CO and the Internal Combustion engine

December 19, 2006 1:53 PM

At what CO concentration would a generator stop running?

Here in the Puget Sound region, there have been several deaths recently from people placing generators inside their homes. It's got me wondering, at what concentration of Carbon Monoxide, would an internal combustion engine fail to combust?

posted by nomisxid to science & nature (8 comments total)

carbon-monoxide is flammable, so you would have to have so much that there wasn't enough oxygen left in the air to burn the fule and CO.

In fact before natural gas was common, gas was produced from coal and CO was a major component of that gas.
posted by MonkeySaltedNuts at 2:06 PM on December 19, 2006 [1 favorite]

The short answer - a much much MUCH greater concentration than one that would have killed every blood-based lifeform in the area a long time ago.

Both respiration and combustion use oxygen, but red blood cells greatly prefer CO over O2, and once carrying CO, will not release it. Hence the large discrepancy between the concentrations needed to have an effect.
posted by -harlequin- at 3:14 PM on December 19, 2006

The CO will kill you long before it (and the other combustion gasses) kills the generator by displacing all the oxygen. Generators do not belong in houses. Wow, what stupidity. That is like running a pipe from your car exhaust into the house.
posted by caddis at 3:19 PM on December 19, 2006

In fact before natural gas was common, gas was produced from coal and CO was a major component of that gas.

And they piped that gas right into people's homes, too-- and that was before valves which would shut the gas off when a pilot light wasn't lit, so that if gas pressure fell enough so that the light went out and then increased again, you could end up with a house full of explosive, highly poisonous gas.

Here is a letter Mark Twain wrote to his gas company after such an event:

Hartford, February 12, 1891

Dear Sirs:
Some day you will move me almost to the verge of irritation by your chuckle-headed Goddamned fashion of shutting your Goddamned gas off without giving any notice to your Goddamned parishioners. Several times you have come within an ace of smothering half of this household in their beds and blowing up the other half by this idiotic, not to say criminal, custom of yours. And it has happened again to-day. Haven’t you a telephone?

Ys
C.L. Clemens

An example of his invective at its most sincere, I suspect.
posted by jamjam at 3:34 PM on December 19, 2006 [3 favorites]

A quick Googling gives a 1% level of CO as fatal to an adult in one minute, and a typical concentration of 15% CO in 'town gas' of the sort MonkeySaltedNuts was talking about, I assume.

MSN, do you suppose 'natural gas' was a marketing inspired term meant to call attention to health benefits, sort of like 'organic food' is today?
posted by jamjam at 4:19 PM on December 19, 2006

caddis writes "That is like running a pipe from your car exhaust into the house."

Worse really. Cars are pretty clean and generators are dirty, especially the two strokes.
posted by Mitheral at 5:29 PM on December 19, 2006

do you suppose 'natural gas' was a marketing inspired term meant to call attention to health benefits, sort of like 'organic food' is today?

Not really. It just meant it wasn't an "artificial gas" or "manufactured gas" like coal gas or other options of the time. It used to be known mainly as "marsh gas". Cf. 1894 .

By the way, gas from coal is a cutting-edge technology. They just extract it directly from the coalfield now.

Anyway, yes -- the silent killer. There's a reason they give natural gas a funny smell.
posted by dhartung at 10:21 PM on December 19, 2006

Natural gas itself won't kill you until the concentration is high enough that it has displaced oxegen below breathing levels. It is mostly methane with some ethane, propane and butane mixed in with small amounts of hydrogen sulfide, carbon dioxide, nitrogen and mercury. Some fields have significant fractions of helium, enough in some places that the gas straight from the field won't burn.

At least it won't kill you until something sparks a leak off and your house explodes. Leaks are why they scent NG and LPG.
posted by Mitheral at 7:52 AM on December 20, 2006