USN decompression 30fsw/9m with 100% O2

[rjack321]

@OTF, humans don't inexplicably tolerate higher PPO2s in dry chambers than they do in the water.

Except we do tolerate higher PPO2s in the dry chamber vs in the water

Understanding Oxygen Toxicity

Oxygen toxicity is still being understood by researchers. Learn more about oxygen toxicity, including who is at risk more.

dan.org

Frontiers | Oxygen Toxicity and Special Operations Forces Diving: Hidden and Dangerous

In Special Operations Forces (SOF) closed-circuit rebreathers with 100% oxygen are commonly utilized for covert diving operations. Exposure to high partial p...

www.frontiersin.org

plus, on top of that the consequences of O2 toxicity in a chamber tend to be less

 

[TeamBubbles]

Except we do tolerate higher PPO2s in the dry chamber vs in the water

Yes, but not inexplicably (as evidenced by the articles you linked)! I was focused on the mitigation of seizure risk, as it had been mentioned up-thread and should have chosen my words more carefully. I apologize for any confusion. Be safe!

 

[tursiops]

Yes, but not inexplicably (as evidenced by the articles you linked)!

I don't know what you mean. Do you mean: Yes, but we don't know why? If so, I agree.

 

[Tom Agneessens]

Perhaps back up a step. Why are you trying to adapt USN tables which use surface supplied helmets or 2ata dry chambers for O2 deco to plan your dives in 2021? We have tools specifically for sport diving nowadays.

Hello,

I do not try to adapt. I try to understand and out of interest These are tables that are publicly available and even regular sport diving agencies like PTRD are ‘using’ them. But rarely or even never you see diving examples (scenarios) in the theory lessons that use deco with 100% oxy at 6, let stand 9m or propose an alternative for the 9m ‘issue’

Thank you all for your answers. It helped a bit.

 

[Wibble]

Some technical divers do use 100% deco gas at 6m. Some agencies prefer this over other mixes (e.g. 80%). Long decompression hangs on 100% require “air breaks” periodically to reduce the pulmonary oxygen toxicity and give your lungs a break.

 

[tbone1004]

Some technical divers do use 100% deco gas at 6m. Some agencies prefer this over other mixes (e.g. 80%). Long decompression hangs on 100% require “air breaks” periodically to reduce the pulmonary oxygen toxicity and give your lungs a break.

I'm not aware of any agency that does not advocate 100% deco gas at 6m and certainly not one that advocates 80%. 70-80% gases are only used by cheap divers that don't want to buy a booster *note that filling 70-80% is convenient because an O2 bank bottle comes in at 2000ish psi and if you top it off to 3000ish psi with air then the mix is in the 70-80% range. It has nothing to do with decompression efficiency.

 

[Andy in Gap]

I disagree. 70% gets me out of the water faster than 100% O2 on dives in the 150ft range that require 30-45min of deco. I can get on my deco gas at 40 ft instead of breathing backgas all the way up to 20ft. Has nothing to do with being cheap or making a poor selection.

 

[tursiops]

I disagree. 70% gets me out of the water faster than 100% O2 on dives in the 150ft range that require 30-45min of deco. I can get on my deco gas at 40 ft instead of breathing backgas all the way up to 20ft. Has nothing to do with being cheap or making a poor selection.

Sure, 50% or 70% are great first deco bottles, but you still are better off with 100% at 6m. That is all that is being said.

 

[boulderjohn]

@OTF, humans don't inexplicably tolerate higher PPO2s in dry chambers than they do in the water.

I believe humans do tolerate higher PPO2s in a dry chamber. We have had a number of threads on this topic over the years I have been on ScubaBoard.

 

[Andy in Gap]

Gotcha, I guess I misunderstood the contention. I would never advocate for anything but 100% for only a 20ft stop.