Why wouldn't a 30ft long snorkel work?

Calvin.

Calvin.

Member
Other than the fact that you would eventually be breathing old air.There is something involving pressures and i can't figure it out.I feel like an idiot
 
what is the pounds per square inch at a 30ft depth? i dont think it would stop you from breathing but it would make it more difficult.
 
i rember seeing something about this on tv like ur lungs under pressure and normal air wont work i dunno.. i just know that why scuba tanks arent just filled with normal air
 
it would most likely be too heavy and tip over? im in physics but we arent at the pressure chapter yet.. sorry
 
2 resasons I can think of, I dont have clue if they are true or not but its what I can think of.

1) You dont have enough pressure in your lungs to push 30ft of oxygen depleted air out, to replace with oxygen filled air?

2) You can push some of the air out but it is not fully replaced with oxygen rich air, resulting in less and less oxygen every breath?
 
Provided that the pressure of the water at 30 ft isn't high enough to collapse your tube, you would have some problems.

The pressure pushing/acting on your lungs would be very high, while the pressure of the air would be very low. Your lungs would not have the strength to inhale any air at atmospheric pressure from your snorkel. If your lungs are at a higher pressure, and the snorkel is at a lower pressure, the higher pressure would want to be released somewhere, so the snorkel would almost work as a vacuum. Your airflow would need to be pressurized to fill your lungs, which is why air tanks are under pressure.

I think that is right, I don't really have any sources tho, just prior knowledge.
 
That's a good point. I was thinking that the volume of the tube would be more than the volume of your lungs (or at least close to it) so you'd wind up just asphyxiating yourself like breathing into a plastic bag, in which case exhaling into the water might work. But your lungs might not be capable of breathing ambient air with that pressure on them, I'm not sure, I'm not a doctor or a physicist.

 
If you did that your tube would be open to the water, and the water being under a higher pressure would just rush into and up your snorkel until it equilibrates with the atmosphere.

If you ever take a drink and put a straw into it, and then look into the straw, you can see that the straw fills with water but only like 3/4 of the way up. Not all the way to the top. That is how far the air pressure can push the water down before it equilibrates. Same thing would happen if water got into your snorkel I'm guessing.
 
You sir are a scholar and a gentleman.I knew it was something like that, i just couldn't wrap my head around it.
 
ONE WAY VALVES!!! THERES YOUR ANSWER!!!!

HAVE ONE COMING WITH FRESH OXYGEN IN, WHEN YOU BREATH OUT IT CAN'T GO BACK UP THE TUBE THANKS TO THE ONE WAY VALVE, THEN YOU COULD HAVE ONE THAT GOES OUT, SO NO WATER CAN COME IN!!!!



FISSION SOLVED!!!
 
Yep, some kind of check valve might work... but could you imagine the drag from swimming 30 feet under with a tube sticking all the way up to the surface?
 
tube crushed? in 30 feet of water? have you guys ever been under water?

the only problem I can think of would be that your breaths wouldn't make it to the end of the tube so you'd just keep breathing the same air in and out and suffocate yourself.
 
aahaha i laughed at this thread.

okay so the main reason is that the water pressure at a depth more than a couple feet deep is too great on our body, specifically our lungs, to allow us to inhale any air that has a pressure of 1atm (the air pressure at the surface).

In other words- as we go under water deeper and deeper, our lungs are being squeezed tighter and tighter. the air at the surface, at 1atm, is not being squeezed very tight, and therefore not very 'compact' (remember, air is made up of molecules, mainly oxygen and nitrogen). so it would be to hard for us to fit this uncompacted surface air into our lungs that are being squeezed and squeezed. the way scuba works is by squeezing (pressurizing) air so the molecules are more compact and this makes it much easier on our lungs to breath in.

get it?
 
pressure = rho * g * h,

if you're 30 ft underwater (assume 30 ft=10m and g = 10 m/s^2), pressure = 1000 kg/m^3 * 10 m/s^2 * 10m = 100,000 Pascals.

