Carbon Monoxide in enclosed spaces

[Jaybird180]

This wikipedia article says that CO is slightly lighter than air. I was wondering then what happens when CO is in confined spaces, like a hangar. Does it rise and eventually evacuate?

And secondly, how does CO behave at altitude? I would imagine that it's heavier than air at 8,000 MSL and that it would decend and thus pose little risk to aviation, but obviously that's wrong too.

Can someone explain what happens to the gas during altitude changes?

 

[Jim Logajan]

This wikipedia article says that CO is slightly lighter than air. I was wondering then what happens when CO is in confined spaces, like a hangar. Does it rise and eventually evacuate?

According to my math, the molecular weights of some common atmospheric gases are:

O2 = 32 (molecular oxygen)
N2 = 28 (molecular nitrogen)
CO = 28 (carbon monoxide)
CO2 = 44 (carbon dioxide)
H2O = 18 (water)

All the above are generally "well mixed" in the atmosphere and you would have to have very still air for a fairly long time for them to segregate into layers.

Only carbon dioxide is heavy enough to "pool" in low spaces; this is why dry ice is used to create fake fog in films and theaters. And only water is light enough to rise, causing clouds to form due to the temperature lapse rate with altitude.