History Question About o2 and Compressed Air

[CptGlub]

With so much compressed air on board, why wouldn't a sub squeak a little into the pressure hull when the o2 ran low? Let it in one end and a small valve lets a bit of the bad air out the other end?:hmmm:

?

[ETR3(SS)]

Mostly because that compressed air has a specific use, like surfacing the boat in event of emergency. Also because none of the ventilation system hull valves were designed to be operated underwater. There were oxygen candles and a CO2 absorbent for extended submerged periods.

[mikesn9]

On today's boats, they have oxygen generators, Carbon Dioxide scrubbers on line. Oxygen tanks with constant O2 bleed, like you were thinking, CPT. And, as ETR3 said, no link from outside to in. (makes for a much dryer Upper level AMR2)

ETR2 SS, SSBN609 (B)

[CaptBones]

Still missing the key issue...

Lack of oxygen is not the problem, excess carbon dioxide is the problem. Releasing compressed air into the boat doesn't do any good.

Your lungs only absorb 4% of the oxygen in the air that you inhale. When you exhale, you send the "excess" oxygen back out, along with "waste" carbon dioxide that ads to that already in the air. You can live and function for a long time in an atmosphere with steadily decreasing oxygen level; as low as 15-16% has been proven to be livable. Saturation divers typically work with gas mixes that have as little as 11% O2.

But, you can't function very well at all when the carbon dioxide level rises above a mere 1%, and 2% is deadly. The type of CO2 scrubbers used today didn't exist in WWII; the ventilation system had bypass sections where canisters of CO2 absorbent could be used to control the carbon dioxide level. Of course, when running silent, you can't run the ventilation system, so simple cans of "quicklime" CO2 absorbent were available.