Atmospheric pressure on dry land below sea level?

bbsrs

Hi All,

As altitude increases pressure drops and at about 14000ft it starts to cause problems for us but what I want to know is on dry land, how far below standard day sea level would we have to go for an increase in atmospheric pressure to start causing humans problems due to the insreased pressure. If anybody could tell me what is the max theoretical depth on dry land we can go to without any issues and what would the pressre be at that depth?

many thanks.

tricky D

At the bottom of this article: http://www.livescience.com/34128-limits-human-survival.html

Looks around 20000ft

Furez

Fun question, Im assuming nitrogen narcosis will cause problems first and will ignore oxygen toxicity, which I think may not apply.
Assuming 101 kPa @ ground level, a constant air temp 20C (Think heat would be a big issue, but its a pressure question.) the whole way down and at say 10 KM/h.

-6000m =203 kPa = ~2 Bar. Mild impairment of performance of unpracticed tasks. Mildly impaired reasoning. Mild euphoria possible.

-12000m =409 kPa = ~4 Bar. Really tipsy.

-15300m =601 kPa = ~ 6 Bar. Drunk

-17800m =804 kPa = ~ 8 Bar. Stupidly stoned

-20000m = 1040 kPa = ~10.4 Bar. Probably unconscious before you got here and probably dead now.

So start digging a 15 KM deep hole for a free fresh air high. Or alternatively scuba dive to ~50m.

Used a wiki table and this calculator

Capt'n Midnight

https://en.wikipedia.org/wiki/Hydreliox would suggest it's possible to go to 500m underwater which is about 50 bar

bbsrs

Furez wrote: »

Fun question, Im assuming nitrogen narcosis will cause problems first and will ignore oxygen toxicity, which I think may not apply.
Assuming 101 kPa @ ground level, a constant air temp 20C (Think heat would be a big issue, but its a pressure question.) the whole way down and at say 10 KM/h.

-6000m =203 kPa = ~2 Bar. Mild impairment of performance of unpracticed tasks. Mildly impaired reasoning. Mild euphoria possible.

-12000m =409 kPa = ~4 Bar. Really tipsy.

-15300m =601 kPa = ~ 6 Bar. Drunk

-17800m =804 kPa = ~ 8 Bar. Stupidly stoned

-20000m = 1040 kPa = ~10.4 Bar. Probably unconscious before you got here and probably dead now.

So start digging a 15 KM deep hole for a free fresh air high. Or alternatively scuba dive to ~50m.

Used a wiki table and this calculator

Many thanks, excellent answer to my question. So if I get a sealed cylinder with me inside and pressurize it to roughly 10 bar , I would survive with no ill effects except feeling drunk. The plans for my natural high spa therapy retreat are coming together.

locum-motion

bbsrs wrote: »

Many thanks, excellent answer to my question. So if I get a sealed cylinder with me inside and pressurize it to roughly 10 bar , I would survive with no ill effects except feeling drunk. The plans for my natural high spa therapy retreat are coming together.

No.

Air has 21% O2.

So, if you're breathing 1 bar, the Partial Pressure of the O2 you're breathing is 0.21 bar, and (ignoring the small amounts of other gases like Ar & CO2) that of the N2 is 0.79 bar.

If you raise the pressure to 10 bar, the PPO2 = 10 x 0.21 bar = 2.1 bar.

O2 becomes toxic at a PPO2 of approximately 1.6 bar.

You'd start to suffer convulsions and lose consciousness immediately.

Now, if this happens while scuba diving - ie breathing ordinary compressed air at a depth of 90m [each 10m of descent in sea water adds 1 bar of pressure] - you'd spit out the regulator from your mouth and drown instantly.

Breathing air in your sealed cylinder, though, drowning isn't a possibility. You would certainly lose consciousness, though, and I don't know what after effects you would suffer from the convulsions.

bbsrs

locum-motion wrote: »

No.

Air has 21% O2.

So, if you're breathing 1 bar, the Partial Pressure of the O2 you're breathing is 0.21 bar, and (ignoring the small amounts of other gases like Ar & CO2) that of the N2 is 0.79 bar.

If you raise the pressure to 10 bar, the PPO2 = 10 x 0.21 bar = 2.1 bar.

O2 becomes toxic at a PPO2 of approximately 1.6 bar.

You'd start to suffer convulsions and lose consciousness immediately.

Now, if this happens while scuba diving - ie breathing ordinary compressed air at a depth of 90m [each 10m of descent in sea water adds 1 bar of pressure] - you'd spit out the regulator from your mouth and drown instantly.

Breathing air in your sealed cylinder, though, drowning isn't a possibility. You would certainly lose consciousness, though, and I don't know what after effects you would suffer from the convulsions.

Thank you , I meant to say pressurise the cylinder to 6 bar. Would 6 bar be ok apart from feeling drunk as was said in a previous post?

locum-motion

bbsrs wrote: »

Thank you , I meant to say pressurise the cylinder to 6 bar. Would 6 bar be ok apart from feeling drunk as was said in a previous post?

6 bar = diving to 50m in seawater = PPO2 of 1.26

Yeah, that would be fine in terms of O2 toxicity.

You'd still be running the risk of decompression sickness and/or lung overexpansion injury if you reduced the pressure too quickly on the way out!