Hi all, I'd like hear some comments (positive, negative or any at all) from you guys about this: I'm having a 1961 Petromax 826 (2612 stamped on fount's bottom). The pump knob, fuel cap, spirit cup, glass globe and the original upper generator that's supposed to have a central reinforcing rib were missing. The original central plate was unworthy for repairs and had to be replaced with another unknown plate of similar size. The rest of the lantern is still original Petromax. Therefore, I replaced the above missing parts with the following:- 1. Upper generator part: Preston loop from a Butterfly lantern. 2. Fuel cap: a winged fuel cap similar to an older(1930s) Petromax, which I found amongst some other lantern parts from a flea market. 3. Pump knob: machined/turned out from solid brass in a local machining shop (size and shape similar to the original phenolic/bakelite except for the rim knurling/ribbing). 4. Spirit cup and glass globe: Butterfly parts. The inner burner hood was original but extremely corroded/rusted with pits and holes all over it. Removed all oxidation with citric acid and coated it with a homemade refractory brew.(CRC COPPER BLOCK WELD; only taken the aqeous sodium silicate without the copper powder and mixed with a predominantly metakaolin powder which I produced at home as well). Seems to work satisfactorily as it adheres tenaciously to the steel, does not crack or flake off despite getting though all the heat-cool cycles in the lantern. I've tested heating it to cherry red with a blowtorch: no adverse effects to both the coating and the underlying steel.(all these trouble was just because I couldn't find another original inner hood to replace that). I'll be using 100% diesel( shown in the plastic bottle) as the sole fuel...till generator really clogs up. Still burning bright after a number of founts. It burns really hot, and the fount was barely touchable after an hour of operation. No pulsations but steady light. Mantle is radioactive. I'll be using it as a workhorse every night from now onwards till it shows some operational defects/discrepancies.
Yes. Besides that, to seal off the pin holes that would leak combustion products into the air intake compartment. I have more than one of these inner hoods that have been so corroded as to be hardly serviceable. We have very humidity here. The high operating temperatures of the lanterns further accelerate the oxidation process of the corroded areas. Once cooled down, rusting takes over again. The coating would reduce these to a great extent. I find this more durable than any muffler cements that I've tried. It wets the steel better when applied as a slip. I noticed that its even more resistant to high temperatures and rapid cooling than porcelain enamel (which would likely crack or flake off if heated to red hot and allowed to cool rapidly to room temperatures when exposed). No intention for decorative coatings here.
I don't why it doesn't crack or chip off when treated as such. Perhaps I've accidentally made something with a similar thermal coefficient of expansion to the underlaying steel. It doesn't stick well to brass or copper though.
That's a nice job. I don't have a petromax - they are definitely a pretty lantern! Why no intention for decorative coatings? Did you look into adding a bit of shellite into the diesel to keep it running cleaner/longer. Might be worth a look but I'm not sure - someone else here with more experience could comment on that I reckon.
Sure, Pauly. Shellite is definitely a much cleaner option, if only I could obtain it locally. The reasons for diesel being used for this particular lantern are: 1. Its so much cheaper than any other useable fuels here.(at least twice as cheap). 2. Its easily available from all local gas stations. 3. Less important compared to the above, is that I would like to test the generator on how soon it'll coke up beyond an acceptable/useable limit. I still have a number of Butterfly generators to spare. I wouldn't do this if its an original Petromax part. I mean I have no intentions of using that refractory coating for decorative purposes because that's the only colour it happens to have, and its non-glossy(unlike porcelain enamel). I'll just leave it as bare brass instead.
Hi MYN, I understand. Although you say less important, I do look forward to finding out your experience on point 3 as I haven't seen any really definitive info on this.
I'm intrigued by the coating you used. It sounds like a good solution for old rusty inner hoods. How easy is it to make and use?
