Dears, I would like to share my story regarding Optimus 1350 fettle. It is not my lamp, I just promised to do it for some friend, so he could use it while camper camping. He has several lamps but no idea how to maintain and service them. The lamp is missing the red top located on the top of the hood, but that is not a big deal for the lamp owner. He just wants the lamp to be reliable and functional. OK, so after standard dismantling, cleaning, replacing seals etc. there was a “fire ball” problem – flames on the mantle. I tried various jets and needles sizes (200-500cp) and various air gaps – flames on the mantle were still present. I added brass mesh to the generator – situation improved a bit, but fire ball was still present. I added small plate (made of flattened bottle cap - patent pending ) above the mixing chamber (similar solution like in old Petromax lamps) to retain more heat close to the generator – some improvement, but flames on the mantle were still present, pulsing effect etc. I just put the Petromax 829 (one-piece, all brass) hood - problem solved. I was really surprised that the missing Optimus red top was causing all these problems. I am used to old Petromax and Optimus lamps and sometimes these lamps were working even better without the hood with smaller 150-250cp jets. Often I had problem with overheating the J-tube instead of lack of heat down below. Construction of those old inner casings and hoods allows to retain much more heat INHO. That, pretty modern Optimus hood has bigger vent holes on its sides, bigger holes on its top and construction of the inner casing is also more ”open” allowing more heat to escape. I did not want to waste my Petromax hood for that lamp so I installed other Petromax hood which was in worse condition – some dents etc. Lamp had again a minor fire ball problem… I noticed that the other Petromax hood has different construction – there is some steel plate inside of it. It is rusted and visible on attached pics. Maybe that construction with steel plate retains less heat and generator is not hot enough. I am not an expert, but these two almost identical Petromax hoods make lamp to work o bit different. To retain more heat close to the generator I made a bigger plate (made of aluminium can bottom – patent pending ) and I installed it above the mixing chamber. It works – lamp works without the “fire ball”, not pulsing effect etc. The jet is old enlarged 200cp, so currently it is approx. 300cp. Maybe I could swap the J-tube or generator to check results, but I do not want to use my parts for that lamp. Added modified can bottom works just fine in this case. Lessons learnt for me – Petromax clones may look almost the same, but these small construction differences matter. Even that steel plate in some original Petromax hoods makes a difference – obviously they changed designs on purpose. I hope that this story may help someone while fettling lamps. If you have some other ideas, advices then please do not hesitate to share them. All the best, Piotrek
Dears, I was “playing” with that Optimus a bit more yesterday. With my additional heat retention disk lamp was functioning very well with all hoods: Original Optimus with red hot top missing, both Petromax and even some steel Chinese hood. To be sure that lamp is 100% OK I put it outside my apartment. It was very windy and temp. approx. 5 centigrade. Outside the lamp was working as follows: 1. Petromax hoods - flames on the mantle after approx. 15-20 minutes outside 2. Chinese hood - flames on the mantle after approx. 5-10 minutes outside 3. Optimus hood - flames on the mantle after approx. 2 minutes outside Lamp was working ok after bringing back to the apartment. I have very limited experience using lamps outside, but had no issues with several winter camping with old 826 and 829 lamps. I believe that there are real winters in Sweden, so Optimus 1350 should work in winter conditions. Maybe very windy conditions are crucial? I will try with bigger jet today, but I am not sure if it is possible to make air gap large enough for 500CP. If anybody can advice me/share your ideas about the abovementioned problems, then I will appreciate it. All the best, Piotrek
I find it strange that the lamp needs modification. I have had several lamps from this series running well. Just last weekend I had a 350 (same as 1350 but without quick starter) running for several hours outside without an issue. It was probably 10 degrees and not very windy. The only difference between a 1350 and 1550 is the jet and needle (and the label). The air gap is the same.
