Carbon Monoxide and alcohol stoves

One of the causes of carbon monoxide production in stoves is the premature cooling of the flame prior to complete burning. Since alcohol stoves have longer flames than compressed gas or white gas stoves, I would assume that they also produce more carbon monoxide. BPL has done a study with a gas meter and has a link to the study. I was wondering if someone with a paid subscription could read it over and comment?
Jim

I think zen stoves has and incredible amount of info on combustion--- maybe to the point of overkill. http://zenstoves.net/COHazard.htm
This is interesting: “Setting a stove at the highest output level that still produces blue flames produces the lowest levels of CO. Counter intuitively, setting a stove for low output, such as simmering, causes larger amounts of CO production than any other setting.” However, BPL looks at this differently… (I’ll leave it to subscribing).

Zen does theorize about alcohol; “If the molecular size of fuel particles has an impact on CO production, then fuels such as alcohols and liquefied petroleum gasses should in theory produce less CO than even white gas. ”

Another interesting Zen point: “The more a flame is disrupted, the more CO is produced. Placing a pot, or anything else for that matter, on a stove drastically increased CO production. So relatively speaking to the effects of CO production, using a stove to heat a tent is far less dangerous than using it to melt snow or cook with.”


In the BPL article, canister and gas stoves are all over the CO map. And they’re just relative measurements. So they have recommendations on good stoves in terms of minimum CO.

In general, both articles point out stoves should not be used in environments where CO can build up. This makes sense; the readings go to 0 out in the open.

-Barry

IIUC more than CO production, the greater consideration with alcohol stoves is the fuel being used. What is the methanol fraction and what other denaturing compounds are in the mix? Reportedly, certain alcohol formulations are vile-smelling and quite headache-inducing.

To piggyback on the Zen stove notes, a major factor re. CO production is the distance between pot and flame. Many stoves have responded well (lowered CO levels) to raising the pot above the standard support height. Fiddling with one's own stove to figure this out would require a lab setup and instrumentation, of course.

Cheers,

I use plain old *methanol* (methyl hydrate) most of the time. It stinks no worse than anything else and certainly hasn't produced any ill effects.. No I don't *drink* it.

I've also used pure ethanol (everclear) as well as denatured alcohol. same thing..

Then there's "methylated spirits" which is the UK and australia's answer to denatured alcohol. they deliberately
add smelly stuff to it. but it worked fine in the stove
for me.

I'll add that I wouldn't use any stove where CO might be an issue. I don't use them in enclosed unvented spaces.

If you have to worry about a windscreen then CO is not going to be a problem.

Barryp said
"Another interesting Zen point: “The more a flame is disrupted, the more CO is produced. Placing a pot, or anything else for that matter, on a stove drastically increased CO production. So relatively speaking to the effects of CO production, using a stove to heat a tent is far less dangerous than using it to melt snow or cook with.”

An article I was reading in an Australian group with a lot of climbers was saying that modifying your white gas stove by raising the pots above the top of the normal flame pretty much eliminates CO production and makes them safe for use in tents.

I personally do not use alcohol stoves but I have noticed that they always have tall flames and thats why I was thinking that every alcohol stove has its flame majorly interrupted by the pot. The zen article said that heating your tent without a pot would produce far less CO than any use with a pan on it. Onereason I don't cook in my tent with white gas (or liquid fuel of any kind) is the smell of priming and the toxic fumes after extinguishing the flame. I cook in my tent with my Coleman Xtreme compressed gas stove with liquid fuel feed and ventilate well. As far as I know - popular alcohol stoves do not have air intakes to premix O2 but depend on it happening under the pot, thus pressurized stoves with premix air intakes should be safer by burning with a shorter flam.

From the zen article "Yellow flames suggest incomplete combustion's and generally associated with production of large amounts of CO. If you get yellow flames, you should consider shutting off your stove, possibly cleaning it (special attention given to the jet), replacing the fuel, and/or making sure it is sufficiently pressurized instead of subjecting yourself to deadly levels of CO. "
Jim

If you use a gas stove inside without a chimney you will never know if you are going to be gassed with CO or what ever.

I would never use a gas or alcohol or wood stove inside a tent--too much risk of fire! On rare occasions I've used the stove just outside the vestibule, where I can knock it away from the tent if it flares up. Silnylon, of course, is not fireproof, but even the supposedly "fireproof" tents still melt awfully fast!

If you absolutely must use the stove inside the tent, obviously plenty of ventilation is needed.

I'm not too worried about Carbon Monoxide because I usually don't sit close enough to the stove to breathe it in. Often, I'm off doing other chores at a safe distance while my water boils (but close enough to keep an eye on it of course).

There is an article dedicated to this at BPL (http://www.backpackinglight.com/cgi-bin/backpackinglight/stoves_tents_carbon_monoxide_pt_4.html) but you need to subscribe to read it.
According to that the lowest emission was the Ion stove (114 co ppm), the highest the Triad XE at 313.
The White Box was at 160 and the 10-20 (Caldera cone) at 193. The Trangia was at 285.

Franco

Why is this a topic of discussion. I do not think it is cause for concern when the stove is outside.
The reason it is being dicussed is because it is winter and when its cold and the wind blows and its getting dark and you are hungry it is not much fun outside cooking and eating.

All that is needed is a simple little chimney so you do not have to risk your life or health by taking the stove inside with no chimney.
The chimney has the added bonus of heat inside out of the wind.
We are talking 12 ounces more weight and maybe the comfort is not worth it.

Good point chimpac. If you plan to cook inside your tent, you might as well get a chimney. If you cook outside, why worry.