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  #11  
Old 07-18-2013
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Re: Need answer to something I've always Wondered About

Anyone ever tried adding a one way valve to make a "regulator" of sorts? Utilize two tubes, one a supply and one an exhaust?
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  #12  
Old 07-18-2013
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Re: Need answer to something I've always Wondered About

3' is the standard answer to the OP's question. As mentioned previously, your lungs simply aren't powerful enough to draw air from a snorkel deeper than that.
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Old 07-18-2013
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Re: Need answer to something I've always Wondered About

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Originally Posted by KIVALO View Post
Anyone ever tried adding a one way valve to make a "regulator" of sorts? Utilize two tubes, one a supply and one an exhaust?
I seem to recall seeing something like that once. But it doesn't get around the pressure problem. As Fst said, 3ft (1m) is probably the realistic max. Even then, middle-aged/older folks, with less elastic connective tissues, might find lung collapse a real risk.
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Old 07-18-2013
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Re: Need answer to something I've always Wondered About

Even just a few feet below the surface your diaphragm can't expand your lungs against the water pressure. Sucking from a tube and exhaling elsewhere won't work very deep. Back to that three foot limit.
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Old 07-18-2013
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Re: Need answer to something I've always Wondered About

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Originally Posted by minnow1193 View Post
At what point (length) would a snorkel type tube become ineffective?

Steve
Great question!

There are a few considerations here. First, is resistance and strength of your breathing muscles (of which the diaphragm is only one). Clearly 1' of 1" tube is not too much resistance because that's what a snorkel is. You could calculate how much resistance that is, and create a longer, but larger diameter tube. I imagine your breathing muscles would have no problem sucking air through a 6' tube if it were, say, 6" diameter. But that leads us to the bigger problem...

A standard snorkel doesn't hold much air in it's tube. When you breath in your second breath through a snorkel, the first part of what you breathe in is your own used air in the tube. Used air has too much CO2, which you're trying to get rid of. Keep re-breathing the same air, and pretty soon you've used up all the O2 and your getting other problems from accumulating CO2.

Lucky for you, when you inhale your own used air in your snorkel, it's only a small percentage of what you breathe in that breath. In the 6"diameter 6'long tube mentioned above, you'd be breathing in and re-breathing your own air because when you exhale your entire lungful of used air would remain in the tube. That's part of why scuba regulators have a flapper valve that sends the exhaled air in another direction. Snorkels don't have this feature. But they do have a purge valve....

WARNING: This is where Medsailor should have stopped his post.

What if you put a standard one way valve on the top of your snorkel. Something like this:


Then attach your large diameter (read low resistance) tube to the top of this. What you would do is draw in air through the low resistance tube, then the one way valve, then the snorkel. When you exhale, the one way valve would stop the air, forcing it out the purge valve at the bottom of the snorkel.

Crazy? Probably. Dangerous? No, not if you test it in your living room first and don't go deep with it. Is it the most hair-brained-hacked-together-improvised-idea-ever? Not by a long stretch! The famous improviser Bernard Motessier created, and successfully used a system of multiple tubes and upturned and submerged buckets that makes my idea look like a commercial pearl diver's hookah.

His system can be found on page 167 of Sailing to the Reefs. Sailing to the Reefs - Google Books

MedSailor

P.S. From a medical prospective, I can assure you you can't collapse your lung from sucking too hard. If you could there would be a whole lot of.... um... well... oh never mind.
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Last edited by MedSailor; 07-18-2013 at 11:07 PM.
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Old 07-18-2013
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Re: Need answer to something I've always Wondered About

But if your check-valved tube leaks or otherwise takes in water how do you clear it?

You can do a minute underwater snorkling - more with practice. I find that sufficient for casual boat work, clearing tangles and inspections.
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Re: Need answer to something I've always Wondered About

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Originally Posted by Delirious View Post
But if your check-valved tube leaks or otherwise takes in water how do you clear it?
Surface. (verb)

We're only talking about 6 feet here and we're all boaters right? We know how to make hose connections pretty darn leak-proof. There are MANY below the waterline connections that I'm currently betting my boat on every day.

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Old 07-18-2013
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Re: Need answer to something I've always Wondered About

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Originally Posted by Quickstep192 View Post
For what it's worth, I'm also told that you should not attempt to pressurize a snorkel with a regular compressor because the air always has some atomized oil in it
What is a "regular" compressor? There are oil-lubricated compressors and there are oilless compressors. Both can be used in a hookah rig, although you would need to use a special oil in an oil-lubricated model (and honestly, at the recreational & light commercial level, I don't know why anybody would attempt it.) There is nothing "special" about the compressors used in hookahs. Every commercially available, recreational level hookah is built around an air compressor that was originally designed for another purpose.

Last edited by Fstbttms; 07-19-2013 at 02:47 AM.
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Old 07-18-2013
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Re: Need answer to something I've always Wondered About

The reality is that the standard length of a snorkel is the max a normal human can breath underwater.
Even a 1' extension will not work. No amount of valves will change that without pressurizing the air. Snorkels are pretty uniform in length for a reason. There are no extra long snorkels available for the macho man (or woman).
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Old 07-19-2013
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Re: Need answer to something I've always Wondered About

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Originally Posted by capta View Post
The reality is that the standard length of a snorkel is the max a normal human can breath underwater.
Even a 1' extension will not work. No amount of valves will change that without pressurizing the air. Snorkels are pretty uniform in length for a reason. There are no extra long snorkels available for the macho man (or woman).
Naaaaaaaw! Not true! Maybe you're weeny lungs. The reason they're the standard length they are is because the human head is a pretty standard size and that's all the length you need to clear the surface.

Even if it were true that 1 foot of 1" tube was all you could do, you could calculate how much resistance that is, and increase your diameter (ie lower the resistance) in order to compensate for your increased length.

Medsailor
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