May 5, 2009 at 8:16 pm #1236126
Companion forum thread to:May 5, 2009 at 11:30 pm #1499346
@markhurdLocale: South Texas
Tony and Roger,
It is great to have the scientific method applied to this analysis. I have used and advocated blended fuels in the past, but have gravitated to plain ethanol over the last year. Looks like I made the right choice.
On a related side note, I know your experiments were confined to specific stoves, but if a stove was designed specifically to more completely combust isopropyl alcohol do you think that would be a safe way to use iso as a fuel? Or is using it just generally a bad idea?
-MarkMay 6, 2009 at 3:05 am #1499370
Thanks from both of us.
Once the alcohol has vaporised and left the vicinity of the stove to become a flame, the chemistry is fixed. What the stove looked like ceases to matter. So I don't think that the stove will make any difference to how the alcohol burns in the flame. IPA is just bad stuff for burning.
CheersMay 6, 2009 at 4:00 am #1499375
@row435Locale: Mid Atlantic
Nice work on the article. The comment about the stove having no affect on the byproducts I disagree/agree with. On the one hand, the stove can affect the fuel/air mixture, rate, temperature that a fuel burns at, all of which will affect the resultant byproducts. Similar to how the oxygen fuel mixture in a car will affect the resultant byproducts in the exhaust. My conjecture is that the sooty mess that ISO-OH leaves behind means that there is a lot of carbon that is not being burned, thus not enough oxygen in the fuel mixture (and most likely, to low of a burn temp as well).
Having said that, I do not think that it is practically possible to make a simple alcohol stove that can get enough oxygen and heat to burn ISO-OH properly. So in the end, the stove type will not make a difference.May 6, 2009 at 7:59 am #1499403
@mn-backpackerLocale: Land of 12,000 Loons
I just wanted to say, great article! I enjoyed the read and really appreciate the scientific approach taken in many BPL articles.May 6, 2009 at 8:26 am #1499410
@ksawchukLocale: Northern California
Excellent article and the kind that keeps me coming back to BPL. This is data you just can't get anywhere else. Will there be a follow up comparing the different types of solid fules "Esbit style" coming?
IPA might not be a good choice in your garage or tent but using it in the backcountry where there's nearly always a breeze to blow away any byproducts might make it worth a consideration. Did it otherwise burn well?May 6, 2009 at 10:13 am #1499436
A very interesting article, Roger and Tony. Thanks. For UK readers and anyone visiting the UK with an alcohol stove the methylated spirits sold here (the standard fuel for alcohol – so standard that the stoves are known as meths stoves)is a mixture of methanol and ethanol. What the percentage of each is I don't know however – it's not listed on the three different brands I have at present.
The methylated spirits sold for backpacking stoves in the UK is called mineralised methylated spirits and this is defined by Customs and Excise thus:
"in the case of mineralised methylated spirits, with every 90 parts by volume of spirits there shall be mixed 9.5 parts by volume of wood naphtha and 0.5 parts by volume of crude pyridine, and to the resulting mixture there shall be added mineral naphtha (petroleum oil) in the proportion 7.5 litres to every 2,000 litres of the mixture and synthetic organic dyestuff (methyl violet) in the proportion 3.0 grammes to every 2,000 litres of the mixture".May 6, 2009 at 10:47 am #1499447
@markhurdLocale: South Texas
>Once the alcohol has vaporised and left the vicinity of the stove to become a flame, the chemistry is fixed<
Thanks Roger, but I see merit to David R's argument that the air fuel mixture and heat of the vaporized fuel would make a difference in how completely the fuel burns: partial verses complete combustion. However, I also agree with David that the difficulties of making such a stove may make it a moot point. Of course that hasn't stopped people like Tinny from trying. See URL below. (He later took this stove off the market.)
-MarkMay 6, 2009 at 11:22 am #1499457
The additive 'Wood Naptha' is another term for methyl alcohol, which suggests that the 90% is ethanol.
A quick google search on [ "mineralised methylated spirits" msds ]showed most products in England to be 90%-95% ethanol.
MSDS – Materials Safety Data Sheet
If you search from there and include a manufacturer name I think you'll find the details.May 6, 2009 at 11:27 am #1499461
Thanks Greg. I didn't know to search for MSDS. Searches suggest the composition is 60-90% ethanol and 5-10% methanol.May 6, 2009 at 11:35 am #1499464
The UK products are generally 90% ethanol, then methanol and the minor additives as listed above.
The MSDS can be a bit vague – they typically say something like 60-90% ethanol.May 6, 2009 at 11:39 am #1499468
Chris and Neil,
On the MSDS look for the section on the additives. It will usually give the parts in percents, the remainder of the product then being ethanol.May 6, 2009 at 1:48 pm #1499509
@conductorLocale: Sierra Nevada
Tony and Roger
Excellent work! As was mentioned above, this type of analysis, along with the sheer creativity of BPL’ers, is what keeps me coming back. It is nice to see some numbers behind the rhetoric.
