Pressure lamps: gaslighting on the go
Here’s a package from Amazon. Here’s a Geiger counter. [Geiger counter clicks ferociously] Neat! Well now, it’s time we finish up talking about the light sources of old which make their light by burning stuff. We last talked about gas mantles and a bit about the towngas industry. You can check that video out with the links I put in the places. Like that one.
Or the description. Maybe even a pinned comment. Ya know it really forces my lute when people don’t read pinned comments. Anyway, I teased that we’re gonna talk about these things.
These Coleman lanterns, as we often call them over here, are a kind of pressure lamp. Other parts of the world might call them something else, like Tilley. Or Petromax. Or Reginald.
Remember that we need to burn a fuel with a Bunsen flame to make use of a gas mantle, and that means we need the fuel to be a gas. Coal gas, natural gas, and propane at atmospheric pressure are all vapors so… job done. But if you want to carry your gaslight around with you, and it's before the days that bottle propane was available, you’ll want to use a liquid fuel like kerosene or gasoline for their greater energy density. And now you have a problem. Several, actually.
First, how do you deliver fuel to where it needs to be burned? A gravity-fed fuel tank is an incredibly bad idea here because of how hot these lanterns get. Don’t put the fuel above the fire, is what I’m saying. But liquid fuel won’t just find its way up a tube without a little help. So, we’ll give it a little help. These are called pressure lamps because using them is anxiety-induc - Wait. That’s not quite true.
They are pretty anxiety-inducing, actually - especially this one, but - they’re called pressure lamps because they have a pumpy bit which is very fun. The fuel tanks of these lanterns are sealed. Look at the fuel cap and you’ll see there’s a rubber gasket. Across from the fuel cap is the pumpy bit. To use it, you give the metal piece here a turn in the counterclockwise direction which releases it, hold it so that your thumb covers the little hole on its face, pull it out and start pumping.
What this is doing is forcing air a little bit of air into the tank with each stroke. If I unscrew the fuel cap you can hear it escape. [hissing] The point of doing this is to force the fuel up into the burner.
A pocket of compressed air above the fuel will put a downward force on it, and with the help of a dip-tube collecting fuel from the bottom of the tank, that will result in fuel being delivered to the top. About 30 or so pumps and the lantern is ready to be lit. It helps if you stare at the camera intensely. [stares at the camera, intensely] Then you simply close the pump by turning the stem clockwise, push it in, light a match, and…. I am not lighting this one indoors.
The fuel that's in here is strikingly similar to gasoline, and in fact this model can actually run on standard automotive unleaded fuel. So we’re taking this outside. OK, the tank is under pressure, there’s fuel in it, and we’re ready to go.
To those of you who are used to Petromax and Tilley lamps it’s going to seem like I’ve skipped a step here, but I haven’t. Coleman lanterns have a huge advantage compared to those two thanks to their fuel which I’ll explain shortly. But to light this you simply light a match, stick it into the globe right below the mantle, prepare for calamity, and open the fuel valve. This next part may be interesting. When the lantern is cold, small amounts of liquid fuel are getting shot into the top of the burner. Because this fuel isn’t that far off from gasoline it will vaporize pretty quickly and so we get fire.
But it’s not working quite right, as you can see. It’s sputtering, the mantles aren't very bright at all, and there’s... fire... Like a lot of fire. But after a short period, the thing calms down and the mantles get very very bright. This lantern is significantly brighter than the propane one we saw earlier. This one.
Why is unclear, though I have a theory. So, why did it behave like that at the start? Why didn’t it just light like the propane lantern does? Well, it has to do with the tube traveling up the center of the lantern. That’s what Coleman calls the generator, and it’s a critical piece to the proper function of the lantern. To understand why, we should take this apart. And, through the magic of buying two of them, I have an already-taken-apart one right here! These are really quite simple devices.
Almost astonishingly so. Although the fuel valve does more than you might expect. With the globe, burner, heat shield, collar, all that removed you can see that this is really just a tank with a valve and the generator. At the top of the generator is a small orifice.
This is where the fuel actually comes from. In fact, I’m feeling brave enough to show you that. Just a wee bit of gasoline, no biggie (yes biggie, don’t do this yourself). Now you might think that the valve just lets fuel up into the generator but that’s only the third of it! It also cleans the tip of the generator when you move it back and forth thanks to a clever little pokey contraption inside, and it contains one of Coleman’s signature innovations - the fuel and air valve. That’s why this lantern may seem astonishingly easy to light to some of you out there.
