This blog is my attempt to reconnect with the world of chemistry. I have a PhD in Inorganic Chemistry and make a living doing research for a large company in Michigan. As times have changed, that company has changed its focus and I no longer have as much chance to do the basic, fundamental research which I most enjoy. Through this blog, I am hoping to recapture the magic which I felt during my graduate (and undergraduate) days in college. Expect topics on chemistry and alchemy along with some non-chemistry related items which I think might be interesting.

"The chymists are a strange class of mortals, impelled by an almost insane impulse to seek their pleasure among smoke and vapour, soot and flame, poisons and poverty; yet among all these evils I seem to live so sweetly that may I die if I would change places with the Persian King."

Johann Joachim Becher (phlogistonist)
Acta Laboratorii Chymica Monacensis, seu Physica Subterranea, (1669).

Friday, March 14, 2008

CO2 and Fire Suppression

A few weeks ago, our group attended a mandatory safety class at one our company's facilities. This is where we test some of our products under (almost) real world conditions. Since fire can be a significant hazard during these tests, the majority of the class dealt with the fire suppression system. Basically, if any of the sensors within one of these rooms detects a fire, an alarm sounds, giving you 20 seconds to get your butt out of that room before the doors close and the room is flooded with carbon dioxide. The safety guy made sure we understood that it was important to be out of that room before the CO2 was released. Of course someone asked the question, "Couldn't we just hold our breath and stay past that 20 seconds?" The safety guy said "No," and gave two reasons. First, the initial release of CO2 creates an impenetrable fog, which takes a while to dissipate. This makes it easy to get lost, even though the individual rooms are fairly small (about 30' by 20'). Second, and this is where he caught my attention, he stated that in an atmosphere of mostly CO2, holding your breath does no good since enough O2 diffuses out through your skin that you would pass out within 15 seconds.

A couple of us looked at each other after that last statement. It didn't seem possible that O2 could diffuse out of us that quickly since it apparently doesn't diffuse in that quickly, hence the need for lungs. And what about holding your breath underwater? Wouldn't that lead to the same sort of problem? Of course this wouldn't be the first time I was wrong about this kind of thing and so I searched the net for information. As of this writing, I have yet to find any mention of this anywhere. However, I did find that breathing an atmosphere of 10% CO2 for a few minutes can produce unconsciousness, so perhaps in a 50% CO2 atmosphere, one or two breaths are sufficient to knock you out. If any of you have an answer to this question, I would love to hear from you. In the meantime, regardless of the answer, you can be sure that when that alarm goes off, I'll be getting my butt out of that room within 20 seconds.


Teratohmy said...

That seems kind of unsafe... 20 seconds or your dead?

Chemgeek said...

I thought of two things as I read this:

1) what a great way to convert all of your Grignards to carboxylates. YOu better follow the CO2 with an acid atmosphere to protonate them.

2) This CO2 atmosphere doesn't sound to great for the incapacitated coworker on the floor.

Cyberax said...

CO2 doesn't diffuse through the skin, you can quite happy work in CO2 atmosphere with a SCBA.

HOWEVER, if you take even a small breath - then it's BAD for you. CO2 irritates the lungs and produces a strong desire to breathe - which will be deadly.