Man, I keep misspelling words... I need to take a break from the internet today... (plane vs plain, then vs than etc.)
Yes. I bought mine from KMart.Originally Posted by aero-hiker
Here is a good link for general information.
http://www.engineeringtoolbox.com/th...als-d_858.html
I do not consider Ti a reasonable investment. I suppose if money is no issue, then the durability might be a consideration. There has to be a greater advantage before I consider a superior material. Ti makes a great trowel. Cuben fiber makes great ditty bags. I do not see a reason to spend more money for a Ti pot. Testing shows the thermal conductivity does not translate into significant differences in boil times. Ti is an insulator in comparison to Al. I am likely still dancing about your intent. My comments are meant to be useful. The property to consider in Ti is ability to retain shape. That is far more important than differences in ability to transfer heat. When Al transfers heat 10 times faster than Ti, but does not translate into differing boil times, then marginal differences in Ti alloys will not show any measurable differences. Ti is expensive. Too expensive for such testing. It has a use in cone construction. However, ability to retain shape trumps any heat transfer considerations there as well. It is enough that, on average, Ti is a 10 times better insulator than aluminum.
Beyond my blathering above is the likelihood that OMO's innovation may have just rendered my observations irrelevant. I am blown away at his simple idea.
In the end, it's not the years in your life that count. It's the life in your years. - Abraham Lincoln
Looking back over my notes from last August, I see I was mistaken and there was not an increase of efficiency, only power.
for 16 oz water -
mL fuel to boil - deg F/min - min to boil old system
new system
I measure a 1.5% decrease in efficiency. This may be within the margin of error and not significant (not enough data to know for sure). There is a more substantial increase in power of 5.9%. I am more confident that this is significant (but again, not enough data to do the statistics). I can't find the data for boil times, but based on these numbers, the new system is burning fuel a little faster, which accounts for the higher power. I suppose in the more confined space I may be getting some thermal feedback. I probably should repeat these tests.
One concern is that the new wind screen is that the top may get hot enough to fatigue the aluminum. This does not seem to be a problem. After multiple tests I don't notice any discoloration. I've wondered about trying this set up with Titanium. It certainly won't be damaged by heat, but may be too flimsy. Not used Ti windscreens before.
I still think BB's system preforms as good as this one. The thin aluminum and wide diameter of his pot, along with the cone, essentially replicates the effect of the Olicamp heat exchanger, just in a different way and a lighter weight package. For me, one of my "must haves" has been a pot with handles that don't get too hot to use. I just can't bring myself to using pot lifters of gloves. I've spilled enough meals to know that turns out badly for me.
TI is great for cooking water. (Evernew is a bit better than toaks in that regard, but double the price.)
Al is great for everything else.
That simple for me.
OMO- if it's only handles- Evernew Ultralight series handles are generally longer and the "ultradeep" series has them mounted high on the pot in closer to the one to one ratio you like. http://www.evernewamerica.com/overview/
OMO, thanks for the data. Do you have a thermo couple hooked up to lab-view or something? Or do you just take thermometer readings at fixed intervals? Also, do you know how much the XTS weighs without the lid? Without the handles?
BB, two questions:
1) how much does your grease pot (no lid/strainer) weigh? The only numbers I could get were from zenbackpacking stoves and another website, which disagreed by nearly an oz.
2) How does the durability compare with say a Fosters keg can pot?
Also, I ran the numbers that I could find for Ti and Al. Al has an order of magnitude higher thermal diffusivity (alpha = k/cp/rho) and thermal conductivity (k). In the thermal circuit, if the other components are larger bottle necks (radiative and convective transfer from the stove to the pot, convective transfer within the pot) then this order of magnitude difference won't matter much. However, I don't have enough personal experience or somewhere to look up tests to indicate that this won't make a difference. Both you and OMO use aluminum pots, which should have an efficiency advantage over Ti if the pots are the same geometry/thickness. Looking at the densities of these metals, it seems Ti is about twice as dense. However, Ti pots usually weigh about the same as aluminum pots, maybe slightly less, for the same capacity. So if we assume the thickness of the pot must be doubled for Aluminum from the density numbers and pot weights, then the R value (same area, double thickness for aluminum) will still be lower for Aluminum due to the order of magnitude difference in thermal conductivity. Now the big question is: are these R values (associated with the pots) small relative to the other parts of the heat transfer system. Your experience seems to indicate that this is the case... so maybe I should stop worrying about this.
The pot I was considering buying was the Toaks light 700ml. One source I found says it's about an ounce lighter than the aluminum grease pot, and I sometimes worry about the dangers of consuming aluminum; IIRC it has been implicated in Alzheimer's and dementia, both of which run in my family. (To be fair, however, it is a 700 mL pot whereas the grease pot is ~1.3 L, so it's actually almost half the capacity for 2/3 the weight.) The other problem with Aluminum is the ability to put it on a camp fire. I am thinking about making a caldera cone rip-off out of titanium... I know Dutch sells some Ti sheet.
