Another thing to throw out into the mix: doesn’t carbon dioxide sink? I seem to remember something about this, and this would in effect limit the length of the tube (all other factors notwithstanding).
Sure, you could exhale as hard as you can, but eventually the carbon dioxide buildup would “plug” the bottom of the snorkel thus blocking any valuable air.
IIRC, this is why they have to pump fresh air into mines, and why well digging was so dangerous back in the ol’ days. . .
Tripler
I could be wrong. I’ve been wrong before, I’m sure I’ll be wrong again.
Just to add a couple of data points to this discussion:
When I tried to inhale, it was like trying to inhale on a solid pipe. I could pull no air in. I felt no force trying to push air out of my lungs (but considering the passage of time, I will admit my recollection could be faulty).
No, you wouldn’t. One of the drills in SCUBA is to remove the regulator from your mouth and to put it back in. (Just in case it gets knocked out or something.) You just hold your breath. No worries. On my first open water dive the instructor pried a shellfish off of a rock and ate it at 65 feet (about 3 atmospheres).
Upon further reflection, I agree that there is some force exerted trying to push water up the tube. It seems to me that the total force would be the total weight of the water that would fill the tube minus the weight of the air in the tube. There may also be factor of 0.5 involved (i.e. divide by 2), but I’m still haven’t worked it all out yet. That force, if it’s a relatively narrow tube, would likely not be enough to cause any damage at swimming pool depths. At 100’, it might be a different story.
That doesn’t sound quite right; the pressure is coming from the fact that you’re under a massive pile of water that wants to fill the tube back the the surface level; that the tube is big or small doesn’t affect the magnitude of the pressure, as far as I can work out.
It will affect the amount of work that the system can perform; so a narrow tube will suck really hard, but only briefly until it’s filled (either with water, or parts of the hapless diver). A wider tube will suck just as hard (no harder), but for loger, or more voluminously.
Carbon dioxide is heavier than air, but not so significatnyl that’s it’s likely to be a significant factor in a system that is turbulently circulating (otherwise it would also pool in the unexpelled air volume in our lungs).
Far more significant (apart from the pressure considerations, etc), is that, on reaching a length of tube containing a volume of air equal to the lung capacity of the experimenter, there’s simply no way for thim to expel the exhaled breath all the way out of the tube in order to get fresh air to breathe in again.
easy way to test. You can suck in and blow out with about the same force. Take a tube of the diameter of your proposed snorkle, and see how far underwater you can put it and still exhale. Like a bucket of water, you will not need a very big bucket. I am guessing it will be about 18" maybe a lot less. That is the same depth you could suck air in. Funny thing about gravity (Which creates air pressure), it works every time.
could you encase your chest in a sealed container with air inside that would be light enough to allow submersion, so not too much air space that would just bring you to the surface, and a series of weights you could carry and drop should something go wrong. Thus you could still breath underwater, no pressure issue. I guess you would in theory need to make yourself a submarine? This could work, don’t give up on your dream, unless you have already drown. On second thought, maybe its the diaphragm you would want neutralize the pressure for?
I’m linking a picture. The chest depressurization suit would space to allow chest movement, would the air need to be removed? On second thought, the chest piece could have an mechanically assisted expansion feature that allows expansion when the chest expands.
I guess air has a buoyancy of about 8lbs per gallon.
Here’s a rough idea of what something like that might look like
That doesn’t help. But setting aside air pressure, probably the biggest limitation is that your lungs cannot exhale enough volume to evacuate enough CO2 from a long tube. It would basically be like breathing into a bag.
This. I once laid on my back on the bottom of a hot tub, with a copper-pipe snorkel to the surface. I could breathe, but only with very great effort. If you were to look straight down at me from above, you might estimate my chest to have an area of about 1 square foot. At a depth of two feet, that means I had two cubic feet of water pressing down on my chest. Water has a weight of about 62 pounds per cubic foot, so I had about 124 pounds of weight pushing down on my chest, trying to squeeze the air out of it through that snorkel.
Someone trying to breathe through a snorkel with their lungs at a depth of three feet would feel like they had 186 pounds parked on their chest; it would likely be impossible to inhale at this point.
This is why SCUBA gear uses tanks of high-pressure air with a regulator to automatically supply air to the mouthpiece at a pressure just a smidge below local at-depth pressure (“a smidge below local” so that it doesn’t release any air until you lower the pressure inside the mouthpiece a smidge by trying to inhale). IME these regulators are exquisitely sensitive: I can feel the difference in breathing effort that is required when in a vertical orientation (lungs 1’ below regulator) versus a prone orientation (lungs at exact same depth as regulator).
It occurs to me now that whales, esp. the very largest ones, must have immensely strong breathing muscles; with their blowhole just above the surface of the ocean, their lungs are surely several feet below the waterline. inhalation must require a lot of effort.
[inevitable zombie joke] Everyone knows that zombies don’t need snorkel tubes, as one of the perks of being undead is ignoring the whole breathing problem. [/izj]
I almost missed this being a zombie thread, as no one from the first 48 posts made almost 10 years ago was banned. I think that says something about divers, but I’m not sure what yet.
Also, if you have ever used one of these pressurized-hose breathing apparatuses, then you know there is a real risk of somebody farting in the intake tube. I mean if you were in the Army Engineer Corps, I have no idea how frequent this is in the private sector.