I had to stop watching

[SapphireMind]

I believe the 130 ft/40m NDL was made using doppler research with NASA - taking into account the partial pressure of oxygen and nitrogen.

Dive Risk Factors, Gas Bubble Formation, and Decompression Illness in Recreational SCUBA Diving: Analysis of DAN Europe DSL Data Base interesting article about DCS
Historical Perspectives on Dive Tables and Decompression Models – Divers' Blogs good info and links out to more research and history of development of NDL

 

[tursiops]

I believe the 130 ft/40m NDL was made using doppler research with NASA - taking into account the partial pressure of oxygen and nitrogen.

Dive Risk Factors, Gas Bubble Formation, and Decompression Illness in Recreational SCUBA Diving: Analysis of DAN Europe DSL Data Base interesting article about DCS
Historical Perspectives on Dive Tables and Decompression Models – Divers' Blogs good info and links out to more research and history of development of NDL

The 130 ft limit long predates the existence of NASA.

 

[SapphireMind]

I wouldn't say long predates - NASA has been around in some form or another since the 50s, which is when the depth limit was generally agreed upon it seems, according to some articles. This article explains partially, and one of the comments includes that at 130 ft. the pp of O2 is 100%, which would also go into why it was determined.
Why is 130 Feet the Depth Limit for Recreational Scuba Diving?
SCUBA Q&A: Deep Diving Below Recreational Scuba Depth Limits?
History of Scuba Diving | Diviac Logbook

But I know they continue to do research about DCS and oxygen toxicity and nitrogen narcosis.

 

[Dan]

Partial pressure (pp) is not in %. It’s in pound-force per square inch (psi) or Bar or atmosphere (atm). At surface air (containing 21% O2), pp O2 = 0.21 atm. At 130 feet depth (~5 atm), pp O2 = 5 x 0.21 atm = 1.05 atm.

The % O2 in the tank (say, you are using air) is still 21%, no matter how deep you are in the water. 100% O2 means pure oxygen, which is not the case here.

 

[doctormike]

56m (which, not incidentally, is the depth where you reach 1.6 bar pPO2 on air)

I'm not sure that your math works 56m = 1.6 ATM?

Storker is referring to PP02, not ambient pressure.

56 m = 6.6 ATA

If you are breathing air at 21% 02, then the PPO2 at 6.6 ATA = 6.6 x 0.21 = 1.4, which is the generally accepted PPO2 limit at depth.

 

[johndiver999]

He indicates it is 1.6 atm, but you say it is 1.4. I’m so confused.

 

[doctormike]

He indicates it is 1.6 atm, but you say it is 1.4. I’m so confused.

Maybe a typo. But the point I was responding to was your question about how 56 m = 1.6 ATA.

 

[johndiver999]

Maybe a typo. But the point I was responding to was your question about how 56 m = 1.6 ATA.

Thanks for the clarification, but I never said 56 m = 1.6 ATA.

 

[doctormike]

Thanks for the clarification, but I never said 56 m = 1.6 ATA.

My mistake. This is what you wrote:

"I'm not sure that your math works 56m = 1.6 ATM?"

I must have misinterpreted what you were saying. What did you mean by that post? I though that you were interpreting Storker's post as if he was saying that 56m = 1.6 ATA. All I was saying was that that wasn't what he was saying.

 

[Sam Miller III]

I believe the 130 ft/40m NDL was made using doppler research with NASA - taking into account the partial pressure of oxygen and nitrogen.

Dive Risk Factors, Gas Bubble Formation, and Decompression Illness in Recreational SCUBA Diving: Analysis of DAN Europe DSL Data Base interesting article about DCS
Historical Perspectives on Dive Tables and Decompression Models – Divers' Blogs good info and links out to more research and history of development of NDL[
/QUOTE]
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@SapphireMind
Thank you for your research -- your efforts is appreciated

However American recreational and professional SCUBA diving began long before the establishment of NASA

It is suggested that you research 1940s recreational diving-- where it all began by bunch of sun tanned athletic SoCal youths

Sam Miller,III