depth and pressure limitations

[DiverBuoy]

Of course there was the thread of Dave the guy that did the 880 foot dive with a CCR and I think the record for deep dive on scuba is deeper right? Anyway the parts of your body that are incompressible can probably survive to 8,000 feet (being 98% water and all) ... its the compressible bits you'd have to worry about, those kind of forces might make magical things happen.

 

[homo maris]

The current record of depth is held by Theo Mavrostos of the French Comex in the 90s at 701m (2300ft) part of the Hydra 12 project (in chamber).

Gas problems set aside:
At depth of 8000ft the pressure is 367psi. Your second stage would need to provide a higher pressure than the regular ~120-160psi to inflate the lungs and avoid being crushed (or increasing blood in the lungs).

We are made of about 62% water. Fluid are actually compressible at about 1% for 100bar of pressure. This is insignificant and can be ignored for all diving but at a depth (~25bar) you are getting 1/4% of fluid compression in the body. That compression is probably not enough to affect the renal/endocrine or musculo-skeletal systems but it probably needs to be considered.

Hope that helps,
JL

PS: I am nota doctor and I would not send any living being but myself to test what happens at 8,000ft ... and it's not on my future dive plans. Sending animals to be crushed at depth is cruel.

 

[Atticus]

At depth of 8000ft the pressure is 367psi. Your second stage would need to provide a higher pressure than the regular ~120-160psi to inflate the lungs and avoid being crushed (or increasing blood in the lungs).

1. At 8000 feet depth ambient pressure would be 3578 psi ((8000 / 33 + 1) * 14.7).

2. Scuba regulators should always (try to) provide ~140 psi *above ambient pressure*, not absolute pressure. On a recent dive to 300' I would have been very dissapointed if I'd only gotten 140 psi as ambient pressure was 148 psi - in other words I wouldn't have been able to draw gas from my tank.

 

[Atticus]

So are we talking freediving...so you can avoid the deco obligation???

Freedivers (usually) avoid deco obligation not because they aren't breathing off a tank, but because of their very short bottom times.

The lungs of a freediver compress as water pressure increases. This in turn compresses the air present in their lungs, and can lead to decompression sickness, particularly if a freediver is doing many freedives back to back.

There are several recorded cases of freedivers getting bent.

 

[homo maris]

You are correct. Thanks. I made an error calculating the pressure. It is 244 ATA or 3673 psi.

With a 3000 psi tank I don't see how the regulator can provide 140 psi above ambient pressure when the pressure is greater than 3000 psi. You'd need to fill the tank to say 5000psi . Your working gas volume would be 1327 psi which is half that of a regular OW dive. Better have huge tanks.

As for the body compression it would be 2.5% which is significant.

JL

1. At 8000 feet depth ambient pressure would be 3578 psi ((8000 / 33 + 1) * 14.7).

2. Scuba regulators should always (try to) provide ~140 psi *above ambient pressure*, not absolute pressure. On a recent dive to 300' I would have been very dissapointed if I'd only gotten 140 psi as ambient pressure was 148 psi - in other words I wouldn't have been able to draw gas from my tank.

 

[spacemanspiff1974]

Thanks for the info.

I realize this question was WAY out of the realms of normal or technical scuba diving.
Has there been any study regarding other animals, such as mice at greater pressures?

I tried pubmed, but it didnt seem to help. BTW, it is a good source of everything biotech in terms of journal articles in case anyone is interested. http://ncbi.nlm.nih.gov

As for regulator pressure, I figure that if I was able to go to such a depth I would also be able to have someone build an air delivery system for that purpose. Still, I don't plan on doing anything as stupid as the question I posted... unless I was rich, retired and had terminal cancer or something.

 

[rawls]

Based on the air density at that depth wouldn't you have to have a REALLY BIG cylinder...

 

[Nomad]

I *believe* that at that extreme depth, even helium could have narcotic properties. Anybody know specifics about helium narcosis?

 

[dannobee]

Yes, helium's 0.23 x as narcotic as N2, so the depth should be ~1200fsw, irrespective of the HPNS problems.

Sperm whales can dive deeper than 9600 feet. The main difference between us and them (well, at least that which would keep us from freediving that deep) is that their rib cages collapse, ours don't. Our ribs would break as the pressure collapses our lungs.

Why not hitch a ride on a submersible instead? It'd probably be cheaper and you wouldn't have a 6 month deco obligation.