Thank you for info Nils. So 500CP jet should be fine as well in this lamp. Yes, Optimus is a top quality company and 1350 a popular model, so it should be running well. I will remove brass mesh from generator, my heat retaining disk and replace some parts one by one (bigger jet, J-tube, generator upper part, the whole top etc.) to find the problem source. There is missing that red top, but with PX hood lamp should be working just fine. Definitely there is a significand difference when lamp is working with full PX hood and topless Optimus hood. Wind may be some factor, but it is suspicious to blame everything on wind. From the other hand I do not own any "such modern" lamp, so I am not sure what to expect. Definitely these younger inner casings and hoods are more "open/airy" compared to older designs. These changes were introduced for reason and must have some impact on lamp performance.
@Piotrek I've juggled with old and "new" parts for users that I take rotate from my displays and don't see any issues with operation. Strong wind will always upset lanterns. Even my Colemans are affected. Basic Boyle's laws are at play here. Hot air is alot less dense than air at ambient and more so when it's in the winter. All that winter air is rushing through all convective openings trying to equalize the pressure inside the hot lower pressure environment inside the globe. These turbulences and eddies will upset the dynamics of your lantern leading to affected operation.
This is comforting . I have to admit that yesterday while watching through the window that lamp struggling on the wind I was thinking that petrol/white gas fuelled Colemans are better solution for that guy to use while camping... From the other hand, all these kerosene lamps were/are used in Sweden, Norway and other countries with pretty rough weather conditions and Primus/Optimus would come up with better solution if required. Anyway, as I am doing that lamp for someone else, I will do my best to eliminate my potential mistakes and try different options. Bigger then 300CP jet will be tried first to provide more heat. Also I will light some other trusted and tried lamps next to that Optimus to check how they perform.
Your post was very enlightening. After reading everyone's posts, I don't know what is causing the problem this time. But at least the measures you took are working well, so I think it's a good thing that a record is kept here. By the way, my 824 also had a part like an iron umbrella on the nozzle. After reading your article, I thought that maybe that part was for increasing heat storage. Thanks for sharing.
I expect that my problems are caused by my laziness/mistakes, as usuall But there is also some positive side of such a story - I learn more when have to try approx. 50 times to light and try different solutions... Piotrek
Hi @Piotrek! I have a later Optimus 1350 with the lever operated quick lighter. Lantern worked fine but smelled a lot so I tried to change parts between my other lanterns that does not smell. Still smelled a lot. I believe that the J-tube on the inner hood must be without dents, and the mantle must be the bigger pear shape ones for the lantern to not smell too much. I use NOS Optimus 350CP mantles. On your friends lantern the inner hood looks different to the one I have on my 1350 lantern. I had a heat deflector lying around so used it on mine. Attached some photos. Regards Matti
Hi Guys, thanks @Matti Kucer I was about to give up on this lamp and say to the owner to use it only indoors, but if other users have some issues with this model then maybe this is not only my foul. So I push on with this project. Now it has approx. 500Ccp jet. I do not have and use any bigger jets then 250CP on my old lamps, so I had to take some used, enlarged one. 500Cp needle fits snugly so it is approx.500cp. J-tube – it is dented. I had to add tiny nut between screw top and steel plate holding the J-tube to make that holding mechanism works. Otherwise top of the screw was going to the old dip in old J-tube. You can see that tiny nut on the attached picture. That nut holds the J-tube firmy in any place I want now. I replaced J-tube with brand new Optimus J-tube – no difference on lamp performance. I put back the old J-tube after that experiment. I removed brass mesh from generator and my heat deflector. I checked air-tightness again, try to light the lamp (big Butterfly 500-600CP mantles all the time) and flames on the mantle were visible from the very beginning I put back mesh and heat deflector, Petromax hood and lamp works great indoors. With mantle and without mantle it looks OK as long as it is inside my apartment. I added stainless steel burner instead of ceramic. I used that steel burner only when dismantling or repairing stubborn mixing chambers from lamps. When steel burner is located inside the stuck mixing chamber then I am not afraid to damage it when unscrewing. Also when mixing chamber is misshaped I can repair it using steel burner. Anyway, there is a significant difference in lamp brightness with steel burner. I was really surprised how much brighter it is with steel burner. OK lamp with 500cp jet, brass mesh, heat deflector, steel burner was very bright and stable inside apartment but outside (small wind and minus 2 centigrade): - developed black spots after several minutes with Chinese hood - - developed black spots after 20 minutes with Petromax hood You can see significant design difference between inner casings and hoods of older Petromax and Optimus inner casings and Chinese hoods. Petromax design is much less open, heat transfer and lamp performance is completely different. OK, I know that Optimus 1350 should be working in different weather conditions in original setting, but I am not able to do that. As an excuse I do not have original complete Optimus hood (missing red top) and my jet size is approx, not exactly 350cp or 500cp. Nonetheless that lamp is challenging for me to use outdoors even in mild winter conditions. So I bought some brass parts today on a flea marked and I will try to make bigger hear deflector and somehow reduce vent holes in Chinese hood. We will see Piotrek
