned that there were sold to India? The lantern came with Px 300 jet. 150cp I think will be much darker I think? And for this will I need suitable mantle? Regards Borgi
Wooohaaa! It works! But it's just the beginning and not the easiest way. I dissassebled upper part of vaporiser and cleaned the conical section with valve lapping paste to make sure that it's tight. Then screwed J-tube to inner hood on the remaining threads, and attached new mantle. Then rised inner hood on four nuts in order to get more or less right distance between J-tube and jet. I don't have Petromax wrench so I've 3d printed distance measuring tool. The jest is almost under the inner hood but still in the hole. I didn't install top hood. I went out of workshop for tests. Preheated four times with small portion of alcohol, pumped to about 2 bar and tried to fire up with fifth portion of alcohol. Again lot of flames came out on inner hood. I've seen stream of kerosene camed out from jet and it casued the fire. I've left it as it was for minute or two and then the stream changed to gas and mantle started to light bright! It started working! The flames went out and the mantle shone brightly. I left it as it was for an half of hour. It was lit whithout any issue and kept pressure. At the end I've reduced pressure to see how it will behave to almost zero, pumped again and finally extinguished. Tests completed. Now, I have to decide what to do. Short the J-tube above the jet, look for someone who silbraze the extension of the J-tube and for sure look for some J-tube donor. Now I know that lantern works so it's worth to keep it and fix.
Congratulations on the quick fix. Now I actually recall using a similar trick/approach to widen the gap between the jet and the J-tube inlet. I've forgotten on which lanterns but definitely on more than one instance: 1. Using a flat metal ring under the inner hood of a Petromax or similar lantern. 2. Using 4 pieces of short, bent metal wires inserted and equally spaced around the periphery under the bottom rim of the lantern collar.
- yes. You can search for "Racek" and find plenty information on the forum. Of course 150CP will not be as bright as 300CP, but who cares? It is just some idea to try if you have already 150CP jet/needle/ mantles and would like to avoid further works on the J-tube. You can also buy some cheap MAPP torch and try to solder as John described. There is also that option from Petromax shop: Mixing tube HK350/500 | Petromax all the best, Piotrek
Hello Finally, I had a moment and got to work. I drank a beer to make a decision and finally cut the J-tube to the right size. Now the distance between the nozzle and the tube is just right. I heated the lantern thoroughly with alcohol, inflated it, and heated it again. I lit the lantern on the first try without any flames on the hood. Gas was coming out of the nozzle immediately, not a stream of kerosene. The lantern is fixed! It works, it shines, and it holds pressure. Thank you all so much for the great ideas. You've been a huge help. I realize this is a temporary solution because the J-tube gets red hot, but now I can take my time looking for another one, since the lantern is staying with me. Maybe it's time to start a lantern collection? Thank you! Borgi
Thank you Martin. Hello again. The Petromax repair kit included a new 500 nozzle with a needle. Out of pure curiosity, I wanted to see how the lantern would light with it. It's even better. It's bright as hell! But a bit louder I think. I also learned how to light this lantern. This type doesn't have a valve, just a needle that blocks the nozzle. Heating it several times with small amounts and pumping it before lighting it causes the kerosene to leak from the nozzle and burn out in the inner hood. My new method is to pump it cold, heat it with a full tank, and then unscrew the knob before burning the tank. It starts immediately.
Best way of a cold start is to pump AFTER the pre heat. just before the flames go out. Even with the air screw on the filler cap open. This prevents pressure building up and therefore leaky jet. The needle isn't designed to operate as a valve or shut off. 1) Pre heat > close air screw > pump gently. 2) Fire ball > release pressure > go to 1.
You absolutelly right. I've tried this way yesterday. Preheated with almost full heating cup, before flames go out closed the air screw and started pumping. The lantern even with the needle up (brand new set with nozzle 500cp) started glowing and when almost extinguished I turned the knob. No leaks, no flames, just soft start. Thank you. I learned something new.
I did. Even better. Immediately after start pumping, the mantle starts to glow slightly, and it gets brighter until the tank is full. And by the way, today the lamp illuminated a pleasant evening with the neighbors :-)))
