Breathing from a 30ft. snorkel

[costi]

All right guys, help me out on this would ya?
A guy asked at work today a hypothetical question:
If a person had a 33ft. long snorkel with an exhaust valve on it so that he could exhaust the c02 rather than sending it back up the snorkel, why wouldn't he be able to breathe through it?
I didn't have the answer. Any takers?
Oh, BTW, As I said at the top of the page, this was only a hypothetical question asked to help pass the workday (or evening)........he doesn't really want to do this (I don't think)
I did tell him though, that even though you are not breathing compressed gas from a tank, I believe the effects of surfacing while breathholding would be the same since the air has been compressed by the depth.
Anyway, not a question you folks need to take too seriously, I was just curious how to figure the answer.
Bob

 

[Cave Diver]

As I recall, we are not capable of keeping lungs inflated at that depth without having air delivered at ambient pressure. The muscles are not sufficient to expand your lungs and basically all of your air would be squeezed out with no way to draw a fresh breath in.

Not to mention the dead air space and CO2 build up.

Previous thread on the subject: http://www.scubaboard.com/forums/do-yourself-diy/133781-breathing-underwater-7ft-diy.html

 

[k ellis]

Ok I personaly would think if the C02 was released seperate from the main intake it would not be too big of a problem They have snuba which is basicly a 30 foot regulator hose connected to a tank that never leaves the surface. cave diver makes a good point as I recall something to that effect.

 

[dhaas]

Exactly as cavediver says....

The human body can barely inflate your lungs past about 3' - 5'!

We used to take a "Super Snorkel" to scuba class in the 1970s and have people try and lay in 3' of water to breathe. 99% couldn't get past 2'......

In a word, pressure

dhaas

P.S. - A hookah rig is pumping gas down to the pressure at depth! I.E. - 14.7 PSI times two atmospheres!

Not the same as tying to draw down surface air by lung power......Can't be done.....

 

[Bubbletrubble]

The answer to your question requires knowledge of:

• increased ambient pressure at depth.
• the inability of normal/accessory breathing muscles to overcome ambient pressure to inhale unpressurized surface air.

(Edited later: Looks like a few people beat me to it!)

 

[TMHeimer]

Nah. Can't be done. It's the pressure thing even more so than the CO2 thing. An exhaust for the CO2 would eliminate some or all of the dead air space, but you still can't suck air down any more than a foot or two from the surface (It needs the mechanics of "surface-supplied" air ei.-"hard hat helmet divers"). If it could've been done with something as simple as a snorkel it probably would have been done decades ago. Others may want to elaborate. Oops, they did as I was posting.

 

[Guba]

Just try the reverse...get a 33 foot long "straw" and attempt to suck water up the straw, say from a third story balcony. The effect is the same. Our diaphram is not capable of overcoming the weight of the water. It is precisely that same "weight" that applies the pressure that must be overcome to pull air down through the snorkel.

 

[Splitlip]

Oh come on. What Kind of question is this LOL.

This is not even worthy of a response.

He's jerking our chains.

 

[costi]

As I recall, we are not capable of keeping lungs inflated at that depth without having air delivered at ambient pressure. The muscles are not sufficient to expand your lungs and basically all of your air would be squeezed out with no way to draw a fresh breath in.

Not to mention the dead air space and CO2 build up.

Previous thread on the subject: http://www.scubaboard.com/forums/do-yourself-diy/133781-breathing-underwater-7ft-diy.html

Thanks guys! I never gave it a thought that someone else would have asked a similar question or I would have checked out search! The guy had given thought to avoiding the co2 buildup via the exhaust valve, but the fact that the muscles aren't strong enough to expand your lungs under the pressure makes perfect sense.
Darn.... that was too easy....Now what can we talk about tomorrow? Guess we'll just have to Work!
BC

 

[redacted]

Let him see if he can drink a bottle of coke through a 33 ft long straw.