@Pauly, Less important my context above was because I'm already expecting the generator to get clogged-up by the heavy diesel being coked by the heat. I'll need to run the lantern every night to find some sort of definition on 'how soon' that'll be.
@Nils Stephenson, Its very easy to make. Just like mixing the metakaolin(impure) into a bowl of the aqeous sodium silicate into any consistency you'd like and then either painting that onto the workpiece or just by dipping. Allow it to air-dry for a day and then gently bake it in a heated container to further remove any moisture, curing that at the same time. Similar to firing a ceramic ware but you need not get to such high temperatures that'll melt steel as well. You can also add in some coarsely-pulverized clay bricks for even higher temperature or crack resistance. It'll be water-resistant as well. Its not exactly a true ceramic but more like a form of 'geopolymer'.
Ok. An update on running this with pure diesel: Last night, it was on its fifth fount of diesel. The light started dimming to the point where it flamed sootily around the mantle. I had to operate the pricker frequently to get it back to its normal intensity.
Its either I just stick back to good old kerosene and mineral spirits or I better find a convenient way to clean out the carbon in the looped generator. The real problem with diesel is that being a heavier fuel with longer hydrocarbon chains, these tend to breakdown(non-oxidative) within the hot generator...coking. I don't even mind that its laced with fuel additives. Otherwise, all other parameters are fine, except I usually require three cupfulls of spirit for the preheat. I would say a near perfect combustion while operating the lantern. Clear bright light without odours. Its a compromise...price and availability is still King in the long run. But diesel is certainly not an easy piece of cake for any lanterns.
Cleaning the generator that often would be a pain. A thought - a cleaner burning MIX of fuel - diesel and whatever else you can readily get in a set proportion - even if that part is more expensive fuel... or running 100% diesel but every nth time running a fuel or additive that clears everything out. Same principle as running a diesel fuel additive to clean injectors on a diesel engine. I'm just guessing here mate but interested in the problem and the solution.
A mix with Shellite or any light naphta-like fuels would certainly improve the mean time between failures(unfortunately these are not available locally). Gasoline is not a good option due to the additives that would foul up the generator. These additives do not function like the way they do for fuel injectors in automotive engines. That's because the design and working principles between those injectors are different from a lantern generator, in which the fuel is heated and vaporized instead of being atomized and injected 'cold'. Now, my only available options for blending with diesel would be: 1. Kerosene or paraffin. 2. Mineral spirits used in paint thinners and brush cleaners. 3. Preferable would be pure alkanes(lighter ones). The stuffs I could obtain here almost always contain some aromatic and cyclic hydrocarbons, which burns in the open with rather sooty flames. At least they'll still make the mix lighter and more volatile than 100% diesel. But the real problem for me here is not any troubles concerning the vaporization of diesel. Diesel easily vapourizes in the above lantern. Its about high temperature ìnstability of diesel itself. It inherently has a lower auto-ignition temperature than both gasoline and kerosene. It decomposes more easily into free carbon than the lighter hydrocarbons. I'll need to, by some means, make diesel more stable at the temperatures that the generator operates. If this could be done, I believe there'd be very little, if any coking within the generator.
I'm wary of diesel because it seems to react with certain things when you might not expect it. My father in law mis fuelled the lawn mower with diesel. Not only would it not go, all sorts of plastic and rubber bits became swollen and had to be replaced. Not saying there is anything like that in a lamp necessarily but I would be looking for the signs anyway.
That's strange. To my knowledge, any petrol-resistant rubbers or plastics are resistant to diesel as well. Unless its the different additives that are responsible.
Before giving up, here I am again on 100% diesel. Replaced the upper generator-jet pair and the lantern's back to normal. No brass or copper gauze inside the generator this time. No flames around the mantle or any pulsations so far. I didn't check the earlier generator or the jet nozzle. Maybe it was a little leaky, which could also adversely affect the air draw and fuel-air mixing in the J-tube mixing chamber.(at least that's what I'd hope that actually happened).
