I just restored a very mistreated Petromax 829 super rapid, and lit it for the first time, new pricker, new foot valve, new pump leather and spreader, new lead gaskets, thoroughly clean with denatured alcohol and shined as best I could, it started right up, no soot, maybe I need to adjust the distance between the jet and the "U" on the mantle section, but it startled me a little that when I cleaned the jet ( turned the knob once) it flared up alarmingly, turned it off, started it again, and after maybe five minutes of use I turned the tip cleaner again, and again a big flare...is it normal?...or I may need to adjust/replace something else? Here is the patient:
Flaring up is usually a sign for paraffin that is liquid and not vaporised, so the reason might be, that the vapouriser doesn't get hot enough. On a paraffin Petromax the vapouriser has a loop at the top to heat the paraffin. It could be that something blocks the loop and the fuel doesn't get hot enough, you can use a bowden cable to clean the loop. Another reason could be that the wrong vapouriser is fitted, there are petrol ones from the swiss army that don't have a loop. It isn't clear on the photo. Did you run the lamp without the globe? What temperatures are where you live? Maybe it's just too cold outside to get the vapouriser hot enough without the globe. Strange is that the flaring occurs when turning the wheel to clean the jet.
It could be something to do with the pricker-rod going through a 'tube' which effectively short-circuits the Preston ring. If the walls of the channel are worn, then maybe moving the pricker-rod up and down allows liquid kerosene to by-pass the loop and get to the burner. I'm only guessing, but it's a possibility I suppose...
I have been thinking, that the foot check valve may not be the right one, the old one was hexagonal, and the new one is cylindrical, it is possible the new foot valve is acting like a pump and pushing raw fuel up the Preston ring, just like a syringe...causing the "flare up", I will change it for the old one and see what happens. If that is the case, I may need to find a new one of the right shape.
Try it without the foot valve. It is a semi redundant feature anyway and the lamp will work fine without it. If removing th evalve does not cure then you know that was not the problem. Oh yes and please show us the generator. ::Neil::
Without the foot valve I will have an "always on" condition,without the possibility to properly pressurize it and light it at the same time, not safe. I will take it apart tomorrow and see, just came back from work and the tribe demands my attention..hehehe.
Nonesense. It's a kero lantern and they don't need a contol valve. I grant you it is handy when you want to use a blow torch pre heater. There is no valve in a Bialaddin and older Optimus don't have one either and they work perfectly well. You don't need pressure to light it. Use the alcohol pre heater and only add pressure when you have the generator heated. In fact a lot of well used Petromax lanterns have the valve but it no longer works right because the seal has worn and they work perfectly well. ::Neil::
I have a five pound Halon fire extinguisher, aircraft fire rated, as well as a Dry chemical powder in the living room, a CO2 fire extinguisher in the garage, and another dry chemical powder in the laundry room...I just hope I do not need them......
Good to see one repaired. But do you understand how it works ? (sorry I have to ask) The cleaning system operates a needle this "blocks" the jet for the time you need to operate it. It is normal that you see a flare when you are not fast enough. No reason to blaim the foot valve. When it shuts off the fuel when closed during pumping it functions.
I do understand how it works, the wheel moves the excentric block, the excentric block moves the foot valve stem, which is connected to the cleaner tip in a linear fashion, in this case the new foot valve is of a round shape ( view from above) instead of a hexagonal ( view from above) like the old one, the surface area is bigger than the original and when I use the tip cleaner, it is supposed to close the foot valve, which in this case pushes up fuel into the generator because of the bigger (rounder/ less space between the valve and the walls of the tube) surface area, the fuel can not go around the valve and is forced up stream, the flare is big, almost as if the mantle is flooded with fuel, and there is a gurgling sound simultaneously as I move the tip cleaner... I will test it again as soon as I get more mantles.
Hi WN Before you use a lot of mantles I might suggest you (if not already done) to take of the top-hood and the innerhood. Then pump pressure on the tank with the control-cock in "closed" position. Then observe what happens. The cleaning-needle should now be in top and you should be able to see app. 0,5 mm sticking out. The needles hole should now be fluidproof. If it constantly drips you might have at needle in too small. When you turn the control-cock to open, the needle goes down and you should get a thin fine jet up in the air where it will vaporise. If that works there is a "hole through the system" and no matter the bottomvalve your lamp should work. If it doesent the there is a adjustmentpossibility in the U-shaped vapouriser leading to the burner. How to adjust it, you must ask for technical information here on CPL for the messures belonging to your lamp. The last thing I think of is if the tube where the needles thin brass-stick is inside, might be full of old glass-like soot. This tube is worth cleaning and you can use amonium for that, it will clean it of quickly. Amonium destroys brass if you leave it in for hours, not minutes and afterwords you have to clean the tube with ex. vinegar and dishwater. The tube can be so clogged that only the needle-stick can move and the heated kerosine cant. It is difficult when one dont have the lamp in the lap but I hope some of this will come in usefull for you. Good Luck. The Petromax is normally an uncomplicated hardy lamp. Claus C
Graham is correct, I always run a test without a mantle fitted on 'new' (as in 'old but latest arrival at mia casa' ) Pmaxes and their clones. Infact, a lantern is a small "stove" that heats up the mantle to make it 'shine'. Running a Pmax or similar sans mantle should produce nice bleu flamelettes. Yellow tips or erratic burning means 'back to the shed for more fettling' , but at least one doesn't waste a good mantle . Best regards, Wim
hhmm, I don't think the foot valve seal will "push up" any amount of fuel. When hot the pressure in the vaporizer will be high and seek the easiest way out: the nozzle. Claus suggestion of cold test is a very good one. You can test the basic function of the petromax principle. Besides a major unseen problem I guess that you "needle" to slow. So the blockage of fuel support is to long, gas flow in the u-tube drops and flame follows backwards. A gurgling sound and a flame blasting backwards means normally there is not enough gas flow and needling must be done or the pressure in the tank is too low. This happens also for a short time when letting the lantern burn all the fuel. Pressure drops gradually and a fragile pressure balance is broken. The opposite is releasing the pressure with the knob on the gauge. Then pressure drops fast and flame will not follow backwards. (most of the time ;-) Btw: the best valves are the old round ones with the copper "tit"in the middle where the rod pushes onto.
Ok, I did a full teardown on the lantern, cleaned the brass parts with Carb cleaner ( it let the parts shiny) inside and out, made sure the J tube is at 14.2mm from the jet , I had to fabricate a gauge with stainless steel at work, I am keeping it, changed tip cleaner for a new one, made sure the tip cleaner protrudes .5 mm from the jet, it was interesting that there was a lot of foul smelling residue coming from the Preston loop as well as a lot of carbon residue, after a "dunk test" and making sure there was no leaks under 2 bar pressure in the fount, warmed up five minutes before rotating tip cleaner, no flare up,no gurgling sound, it is blinding bright, here is a picture from the lantern in action. Currently going for two and a half hours with a drop of .5 bar fount pressure, looks quite good. My assumption that the foot valve was the culprit was unfounded, with pressure in the fount during rotation there was a definite high fuel stream while open, and no fuel leak while closed, did that several times and there was no appreciable increase in "height" of the fuel stream. PS according to the person who sold it to me, it was in a garage at a house near the beach in Barranco, Peru for more than thirty years, and he remembers using it in the eighties when blackouts were frequent.
A good clean often does the trick! As collectors we are mostly dealing with used lamps and a point to remember is that we do not know what fuels have been used in those lamps before we obtained them. That's an excellent lantern and I use one in my shed, Jeff.
I haven't kept a tab, but on one liter of jet fuel I am getting around seven hours of light, is that average?