So roughly, every 30 feet you go underwater, the pressure increases by 100 kPa. Atmospheric pressure is only 101.325 kPa, so at 30 feet underwater, the pressure pushing in on your body is double atmospheric pressure, yet the air in the tube is at atmospheric pressure. That is why it won't work.
 
my friend bought an impact vest that also has a built in air tank that has 25 breaths, for towing in at jaws. hope he doesn't kill himself haha
 
You can't do it because you're a pussy. The problem with the long-snorkel idea has to do with the fact that the muscles we use to expand and contract our lungs during breathing are not strong enough to overcome much pressure. Even just a few feet beneath the surface, the pressure is great enough that we can't expand our lungs against the water pressure to inhale a breath of air from the surface.
 
Freezed and Static pretty well summed it up. My dad explained this to me when I was about fourteen, and I didn't understand/believe it, so I grabbed a four foot PVC pipe and headed out to the hot tub. Long story short, it doesn't work. Lying on the bottom of the hot tub, when I opened my mouth to breathe through the pipe, the pressure tore whatever air I had in my lungs out through the tube. My lungs hurt for the next few days. I wouldn't recommend this experiment to anybody. And REALLY don't try it at thirty feet.
 
Ya, thats pretty much what I guessed would happen with the tube/straw. What did you do to keep air all the way to the bottom of the pvc? Did you just hold a breath and then exhale it into the tube?

It's basically all Boyle's law. Like Freezed said, your lungs aren't strong enough to breathe at multiple atm. Due to Boyle's law, if you ever were able to find a way to take a breath at like 4' underwater, and then didn't exhale while you went to the surface you could kill yourself. Even in 4' of water, kinda scary. The pressure would decrease, so the volume of the gas in your lungs would increase. The alveoli burst with the increased pressure, oxygen is absorbed into your blood stream which can then travel to your brain and give you a stroke and hit your heart and give you an irregular heartbeat. That's why divers have to be so careful.
 
yup. Basically to snorkel or just breathe in general, your lungs act like a vacuum which forces air at higher pressure into them. At 30ft, even a perfect vaccum could not suck air through a snorkel because the pressure at that depth would be greater than the pressure of the air. It might be easier to think of drinking water through a 30 ft straw, its the same thing just reversed.
 
I have no idea how the physical anatomy works but I do know that this problem has absolutely nothing to do with the strength of the lungs. Even a robot couldn't do it, its physically impossible
 
wrong. it has everything to do with the pressures being exerted on the body and the lungs not being strong enough to overcome those pressures.

some of the oldest scuba diving equipment pumped air from the surface to depths of up to about 60 feet through a hose/tube using manual pumps.
 
I don't know the structural integrity of the body, but I do know that it is physically impossible for a human, superhuman, vacuum whatever to suck air through a 30 ft snorkel. Even assuming that the body can take it, and your lungs are made of iron, it would still be impossible.

And scuba equipment has nothing to do with this. The pumps would raise the pressure of the air so that it could overcome the pressure of that depth. Its a completely different problem.
 
i've been a certified diver for over 15 years. my old man is an instructor and we run a scuba company on the side. (claim) I'm not going to argue with you over why you are wrong, just know that you are.

 
scuba tanks are filled with normal air, it is that you go to 2 atmospheres at 30 ft, scuba tank is with you so you are both going to be at 2 atmospheres but a 30 ft snorkel would be no different rthen the olddive bells. but the problem is expelling the air and getting it in no one has the lung capacity to clear 30 ft of tube
 
1227112080-711206-600x450-1227112022water_pressure.JPG


SRSLY. PAY ATTENTION IN CLASS. FUCKING n00bs
 
Then you must not have to take a physics test to be a certified diver. I know your body can't breathe through a snorkel at 30 ft, it cant even do it at 3 ft. Thats not the problem though. The problem is that it is physically impossible for anyone, or anything to inhale air at 30ft underwater, regardless of muscles, lungs whatever. Look at the picture above
 
there was a bill nye on this.

he actually tried it.

like 20 feet under.

the snorkel just collapsed on itself.

somethings about water pressure....
 
for some reason i have never thought of it im gunna try it even if u say is impossibe it would be so sick
 
It has everything to do with pressure. Your lungs create a vacuum when they expand. A vacuum doesn't actually SUCK anything. The noise you hear is from the atmosphere filling the empty space created by the vacuum, so the air is rushing in, not being pulled in.