When cold, there's a valve inside the tank that allows some of the pressurized air at the top into the generator. That air has a lot of evaporated fuel in it, so the lantern can actually start running on this fuel-air mixture. But that’s not enough to keep it going. The reason it sputters so much and takes a while to become steady is that the generator needs to get hot before it can do its job. That job? It’s to boil the fuel. Yep! So what if we have a liquid fuel? We can just get it stinking hot and now it’s a vapor just like town gas! The generator travels up right through the center of the two mantles because it uses the intense heat they give off to boil the fuel that’s being pushed into it by the pressure in the tank.
After that point it’s no longer liquid fuel spritzing out of here, but instead a stream of vaporized fuel. Then, push that into the burner through the hole that you can see there, hopefully... and it will combine with fresh air entering from this tube below.
Now you have the perfect flame for making a gas mantle glow nice and bright. Pretty neat, huh? Pressurize the tank to move the fuel into this tube, then boil it to make it a vapor. Simple yet effective. Here’s another example of the same idea. This camping stove has essentially the same exact fuel tank as the lanterns, but look at the generator. Here, it travels over the stove’s burner before bending back down below to supply it with fuel.
The fuel tank sends fuel into the generator from here, then it’s boiled as it passes over the burner, and comes out as a vapor from below. Lighting this stove is a wee bit terrifying as, just like the lanterns, it starts burning a bit of liquid fuel and makes lots of fire. But as that fire heats the generator, the fuel supply becomes purely vapor and we eventually get a clean, blue flame.
Take a listen to what it sounds like as the fuel starts to boil. [whoosh of flame igniting, followed by a hissing and crackling] [crackling diminishes and steady whoosh takes its place] This stove, by the way, is burning actual automotive gasoline. And it should be noted that Coleman made table lamps using this technology, not just lanterns. Compared to the Aladdin lamp this could be considered superior, although there’s a complication which we’ll discuss shortly. Just about the worst part of this approach is the noise.
It’s fairly loud on its brightest setting, with a pronounced whooshing sound. [a pronounced whooshing sound] It’s not that different from an ordinary stove burner, but it’s not quite the same either. Definitely its own noise, probably due to the boiling fuel. Meanwhile the Aladdin lamp is completely silent.
Now of course, this won’t even work without the tank being pressurized, and as the volume of fuel in the tank drops as it’s used up, the pressure in the tank does, too. So periodically you need to get some pumping action going again otherwise the lamps will dim over time. But it’s not something you need to attend to constantly - perhaps every half-hour or so. Even less on lower brightness settings. This also means you need to ensure the fuel cap is tight and also that the gasket isn’t damaged.
In fact you need to make sure everything is tight because with the tank under pressure, leaks will happen wherever a fitting is loose. Ask me how I know. Alright, so now let’s talk about the fuel these lanterns use. Believe it or not, Coleman’s first lanterns were developed to run on gasoline, but the gasoline of 1903 was very different from gasoline of today.
Also, dates are really fuzzy because deciding what Coleman’s “first” lantern even is could be arguable. But anyway, back then gasoline was considered this weird byproduct of kerosene production (which remember you may know as paraffin). Kerosene was the fuel everybody used for everything, and this gasoline barely had any market yet. Over time, as we know, we found plenty of uses for this new gasoline, particularly in the internal combustion engine. But lots of different tweaks to it would soon occur. Of course you probably know about the introduction of lead to reduce engine knocking, but even things as simple as different refining methods led to gasoline with very different properties.
Over time, this meant that new gasoline was so different that it was no longer compatible with older stuff, and eventually an old-school formulation was required. And this is that! White gas, which also goes by the names camp fuel, Coleman fuel or simply naphtha (though that term is very, very imprecise in addition to being a mouthful) is basically an antique form of gasoline. The “white” is both literal - it’s perfectly clear and colorless - and is meant to suggest purity. Because this is kinda-sorta what gasoline would be without any additives. Now, could you use it in your car? Uh, no.
It has an octane rating of about 50, so it’s not great for use in any remotely modern combustion engines. Unless you want to tell a knock knock joke. But it’s great for these lanterns. A volatile, high-energy fuel but without any modern fluff. It simply doesn’t need any of that. This model, and other dual-fuel models like it, is able to run on standard automotive gasoline.
