Long snorkel breathing

[arew+4]

The pressure at the bottom of a under water tunnel is higher than at the entrance that's why your ears will pop some times. But the pressure differential between the ai inside and the water outside is much greater.

Say the tunnel bottom is 45 feet under water pressure outside of tunnel underwater is 2.5 atmospheres, pressure inside the tunnel is 1 atmosphere plus 45 /10,000 (effectively very little air above that) or 1.005 atmosphere

 

[oly5050user]

Correct--your lungs are unable to overcome the added pressure of the water at depth to expand.

Actually during exhale would feel like breath being sucked away due to increase of ambient pressure. Back in 70’s teaching a class we demonstrated this with a pvc pipe fitted onto a snorkel in 2-3’ of water in pool

 

[Celt]

The worker should have left the man that came up with the idea do it.

 

[SlugLife]

The guy OP is talking about appears to be making a mistake I have many times. There have been numerous instances, where I've spent far more time, money, and effort on a DIY project, than it would cost to just pay for the same thing. Over time, I've mostly corrected that bad instinct, with a "rule" that to pursue a DIY project, I must be okay with the prospect of it being a failure and the resources, time, and money being "wasted." Typically, the things that make a (failed) DIY project worth it are that I get something out of it, like (1) it's fun (2) it's educational (3) the custom one-of-a-kind nature makes the risk worth it.

Often, that results in me prototyping something "sloppy" and learning a lot in the process. For example, I recently tried to make a DIY sidemount buttpouch. Lets just say, it sucked. However, from that I learned a few things, and ended up customizing an existing pouch, which took very little time and turned out great.

His friend should hire someone who knows commercial-scuba. Keep in mind a regular scuba-diver is often not prepared for underwater construction tasks, even at 4-ft, so if your friend asks you, I'd say "no." There are numerous ways you could get trapped, entangled, or injured in the process that aren't exactly intuitive or obvious. Also friends tend to vastly underpay friends, and underestimate what things really cost.

 

[Divrtim]

It doesn't work because its not a well thought out idea( that is more PC than saying dumb idea..hey I'm trying to make personal progress here.)
As noted in other posts, the physics involving atmospheric pressure suggest an exponential doubling and increase in the internal working pressure from when working on the surface and breaking the surface plane of water even one foot. The atmospheric pressure changes/doubles going from 0 to 1 atmosphere descending under water from 1- 30 feet+/-. And then continues to double with every subsequent 30 feet of decent.
Using the same dimension of pipe 100 feet long at now at 3 atms it would be almost impossible to breath in and more importantly exhale against.

 

[Ryebrye]

Clearly the person on the surface just needs to connect a leaf blower to the top of the snorkel. Then it'd work just fine.

 

[DogDiver]

Well, just think about it. If the concept of breathing off a four foot hose really worked, don’t you think there would be a whole sh$t load of divers using that method.
Oh ya, don’t forget about rebreathing your own carbon dioxide from the 4 feet of dead air space.

 

[SlugLife]

Well, just think about it. If the concept of breathing off a four foot hose really worked, don’t you think there would be a whole sh$t load of divers using that method.
Oh ya, don’t forget about rebreathing your own carbon dioxide from the 4 feet of dead air space.

There are ways to solve the carbon-dioxide problem. Mostly, not having air you exhale going through the same tube as what you inhale. The problem is you need compressed air to effectively breathe at depth.

 

[Bob DBF]

Say the tunnel bottom is 45 feet under water pressure outside of tunnel underwater is 2.5 atmospheres, pressure inside the tunnel is 1 atmosphere plus 45 /10,000 (effectively very little air above that) or 1.005 atmosphere

Add whatever pressure, positive or negative, they use for ventilation, which will effect one more than the minuscule change in atmospheric for the air column.

Using the same dimension of pipe 100 feet long at now at 3 atms it would be almost impossible to breath in and more importatly exhale against.

If it was open to the surface, not only would it be impossible to breathe, it would suck your lungs out.

 

[Doc]

Well, just think about it. If the concept of breathing off a four foot hose really worked, don’t you think there would be a whole sh$t load of divers using that method.

With all the PADI Derangement Syndrome anti-Snorkel hatred? That alone would kill it.

When I was a kid, my folks bought me a 2’ snorkel. Probably seemed like a good idea to someone. It got tossed.