Hi everyone, anyone with experience with Petromax who can give me some advice? My 829 starts without any problems, no smell, but after a while, when it finishes warming up, the light turns yellowish. What could be happening?
It can quite a few things. Fuel partially blocked by dirt, cleaning needle or something else, insufficient effective pressure, vaporizer dirty, poor fuel-air mixing, unnoticed fuel leakage, inadequate preheat, insufficient air, etc. Make sure all the parts belong to or are rated for the 829. A wrong jet or gas tip can puzzle and mislead anyone for quite awhile . When it had just started up after preheating, was it brighter than later-on? Or was it instantly not as bright as what you'd expect immediately upon startup? How did it go later. Did you increase the pressure? Some might require a while for everything to heat up and stabilize. You'd need to describe the problem with more details and any attempts to increase its brightness. That'd help others to diagnose the problem with better clarity. Pictures might help too.
I can add: - operator error: a lot of people still thing the lamp can be dimmed by the knob, - wrong size/shape mantle, - wrong fuel - your first petromax lantern?
Thank you MYN and WimVe. The lantern starts with very good light, after some minutes start going yellow. There are no leaks and the the lantern keep the pressure. This lantern is with me about some years. In the past had some leaks and smell so I change the vaporizer, some way starts this failure, may be the vaporizer? It seems to be the same, but...
@Leonardo Collares These vaporizer coke more or less quickly. They must be cleaned with a bicycle cable and a small screwdriver.Heating and quenching them several times can also help for remove the coke. Your first vaporizer is probably just clogged.
@Leonardo Collares From first impression, it seems that the mantle heat couldn't sustain the vaporization of the fuel. But it can also be due to other things. From what you mentioned, the lantern started up fine with bright light after the preheat. Is this being repeated for every startup? Do you mean the lantern only behaves in such a way after you replaced the vaporizer? It was actually working fine before that? Or was it only after a while using the new vaporizer? I suppose the vaporizer is new and not a used unit? It needs to be clean. A typical 500hk Petromax runs pretty hot. Sometimes, you might even find that the loop on the vaporizer turning slightly red during full operation. Such high heat can coke up kerosene easily. The coke would eventually build up to the extent that heat conduction from the vaporizer wall to the fuel becomes seriously impaired. It can also be the mantle is too slim or far from the vaporizer. Also observe and check the J-mixing tube under the hood during operation. It should not be glowing red. Sometimes the fuel-air mixture starts combusting inside the J-tube, especially when it gets hotter. This will also cause the mantle to eventually dim down after a few minutes.
You're all very kind. I'll start by thoroughly cleaning the vaporizer because it's used. Send you some photos, it is a 350 hk.
It is not so easy to tell from the photos if the lantern is at full brightness or not...due to different camera's automatic brightness and colour rendering/adjustments. That's especially when exposed to an intense mantle glow. Is that after or before cleaning the vaporizer?
This is before the cleaning, the lantern was much brighter before the vaporizer change, but it had a leak in the base and in the nozzle adjustment, so I change it. I canibalize a chinese copy but the result is not the same. There is not smell but the ligth is significantly poor.
Normally, provided everything is clean, changing the Preston loop vaporizer from a non-Petromax clone won't affect the brightness to any appreciable degree if done correctly. Example, I have, in the past, actually used a vaporizer from a Butterfly on a genuine Petromax lantern that's missing its vaporizer. Not all of them have exactly the correct lenghts to match the original. You need to make some adjustments so that the cleaning needle height and rod length is correct and could function properly to both open up the footvalve as well as to clean the jet/gas tip orifice. Care should be taken so that the lowered needle during operation isn't partially obstructing fuel flow in anyway. It must be fully retracted slightly below the conical inlet behind the jet orifice. You can test it by discharging fuel when cold. The kerosene fuel should be discharged in a thin, sharp stream vertically upwards. Otherwise, it is guaranteed to impair performance if you're not extra careful about it. However, I don't think the above really explains what you are currently facing. What you're having is a seemingly perfect startup and brightness but it eventually dims within several minutes. Besides basic cleaning, do check what had been mentioned before by others and myself. By the way, at what pressure are you running the lantern? If you're preheating using the rapid torch, the pressure would drop quickly. You need to pump it up again, preferably to a pressure between 2 to 3 bar for satisfactory brightness. Make sure the J-mixing tube isn't glowing red after some minutes into the operation. Do come back as you progress with what you'd be doing with it. Goodluck.
Thank you very much MYN, the "new" vaporizer is from a used lamp, is not new. I take some measurements and is identical. I take care of the correct funcion of the needle and the bottom valve. The vaporizer was at first sight clean but I will check. I am using the torch to start it. The new thing for me is the working pressure, I never presurize it above the red mark, I belive is in 2kg, and normaly operating between 1 and 1,5 kg, may be this is one of the problems
Other than during rapid torch startups, 1 to 1.5 bar is a little low for sustained operation of the Petromax 829. Many smaller lanterns would work satisfactorily with such lower pressure range, especially when some self heating of the fount is already ensured after a while. If the vaporizer is used, it might have a lot of carbon or hard coke inside the loop section which cannot be seen. Other than using a steel brake cable for cleaning, there's also something called the heat-and-quench method for extra stubbon coke build-up. The latter needs to be done very carefully to avoid permanent damage, braze failure or melting of the brass vaporizer.
Have you checked the gap/space between the top of the vapourizer and the opening in the "U" shape breather/burner tube ? They tend to loosen up after repeated lighting/heat cycles , if it's adjustable there should be a set screw under the hood , if I recall the space should be approx 12cm , is the orifice tip on the vapourizer tight , ceramic burner cap screwed on tight ?
Thank you both, the vaporizer is clean. Finaly I presurize it at 2 kg and the light is better. For now I am satisfied, send you some photos, best regards
Congratulations. It looks a lot brighter than before in the pictures. Sometimes, you'd be surprised by the amount of carbon that could be found inside an old vaporizer. Was it very dirty inside?
Just a remark: the red line at 2bar is not more then an indicator. The whole concept of the pressure gauge is: Indicator. To check the correct pressure, use the gas lighter can method (search function).