And as a matter of fact, most any Coleman lantern *can*, but you’ll notice that the generators are pretty different between these two. The dual-fuel model is better able to tolerate the additives that are found in modern gasoline. I haven’t found what exactly is special about the generator in this lantern, other than being a little bit thicker, but multiple sources suggest that while most Coleman products will function on gasoline the additives significantly reduce their lifespan. But now let’s talk about kerosene. There’s nothing stopping us from using kerosene in a lantern like these, except for the fact that kerosene isn’t the biggest fan of evaporating. Now we’re gonna get to the part that makes Tilley and Petromax lamps so...
fun. Coleman made (and I think continues to, though they’re backordered at the moment) lanterns that run on kerosene. Here is one such lantern. Now, this is, without a doubt, the least user-friendly product I have ever experienced. I have no idea why these are still made or why you would ever want one over a white gas lantern, unless you had a huge supply of really cheap kerosene or something. For those of you in places where white gas just isn’t much of a thing I suppose this seems normal to you but to my sensibilities… just...
Wow! Let’s now discuss why this is so clunky to use. Here’s the problem with kerosene. It has a high flashpoint and doesn’t evaporate quickly at all. That means the lantern isn’t self-starting like the ones which run on white gas.
And to start it, you need to not only take this apart, but also you’ll need some alcohol onhand. How’s that for convenience, huh? You not only need the fuel it runs on but also a different fuel to start it. Great! However, and here’s what I consider its one advantage, because kerosene isn’t quite as volatile as gasoline, I’m j u s t b a r e l y comfortable using this lantern indoors. That’s 100% not an endorsement to do so, and the product itself is being pretty clear that you shouldn’t, but if this lantern were to leak it’s nowhere near as terrifying as either of these because kerosene isn’t actually all that flammable on its own. Except oh boy can things go wrong if you don’t follow these instructions precisely. The first time I lit this, there was lots of fire.
So, do not use these indoors. The only reason I feel comfortable doing it is because I have lots of practice lighting this now. And also I have a fire extinguisher ready over there… this time. Alright, notice that there’s a little cup thing at the base of the generator. This is the pre-heater cup.
Fill this cup with alcohol, set light to it, and the resulting flame will heat the generator so that it can begin to boil the kerosene. If this sounds fiddly, that’s because oh boy is it! Remove the handle like so [CLANG] which is itself quite fiddly, take the top off, and remove the globe. Now comes the alcohol. You want to fill this cup most of the way full, and be careful not to spill! This looks super easy to pour into, right? Yeah, the main reason my first experience with this lantern was so calamitous was how poorly this went.
Lots of alcohol went where it shouldn’t have. Using a drinking straw or a small syringe makes this much, much easier, especially because you also need to be careful of the mantle. It’s very fragile, remember. Oh, and the reason the cup’s insides look crusty and gross is that I experimented with using hand sanitizer gel and in fact that works! The gelling component just leaves this residue behind, unfortunately.
OK, so you’ve got the alcohol in the cup. Great. Now you can light it.
At first it’s going to burn very slowly and with a dull blue flame and in fact you may need to re-light it. But once you know that it's for sure gonna stay lit, you can reassemble the lantern. If you haven’t already done so, now you can start pumping to pressurize the tank, though you may want to wait a bit if you filled the cup to the brim. And now, and this is very important, YOU WAIT. You must wait.
If you open this valve too early you will get liquid kerosene coming out of the generator, and it will hit the top of the burner and fall back down into the mantle and out onto the valve itself through the air intake. Ask me how I know. As the alcohol heats up it will eventually start boiling - you can see that happening on the surface - and the flame will become pretty intense, occasionally making it out the top of the lantern.
Still though, you wait. Specifically, you wait until nearly all of the alcohol has burned away. This sounds so easy to do in an emergency, right‽ Anyway, once the alcohol is nearly gone it’s safe to assume the generator is hot enough to boil kerosene and you can open the fuel valve. Vaporized kerosene will be mixed with air and shot into the mantle, and the burning alcohol will provide the source of ignition. And so… [loud whooshing] Now we have light! Quite a lot, too. It's quite a bit larger than the mantle in these so even though we only has one of them this is perfectly bright.
Maybe even a little brighter. And of course, the heat from the mantle will keep the kerosene boiling, so once it’s lit you don’t have to deal with alcohol again. Except for when you need to refuel it. Super convenient! Now I’m being overly harsh on it. I was actually fairly excited at the idea of using this lantern as an emergency light source during power outages (though you’ll definitely need a flashlight to help you get it started) Although it is objectively a terrible user-experience, there is a sort of romantic, ritualistic aspect to using it that I appreciate. And I thought it would combine the best aspects of the Aladdin lamp and Coleman lanterns.