@Piotrek Please refrain from using stainless steel burners. Stainless steel expands more than brass when at operating temperature so as a consequence, it'll permanently stretch out your brass mixing chamber until the nozzle is no longer tight inside the thread and ultimately fall out. Stainless steel at ambient condition will not corrode but when you introduce it to extreme heat like the intense heat of a bunsen flame which exists inside the mantle, it'll start to oxidize regardless of grade of steel One nasty habit of steel is it starts to flake and eventually chunk off from constant exposure to flame, throwing slag into your mantles and ruining them. Always use ceramic or even better, alumina oxide nozzles, which are alot more shock resistant than clay and ceramic.
Some update. Yesterday during the daytime, I lighted again the lamp with the same parts setting like evening before - Petromax hood, steel burner etc. It was working ok at the temp. of approx. 10centigrades. So that 10 degrees temp (between zero and +10) makes a difference at lamp performance. I made bigger heat deflector from some brass disc. also I reduced air vents in Chinese and Optimus hoods: · Chinese – I put inside approx. 1,5cm high steel box lid and additionally I flattened edges of the hood vents so these cover more area. · Optimus hood - I put inside approx. 1cm high steel box lid and additionally 2cm high brass ring (just a strip of brass cut from the old Primus stove). I can even move up and down that bras ring to modify the vent area. I tested it again during the evening/night at the temp. of approx. 2-3 centigrades. With my new, bigger heat deflector and modified hoods lamp was working fine for approx. 30 minutes and after that time developed black spots on mantle etc. So similar problems as before, but this time problems occurred after longer period of working time and I did not even use Petromax hoods. So there was some significant improvement, but problems were not solved. I started thinking again (usual waste of time ) what I am doing wrong… When you do not have all original parts and especially not accurate and reliable jets there are plenty of factors to play its part. Then lampie spirits had some mercy on me and I realized that problems after 30 minutes seem to relate to low pressure = heat loss. There were no leakages, so? I pump that lamp inside my apartment, close to all lights, close to me, so the pumped air temp is approx. 25 centigrades. Outside it is approx. zero. So when that lamp full of hot air gets outside pressure is reduced after some time just by temperature difference. Just like mattress during winter camping – you have to pump it some more again after it gets cold. Additionally, I use really big jet – approx. 500CP, so after half an hour it may makes some difference on the pressure inside the tank. So after 15 minutes of lamp working I pumped it more outside and lamp was working without any issues… I tried modified Chinese hood, but expect similar results with modified Optimus hood I will check that today. Usually, when I use lamp outside, then I pump it outside. If inside – I pump it inside. Usually I use 150-250CP jets so lamps lose pressure slower. I will play some more with that lamp. As advised, I will remove steel burner and will use it just as a tool for mixing chamber disassembling or for some experiments. Optimus 1350 is very “airy” lamp with plenty of vents and different heat transfer then older lamps that I am used to. In my opinion one has to learn that lamp to use in winter conditions. I am not an expert and there are plenty of these lamps in Norway, so that lamp has to to OK during real winter as well. Different design, as well as lack of original parts and reliable jets made this (seemingly easy) project so time (and methanol )consuming for me. And one of the key factors was to keep proper pressure of that lamp – pump it more and/or pump it outside. Big mantle close to generator is recommended as well. Anyway, with proper (relaxed) attitude and plenty of time it was quite interesting to check how one lamp can perform in different conditions and with various parts configurations. @Dashwood – thank you for info regarding steel burners. Have you tried brass burners that are available on e-bay? All the best, Piotrek ps. looking at the hoods pics below one can understand the difference between "made in Sweden" and "made in China"
@Piotrek You indicated that you needed more pumping? One common mistake alot of petromax and clone owners make is misinterpreting the red line on the manometer or "pressure gauge" as the max safe or optimal pressure when the literature or manually clearly states that the red line or 1.5 Bar is the optimal pressure for using the rapid preheater or the absolute minimum pressure the lantern can properly operate. The literature states once lit, pump the lantern up until it reaches 2.5 Bar for normal operation.
