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Posted: 6/12/2002 11:07:58 AM EDT
Link Posted: 6/12/2002 11:13:34 AM EDT
[Last Edit: 6/12/2002 11:14:48 AM EDT by Polyak]
Link Posted: 6/12/2002 11:16:35 AM EDT

hmmmmm....it's been many, many years since my basic SCUBA course, but if I remember correctly, for every 33 feet you descend, the pressure increases by 1 atmosphere.  So, at 40 feet you'd be at a little over 2 atmospheres of pressure, at 60 feet you'd be at almost 3 atmospheres....

Basically, what this means is that if you are sitting in 33 feet of water, take a full lungfull of air from a tank and ascend while holding your breath...then the amount of air in your lungs would double by the time you reach the surface....result would be a blown lung or an embolism....neither of which is desireable :-)
Link Posted: 6/12/2002 2:40:07 PM EDT
Originally Posted By Polyak:
Water gains or loses .433 psi per ft.

HTH


gains going down, loses going up
View Quote

Going under is exponetial.
GG
Link Posted: 6/12/2002 3:38:31 PM EDT
Link Posted: 6/12/2002 3:41:40 PM EDT
14.7 psi at 33 feet
Link Posted: 6/12/2002 3:43:48 PM EDT
Link Posted: 6/12/2002 4:09:03 PM EDT
Isn't 14 and something psi the air pressure at sea level?
Yep I think its 14.7


Water info I remember from SCUBA diving
14.7 psi at 33 feet  =     .445 psi per foot
checks pretty close to
Polyaks answer
Water gains or loses .433 psi per ft.
Link Posted: 6/12/2002 4:17:22 PM EDT
Link Posted: 6/12/2002 4:25:02 PM EDT
No, the problems potentially arise in diving with pressurized air only.
Link Posted: 6/12/2002 4:38:23 PM EDT
[Last Edit: 6/12/2002 4:46:52 PM EDT by IMHO]
Using these non SI units, and assuming that we're talking about fresh water:
[Edited because I really ought to express all units:"

34 feet of depth in water=1 Atmosphere,
1 Atmosphere=14.7 pounds/square inch (psi)

14.7psi/34feet of depth=.432 psi/foot of depth

So, at 40 feet:  40feet*.432psi/foot=17.28 psi
This is the gauge (hydrostatic) pressure.

The absolute pressure must include the column of air that is stacked on the water, so we add
17.28psi+14.7psi=31.98 psia (pounds/square inch abosolute)
Link Posted: 6/12/2002 4:40:35 PM EDT
1 psi per 2.3 ft. of water or 0.435 psi per ft of water.
Link Posted: 6/12/2002 4:53:51 PM EDT

Water pressure at depth is linear, because a liquid can’t be compressed.


About 32psi at 40 feet and about 40.5psi at 60 feet.


R/K
Link Posted: 6/12/2002 4:59:38 PM EDT

I should quantify that answer includes atmospheric pressure and like
IMHO pointed out, would be absolute pressure.


Link Posted: 6/12/2002 7:39:16 PM EDT
As mentioned before...
1 atm= 14.7 psi (sea level)
2 atm= 29.4 psi (33 feet deep)
3 atm= 44.1 psi (66 feet deep)
4 atm= 58.8 psi (99 feet deep)

This information was obtained from [u]Jeppesen's Open Water Sport Diver Manual[/u] that was given to me when going through my SCUBA lessons.  Hope this helps!!!
Link Posted: 6/12/2002 7:51:44 PM EDT
Link Posted: 6/12/2002 10:28:38 PM EDT
What has always puzzled me is to see fish swimming about in the oceans deepest waters and knowing at those same depths a steel hulled submarine would be crushed. I know there is a scientific/mathematical answer,  but It still amazes me.
Link Posted: 6/13/2002 4:44:19 AM EDT
Originally Posted By Am-O-Tramp:
What has always puzzled me is to see fish swimming about in the oceans deepest waters and knowing at those same depths a steel hulled submarine would be crushed. I know there is a scientific/mathematical answer,  but It still amazes me.
View Quote


I believe it's due to that the fish has equal  internal and external pressure. Whereas the sub requires 'air' within, hence the pressure difference.
Link Posted: 6/13/2002 5:05:43 AM EDT
Thank your Older_Crow.  Am-O-Tramp
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