Hi guys, jeeze, it's my hippo 502 auto, it's been AMAZING, top quality, performance etc, until the last light up. Lit it, perfect, then after about 15 mins, it went very dull with flames appeared around the mantle, a butterfly mantle , same 1's I've used for years, it still holds pressure when like this. I've stripped it, cleaned it, replaced the vaporizer, the rod, needle, nipple, mantle, new fuel, re lit it , going great then the same happened again, clearences etc are all perfect, I AM PROPER STUMPED ..... HELP
Sorry Jeff, what do you mean by the jet ? The vaporizer rod ? The needle ? The burner tube ? I've had it apart again, back together, taking my time, it's still doing the same thing
@Burkster Jeff is referring to the nipple at the top of the generator that has the very small hole (jet) through which the vapourised fuel emerges. If it is loose, you will get all kinds of problems. In this diagram it is Part 50: Cheers Tony
Yup but not after 15 min. Seems to be a pressure or heat related problem. Or dirt in the fuel which get trapped in the valve or jet (> cleaning needle). or a too small mantle which causes lack of heat. Pictures may also help. How does the mantle shape looks like?
Also check that you're not having a back-burn in the J or U-mixing tube. If this happens, you'd get a red glowing J-tube and some rather loud growling noise. The light would be drastically dimmed and eventually, yellow flames and soot will start to appear around the mantle.
Fettling a lantern to full working order is often a process of elimination and all of the advice in the previous posts is correct. I have had jets enlarge when the lantern is working and sometimes the whole nipple can loosen while the lantern working.
Yes Myn, that's exactly what was happening, it's all sorted now, I've got this lamp running like a song . Thanks
There are various ways, depending on the condition of the lantern. Check that the burner cap doesn't have overly large holes or breakages. The fount pressure should not be too low or the fuel-air velocity will get reduced too much to the point of possibly triggering a back burn. Less obvious, the back burn might be sorted out by replacing the J-tube. There are other reasons too. What have you done to rectify the problem in yours?
Myn, I’m not experiencing the issue, I’m new to the hobby and just hoping to learn. The OP seemed to had already addressed most of the causes you mentioned but to no avail. So, that left me wondering what was wrong.
So what did you do to prevent it from happening again? Main reason for back burning is "drop of pressure" due to a blocked jet > hence there is a cleaning needle. But also people try to dim a lantern with the needle which also blocks the jet off coarse.
@Briar As long as you continue to collect, refurbish and fettle old lamps and lanterns, it will just be a matter of time before you encounter one having this issue. One of the key points would be to ensure unimpeded fuel-air flows in the mixing chamber. As mentioned, low pressures and partially obstructed jets/gas tip orifices can lead to lower mass-flowrates of the fuel-air mixture in the J-tube or mixing chambers/tubes with other geometries. This is one of the more obvious reasons. Poor mass-flows results in too long a residence time in a typically hot J-tube or mixing chamber. If the actual reason isn't due to back-propagation of the flame from the burner, then it can be(less common) from autoignition of an overheated fuel-air mixture. Do be aware that the typical autoignition temperatures for kerosene, jet fuels and diesel is only around 210-220°C. Gasoline's autoignition temperature is somewhat higher at around 280°C. Since the mixing chambers are usually located under the lantern hoods, they are easily heated well beyond those temperatures. To avoid autoignition of the fuel-air mixture, you need to prevent them having excessively long residence times in there. Having very long mixing chambers or too wide an air gap between the jet and J-tube can also reduce the average flowrates of the fuel-air mix. This increases the chances of the mixture picking up too much thermal energy along the way before reaching the burner caps. Anyway, user experiences might differ quite significantly and the same goes for the exact reasons or root causes.
