Just another question I'm hoping someone would be kind enough to answer = )

[DivemasterBob]

Quote "discover SCUBA. This program includes a brief lecture followed by a brief lesson. The lesson covers just the very basics of how to breath safely underwater, as well as some other important skills. Then you get to play, under supervision."

Discover Scuba is your best and safest choice to see and feel SCUBA.

 

[The Chairman]

this fun experiment is anything but "Extremely Dangerous". Once your body is greater than 18" deep breathing ceases to be "easy" as it takes ALL you can muster to just take a breath. The uncomfortable feeling of your chest caving in ends it rather abruptly. As for the CO2 buildup happening "that fast"... well I don't think so Chester. No student has EVER complained about the headache/dizziness that would accompany a CO2 buildup. Again, it is so uncomfortable that the experiment usually lasts less than a minute and maybe up to two.

Think about it for a moment... why do I bring out a 6' snorkel??? When the kids see it they think that they are in for a real treat... just like breathing out of a straw in the movies. I do not give the ending away... but I let them try and deduce just how "long" they can stay down using that snorkel. IF they ask, I tell them that no one has broken 20 minutes (which is true). It's always a contest just to see who gets to go first, cus they ALL want to try it.

When the first one barely gets his head under water and comes up gasping for air, the others laugh at him and they really want to show everyone just how "tough" they are. One by one they give up in the futility of the process. Their bravado has just been tempered by reality. But, you might ask (or might not), just what are the points I teach through this...

1) You can postulate (and argue) all you want, but nothing beats a controlled experiment.

2) Not all ideas are possible or even good.

3) Water weighs a ton (literally).

4) Why snorkels are never over 18".

5) Why the second stage has to deliver gas at ambient pressure.

6) You can't circumvent the laws of physics just because it would be more convenient.

7) A good dose of reality can squash the best theory in 3.2 nano-seconds.

8) If your chest feels that constricted with only 20 inches of water around it, think how it will feel with the pressure of 20 feet inside of it if you surface and don't breathe out.

Lastly… I do recommend a controlled (supervised) environment for any type of experiment like this. Also, I whole heartedly recommend that you do NOT try scuba on your own (which is why I recommended the Discover Scuba class in the first place). There was a story passed on to me during my ITC, about a candidate who tried to show that there was no danger in a pool. At the bottom of a 6 foot pool, he inhaled from a regulator and then stood up. He never regained consciousness.

 

[bermudaskink]

OK guys - sorry for getting emotional earlier.

I was like :livid: !!!

It was early for me. I had just switched on PC and checked my mail....while brewing coffee.

And this whole thread just makes me feel :grrr:

I was "reacting" to be attacked though.

There is a big difference between going on the attack, being nasty in reply to someone's intial message - and defending yourself agaist people accusing you of giving someone unsafe and unsound advice.

But I am still sorry.... eace:

Anyway, you can see why I asked you if had read the posts properly cos you didn't just talk about C02 with regard to forgetting to take the hose out to exhale. But that still wouldn't be dangerous (like NetDoc says). Haven't you ever put a paper bag over your mouth and seen how long you can breathe for?

anyway blah blah - I'm bored of going round in circles. :snore:

It was a suggestion, and yeah - perhaps looking back now, it was a little lame! My original idea was to just make friens with a scuba instructor and the breathing through a tube thing was just a crappy alternative.

But please stop trying to tell me I was endangering someone's life! That is absolute crap and a completely unfounded accusation. I got very upset by that and I think you would to. I'm an instructor after all, so think how it feels when everyone is telling me I am giving out "dangerous" advice.

Maybe it was a bit of a pants idea. I can accept that. But life threatening? Physically damaging??

Come on, give me a break!

Anyway - apologies for getting a little overly pissed about it all.

I'm done now...

:flusher:

 

[Boogie711]

Bermudaskink, dear, gentle lady:

The 6' snorkel idea has one major fallacy. I can understand your point about inhaling only, and exhaling through ones nose. I also think it's more than a tad silly. In addition to all the points listed above vis a vis ambient pressure, there's one major problem here -

- as soon as the snorkel is released from his mouth, water will fill the snorkel up to the water line. He would have to inhale 5 feet of water just to get the air.

 

[The Chairman]

Incredible Super Sonic Blast Method to clear it!!! :tease:

Get real... you won't make it below 20". Really, you won't. And why would you take it out of your mouth, anyway? It's just a cool thing to play with and to get a feel for the forces that you are compensating for while you dive. Learning to dive should be a fun thing... filled with wonder and exploration. Not just a time to memorize arcane facts and regurgitate safety lessons. My kids really want to understand the environment that they are getting ready to invade. ANYTHING you can do to help them understand just how in-hospitable it is, the safer they will be in the long run. KnowhatImeanVern?

I like to bring a 1 or 2 liter bottle on their first dives too... a GREAT way to demonstrate Boyles' law. Using these types of teaching aids will do far more than just teach how these laws affect you... they will ingrain the concepts deep into your mind and psyche. I show everyone the collapsed bottle on the bottom, and then fill it with air at depth. The ruptured bottle on the surface helps them to remember...

