In a previous forum question I inaccurately made the statement that propane, when it burns, does not produce carbon monoxide. I was wrong. In fact, any fossil fuel, regardless of type, will produce varying amounts of carbon monoxide, hence the importance that all spaces be properly ventilated and the heating source itself be properly vented when propane is being used. Typically, sufficient fresh air flow into various areas being heated by fossil fuels prevents dangerous build ups of CO. Quality and relatively inexpensive CO monitors -- which are generally available everywhere -- should be used and properly maintained. As a rule, however, propane and CNG burns cleaner than diesel or kerosene, provide longer burn times and don't generally produce as much CO as other fuels and can provide a wider margin of safety in their use. While I remain a proponent of safe and efficient use of propane aboard ship, I do stand corrected on the issue of propane and its generation of CO. I apologize for my inaccurate information which just goes to show that regardless of how right one thinks he might be, from time to time, one can be wrong.
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Bob, Thanks for your re-posting on this subject.
One evening last spring my wife and I has used our alcohol galley stove and our propane lantern for a couple of hours. We made cocoa and read with only one hatch open slightly. We then slept in the lower aft bunk where the CO fumes had gathered. Fortunatly we arose the next morning, but with massive headaches and flu like stomachs. I had totally missed the fact that CO is heavier than air and settles to the lowest point in the boat. A very lucky lesson learned, or, a hard lesson with a very lucky outcome. Ray S/V Speedy
One evening last spring my wife and I has used our alcohol galley stove and our propane lantern for a couple of hours. We made cocoa and read with only one hatch open slightly. We then slept in the lower aft bunk where the CO fumes had gathered. Fortunatly we arose the next morning, but with massive headaches and flu like stomachs. I had totally missed the fact that CO is heavier than air and settles to the lowest point in the boat. A very lucky lesson learned, or, a hard lesson with a very lucky outcome. Ray S/V Speedy
Fortunately, CO is not heavier than air
Since its molecular weight (C12 O16 = 28) is the same as that of nitrogen gas (N14x2 = 28), the main component of air and slightly lighter than oxygen gas (O16x2 = 32), the remaining 20% or so. In a very humid atmosphere the contribution of water (H1x2 O16 = 18) will somewhat reduce the average molecular weight of the air but even then one should not expect CO to settle out anymore than nitrogen gas itself would. This is not to say that the problems described by Ray could not be due to accumulated CO. In fact, acute symptoms could appear at levels as low as 100 parts per million, if I remember well. With an alcohol stove, and to some extent even propane, burning in a closed space there may be accumulation of many so-called PICs (products of incomplete combustion), of which CO is the lightest and soot (formed if the flame is too rich in fuel and/or too poor in oxygen and starts sooting)is the heaviest. In between are literally thousands of other PICs, ranging from acetylene and benzene/toluene/xylene (known as BTX)to the even more infamous polynuclear hydrocarbon (PNAH) compounds. In addition there are various alcohols, aldehydes, ketones and acids which are especially prominent in poorly burning liquid fuels such as lamp oils and can give those types of flames their characteristic smells. In short, there is enough of a witches' brew to cause all sorts of headaches, sore throats, red eyes and so on, even if the amount of CO formed was relatively insignificant. Moreover, with the exception of C1 and C2 compounds, most of these other PICs are much heavier than air and will indeed tend to accumulate. All this is reason to provide plenty of ventilation when using open flames, especially if the flames have a tendency to soot. Fortunately, propane flames almost never soot (unless air flow is severely restricted) and alcohol flames have only a relatively low sooting tendency. Lamp oil and candles are a much more common culprit as the black deposits on the lamp glass will quickly tell you. Sorry for the long message. However, combustion research is one of the things I do for a living and I thought some people on the board might be interested ;-) Flying Dutchman
