Hi I wondered if anyone can tell me why these lamps need such an unholy amount of pressure to operate , the figures seem mind boggling, I am a bit of a noob with lamps, I was until recently more of a vintage blow torch collector, any reply’s would be greatly appreciated
@Thomas1 I don’t believe they require pressurising any more than blowlamps or stoves do. Take for instance an Optimus 155 paraffin stove and its 1550 lamp stablemate. They’re equipped with the same tank filler cap incorporating a pressure gauge and the working pressures are the same. Neither do paraffin stoves require greater pressurisation than blowlamps. They both commonly have a jet with an orifice of 0.32mm and require similar working pressures in their tank. If your hypothesis were true lamp tanks would require much more substantial construction as pressure vessels than those on blowlamps or stoves, but they don’t. HERE and HERE are the same fuel tanks in use on ‘convertible’ stoves/lamps, same working pressures for each role. John
I do have a HC firefly and mines works at full throttle at 60 psi, I’ve heard other pushing 80 psi but these lantern/lamps at 25 psi they aren’t very bright. Here is mine (lamp head that I built using a recycled propane tank and runs on kerosene) at 60 psi with a shade, without it you need sunglasses or welder’s hat
@presscall cool @Pancholoco1911 that is cool @Thomas1 here is a picture which shows the size of one of the HC burners, thanks to D. Durdin & T. Garner I just had a look at the website, very reasonable for handmade lantern parts imho
My Lighting Bug lantern seems to perform better at high pressure, when it drops down to around 30psi it needs the cleaning lever spun frequently, I now start it at 70psi and use a handheld electric pump or a foot operated bicycle pump to pressurize it. It consumes a lot of kero running, but throws a lot of light, with the reflector on it I hang it in my non-electric barn when I'm working in there on a tractor or what not.
@Thomas1 I'm not sure if I'm understanding your question correctly. I would think the reason is a little technical. Accordingly, HC recommends 40psi or higher operating pressure for better results. Most other pressure lamps operate at around 30psi by 'normal standards'. Assuming you're referring to the HC Lightning Bug, 2 x 500cp /1000cp lantern, I'd like to ask anyone here what is its jet or gas tip orifice size? A single 500cp lantern jet orifice size is around 0.24mm(eg.; Petromax 829). The light output during operation would in a sense, be proportional to the amount of fuel consumed by complete combustion, hence its flowrate through the orifce. The fuel flowrate through the orifice is proportional to the square of its radius. A 1000cp kerosene lantern might then require a jet with an orifice of about 0.34mm diametre to approach its rated output, assuming you're operating it at around 2bar(30psi). Now, if the HC Lightning Bug does not have a jet orifice diametre as large as the above, then in principle, it'd require a higher operating pressure to deliver the necessary amount of fuel to the burner via its orifice. It has 2 burners rated 500cp each. I suppose you might use any suitable mantles like the Peerless 24A or equivalent for those. I won't elaborate the actual relationships between the operating variables and the flowrate but you can go through the following link to get the basic idea: Nozzle Pressure, Orifice Diameter, and Flowrate I'm not sure what would be the full-load operating pressure difference between the inlet of the jet orifice and its outlet. That'd largely depend on the fuel pressure in the fount/vaporizer inlet minus the resultant back pressure due to fuel vaporization/expansion and that of the surrounding atmosphere. But whatever that is, you'd require a fount pressure to push the necessary amount of fuel through the orifice in order to produce a full, 2 x 500cp output. According to basic principles, a higher inlet pressure would be needed to make up for a jet orifice size that might not produce the required fuel flowrate at reduced pressures.
80 psi is nearly 3x the pressure of a car tyre, ( the little cars we have in Europe anyway) and just seems like a massive amount to me, like I say I’m new to the world of lamps but as you and the other nice folk on this forum have explained it is a large lamp that burns a lot of fuel to achieve the high brightness, TBH I’m blown away by the amount of replies I have received so quickly, thanks again guys
Also can anyone pls tell me how to start a message with another members name i.e @Joe Bloggs ( in blue and underlined) thanks,
80psi isn't surprising. Increasing the operating pressure does not increase the flowrate or output very much. That's because the fuel flowrate would increase only at a rate proportional to the square-root of the pressure difference between the inlet and outlet of the gas tip or jet orifice. What is the gas tip or jet orifice diameter of the Lightning Bug? By working out the relationship provided by the link, and comparing it with those single 500cp jet sizes, you'd pretty much know why such a seemingly big increase in the operating pressure of the Lightning Bug is required.
@MYN It would still increase the velocity of the fuel due to the venturi effect just passing through the jet, faster moving vapors allows more air to be drawn through the air tube and mixing chamber for a hotter burn, which we know mantles glow from the heat, not by the actions of the flame. This means the higher temperature from the air rich flame will result in increased brightness.
