SB Forum--Bad Air Incident

[Greenwood_60]

Do CO meters register CO2 as well?

[MichaelAngelo]

Do CO meters register CO2 as well?

No sir differant sensor

[allen]

You must have a source of carbon to get CO. I suspect that the seawater was dirty. I wouldn't take much diesel fuel to react with oxygen and produce 80 ppm CO.
80 ppm would not kill of itself, but would depress brain activity and be likely to cause the diver to make a fatal mistake. OSHA says 1000 ppm is lethal at sea level. Thus 250 ppm would be lethal at 90 feet.
A non-smoker's breath should contain 1 ppm CO. I use my breath to calibrate my Analox.

[gschaut]

Interesting. How does salt water cause 81 ppm of CO?

To answer an old question... Your LP 85 tank is steel. A mixture of Iron AND CARBON, along with other elements.

High Carbon Steel contains between .3% and .9% carbon by weight.

That means that your LP85 tank contains about 2 to 7 ounces of carbon.

IF... ONE PERCENT of the steel in the tank rusted, that would release between .00125 and .00375 pounds of CO into your gas mix.

That would be aprox. .0156 and .0468 cubic feet of pure carbon monoxide.

OR... 195 to 600 ppm CO in an 85cuft tank.

Please forgive any math errors, I'm just running rough and dirty numbers thru my calculator.

[DogHouseDiver]

Gschaut +1 on that... I love this community for posts like this. I assumed it had something to do with carbon steel and oxidation (rusting) but I just KNEW someone smart here would have the answer, share it, and now we all know why. I'm not going to do the math but I'm glad someone did and shared it.

I took a year plus hiatus from Cave Diving due to my relocating which included stopping diving to save up a few months, spendi g 3 months in Costa Rica building on my property with funds from a great (and voluntary) severance package. then relocated to another state, spent a year getting a good foreclosure condo, rebuilding that, and spending a year on the new job.

I'm smart enough to know I can't just go back to full cave. I need to rebuild skills, muscle memory, and ease into the complexity. So I hit the pool, then some OW, then a cavern, and I'm easing back into it. But the first step has been following the forums and THINKING about cave diving months in advance while working on my gear. I've read enough stories of hero to zero to dead hero of those that take a hiatus but think they can go right back to where they left off... you know... a nice easy FULL cave diver with just one scooter and only three stages and deco?!?! Crazy.

So for me, some armchair diving and mental prep goes a long way. As do patient dive buddies who will always dive at any lower level. So I appreciate great topics and good explanations like this. Really helps to bring the returning caver back to thinking about all the little things that can kill you that you USED TO think about often... this kind of stuff is great mental pre-dive breifing before the gear hits the car.

Thanks for participating in keeping cave diving safe. its refreshing to take a break from flame wars and underwater social politics to learn something.

Now, back to the circus...

[Sludge]

I don't get it. Where's the chemical reaction? You can't just add a pound of carbon to a pound of oxygen and get two pounds of carbon monoxide.

[gschaut]

I don't get it. Where's the chemical reaction? You can't just add a pound of carbon to a pound of oxygen and get two pounds of carbon monoxide.

The oxidation reaction that turns steel to rust is, by definition, incomplete combustion. CO is produced on a molecular level as the iron oxidizes. Fe+C+O2= FeO + CO. Iron causes the reaction, the carbon goes along for the ride.

[Greenwood_60]

From the little bit of research I did, CO and iron oxide --> iron and CO2.

[rddvet]

The oxidation reaction that turns steel to rust is, by definition, incomplete combustion. CO is produced on a molecular level as the iron oxidizes. Fe+C+O2= FeO + CO. Iron causes the reaction, the carbon goes along for the ride.

From the little bit of research I did, CO and iron oxide --> iron and CO2.

It's been quite a while since I got out of organic chemistry 2, but while it's a balanced equation I don't think the above equation creating CO is actually representative of the real oxidative reaction that happens.

My brain already hurts too much to rummage through a textbook to figure it out.