Since its molecular weight (C12 O16 = 28) is the same as that of nitrogen gas (N14x2 = 28), the main component of air and slightly lighter than oxygen gas (O16x2 = 32), the remaining 20% or so. In a very humid atmosphere the contribution of water (H1x2 O16 = 18) will somewhat reduce the average molecular weight of the air but even then one should not expect CO to settle out anymore than nitrogen gas itself would. This is not to say that the problems described by Ray could not be due to accumulated CO. In fact, acute symptoms could appear at levels as low as 100 parts per million, if I remember well. With an alcohol stove, and to some extent even propane, burning in a closed space there may be accumulation of many so-called PICs (products of incomplete combustion), of which CO is the lightest and soot (formed if the flame is too rich in fuel and/or too poor in oxygen and starts sooting)is the heaviest. In between are literally thousands of other PICs, ranging from acetylene and benzene/toluene/xylene (known as BTX)to the even more infamous polynuclear hydrocarbon (PNAH) compounds. In addition there are various alcohols, aldehydes, ketones and acids which are especially prominent in poorly burning liquid fuels such as lamp oils and can give those types of flames their characteristic smells. In short, there is enough of a witches' brew to cause all sorts of headaches, sore throats, red eyes and so on, even if the amount of CO formed was relatively insignificant. Moreover, with the exception of C1 and C2 compounds, most of these other PICs are much heavier than air and will indeed tend to accumulate. All this is reason to provide plenty of ventilation when using open flames, especially if the flames have a tendency to soot. Fortunately, propane flames almost never soot (unless air flow is severely restricted) and alcohol flames have only a relatively low sooting tendency. Lamp oil and candles are a much more common culprit as the black deposits on the lamp glass will quickly tell you. Sorry for the long message. However, combustion research is one of the things I do for a living and I thought some people on the board might be interested ;-) Flying Dutchman
The Physics
While some of Henk's explanation might sound like so much techno-babble to some, I think he points out some very interesting aspects of confined-space flames in that some of the by-products of burning fuels for heat might actually be more of a health-risk than CO which, of course, nevertheless remains on the top of the "A" List of things that can unexpectedly kill you or, at the very least, make you pretty darn sick. I think Ray's comments prove up this fact in that it might not have been just the CO that was making he and his wife feel so bad. As to the use of alcohol aboard, I don't know who dreamed up that as an efficient heating/cooking source, but the first thing I did on my boat was toss the Origio alcohol stove in the dumpster. I hate those things and I think alcohol is an efficient fuel best left to hobbyist chemistry sets. I think the one thing that's really coming out here is that we all must be careful about the use of heating fuels below decks and that, as Henk puts it, PICs and CO in confined spaces can really take the fun out of boating in a very tragic way. For years, I have partaken in some fairly seemingly dangerous activities, some more than once and some on a regular basis, but never with callous disregard of the potential for disaster they represent, hence, I believe, my ongoing survival. My primary concern here is that none of us should die out of ignorance while in the pursuit of what we call fun!
While some of Henk's explanation might sound like so much techno-babble to some, I think he points out some very interesting aspects of confined-space flames in that some of the by-products of burning fuels for heat might actually be more of a health-risk than CO which, of course, nevertheless remains on the top of the "A" List of things that can unexpectedly kill you or, at the very least, make you pretty darn sick. I think Ray's comments prove up this fact in that it might not have been just the CO that was making he and his wife feel so bad. As to the use of alcohol aboard, I don't know who dreamed up that as an efficient heating/cooking source, but the first thing I did on my boat was toss the Origio alcohol stove in the dumpster. I hate those things and I think alcohol is an efficient fuel best left to hobbyist chemistry sets. I think the one thing that's really coming out here is that we all must be careful about the use of heating fuels below decks and that, as Henk puts it, PICs and CO in confined spaces can really take the fun out of boating in a very tragic way. For years, I have partaken in some fairly seemingly dangerous activities, some more than once and some on a regular basis, but never with callous disregard of the potential for disaster they represent, hence, I believe, my ongoing survival. My primary concern here is that none of us should die out of ignorance while in the pursuit of what we call fun!
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