@Dashwood Agreed on that effect. I do not know the jet orifice size of the Lightning Bug. If anyone has that info, it'd be great to share it. I'm guessing the orifice has a cross sectional area that's less than twice that of a 500cp jet to allow doubling of the fuel flowrate to produce the 2 x 500cp output at the usual 30psi or so fount pressure. Instead, they designed it to operate at a higher pressure to make up the required flowrate. There could be other reasons behind the higher pressure besides increasing the flowrate. I suppose, by using a smaller orifice instead of doubling a 500cp orifice plus operating at higher pressures would also create higher fuel exit velocities to draw in more combustion air without increasing the air gap too much.
@Thomas1 my HC lightning bug needs 5bar=70psi for full 1000cp, operating with petroleum/kerosene. Below 2,5bar=35psi it simply doesn't work at all. That's the reason, why I wasn't able to start it with the optional hand pump. Instead I use a bicycle pump. Maybe it would nicely work with lower pressure, when in use with Benzin/petrol. I didn't test, but have the optional vapourizer as spare part. Who doesn't believe, the HC throws 1000cp, look here. Lightning bug on the left.
MYN I would ask for the jet sizes on these but the generator do not use any packing material, is just the generator tube, rod for holding the needle and the jet.
@MYN I got the answer from Mr Wilson and the jet orifices are 0.0091 for kerosene and 0.010 for gasoline and these numbers came directly from Aaron
Thank you @Pancho Just like what I would expect. It is just slightly larger than a regular 500cp gas tip for both kero and gasoline. At 30psi fount pressure the Lightning Bug gas tip would never be able get the required amount of fuel to produce 1000cp. That explains the necessity of using the much higher pressure range.
A 236 generator has an orifice of 0.0095” and is not near that bright. My Petromax 523 it’s way brighter than a 236 but not as bright as my HC head
The Petromax 500HK lanterns like the 829 and 523 should have orifices with around 0.24mm or 0.00945" in diameter. Not much difference in orifice diametre compared to the Coleman 236 gas tip/jet. Difference is the fuel. Kerosene on the Petromax while gasoline or Coleman Fuel, light naphtha on the Coleman 236. Odd that they are both rated around 500cp. Even odder, 1cp should be around 1.0869565217HK. So a 500HK lantern should only be around 460cp??? But the outputs indicate otherwise . I would expect the Petromax 523 or 829 running on kero to be brighter than the Coleman 236 on Coleman Fuel. Technically, the heat energy being liberated from an operating Petromax 523 (with kero) would certainly be higher than the Coleman 236 (with gasoline/Coleman Fuel), due to the above. Similarly, a kerosene-fueled Coleman 237 with a 0.0085"(0.2159mm) gas tip orifice is rated at 500cp. That's still smaller than the Petromax 523 or 829 with 0.24mm orifices. Therefore, in theory alone, these Petromax lanterns would be having higher fuel throughputs and CP outputs than the Coleman 237. The HC, on the other hand, would be on a totally different league in terms of output. So, not a fair comparison with any of the 500cp lanterns.
I have the 237 too and it’s pretty dim compared to any Petromax or clone rated at 500cp. Coleman rated the 236 and 237 to 500CP and I believe the 635 it’s rated 550 cp not sure on that but I wouldn’t trust Coleman. my brightest lanterns are the Petromax(es) with a 625 lighthouse mantle. It’s interesting how these Coleman are rated and not even close to being that bright as a Petromax in the same category. I’ll measure the intake tube in my HC head tomorrow and post it here. The burner is huge and very well build to last a lifetime or more
Those valves and fittings on the HC seem to be made with similar constructional built as oil-hydraulic parts used in industrial fluid power applications. Certainly everything on it would have much higher pressure ratings than other pressure lamps. The fuel actual flowrate at any specific operating pressure would basically be limited by the smallest opening in the fuel path, namely, the jet orifice. It can be quite accurately measured or rather, indirectly calculated by the amount of fuel being used up and remaining in the fount after a predetermined time (say one hour, etc) while keeping the fount pressure constant by some means and operating the lantern at full blast.
Interesting: what outputs? I mean if you compare a singe mantle wwith a double mantle lantern, by eye. You will be fooled by nature. A luxmeter at a distance of 1m would be more valid.
Not with the double mantle 2 x 500cp HC lantern. I literally mean comparing the supposedly stated output ratings of the Petromax 500HK and the Coleman 236/237's 500/550cp. That's to basically say, the Petromax 523 or 829's 500HK should equal roughly 460cp. Bearing in mind it has a 0.24mm jet orifice. The Coleman 236 and 237 have a 0.0095"(0.2413mm) and 0.0085"(0.2159mm) jet orifices respectively. Both having stated output ratings of 500/550cp. If comparing just with kero-fueled units, then it'd turn out to be Petromax 523 (assuming 460cp) vs Coleman 237 (550cp). That'd be rather contradictory to their jet orifice sizes.