Toaks Light 700mL: 65g (w/o 25g lid), 4.5" diameter
Olicamp XTS 1L: 190 g, 4.5" diameter
Stanco grease-pot 1.2L: 71g! (according to zen backpacking stoves, and can be trimmed to be 67g), 5 5/8" diameter. However, I couldn't get reliable specs here, hopefully BB can help me out with the weight.
If the numbers are right for the zen backpacking stoves website on the grease pot, this definitely seems like the way to go, due to the larger diameter, and larger capacity for about the same weight.
As for trowels, I just use my bundle of tarp stakes (these are Ti).
just curious why you prefer Evernew. Looking at the specs online, evernew seems few grams heavier and more expensive for the same capacity than Toaks... I only have experience with stainless MSR cooksets.
@a-h. I will provide weights when I am back home later.
In the end, it's not the years in your life that count. It's the life in your years. - Abraham Lincoln
You could probably do the math to tell me why, but applying my PHD (Passed High school and Done)
You just noted the reason, and I suppose the dirty secret with Toaks...
It's cheaper cause it's thinner. Toaks uses thinner TI to make their stuff.
From my end... the hot spot it hotter in the toaks which I'm sure makes fine common sense and academic sense to you gents.
If you're careful you can cook in Evernew TI, but I've had boiling pasta stick in a toaks I stepped away from for a minute.
Evernew can also be hard to get at times, where-as Toaks seems to never have supply issues and has really taken off in the last few years as a result.
On the grease pot... it used to be a Kmart exclusive, then went off the market and then popped up at wally world. Not sure if it was always the same brand either.
Hence the different specs, and if BB mentioned kmart and you mentioned wally world you may have to bite the bullet and pick up the one you can find to know for sure as his may not be the one you pick up.
You're a studious fella, so you may want to look up the AL debates had here regarding health risks to satisfy you're curiosity.
You can put a TI caldera cone in the fire, but you can't put an AL one in.
But you can certainly fill an AL pot with water and put it in a fire.
For most- cost is the first question (though toaks has narrowed that gap)
Next is cooking or just boiling. Toaks does nothing but boil IMO, though alchy stoves are a bit more forgiving than a cannister stove in that regard to be fair. And there's always somebody who will tell you they cook on them. The toaks are harder to clean than evernew as well when you do burn something.
As it relates to the Stenco pot, it is important to note if it has an innie, an outie, or a handle. The link he provided showed the proper version. Therefore, I did not rattle that cage. If the version you are looking at has a handle, it is the wrong one. If the version you are looking at has a rolled lip that goes inward, it is the wrong one. If it looks like the one in his link, it is the right one. Innies trap food and limit cone possibilities. Handles get in the way of cones and are attached to a narrower pot. Of course all of this relates to "grease pots".
Last edited by BirdBrain; 11-06-2015 at 01:32.
In the end, it's not the years in your life that count. It's the life in your years. - Abraham Lincoln
To get these data I get everything set up. I have a digital thermometer (the kind with a metal probe) in the pot to get initial temperature of the water. I try to start close to 70 F. I use a 16 oz Coke bottle to get very reproducible water volume measurements (basically, it works like an volumetric flask). I have a 25 mL plastic graduated cylinder I may have "borrowed" from work for reliably measuring 15 mL of alcohol. It helps to be a Chemistry professor.
Lite the stove, set the pot on the pot stand, start the timer. Then I note the time when the the thermometer hits 212 F (this will be when steam forcibly shoots out the vent). Then I note the time when the steam venting stops (time of flame out). I know from previous tests that these stoves have a very linear heat output from the time they boot to when the flame goes out (there a little bit of delay after the jets light to full power and a little bit of flickering flame before it goes out, but this is just a few seconds so I just ignore this). Because the heat output is linear, I just calculate
Power (deg F/min) = (212-initial temp)/boil time
mL fuel consumed to boil = 15 mL * boil time/flame out time
Efficiency (deg F/mL fuel) = (212-initial temp) / mL consumed to boil
These number are only valid for a give volume of water (16 oz in my case). If you want to be fancier, you can convert power to Watts (using the heat capacity of water=1 cal/g-deg C). You have to convert F to C, oz water to mL, mL=g (for water), cal to J, and min to sec and W=J/sec (fun with units)
I will weight my pot when I get home.