You are right @Dashwood That lamp has no manometer. Most of my lamps do not have manometers and actually I prefer lamps without. I do not consider 80-100 year old manometers as a reliable tools and definitely do not want to fix/replace them. Maybe in the future, we will see. I am not a lamp user. I just collect them and I am happy if it works at the end. I do not make any "fine tuning" with that extra screw at the J-tube, no perfect NOS mantles, no perfect 100CP/200CP/300CP NOS jets. 150Cp/250CP/350CP/500CP jets would be improper for my lamps anyway. If lamp is working for two hours without problems (black mantle, fire on the mantle, smell, strange noise etc.) then it is ok for me. It does not have to be super bright and I have no idea what is the pressure inside Most likely much less then 2,5 Bar, but I do not want to even try such a pressure at some almost 100 years old lamps... This particular lamp is for someone who is going to use it, but only to show off in front of other campers . So I tried it in different weather conditions and made some amendments due to missing original red top/cap. Usually I fix rapids as well, but I do not care about rapid preheating at that particular lamp, because that guy has no idea about pressure lamps. He was trying to use alcohol in this lamp without checking anything before... For his own safety it is better not to touch rapid for him. I decided to help him just to check some "modern" lamps (Optimus 930, Optimus 1350) because I would never buy these for my collection. Optimus 930 I like a lot, but 1350 not really.
@Piotrek Pumping up petromaxes from experience, I'd recommend pumping until your thumb gets a bit sore which would pressurize your lantern right where you need it roughly.
@Dashwood My lantern teacher used to say the same thing. I'd like to read the instruction manual that contains that information, but do you have it stored somewhere?
Petromax R826 instruction | Classic Pressure Lamps & Heaters 40-60 pumps. Pressure will depend on the fuel/air quantity in the tank. I usually use such old lamps with lower pressure to avoid bulged/cracket tank bottom risk.
If very concerned, you could maybe JB weld or solder a bracing ring on the bottom of your fount. @Piotrek
Thank you @Dashwood I am concerned about old rare lamps and do not want to interfere more then necessary to them. I just do not care if they are not super bright as long as they work OK with lower pressure. With that Optimus 1350 it is a different story - I do not care about such a lamp. After my amendments, when pumped 40-60 times it works great inside and outside with modified Chinese hood. It still has problems with Optimus hood (the one missing red top). I will give back that lamp today, so Chinese hood will be used. If the owner wants to try different parts/settings variations with Optimus hood, then I wish him good luck
@Piotrek I wasn't aware it was missing the top section of the hood, that part is pretty important to controlling the escape of heat and for safety for anything that might hang above it. Some wick lamps with exposed open chimneys can release enough hot air that can ignite flammables several feet away which is why they're instructed to make sure there are no lose hanging objects on top of the chimney.
