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Is carbon monoxide lighter or heavier than air?


randyfaas

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He is concerned with CO not CO2. I spoke with one of our chemists from what I gather air has a molecular weight of ~28.56 and CO has a molecular weight of ~28.0 so CO is slightly lighter than air. Since it is so close the the same weight I wouldn't count on it rising all the time. It will end up mixing. Just be safe and leave the window cracked a little. Better safe than dead.

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CARBON MONOXIDE QUICK FACTS

Carbon Monoxide is LIGHTER than air

Carbon Monoxide is lighter than air. CO2 and O2 are products of complete combustion, CO is produced when there is incomplete combustion. If all 3 gases are spilled into an area the CO2 Carbon Dioxide will drop to the floor and the lighter CO Carbon Monoxide will always rise to the ceiling.

Another way to explain this is to compare it to smoke from a fire. Visible smoke from a fire is a particulate which is heavier than air, but it rapidly rises to the ceiling because of the heat. The same applies for CO spilled from an appliance, it will rise to the ceiling and will always be at higher concentration near the ceiling.

Answer to a common question: Placement of a CO detector should be on a wall near the ceiling or on the ceiling but 6 to 12 inches away from where the wall meets the ceiling.

Molecular weight of:

Carbon Monoxide------>28.01 Lighter

Nitrogen------------------>28.0134

Air------------------------->28.975

Oxygen------------------->32.00

Carbon Dioxide--------->44.01 Heavier

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The reason I say it will mix is becasue the air rizing over the heater will push the cooler CO at the ceiling down some and you cant count on it to completely stratify. Anyway thanks for clearifying my approximations. I do agree the concentration will be higher at the ceiling. That doesn't mean you are safe at the floor. Again crack a window or vent.

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 Originally Posted By: Da Beak
CARBON MONOXIDE QUICK FACTS

Carbon Monoxide is LIGHTER than air

Carbon Monoxide is lighter than air. CO2 and O2 are products of complete combustion, CO is produced when there is incomplete combustion.

You forgot H2O. CO2 and H2O are products of combustion. And I think O2 is wrong. O2 is before combustion, not after. If it was after, it was not much of a reaction, is it?

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Although the molecular weights of these gases differ, convection and not

density differences dominate the distribution of CO, methane etc. The

release of gases associated with combustion tend to rise because they are

hotter than ambient. For this reason smoke detectors and CO detectors are

usually placed high on the walls of hallways etc.

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I'm not sure what level commercial CO detectors activate at, but as a Firefighter I know that we are concerned when we reach a threshold of 35ppm on our monitors. OSHA says a person can work 8hrs a day with a concentration of 50ppm.

At 300ppm death can be in 1-2hrs and 800ppm in one hour.

So, a proper CO detector will warn you long before you get into dangerous territory, even if its mounted near the floor.

IT WILL SAVE YOUR LIFE!!

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 Originally Posted By: Black_Bay
So my CO detectors in my house that plug into outlets are basically useless since they are about 14" off the floor?

You are just fine. The air would have to be dead still in order to separate out. That's not going to happen.

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Here is the correct information.

Carbon Monoxide has a natural tendency to rise in temperatures above 32 degrees, like inside buildings. At freezing temps and below, carbon monoxide is heavier than air. But inside a fish house the space is so small it may not have much a differance. Your better off being safe and doing everything possible to avoid it to start with.

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The BEST placement of the detector is in the breathing zone! I mount my detectors (actually all over the place ) where ever my head is going to be also remember most of the home co detectors are cumulative. if Im spending the night I have a home detector with me and I also check it against a dedicated quick respose detector leftover from my previous employment

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CO is lighter but gases mix extremely well if they are close enough in molecular weight. Only pure hydrogen and helium are really light enough to rise significantly. If they did separate completely by molecular weight though we'd all be breathing pretty toxic air: Ozone,Butane, Sulfur Dioxide, Boron Trifluoride, Chlorine, Krypton, Xenon, and Sulfur Hexafluoride. I think we'd all be dead.

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A point that is being missed here. The reason these gases mix so well is because they are being blended by other factors such as wind or temperature. Place these same chemical compounds in a vacuum and they will separate into layers rather quickly.

The original poster's questions suggest that he is concerned about sleeping in an area that may possibly place himself into a situation where the answer could be important. If this is true, then my advice is DON'T DO IT! Exposing yourself to the risk in your sleep is twice as dangerous because you probably will not wake up.

Bob

edit: Placing them into a vacuum? It would no longer be a vacuum then would it. My mistake. What I meant is place them into a controlled environment unaffected by temperature changes or movement. Sorry.

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