I wonder if you would consider the following for your future work. Since your independent variables (X-axes) are categorical instead of continuous, please use bar graphs instead of line graphs. Will you show the standard deviation for you data, or otherwise indicate significant or non-significant differences? I realize that this would increase the sample sizes. How tight are your means?May 6, 2009 at 2:15 pm #1499521
@marti124Locale: Moderator-JohnMuirTrail Yahoo Group
First of all, I commend the authors. Like the others, it is articles like this that make BPL the "Science Magazine of Backpacking".
Is there any chance in future statistical chart presentation if a sidebar arrow can be displayed with the wording "Better" showing which way is better, versus which way is worse.
I had to read considerable text before figuring out which direction in the charts was more desirable, but with the arrow icon, one would immediately know.
Would the Americans reading the article come to the conclusion that Yellow Heet is the best to use outside of EverClear in the USA for stoves?May 6, 2009 at 2:35 pm #1499524
This american favors Sunnyside Denatured Alcohol. It's readily available in gallon cans for about $13, and is around 94% ethanol.May 6, 2009 at 2:42 pm #1499527
@dubendorfLocale: CO, UT, MA, ME, NH, VT
The MSDS for sunnyside denatured alcohol is here:
I've pretty much got my system down so I never come in skin contact with the stuff, and of course ventilation is a priority. Then again, the name is not quite as creative as those brands of everclear…
JamesMay 6, 2009 at 2:58 pm #1499534
> IPA might not be a good choice in your garage or tent but using it in the backcountry
>where there's nearly always a breeze to blow away any byproducts might make it worth
> a consideration. Did it otherwise burn well?
CheersMay 6, 2009 at 3:00 pm #1499535
"in the case of mineralised methylated spirits, with every 90 parts by volume of spirits there shall be mixed 9.5 parts by volume of wood naphtha and 0.5 parts by volume of crude pyridine, and to the resulting mixture there shall be added mineral naphtha (petroleum oil) in the proportion 7.5 litres to every 2,000 litres of the mixture and synthetic organic dyestuff (methyl violet) in the proportion 3.0 grammes to every 2,000 litres of the mixture".
Yes, well, you would NOT want to drink that stuff!
CheersMay 6, 2009 at 3:09 pm #1499536
Destitute alcoholics do drink it though! Back in the 70s when a Trangia was my only stove you had to sign the poisons register to buy meths in Scotland and shops would only sell 500ml at one time because of the problem with people drinking it. I can remember going to several shops and buying a bottle in each on one long walk! I used to take the Trangia with me so I could show it them if they queried my purchase. Now I can buy 5 gallons no questions asked, no signature required.
The purple dye makes it very distinctive, as does the smell. You'd really have to be desperate to drink it.
ChrisMay 6, 2009 at 3:10 pm #1499537
> Since your independent variables (X-axes) are categorical instead of continuous, please
> use bar graphs instead of line graphs
Understood. I will look at this for the future.
Standard deviations – nice idea, but for many of the readings we are taking only 3 measurements. Provided they are consistent (within maybe 5%) we run with the average of those 3. Quoting a SD doesn't seem justified.
CheersMay 6, 2009 at 3:11 pm #1499538
> a sidebar arrow can be displayed with the wording "Better"
Noted for the future.
CheersMay 6, 2009 at 3:12 pm #1499540
Ah, the 70s … Yeah!
CheersMay 6, 2009 at 4:01 pm #1499551
@tbeasleyLocale: Pigeon House Mt from the Castle
I would like to thanks all at BPL for their great comments.
First I would like to thank you for your advice early on in these tests.
"On a related side note, I know your experiments were confined to specific stoves, but if a stove was designed specifically to more completely combust isopropyl alcohol do you think that would be a safe way to use iso as a fuel? Or is using it just generally a bad idea?"
The Trangia burner seemed to handle IPA very well and it still produced lots of soot, I do not think that it would be possible to design a practical stove to burn IPA with no soot.
I would not advise to use IPA even in the open, while it is better than a confined space it is very hard to completely avoid the fumes unless you stay a long way away and after doing these tests even the thought of IPA fumes makes me feel sick.
Thanks for the link to Tinny's IPA stove page, it was interesting that Tinny had to add 30% water to stop the soot. FYI Alcohol/water mixes and flames are covered in part two of this series which will be published soon.
"Will there be a follow up comparing the different types of solid fules "Esbit style" coming?"
If a part three of this series happens it is a possibility that we will look at including solid fuels.
TonyMay 6, 2009 at 8:42 pm #1499601
@halfturboLocale: Northernish California
Excellent, if mind-boggling work, gents.
I hesitate to even bring this up but alcohol regs vary wildly state-by-state in the States, and even county-by-county in some of our more "enlightened" states. The upshot is Everclear and its equivalents are spottily available at best. Myself, I'd have to drive to Nevada.
That said, based on your meticulous research I'm stocking up the next I find myself in South Shore :-)
Cheers (in every sense),
–RickMay 6, 2009 at 8:56 pm #1499602
@marti124Locale: Moderator-JohnMuirTrail Yahoo Group
Thanks, James. That is the fuel I use, it's sold locally; I was not aware of the pdf you provided, I noted in it:
"Carcinogenicity: components have not been identified as carcinoogens by NTP, OSHA, IARC."
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