See, I ran gasoline in this lantern and somewhat to my surprise it was entirely odorless. No lawn-mower-engine smell or really anything I could detect. Just how the Aladdin lamp manages to be odorless on kerosene, I figured the Coleman lantern would be, too but… it’s not quite. It’s nowhere near as smelly as the Dietz lanterns, so it’s definitely a more thorough combustion of the fuel, but there is still a smell. In fact you can see from this carbon buildup that the combustion definitely isn’t perfect, although I must admit I don’t know how much of that is normal and how much of that is leftover from some of my previous… mishaps with this lantern.
It’s been burned off in areas closest to the mantle, but it sure looks like it’s still getting worse everywhere else. In any case, the odor wasn’t enough to bother me after a half-hour of use, and in fact I can't smell it yet so it’s at least much more tolerable, and there’s also another quirk going on here. Notice how if I adjust the strength of the flame, the mantle seems to alternate between a cooler and warmer appearance. At its middle intensities the mantle glows a fairly cool white - just about that of a tungsten lamp. But at its full intensity, although it gets a lot brighter it also gets yellower. This is unique to this lantern, neither white gas one does this.
I can only imagine that this is happening because the air fuel mixture is changing and the combustion is becoming more and less complete. And indeed, the amount of odor this thing gives off changes depending on whether or not the mantle appears whiter or yellower, though curiously it seems the odor is stronger when the mantle is a pure white which is the opposite of what I expected. Though I’m honestly not even sure of that. It’s hard to judge the odor because the amount of fuel it burns varies drastically depending on the brightness it’s set to. And it’s always possible that there’s something wrong with this lantern, but I know for certain that this was a brand-new generator when I first used it. I had to run upstairs and came back down and, uh, definitely there is a smell of kerosene down here but it's honestly not terrible.
But anyway, speaking of mantles that look yellow, now let's get to that thing I teased in the beginning. We'll count some Geigers! For many many years, gas mantles used thorium salts as part of their chemical makeup, and thorium is radioactive. Quite a while ago, Coleman and many others decided to move away from thorium-doped mantles and transitioned to the Ytttrium-based mantles that we have now. This bothered some folks, as purportedly the new yttrium mantles produce a duller, yellower light and also aren’t as bright. Some people also claim they’re less durable. I wanted to see how true that is.
While the use of thorium salts in mantles has largely been phased out, it hasn't been entirely. In fact they’ve never been outlawed. If you know where to look you can find them, and actually it's not hard to get your hands on them at all. But interestingly although I was expecting them to be brighter and whiter than what Coleman offers today based on what people have said, I found this isn't necessarily the case. Take a look at this. This lantern has one original thorium-free Coleman mantle on the left, and it has one of these Peerless mantles on the right.
These do in fact have thorium in them, as you can see and hear from the Geiger counter. However, the thorium mantle is not as bright or even as white. And in fact the light looks to be a little bit greenish to me. Why is the thorium mantle not as bright? Well, I think it's because it didn't shrink enough. I mentioned in the last video that mantles don't normally fwoomp like this one did.
In fact the process normally looks like this. The mantle starts out much larger and flatter than it ends up, and as it burns away to leave the ceramic ash behind it shrinks and forms a tubular shape. And the thing is, there's some element of random chance, here. At least that's what it seems like to me.
I've had some Coleman mantles not shrink as much as the one you see here, in fact I think that’s why my propane lantern, which is supposed to be slightly brighter than the dual-fuel model on paper, isn’t. I’ve gone through a few mantles and none of them shrunk as much as they did here. So far every Peerless mantle I've tried has shrunk into this sack-like shape, so it doesn't stay as close to the burner particularly at the bottom and thus it doesn't get as hot. Indeed when I first tried the Peerless mantles, I put them on this second lantern and it was definitely not as bright as this one with new, standard Yttrium mantles.
In fact, they appeared yellower than the Coleman ones! It seemed to me that despite everyone saying yttrium mantles are duller and yellower, quite the opposite was true. And just so you can see... [Geiger counter ticks a bit] These are the thoriated mantles. However, I also found this different style of mantle which is also setting off the Geiger counter so we know it's got some thorium in here. However it's not really meant for Coleman-style lanterns.
