Hyperbaric Chamber Question.

[Superlyte27]

well, second stage reg has a valve in it, sorta.

Honestly, i'm not quite certain about that Mark V (and really I don't think it was a Mark V), but i'll find out for certain on Tuesday.

 

[elmer fudd]

So... a submarine is not pressurized? How about a jetliner?
I'm talking internal pressure, you're talking external pressure.

Were getting down to semantics here, but my understanding is that a submarine is not pressurized, but a jetliner is. Pressurized generally means that something contains greater than normal or ambient pressure. If you're having to feed something pressurized air, then it's pressurized. If you seal up a tube and submerge it 300', it's still not a pressurized tube.

 

[Superlyte27]

I'll find that out too, same guy going to answer the other question was on a fast attack sub for long time.

 

[vladimir]

A navy submarine has 1 ATA of pressure on the inside. The hull is built to withstand the external pressure.

 

[Aquatic Eagle]

I disagree, because the pressure is the pressure at the other end of the hose 3/8ths of an inch.

If i'm at depth in a desko, and i turn off my air pressure, then burp my neckdam, am i sucked through the hole in my neck dam?

For that matter, if i'm scuba diving at 300' and open my mouth, why is not all the air in me sucked out?

The air wouldn't be sucked out of you if you opened your mouth because the air you breath in has been regulated to match the pressure of the 300' depth. If they're the same pressure then there is no gradient.

 

[diverdoug1]

A mark V helmet and the suit comprise a closed compressible volume that is conectcted to the tender hose (no nice rubber dam around your neck). If we assume an incompetent check valve, and a tender hose which is cut above the surface of the water, a pressure gardient will develop across the surface of this closed compressible system equal 1atm X Depth in feet/33. Imagine you have a weather balloon full of toothpaste with a seven mile long non-compressible tube sticking out of it. Now submerge that balloon seven miles under the surface untill just the end of the tube is sticking out of the water. The toothpaste will be extruded up the rigid tube to equalize the pressure gradient. In fact, if the balloon is flexible enough, it will be pushed up the tube untill it ruptures. Just like when you stick a straw in a glass of water, the water tends to fill the straw up to the water line. Now back to our Mark V diver... If his suit does not rupture, he will extrude into the tube or the tube will become blocked. In essence, we have an old fashioned vertical column barometer, but instead of mercury, we have diver sucking up into the column. Any failure of the suits watertight integrity will just cause a flooding of water, which if fast enough would prevent compression of the suit into the helmet. If the cut was below the surface, water would rush in to equalize the pressures, so no compression of the suit/helmet volume. The inner diameter of the tube has no effect other than the speed at which the equaliztion can occur and the ease of getting blocked or extrusion. It would not matter if the helmet and suit were full of water IF the hose were full of air. If the hose is full of water no compression of the suit will take place (it would be just like the diver disconnecting the hose from his rig). The main question would be, how much pressure it would take to overcome the mechanical resistace and viscosity of the divers tissues resisting being forced into the helmet and tube like so much Play-Doh through a Fun-Factory.

 

[JKPAO]

I know when you get to wear a hat you have already learned some physics that apply to diving.
It is obvious to me some people are getting into a hat and do not know what they are wearing
and why they are wearing it! (or they just have a cool name)
DOES SUCK SOME FACE PLATE MAKE SENSE?
Nice explaination Diverdoug!
See you topside! John

 

[vladimir]

The main question would be, how much pressure it would take to overcome the mechanical resistace and viscosity of the divers tissues resisting being forced into the helmet and tube like so much Play-Doh through a Fun-Factory.

Nicely put.

 

[DCBC]

DOES SUCK SOME FACE PLATE MAKE SENSE?

I heard of a diver in the Gulf in the 80's that had a failure in his non-return valve in his Superlite and experienced severe helmet squeeze (his eyes were sucked out of his head). In Navy Dive School they talked of the earlier MK I & II Morse and Schrader helmet divers displacing divers into the hose. It sure got the point accross; you don't mess with pressure. :shocked2:

 

[diverdoug1]

I heard of a diver in the Gulf in the 80's that had a failure in his non-return valve in his Superlite and experienced severe helmet squeeze (his eyes were sucked out of his head). In Navy Dive School they talked of the earlier MK I & II Morse and Schrader helmet divers displacing divers into the hose. It sure got the point accross; you don't mess with pressure. :shocked2:

I think someone might have been having you on about the superlyte diver's eyes. A crushed orbit can extrude the globe of the eye, but I don't think that an eye can be evulsed from the orbit by exposing the whole cranium to a very low pressure (but they could bulge if the suit was crushing the lower body and increasing the venous pressure - pushing up into the helmet.) I would think the dam on the superlyte would rupture before there was that much pressure differential. I am not an opthalmologist though, so I may be wrong. It does make for a unforgetable mental image though!