How did you determine the linear output? I guess you could just try to sample the thermometer every second or two.... Ah yes, I have remembered the specific heat of water since 10th grade chemistry: 4.184 J/g/K. Should be simple enough to convert to SI units and get power output with very simple experiments. As for units: I'm a fluid dynamicist--dimensional analysis and buckingham's pi theorem is probably 90% of what we do... OK that may be an exaggeration...
OMO, just out of curiosity where do you teach?
When I started using this stove I did tests where I with a qt of water and 25 mL of fuel. This way I got a long burn time but the water would not boil. I then measured the temp every 15 seconds and plotted time vs temp. The data plots as a very straight straight line for the whole test. When you do this with a Starlyte, there is a drop in power when the fuel runs low. You don't see that with the eCHS.
Grand Valley State University
Here are some weights. I have been using an old analog kitchen scale to weigh things and was never sure how accurate it is. But then it occurred to me that I have a set of antique brass balance calibration standards in my office. I weighed them on the analytical balance in the lab and they were still accurate to within a few mg so I weighed them on my scale at home an the scale is accurate to within a gram, which was nice to see. The scale goes from 0-500g, calibrated every 5 g so these should be good to within a gram or two. If necessary I could take these to work and get you data good to 0.1 mg (for all you microgram weenies)
Olicamp XTS pot not handles and no lid = 163 g = 5.75 oz
My DIY handles made of clothes hanger wire = 16 g = 0.56 oz
Pot stand/Windscreen made of Al flashing = 15 g = 0.53 oz
Original lid = 29 g = 1.02 oz
My DIY lid made of a dimpled disposable Aluminum pizza pan = 4 g = 0.14 oz
My eCHS stove = 8 g = 0.28 oz
My DIY heat shield base (same dimpled Al) = 2 g = 0.07 oz
My DIY snuffer (about the bottom 1" of a 7.5 oz Pepsi can with duct tape handle) = 4 g = 0.14 oz
Everything else in the kitchen = 48 g = 1.69 oz
totals:
Pot + Handles + DIY lid = 183 g = 6.46 oz
Everything (but not original lid) = 260 g = 9.17 oz
Everything else in the kitchen includes the Reflectix cosy made from the AGG kit, a piece of onion bag pot scrubber, Bic Mini, and bungee loop to keep lid in place in pack.
I can't find the original handles but they are a heavy chrome steel with rubber/silicone grips/plastic grips. Nice, but heavier than necessary. The handles are easily swapped on and off with no tools and no damage to the pot or handles.
BTW, I also have K Mart Grease pot (outie with no handle).
The pot weighs 70 g (2.47 oz) and the lid weighs 33 g (1.16 oz) for a total of 103 g (3.63 oz).
OMO, thanks for all the amazing info! Looks like I'll acquire a grease pot in the near future! I was also looking into DIY heat x-er construction. Seems like it could be feasible with soldering aluminum or copper fins on. Not sure if it would be worth the weight though.
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Also, if the CHS runs cool, do you think reflectix could be used as a bottom insulator? Or would that be a bad idea due to flammability?
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My cozy is kind of lumpy from use. Still works bot is looking bad. Not sure it would be first choice but could work. I've previously used a thin piece of styrofoam wrapped in foil.
My pot weighs 67 grams. My lid weighs 30 grams. Perhaps I have been eating aluminum.The lid weighs less because I ditched the heavy black knob on top and constructed a basswood replacement knob. So... 97 grams or 3.42 ounces total. I do not use any shielding for the bottom of my stove. Not required. To be fair, my pot gripper weighs 30 grams. That should be added to the pot weigh.
Trust OMO's listed weights. I cannot locate my good scales.
Last edited by BirdBrain; 11-06-2015 at 07:59.
In the end, it's not the years in your life that count. It's the life in your years. - Abraham Lincoln
One other thought and then I must bow out of this conversation. I intend to not blog as much as in the past. It consumes too much time. This conversation is pulling me back in again. That was not the thought. This is:
As you build CHS's, ask yourself why it is getting hot? A better question is, why is it not getting hot?
Run an experiment. Take a solid rod of aluminum about a foot long and 0.5" in diameter. Take a candle, while holding the rod horizontally, and heat one end of the rod with the candle. The rod will heat at a much faster rate than the stove does (if it is constructed properly).
This is not an apples to apples comparison. It is way out of whack. But it should make one think. Aluminum transfers heat very quickly. Why isn't the CHS (being made of very thin aluminum) getting hot quickly? Why does setting this stove on a block of ice not stop the stove from running? Why does this stove run in a linear fashion? Why does this stove not run properly when full (fill to no more than within 1 cm of the aperture for proper performance)... or during the last 5 seconds? Pondering the answers to these questions will allow you to build a more efficient stove.
