Hi all. Yesterday, I used my Petromax 829B ("Bundeseingentum", 1960) for longer period of time, circa 2 hours. The lamp worked OK, but then the light started to pulse slightly, at which time I switched the lamp off. I wonder what may be the reason for this behavior - possibly overheating? The lamp was pretty hot, I guess its temperature was about 50 °C. Thanks.
Hi, from my impression the pressure may have gone low which may have caused the lantern to "pulse". When that happens, the amount of liquid fuel inside the upper part of the vapourizer suddenly starts to boil over and significantly increases the pressure in that part. Following, the pressure releases towards the jet, but also towards the tank, pressing back hot liquid fuel. When the pressure has dropped enough, fuel begins to raise inside the vaporizer again and the cycle starts once more. Because of the amount of hot liquid fuel being pressed back into the tank again and again it starts to get hot. The root cause for that behaviour may be difficult to determine, but some particular lanterns seem to enjoy pretty much doing that. What in my opinion helps best is to put in some brass gauze into the upper part of the vapourizer, which -due to the increased surface- prevents the fuel from suddenly boiling over. Sometimes the fuel valve (located at the bottom of the vapourizer) may be defective, and I also had lanterns that behaved better with a larger mantle or a different brand of fuel. Good luck with your lantern, Martin
Thanks for your suggestions. Would it be possible to use thin copper wires from electric cable instead of the brass gauze? I noticed Pelam sells something like brass mesh (IIRC, it is included in ethanol conversion kit), but I wonder if it is worth the hassle/expenses. Another thing I have handy is steel wool. The lamp is not exactly NOS, in fact, I had to put it apart and clean it with carburettor cleaner and very fine emery paper, but considering its price (some 35 €), I am happy with it. I also appreciate somewhat "dieselpunk" looks of its matt finish.
I wouldn't suggest to put in anything that has loose wires (like cable cores or steel wool) because there is the risk that parts of it come loose and will block the jet. After all it is no big issue to put in some brass mesh, but of course you'll have to get it at hand first. And the success will convince you.
The usual reasons are a lack of pressure or lack of fuel or both or carbon has built up on the pricker rod and it's affecting the flow of the fuel and air.
Thanks for your input. I refilled the lamp with "lamp oil", which does not have the distinct smell of kerosene and works nicely in ordinary wick lamps. The lamp worked a treat when pumped slightly above the red line. It may be that the pressure gauge shows higher pressure. Also, it seems the lamp does not overheat anymore with this kind of fuel. I will leave it as it is (if it ain't broke, don't fix it) and see what happens next.
@Bitzer I'm not sure what "lamp oil" is in your country, but be careful running that lantern on something that isn't (very close to) pure kerosene. You may end up clogging your vapouriser (generator) and jet. Best regards Tony
Well, it says on the label that it is "oil distillate, light fraction". It is clear, odorless and, unlike the standard hadware store kerosene, it also burns odorless in my wick lamps. I tried it because I was short of kerosene.
I have checked the web sites of some of the 'lamp oil' I've used in the UK, generally seems to be refined paraffin / kerosene
hhhmm, what about the first suggestion of Martin ? Just pump the pressure up with some pump strokes. Especially with a completely filled tank the pressure can drop faster then you think. Air volume above the fuel is small.
Don't ever use copper in or near a lamp geneator. If copper is heated enough it oxidises quickly and sheds thick black flakes which will choke the fuel/gas flow. In normal use most lamp generators don't get hot enough but it is borderline so better avoided. ::Neil::
Here, lampoil is expected to contain wax, wich is good for wick-lamps but will clogg carburators in a pressure lamp. I would not recommend this.
