Before lighting, I was checking the tightness of everything on the 500Cp Wenzel when the clay burner fell out of the mixing chamber. This due to it being cracked in a multiple places. Fortunately it didn't happen while in operation. The lantern had been run probably a total of 20 hours in the last week. The lantern when I got it had never been unpacked, but I have no idea how long it may have been sitting. I did go through it after I got it and replaced the seals as there was some leakage of pressure. Other than some pulsing, it seems to run pretty well. I'm sure I can get some answers from those here that have much more experience than I have. 1) Do the clay burners deteriorate with age and is this a rare or common occurrence? 2) What is the maximum pressure that these type of lanterns should be operated at? I was running the lantern past the red line at about 2 bar, the night before. I found that the pulsing was reduced at that pressure and I could go longer without re-pressurizing. Of course there was a lot more heat. Could that be the cause? 3) I want to order some spares. What is best for replacement? I read on the forums that the Stainless Steel ones can have trouble with expansion and mantle failure. Thanks in advance, your help is much appreciated. Paul
Well to start with the last one: stainless is a marketing trick. 2) it is always believed that the red line is the operating pressure but the measuring devices are not calibrated so they are more indicators. 1) normally clay heads last long and mostly fail due to operator error. In transport and use they can get a loose fitting and should be checked. A little exhaust kit will help to keep it in place, or a piece of mantle string, tin copper, alu foil.
@Paul R An operating pressure of 2bar is about normal in these types of pressure lanterns, but as Wim says, the gauges may not be accurate. George Lahde in his seminal book "Light and Heat from Hydrocarbon Appliances" writes about the pressure gage filler cap combination: "This combination was patented in Germany in the 1930s. Because of its smallness the gage is not as accurate as larger gages are. It is, however, possible by careful manufacturing to obtain a fair degree of accuracy in the range of operating pressure. The latter is marked by a red line on the dial". (Lahde, 2000 p89). Elsewhere in his book Lahde says of Petromax lanterns: "The operating pressure is practically always between 25 to 30 lbs/inch (or 1 3/4 to 2 atmospheres). While it is possible to use a higher operating pressure this has been rarely done and today's lanterns are all built for standard pressure". Cheers Tony
@Tony Press Thanks for the reference on the recommended pressure. So I doubt that over pressurization was the cause of the burner failure...unless of course, my gauge is off by a good amount. Since I can pressurize with a Schrader valve, I will verify accuracy with a tire gauge. @WimVe Before running the lantern, I do remove the top and check for tightness of the burner and J-tube adjustment. I have seen how the heat has an effect on these things. I have some exhaust sealer, I've put some on the threads of the replacement burner(a good used, German made one, removed from the Petromax) and on the flange where it mates with the mixing chamber, wiping off the excess. Thanks for your input. Paul
I do not recommend a "Schräder" valve. First it is not original and not intended to be used. Secundo: you do not "feel" if the valve works ok. A good functioning valve has a typical sound as well as air release. You can check the gauge with a bottle of gas lighter fuel. These have a 2bar filling and with the right adapter (often different shapes are in the cap), you can press the gas canister against the small hole in the gauge. Off coarse all be done outside and no open fire in the neighbourhood.
@WimVe I think maybe you misunderstood my use of the Schradrer valve. I used it to pressurize the Wenzel lantern. In the Petromax the pump works pretty well. However in this Wenzel, even with a new leather and bottom valve(#10) assembly the pump is awful, especially once the lantern fount gets warm. The new leather seemed to be of poor quality, somewhat thinner than the original. I'll try another supplier to get a better one. This is why I removed the pump and used the Schrader valve along with a small battery powered compressor to pressurize it. The compressor has a pressure gauge on it that can be monitored while pressurizing the lantern. Of course the accuracy of that gauge could also be off. last night, while laying in bed, waiting to fall asleep, I gave some thought as to my idea of checking the pressure at the Schrader valve, either with a tire gauge or the gauge on the compressor while pressurizing. I realized that neither of these options would work. In order to open the bottom valve and allow air to pass through, the pressure from the pump has to exceed that held the fount. This being the case, the pressure in the pump tube, while pressurizing, will always register higher than what is actually in the fount. Interesting idea, using lighter gas. I do have a couple of cans here. I will give that method a try. Thanks again for the tip and have a great day, Paul