They are open at both ends and I had to experiment with tying them up to prevent flames from shooting out the bottom. But here on the propane lantern I did manage to get one attached and it shrinked well. Indeed it is brighter than the other mantle.
And significantly whiter. So turns out this complaint wasn't all hooey. Although, even here I can see that the light is a bit greenish. This is interesting because apparently Welbach’s first gas mantles were very green in appearance and people found it off-putting. It took him a while to develop a mantle which produced a mostly white light, and I wonder if the thorium salts were primarily responsible for that green appearance.
As someone who has always preferred warm white lighting I have to say that I prefer the way the more modern yttrium mantles look anyway, not only because they're a bit warmer but because they don't have that greenish cast. But I think I can understand why phasing out thorium has bothered some people. Though I do think that perhaps the poor experience with the new mantles may have just been teething pains as the new mantles were first developed. Maybe early on they had the same shrinkage problems as this. I want to add that it's not like the risk to the people using the lanterns with thorium mantles is high at all.
In fact you barely need to move the Geiger counter away from the mantles and it's essentially back to background radiation. But, consider the people in the factories that make these. It's probably better if they're not dealing with radioactive materials day in and day out. Supposedly the reason Coleman moved away from thorium mantles is simply that they feared the need to put a radiation warning on their products.
Seeing as how these peerless mantles are available on Amazon and they don't have any sort of radiation warning on the crust, I mean packaging, I don't think that would've panned out, but it's certainly understandable to want to avoid it altogether. And as I said, it's probably better to allow the people who work in the factories that make these to not worry about getting cancer down the road due to handling thorium all day. Those of you who insist on thoriated mantles might want to think about that.
Lastly, let’s talk about the energy efficiency of these lanterns. It’s horrendous! But certainly better than what a Dietz can manage. I’m gonna calculate this for the propane lantern since it’s by far the easiest to do, but I’m sure the others will all be pretty similar.
These propane bottles hold 1 pound of propane. That contains 6.3 kilowatt-hours of energy. Now this lantern will run for about 7 hours on its high setting. So, roughly, it produces a kilowatt of heat on high, and for that you get 810 lumens. That is well less than one lumen per watt.
Incandescent light bulbs are literally more than 10 times as efficient. Even if you want to account for power plant efficiency, way less fuel gets burned to produce light using what are now the least efficient light bulbs. And also, just think about how hot homes with gas lighting must have gotten in the summer.
To get the same light output as a 60 watt light bulb you’d be adding about 600 watts of heat. Imagine summers where every occupied room is running a space heater. That’s basically what we dealt with. Although things do get more complicated specifically with the use-case of camping or backpacking.
Not the energy-efficiency part, these will always be horrendous compared to anything electric. But with the efficiency of light-hours compared to weight and volume. Plus, when camping in cold environments, having a light source which doubles as a heater isn’t necessarily bad.
And that can even be useful in winter power-outages, although honestly of these lanterns really only the propane one feels safe-ish for indoor use. And even it says not to do that. This video’s long enough as it is so I’m gonna end it here, but if you’d like I’ll be discussing this more casually on my second channel Technology Connextras. It may not be out there by the time this video goes live but if it’s there, here’s a card. And if it’s not there, well you could always subscribe and hit the bell! AND DON'T FORGET TO SMASH THAT LIK - ♫ pressurizingly smooth jazz ♫ We last talked about gas mantles and a bit about the towngas industry.
You can check out... something! Like, that one. Or [coughs] [coughs again] Dangit! I liked how that take was going. [hoarsely] Well now, it’s ti - I’m…did I seriously lose my… [clears throat] oh my gosh. Do I need to go get a drink of water? That sounds pretty normal. We are goo- doing great.
Absolutely great. I’ve probably been recording for 10 minutes and I haven’t even gotten through the first line. The bloopers were weak on the last one but they won’t be on this one. Anyway, I teased that we’re gonna talk about [clunk] these things.
That was a loud noise. Actually they are pretty anxiety-inducing actually. I said actually twice. That was fun.
The fuel tanks of these lanterns are sealed. If you take a look [hissing] I didn’t think it was pressurized. Light a match… [disappointment] After that point it’s no longer fuel spritzing out the top of here but instead a stream of vaporized…. sh... it is fuel.
Then you simply close the pump by turning the stem clockwise, push it in, [laughs, then released pressure] [steadfast pumping] I promise I won't gaslight you anymore. OK, well I suppose on Connextras. By that I mean, discuss the effectives of gaslighting.
For camping and junk.