I will answer part of the question. Most stoves with jets require vapor pressure to run properly. There is no vehicle to deliver the fuel other than by pressure. A CHS does not run that way. This stove has fuel near the jets for a different reason. The fuel is trying to quench the flame. It cannot win. The key is to control the fight. If it sends too much fuel to the fight, the stove will not be efficient. If it does not send enough, the stove will not be powerful. Lack of power is visible in the flame. Lack of efficiency is seen in the bowl (bubble bomb) and is felt in thermal feedback.
Edit:
I am editing this because what I state above is not compete enough. I do it here because it does not deserve a huge part in this thread. My thoughts are likely controversial. They are also unimportant. I only went down this path because I was asked about them. I do not mind giving my opinion. I actually want to give my opinion. Those that read anything I type know that. I also know myself. However, often it would be best if my opinion was held in check. That is too late in this case. I might as well try to give a more complete rendering.
When a person is asked to calculate acceleration due to gravity, they are told to ignore many realities. Beyond the ignored realities, they are told to pick a zero for displacement purposes. Some pick the start. Some pick the end. It does not matter to those that pick whatever they pick. The displacement is the same no matter where they set zero. It matters to me. Zero should be the center of mass and there should be another calculation in the equation that accounts for distance above sea level (in my mind, distance away from center of mass). These things drive me crazy. Not thinking in these terms allows for strange theories. Views on gravity is a prime example. They ignore obvious observation. Pluto and Charon are in a dance around a combined center of mass. Gravity is not a product of bent space.
Why is any of this relevant? It is relevant because stoves are constructed on a premise. Get the fuel to vapor and burn it. This accepted starting point makes for a bad accepted norm. It creates a condition where people think in simple terms of available BTU's and that stove construction is just style points. Because we have been conditioned to ignore insignificant variables, we ignore important realities. We apply definitions that are not constant.
Consider the white box stove. The jets bloom after the fuel boils. Methanol boils at 148.5° F. 148.5° vapors fill and pressurize the void. This creates several realities. Vapors are compressible. The pressure created by setting the pot on the stove is not an issue. The vapors can withstand the pressure. Only so much vapor can escape through the jets. The result is desirable. In fact, most stoves with jets rely on pressure to operate properly. There are many other dynamics about that pressure that I will not go into here. The discussion would be too long. Because the stove relies on vapors pressure to run, if you lower the temperature of the fuel or stove the flame will dramatically reduce. Set a cold pot on the stove or set the stove in cold water and it almost goes out immediately. This condition is an accepted reality in stove construction. It is why people shield their stoves from the ground. It is why people have priming pans in cold weather. The stove needs vapor pressure produced via boiling fuel to run properly.
Now consider what happens if you set a CHS in cold water or on an ice block or in a snow banking. Why does the blame not dramatically change? The simple answer is that the stove runs properly because of what is happening in the hoop, not in the bowl or, by extension, the fuel in the bowl. It does not matter if the fuel is 32° or 100° in the bowl. The fuel must be at 148.5° in most stoves to run properly. That is a design flaw. It is a bad starting point. But because of the accepted starting point, few accept the reality that no stove that requires internal thermal feedback can approach the efficiency capabilities of a CHS stove. How the fuel is delivered in a stove is so ingrained it is hard to relay to others why this design is so superior. It is a reasonable to have varying opinions of why liquid fuel is going up the ribs. That is not as important as accepting the fact that liquid fuel is going up the ribs. Vapors are at or above 148.5°. If vapors were going up the ribs, I would not be able to hold my stove in my hand for several minutes while it ran. If vapors were going up the ribs, setting the stove in cold water would immediately quench the fire.
Successful CHS construction depends on copying what others have done. Successful tweaking of a CHS requires a basic acceptance of what is happening in a CHS. It is all about the hoop. The stove is running in the hoop. The hoop needs the proper amount of fuel. It is all about fuel in and fuel out at the hoop. The majority of the stove is nothing more than a gas tank and a delivery system.
I left one item out on purpose. The mechanics that cause the initial ignition at the hoop are different than the running mechanics. They do not deserve discussion. Make the hoop run right and all will be fine.
Last edited by BirdBrain; 11-07-2015 at 12:52. Reason: For those that care enough to reread :)
In the end, it's not the years in your life that count. It's the life in your years. - Abraham Lincoln
Thanks BB. I have one more question. When making the indentations to form the ribs, does that dent extend all the way to the hoop or does it start below the widest part of the can - the rim just below the hoop. When making the dents it is easy to dent the side as it bends in only one dimension. But the rim bends in the opposite direction, across the rib, so extending the dent to this point requires a bit more force and when it dents it deform the hoop. Without this indentation I worry that fuel won't make around this rim but getting the rim to dent has been problematic. How is this done in your best balanced stoves?
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