When you expand your lungs, it creates a vacuum and the HIGHER PRESSURE air rushes in to your lungs, allowing you to breathe.

When you are 30 ft underwater, the pressure is very great. That pressure is enacting on your whole body as well as your lungs. When you open your lungs to breathe underwater, you are STILL CREATING A VACUUM. However, this vacuum is very small and is only slightly less than the pressure due to the surrounding water. Now if you add in the snorkel. The snorkel is delivering air to you at 1 ATM. The pressure of the air at 1 ATM is significantly less than the pressure inside your lungs even though they have created a slight vacuum compared to the outside pressure. Since air tries to move FROM a higher pressure TO a lower pressure (see first paragraph, air fills a vacuum) the air would leave your lungs, and your lungs do not have the ability to overcome that pressure difference and suck in oxygen at 1 ATM.
 
you can't use a 30 ft snorkel because birds would poop in the top and you would be breathing bird poop, not oxygen which you need in order to not die.

problem solved.
 
i've tried it before with a 20 ft pipe as a snorkel, while in a pool. It didn't work. It just felt like you were suffocating.

And no, i'm not going to argue the physics because i have actually been 20 feet underwater, with a pipe as a snorkel and i couldn't breathe through it. Its just too far to try to suck air down and blow air out
 
If you had your nose open to the water at 2 atm, and your mouth open to the tube of air at 1 atm, I'm guessing the water would try and equilibrate with the lower pressure from the snorkel and it would essentially just force the water through your nose/mouth. I doubt that would be very pleasant.
 
you guys are both pretty much right.

It does have everything to do with pressure exerted on the body as you say...except lungs don't have strength. there isn't a lung muscle that pulls your lungs open. your diaphragm just relaxes. and there is no physical way a human body could relax its diaphragm in a way that you could breathe through a long snorkel.

However, it is theoretically possible, if you had some sort of other organism or robot or whatever, that could forcefully expand its lungs to many times its original volume, then you might be able to lower the pressure enough.

and the old scuba equipment you speak of applies exactly to what i said, except it changes the "atmospheric pressure" at the top of the snorkel to a higher pressure (by pumping), so then the diver can breathe because the difference in pressure between "breatheable air" and the pressure on his lungs becomes 0 or very small.

NS needs more science threads.
 
^bingo. it is possible for machines, but not humans.

the pressure at that depth is pushing so hard on our lungs that they cannot expand to fill up with air that at a pressure of 1atm
 
I agree except for the second paragraph. Even by assuming that at the end of the snorkel there is a perfect vacuum at absolute zero pressure, it would not be possible to get the air from the atmosphere (if its at atmospheric pressure) to the end of the snorkel.
 
You're probably right in that. Vacuum's aren't perfect and they can have alot of flaws. With a very long tubing, you will probably lose your vacuum by the time you get to the top or else the vacuum would be only be drawing in such a small amount of air it would not be significant.

That way to fix this is to have a pressurized snorkel that is pushing air down to you at the exact same pressure as the surrounding water. That way, when your lungs expand and create a microvacuum, the air in the snorkel will be sucked/pushed into your lungs enabling you to breathe.
 
The diaphragm(a muscle) contracts, the intercoastal muscles, and other accessory muscles help under forced inspiration. Sure, it's air pressure that fills the void, a void made by muscles, you don't just open your mouth and let air rush in. Without those muscles you would not be able to breathe on your own. If you can contract your muscles enough to create lower pressure in the lungs outside air will always fill in, how strong these muscles are determines how much pressure you can fight, you can breathe underwater with a 1 foot tube.
 
Interesting thread.

Problems design-wise, you would also have to make the tube so that it could be transported and it would have to stand up straight while you swam down thirty feet.
 
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