Deeeep diving theory

[LSDeep]

Ok, I'll stab at it. My resting SAC rate is .4cuft/min. We'll assume that my resting respiratory rate is 12/min. This means that every breath on the surface is about .033cuft. I get apporximately 2424 breaths from 80cuft @1 atmosphere.

Our goal in this is for one breath to equal 80cuft.

Unless I'm really behind on my math (I'm better at science stuff, like chemistry and biology than math), it would take 2424 atmopheres to drain an al80 (if it really had 80cuft in it...ok the dive shop messed up today and overfilled it) in one breath. .033cuft per breath at the surface, multiply that by 2442 atmosheres equals 79.99cuft.

2424 atmospheres absolute is something like 79,959ft.

seen!!! and that was my first one. did you consider, that you also depending on surrounding pressure inhale a lot more air at any given depth??? it gets a bit more complex! i have to admit i am also a bit lost with your imperial meassurements! while i get basics halfway straight in metric and imperial when it gets complex its hopeless for me

 

[ZzzKing]

It will probably happen at whatever depth that your tank gets physically crushed to the size of your lungs.

Math: .5l = 12l/24 so you'll need 24 x 3000psi = 72,000psi or 4965 atmospheres to compress the contents of a 12l tank to .5l.
At 1 atmosphere / 33ft depth, that yields about 164,000 feet deep.

I think PADI is coming up with a new C-card for this type of diving. I wouldn't recommend trying it until you've completed the appropriate certification course.

 

[do it easy]

about 10 -11ltr in real water volume (or air on surface pressure for that matter).

OK, I edited my answer into my first post, but using a 10L tank, it would be 153,087 fsw.

I think my answer is much larger than PfcAJ's because his .033cf is larger than the .5L that I used. If my fingers and toes serve me well, it's about .93L, so it makes sense that his answer is about half of mine. The rest of the difference might be the tank size that I'm using- an AL80 might be 10.2L, maybe 9.8L.

At any rate, you would have to be friggin deep- If you went that high you would be in space. Everest would be about a fourth of that.

 

[LSDeep]

well i give it an attempt metric. if tank (80cf / 10ltr - give or take a bit) 10ltr x200bar (3000psi - dont yell about minor diff) we look at 2000ltr of air. considering the by you given (and as verified accepted ) 0.5ltr lungvolume for a breath @ the surface we look at ahem, ohh, well, about, doodle, dive and try right now.... at about 20.000mtr (that was a long cesa dude!!!) - thats give or take, very ruffly 60.000ft!

 

[LSDeep]

you actually owe me for a new breitling seawolf now! that got crushed on my dive

 

[do it easy]

I think that you got narced at that last step- Everything looked good until you hit 20,000 meters. maybe 40,000 meters...

 

[LSDeep]

consider that your reg (allowing that it still works) delivers gas according to ambient pressure! means surface 0.5ltr = 10mtr - 1ltr. if 10mtr = 1ltr, than 10,000mtr = 1000ltr, if 10000mtr = 1000ltr than 20,000mtr = 2000ltr.
i dont try to get overaccurate here, no nerve for that right now, but with ruff numbers. open for suggestions what i might forgot. having rum and cokes here since about 6 (its about 12:30 now here) so i dont claim i am completely sober and invinceable (or however you spell it ))

 

[PfcAJ]

It can't happen. Ever.

The tank is a ridged vessle. This would be like sucking all the air out of an empty beer bottle. It just can't happen. If the vessel was flexible and the volume was displaced by something, it would be *possible*.

We can calculate how many atmopsheres 1 breath equals 77 cuft at, but you can never ever empty the tank completely. If it was a 77cuft plastic bag, then it could be done.

Once the ambient pressure equals the pressure of the vessel, no exchange will occur. This is why you can't breath from an "empty tank" at 90 ft, but you can on the surface. With me on this?

 

[LSDeep]

It can't happen. Ever.

The tank is a ridged vessle. This would be like sucking all the air out of an empty beer bottle. It just can't happen. If the vessel was flexible and the volume was displaced by something, it would be *possible*.

We can calculate how many atmopsheres 1 breath equals 77 cuft at, but you can never ever empty the tank completely. If it was a 77cuft plastic bag, then it could be done.

Once the ambient pressure equals the pressure of the vessel, no exchange will occur. This is why you can't breath from an "empty tank" at 90 ft, but you can on the surface. With me on this?

yep, youre right from a scintific point of view. but ts a theoretical question with an theoretical answer. consider the tank empty at the point nothing is "coming out anymore". sure there will be some left and it will even let you breath again as surrounding pressure would be reduced during your accent.

 

[LSDeep]

if you wanna go that far it becomes extremely complex to "figure out"