12 boys lost in flooded Thai cave

[MichaelMc]

You are comparing apple with orange. ...
We also don’t consider the harmful elevated CO2 level that would be in the air as we breathe out in confined space, like in an enclosed garage with a car engine on. The oxygen concentration may still be closed to 20-21%, but people died there due to breathing air with elevated CO2 coming out of the car exhaust.

Car exhaust is carbon monoxide, CO. People in confined space is carbon dioxide, CO2. I'm sure 'air quality in sump spaces' is sump diving 101. And the world experts are there. I wish we had the data, but the experts are there.

The NSS Cave Rescue Commission National Coordinator, who clearly aimed to leave his own speculation out of it in favor of those who are on the scene. "In Thailand." "Underwater."

This ^^^^^^^ ... "in favor of those who are on the scene. "In Thailand." "Underwater.""

 

[RockiesFan]

My all time favorite quote in this ordeal, "How many of you are there? 13? Brilliant!"

 

[JohnnyC]

As I mentioned in another post, I had in mind what I had heard in an interview with Anmar Mirza, the NSS Cave Rescue Commission National Coordinator, who clearly aimed to leave his own speculation out of it in favor of those who are on the scene. "In Thailand." "Underwater." I was really impressed how he related the facts and the options without injecting his own opinions, despite the interviewer trying to coax that out of him. Well done, I thought.

I think it's important to point out that while Anmar is a caver, and also a diver, he is not a cave diver. I think it's also important to point out that he recognizes that, and recognizes that while he is indeed a subject matter expert in cave rescue, he smartly defers to the guys on location doing the work when it steps outside of the bounds of his expertise. He's a smart guy and has done a good job during this whole thing.

 

[Dan]

That's why I said, Dan, lots of fake stories (or hard to believe stories) are coming out. They cited a belgium diver being around... but he is not cited in name. He said the people in charge would have thought there was enough air coming in through small cracks but apparently it isnt...

Another thought:
Normal air has about 0.04% CO2. As O2 being replaced by CO2 as we breathe out in confined space, CO2 would easily elevates to harmful level very quickly. By 0.2-0.5% CO2 you’ll have headache, nausea, etc. as described here: What are safe levels of CO and CO2 in rooms? | Kane International Limited If that is the case, the kids wouldn’t last at that condition in 12 days & the doctor won’t issue “green” health condition as he examined them. So that “15% O2” News is totally fake news to me.

 

[Dan]

Car exhaust is carbon monoxide, CO. People in confined space is carbon dioxide, CO2. I'm sure 'air quality in sump spaces' is sump diving 101. And the world experts are there. I wish we had the data, but the experts are there"

Ya, I forgot about some incomplete combustion of the fuel to CO. But the majority of the combustion of air with fuel turns to CO2 based on what I learned in my 6 years of Chemical Engineering school, right in your town, BTW.

CO is even more harmful than CO2. You’ll die within 2-3 hours after breathing 800 ppm CO.

 

[boulderjohn]

Water absorbs carbon dioxide.

 

[Dan]

Water absorbs many gases, including carbon dioxide. The question is how much carbon dioxide would be absorbed by a normal non-flowing water surface? I would say, not much to affect the CO2 concentration in the air.

 

[admikar]

We all hope for the best. Best thing we can do is let people "on the ground" asses situation and make decisions accordingly.OK, not that we can make much of influence there,but still, let the people on scene do what they think is best.

 

[boulderjohn]

Water absorbs many gases, including carbon dioxide. The question is how much carbon dioxide would be absorbed by a normal non-flowing water surface? I would say, not much to affect the CO2 concentration in the air.
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The guy who survived three days in the sunken ship did so because the water absorbed the carbon dioxide. The water is flowing.

 

[Dan]

The guy who survived three days in the sunken ship did so because the water absorbed the carbon dioxide. The water is flowing.

I see your point. The sea has huge capacity of water. Even though the CO2 solubility in water is low, the flowing water replenishes the high CO2 concentration water after CO2 absorption taking place with the fresh low CO2 concentration water. On the other hand, even though without CO2 absorption into the water, you can survive by breathing the air with elevated CO2 up to 2% for days. All it does is displacing the oxygen in the confined space from 21.5% to 19.5%.

One thing I learned is it is not easy to absorb CO2 with water. When I design CO2 absorber tower for a chemical plant, the process involves spraying mist of slightly basic water with some caustic (NaOH) solution. The NaOH converts CO2 to Na2CO3/NaHCO3 (i.e., baking soda, Sodium bicarbonate - Wikipedia). The mist is to increase contact surface between the gas & the water to promote the CO2 absorption. The mist flow down from the top of the column through a packed bed (like you are getting drench by a heavy monsoon rain) and the gas flows up countercurrent to the falling liquid from the bottom of the packed bed. With such process we only reduce the CO2 concentration by tiny bit (ppm level). So, CO2 absorption into the flowing water I don’t think it’s the major contribution to the survival of the guy. I think it’s more like the oxygen concentration in that confined air space is still sufficiently high enough (above 19%) for breathing.