Esbit burner testing
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So, poking around my local store I found the SOL All-Weather Fire Cubes. Here's what happened when I burned one. Essentially it starts with a simple spark, burns for about 12 minutes, produces a very strong flame at the beginning and leaves a lot of soot on my pot. The tablets could boil 2-3 cups of cold water depending on the cook kit. Because of the smoke I think I will only use this to fire up my grill or fire. It is supposed to be waterproof so a tab or two may come with me in my emergency fire kit. I don't know what the fuel actually is, though I'm sure it's a variation on ESBIT. The complete set of high-res images are in my Flickr starting here: https://www.flickr.com/photos/richardmaycr/22300618722/in/album-72157651260318840/ After a mere 18 seconds the flame was really high and seems to have reached it's peak because it slowly died down after this. .
By 9:07 the flame died down substantially and somewhat abruptly. . It was out a few seconds after 12:42. . It left a pile of ash and a button of unused material. I couldn't get the button to start so I wonder if it actually had any fuel left. . Contrary to manufacturers claims it produced a heavy black smoke that leaves a thick layer of soot on the pot: .
. For comparison this is what an ESBIT tab leaves behind: .Matt, I will chime in here with some impressions of the Coghlan’s round fuel tabs. First, I repackaged a bunch of tabs, 5 to each vacuum sealed bag for use in screw-top bottles designed to hold a roll of quarters. As a true OCD geek would do, I weighed each tablet to a tenth of a gram. The average weight was 6.8 grams/tab, and I separated them into groups according to weight (6.7. 6.8, 6.9, and 7.0 grams; those less than 6.7 grams went into the “firestarter” pile).
I dearly wanted to achieve a 2-cup boil with one tab, using water of a starting temperature of 45* F (from my refrigerator, which is also about as cold as our mountain water might ever be during the summer). I couldn’t get a boil, ever. Then I wondered if I could get a boil with just 1.5 C. of water (for coffee). I almost did, or at least it would work for treated water for a cup of Via. 1 cup was easily achieved with a single tab. So I think I can get by with using 2 separate tabs for my 2 cuppas. Dinner, with its 2 cup requirement, would certainly require 2 full tabs being burned at the same time. Keep in mind that my tests were done with a MYOG caldera “clone” on my patio, which is at 5440 feet elevation. The ambient temperatures ranged between 45-55* F, with minimal breezes.
I learned a few things through my testing. First, the Coghlan’s tabs don’t seem to burn all the way down to ashes like Esbit does. There was always a small bit of unburned fuel at the bottom center of the tabs, apparently smothered by the overlying ash. Secondly, there seemed to be about the same amount of residue deposited on the pot bottom as Esbit does. Thirdly, I had a sneaking suspicion that the distance from the top of the Coghlan’s tab to the pot bottom needed to be different than the 1.25″ I have settled on with Esbit and Bleuet and Firelite tablets. After several tests, I came up with an “optimal” (?) distance of about 1.0″, or perhaps even .875″. I seemed to get some oily residue on the pots from the shorter distance, but I also got the water to get hotter faster. Hmmm…closer to the hot flame, but some incomplete combustion?
Here’s a photo of my Esbit holders side by side with those for the Coghlan’s tabs. Hopefully you can see the height differences of the top of the tabs–1.25″ to the pot for Esbit, and 1.0″ for the Coghlan’s. I made a BGET with side extensions for the Esbit (well, a Bleuet tab in this photo, but its dimensions are identical to an Esbit), and I’m rather proud of my creation to hold 2 Coghlan’s side by side vertically (again with removable extensions).
Here’s a close-up of the Coghlan’s holder. The side and end extensions are removable to more fully expose the tabs for a more robust (and faster) burn. I placed a small piece of carbon felt under the elevated burner to help insulate it from the cold sink from the ground. There is a small rectangular base that the felt and stove “legs” fit into which holds everything together (barely). Then there’s the obligatory circular titanium base disk. It’s likely something that only a mother could love, but at least I think it’s cute, and pretty functional.
The bottom line on these solid fuel tablets, for me, is that nothing works as well as Esbit. The orange Bleuet tabs have performed a bit less than Esbit–close, but not quite as good. The Firelites that I bought years ago at BPL’s Gear Shop are OK, but the paraffin tended to escape in some of my burners (that’s when I became a fan of the pop can holder). For me, the main positive quality of Coghlan’s tabs is the price, as I’m seeing a somewhat lower quality with them (I think, so far). By the way, I did contact Coghlan’s about their tablets. I asked them if there is a way to do a 2-cup boil with one tablet. The response was this: “It would indeed be difficult to get a 2-cup boil with just one tablet. We recommend using 2 or 3 to achieve that.” Hmmm…Esbit for the win!
By the way, what is this liquid thing everyone’s concerned about? I see zero liquid when using Esbit, Bleuet, or Coghlan’s. Only the Firelite’s added paraffin needs some containment.
Test 1 done. 2 Coughlan’s tabs heating 2 cups of cold water. Water was 35F at start. Epicurean stove, home made cone, 4.5 cup grease pot with al foil on top to cover holes. Temp was 149 at 4.5 minutes, and the thermometer went over range before 5 minutes. So over 120 degrees in 5 minutes, with about 50 more degrees to go, so about 2.5 minutes to 212F likely. At 6.5 minutes I heard simmer sounds. At 7.5 minutes I called it “rolling”. This is in line with the approximate temperature rise I had measured and calculated in my head above. Did not see any reason to try to be super precise as let’s face it, this sort of data has lots of opportunity for small (and big) errors.
I had the cover off a lot between 7 and 8.5 minutes. At 9 minutes I called it “Super roll”, which I suspect is really 212F here at sea level. Wish I had a good indicator for this time period, as if the temp kept going up linearly I would have been way over 212 by then. But I do know phase change is a great thermal conductor. Boiling kept at this level until 10:45, when it quieted a bit. At 11 minutes it was a simmer, and at 11:30 it was out.
I will update this later with a couple of pictures of the tablets before and after burn.
One pic shows both new tabs and what was left of the burned ones. There is also a bit of unburned liquid on the tray. My picture of the ash did not come out well, may just pass on that one.
Second test, 2 Coughlan’s tabs and 4 cups of cold water. Start temp was 42F. No boil as expected. After 2 minutes, was consistently going up 15 degrees a minute until 7 minutes. it then slowed down to 10 degrees a minute, and between 9:30 and 10 minutes I went over 160F and my thermometer was over range. Burn ended at 11 minutes. That is, the light coming from the cone went to almost nothing. Pretty much the same burn time as the previous test. No simmer sounds, likely got to 170F or so. That does say if the water started at 70F one could get a simmer out of 4 cups and 2 Coughlan’s tabs. Interesting . . .
Picture of ash and leftovers
I guess black on black does not show so well. Here is the ash on a white background (my data sheet)
And if you are not bored to tears yet, hold on for test 3!
By 9:07 the flame died down substantially and somewhat abruptly. .
It was out a few seconds after 12:42. .
It left a pile of ash and a button of unused material. I couldn't get the button to start so I wonder if it actually had any fuel left. .
Contrary to manufacturers claims it produced a heavy black smoke that leaves a thick layer of soot on the pot: .
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For comparison this is what an ESBIT tab leaves behind: .
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