I installed one in the shop I worked in when we installed an unvented LP radiant heater. The level would stay at zero even with the diesel powered torpedo heater going. BUT start a push mower for 2 minutes and that would drive that thing wild! If you want to test one, just take it to the garage and start a small engine.
A molecule of carbon monoxide weighs 28. C=12 and 0=16.
70%+ (78?)of the air is nitrogen and a molecule of that weighs 28. N=114x2.So they weight the same.
02 weighs 32 (2x16) so that is a bit heavier than the the other two. So I would think that if anything CO would rise, but slowly.The instructions that came with my CO detector said iirc that heightt was not important. I suppose I would still avoid corners, out of the air flow, so the very top or bottom of the wall is a bad idea.
My CO detector is plugged in at the only unused receptacle, which is about 12 inches above the floor and it once went off at 3 in the morning, and I awoke with a headache. Definitely CO.
No offense but I eschew pdf files.
They sell bags of CO with which to test the detector. Flat foil bags a couple inches square. I think I bought one at a hamfest, or got it free somewhere, and iirc when it followed the directions (and opened it near my detector) the detector went off.
I would agree (and hope!) that the manufacturers research and know enough about their product to recommend the best placement. If their recommendations are _not_ followed, it would be difficult to justify complaining about any failure of the device to detect CO
I wonder, how much of a difference there is in the respiration rate of a sleeping vs an awake person sitting at a card table, and it it might account for experience you recounted.
>
..
It is weight per unit of volume at the ambient temperature that is important.
From the link: " The CO sensor shall be of a fuel cell design and shall meet the sensitivity requirements of Underwriters Laboratories UL2034 Single and Multiple Station Carbon Monoxide Alarms. The alarm can be installed on the surface of any wall or ceiling following the UL/NFPA/Manufacturer's recommended placement guidelines.
So what are the UL/NFPA/Manufacturer guidelines?
If the detector was mounted higher, you might have avoided that headache, but at least you avoid far worse.
Oxygen is 14% heavier than nitrogen (16 vs 14). And when you consider that the molecular weight of CO is virtually the same as that of N2 -- but significantly *less* than that of O2 -- it makes quite a difference.
Not necessarily due to CO, however -- other chemicals can cause false alarms.
We had a good example of that a few years ago. We had been using a chemical paint stripper in the basement (no choice -- long story, but the thing we were stripping is part of the house, and couldn't be carried outside), and about four hours after we finished the CO detector in the furnace room (fifty feet and two rooms away) began sounding. Because of the distance, and the separation in time, we didn't connect that to the paint stripper, and called the fire department right away. They came out with a sniffer, and found no problems. The firefighters noticed the lingering odor of paint stripper, and suggested that was probably the cause of the false alarm, which was confirmed by a phone call to the manufacturer the next day.
Well, yes, but a rule of thumb for gases is that density at standard temperature and pressure is approximately proportional to molecular weight.
Taking air to be a mixture of 78% N2 (molecular weight 28), 21% O2 (32), and
1% Ar (18), then CO, with a molecular weight of 28, would be expected on that basis to have a density 0.97 that of air.The actual figure is 0.969 (1.25 g/l for CO vs 1.29 for air).
The problem with all this figuring and carry-the-two business is that air is a mixture - a relatively constant mixture. If not, then the bottom 2.25 feet of a room would be all Nitrogen, the next 2.5 feet Oxygen, and so on. We'd have to walk around bent over (toddlers would have to walk on stilts) or we would perish.
If we fed the gases individually into a room then that could be a problem can easily leak into a room in a way that caused it to stay more or concentrated, much like cold air when you open a window in winter or propane gas leaking and collecting in a basement.
The problem is real and it does happen. If you really want to check it out stop by your local fire station and ask them about it.
The instructions that came with my unit said to place it about 3 feet above the floor.
I place mine on a wall 3 feet off the floor about 3 feet from my wood burning fireplace.
Oops. N=14x2.
Yeah but that varies the same for each.
LOL. Good question. What is the point of saying what they did.
Well, it was high compared to the basement. :-) It's actually almost as high as my nose when I'm lying down. :-)
Not exactly, but I am not sure it plays a big part here.
3 feet makes sense, since you are most likely to become overcome, and not notice the simptoms, when you are sleeping. That seems about head height.
I have more than one in my house, main one is a smoke/co combination unit outside my bedroom and the second is a co/gas detector in my lower levels.
But this is just me....
tom @
As mentioned above by "HeyBub", the stuff we breath is is relatively uniform mixture of several gases of different molecular weights. Here is a reference that might provide some additional explanation:
Those guys are scientists!!
There should be instruction in the package telling you where to put the thing. If you don't beleive them, get two, and put one high and the other low. It's not like they're expensive.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.