Dangers with a diving bell combined with a long snorkel

[Philip Koeck]

TL;DR Summary

What could be the dangers with snorkeling from a diving bell if the snorkel is extended by a hose pipe?

I'm thinking of using an upside down bucket placed at a depth of about 1 meter as a diving bell. Then I want to connect a garden hose pipe to a snorkel and put the other end of the hose pipe into the diving bell. I simply want more time and a bit of mobility under water in order to do a job. I would breath in through my mouth using the snorkel and out through my nose to avoid accumulating used air in the diving bell. Is there any danger I'm not considering, especially if my lungs are not at the same depth as the air in the diving bell?

 

[hutchphd]

How will you pump the air into the bell?

 

[Philip Koeck]

I would work with just one filling, so to say. Lower the bucket upside down. There would have to a valve on the hose pipe (or a clamp), which I open when I'm under water with the snorkel in my mouth.

 

[hutchphd]

You need to be aware of air embolism which is most pernicious in depth excursions near the surface because the relative pressure changes are largest. I think even a meter of depth can give you trouble if you took a big lung full and surfaced holding your breath. So some care is necessary.

 

[Dale]

Summary:: What could be the dangers with snorkeling from a diving bell if the snorkel is extended by a hose pipe?

Is there any danger I'm not considering, especially if my lungs are not at the same depth as the air in the diving bell?

You will need to keep the bell at the depth of your lungs to avoid over or under pressure. The buoyancy of the bell will be very unstable. The hose will tend to collapse if it goes below the bell.

 

[berkeman]

I would work with just one filling, so to say. Lower the bucket upside down. There would have to a valve on the hose pipe (or a clamp), which I open when I'm under water with the snorkel in my mouth.

As a diver, I don't like the idea. Much better would be to use a standard solution to this problem, like a SpareAir tank. They only cost about $100, but I'm not sure whether you need a SCUBA license to get them refilled at dive shops...

https://www.spareair.com/info/info-compared.html

https://www.spareair.com/models/models-index.html

Actually, it looks like you don't need to use a dive shop to refill them: https://www.spareair.com/operation/operation-refilling.html

https://www.spareair.com/data1/images/spareair_banner_1200x400_1min.jpg

 

[Philip Koeck]

You need to be aware of air embolism which is most pernicious in depth excursions near the surface because the relative pressure changes are largest. I think even a meter of depth can give you trouble if you took a big lung full and surfaced holding your breath. So some care is necessary.

Would emptying the lungs as much as possible before coming to the surface be a sufficient safety measure?

 

[berkeman]

Would emptying the lungs as much as possible before coming to the surface be a sufficient safety measure?

When ascending after inhaling compressed air, you blow bubbles all the way up. The air in your lungs is expanding, so you need to keep letting it out or risk the embolism.

Have you considered getting your SCUBA license? It's a pretty fun sport, after all...

 

[hutchphd]

In fact you will be limited to depths less than the bell because your lungs cannot "suck". And pulling the bell below water will require some force...each lungfull is about a gallon (7.5 pounds buoyancy). I say pulling because pushing is very difficult and unstable as @Dale points out.

 

[Vanadium 50]

This thread seems to have the theme "Why go to all the bother of getting the equipment and training to do this safely if I am just going to do this once?"

Let me say that that strategy works. Unless is doesn't.

 

[berkeman]

Let me say that that strategy works. Unless is doesn't.

Reminds me of a saying we have in EMS -- "The bleeding always stops. One way or another..."

 

[Vanadium 50]

The bleeding always stops. One way or another...

How far can I drive on these old tires?
All the way to the scene of the accident.

 

[anorlunda]

Reminds me of a saying we have in EMS -- "The bleeding always stops. One way or another..."

Firefighters have the same saying -- "No matter what you do or don't do, the fire will eventually go out."

Also pilots --- "What goes up must come down."

Also sailors --- "Unless you are in the Southern Ocean, sailing East or West eventually brings you to land."

Other professions?

 

[Ibix]

Other professions?

The second law of thermodynamics?

 

[Vanadium 50]

Also pilots --- "What goes up must come down."

Takeoffs are optional. Landings are mandatory.

More relevant to this thread is: If you can't afford to do something right, then be doggone sure you can afford to do it wrong.

 

[Lnewqban]

You need to be aware of air embolism which is most pernicious in depth excursions near the surface because the relative pressure changes are largest. I think even a meter of depth can give you trouble if you took a big lung full and surfaced holding your breath. So some care is necessary.

Would you care to elaborate on that statement?
I am interested on free diving related to spearfishing, which I have been practicing for many years.

What is the main difference between the situation you describe and free diving or submerging up to 10 meters depth and breath-holding until resurfacing?
Does free diving present a risk of embolism or decompression sickness?

 

[Dale]

What is the main difference between the situation you describe and free diving or submerging up to 10 meters depth and breath-holding until resurfacing?

The main difference is that in free diving a lungful of air is inhaled at atmospheric pressure. The air volume only gets smaller from there. In this scenario a lungful of air is inhaled under pressure. The volume can expand to larger than a lungful from there.

 

[berkeman]

Does free diving present a risk of embolism or decompression sickness?

No, @Dale is correct. In free diving, you are not breathing in compressed air.

 

[sophiecentaur]

Would emptying the lungs as much as possible before coming to the surface be a sufficient safety measure?

If you are at a depth of only 1m, there is no problem at all. You can breath fine at the surface with your body vertically in the water. You are just suggesting the same thing with a pressure of +1m of water pressure. During scuba training, they give you a long tube to breathe through but your lungs won't inflate with your diaphragm 1m below (diaphragm is not designed to do that). With your lungs near the surface and your head down, you can do 50cm better!

I remember reading a book Treasure Diving Holidays by Barny Crile (1950s) and they were not using SCUBA but used air, piped to their face masks and excess air spilled out of the mask. They used a pressure control valve as they were at a depth of several metres but a pump could easily be arranged to supply air to just 1m depth.

There are many electric air pumps (for inflatables, even) that will provide a good excess volume flow of air to that depth (0.1 Bar). You would need a helper to monitor things - but you would be daft to be doing this stuff on your own any way.

I would be inclined to use a small 'diving bell' (clear plastic) - just covering your head and reacting on your shoulders and arrange for a constant spillage of air (behind you) to ensure you always have some air at mouth level. You would need the bell to be held down by a weight, hanging down below you, for stability.

BTW my frequent comment about the need for a diagram of some sort really applies here. How big, how deep and how long for?

 

[DaveE]

I don't like your plan, but others have covered that.

The most important rule in SCUBA diving, if you breath air underwater (from virtually any source):
NEVER HOLD YOUR BREATH!

Your lung tissue is very weak and easily injured by excess pressure. Your open airway is the safety valve.

 

[hutchphd]

NEVER HOLD YOUR BREATH!

Absolutely!. Always breathe out on the way up. A full breath taken at 1m will be 10% bigger (in either pressure or volume) at the surface. That could be enough to do harm, worst case.

 

[berkeman]

Okay, I think we've done the best we can to advise the OP in this thread. I'll go ahead and close it now. Thank you everybody for trying to offer good advice.