Breathe
Or
Your
Lungs
Explode
Sir!

I think it's great to hear yet another instructor thinking outside of the box. You can correct her all you want, and point out the fallacies of this and that, but I bet her students learn all the better for doing these types of things. Even if she IS a lowly PADI instructor... :tease:

 

[bermudaskink]

:mute:

I did say you "could" take the hose out of your mouth if you didn't want to breathe out through your nose.... but yeah it would flood unless you were face up in the water and the hose remained pointing down.... I didn't think that one through.

Does anyone else want to pick apart my fantastic blunder with the hose suggestion?

Go on! Make my day :makeday:

 

[TX100]

o2scuba once bubbled...

Surface supplied air compressors use filtration methods that are far beyond the capability of your garage compressor designed to operate tools, and fill tires. Breathing the air from such a system is dangerous. A surface supplied air system also requires a regulator, with prscise pressure settings allowing the user to breathe normally.

I breathe from one all the time. I have two compressors. When I spray paint, I run one outside that feeds a continuously fed air helmet that I breathe from. The other compressor runs the spray gun. I have been doing this for a few years, as does many, many automotive spray paint shops around the world. I have yet to blackout/collapse/die. btw, the paint that is sprayed (2-pak) is cancer causing, so you have to make sure you have a good seal and are only breathing from the supplied air.

The reason you can't use your auto compressor to fill your cylinder (even if it went up to 3000psi) is because at 100ft, your PP of "gasses other than O2 or N" is 4X higher than normal, which can kill you. At 10ft, it's only about 1.3atm.

So, knowing this, I personally wouldnt have a problem trying to breathe from a regular garage air compressor at 10ft. Lets face it, the difference between a certified person and non-certified person (with regards to lung overexpansion injuries) is that the one with the c-card has (1) a little more in-water experience and (2) has been told to breathe out when ascending.

Well, plenty of people have been telling the dude about the lung overexpansion theory... I say if the dude wants to try it, go for it! Just so long as it's in his own pool, he has someone on the surface and he knows the breathe out before ascending.

And to all the people who disagree: I suggest you don't drive, walk or take public transport home tonight. IT IS DANGEROUS AND MAY KILL YOU! :bones:

 

[jonnythan]

TX100 once bubbled...
The reason you can't use your auto compressor to fill your cylinder (even if it went up to 3000psi) is because at 100ft, your PP of "gasses other than O2 or N" is 4X higher than normal, which can kill you. At 10ft, it's only about 1.3atm.

After working on a few garage compressors, I wouldn't breathe from one in the garage.

 

[pasley]

moogster once bubbled...
... Although I know embolism, being a premed, I don't fully grasp how within ten feet that is achieved. If over expansion of the lung is the problem, I can understand the situation. But isn't that what a mouth piece regulator is for?... John

"I don't fully grasp how within ten feet that is achieved.?" That is the whole contex of most of the responses you have received. You have not been trained and so don't know the risk.

"But isn't that what a mout piece regulator is for?" No, it is not. The mouth piece or regulator is only responsible for delivering air to your mouth at the ambient pressure as the CURRENT surroundings. When you change depth, you change the ambient pressure. It does not in any way control the presure inside your lungs, that is the divers responsibility.

To explain further: Surface presure is 1 atmosphere or 1ATA. At 33 feet of sea water you are under 2 atmospheres of pressure, or twice that of the surface. So at 10 feet depth you are at 1.3 atmosphers of pressure.

So here is what we are talking about. Assume you lung holds 1 cubic foot of air (I know it doesn't but it makes the math simple), and you take a breath of compressed air at 10 feet depth, you have 1 cubic foot (volume) of presurized air (1.3 ATA) in your lungs. Now, without keeping your airway open (or in other words, you either delibertly or accidently hold your breath), you rise to the surface. You lung now has 1.3 cubic feet of air(1 ATA) in it. The surrounding pressure has reduced and the compressed air has expaned in volume and equalized the presure to 1 atmosphere. In the process, you very likely blew out your lung!:wacko:

Experiment for you to try at home. Tools Required: Can of compressed air like you use to clean a computer keyboard, baloon, spring clip to clip off the baloon.

Take a can of compressed air, and a baloon down to the bottom of the pool, 10 feet. On the bottom of the pool fill the baloon to its maximum volume (as in taking a deep breath) and clip it off. Realease the baloon or surface with the ballon. Get the picture? the baloon will have 1/3 more volume at the surface than at 10 feet. You lungs are, I am told, not that elastic or strong.

Bottom line, as you have know doubt figured out by now. SCUBA diving, that is the act of breathing presurized air under water, is dangerous business and you need to be trained to know those dangers and how to avoid them.

Right now, you are not trained and don't know what you don't know and that difference can kill or cripple you for life.

It is kind of like asking you to preform surgery on a live patient on your first day of premed school. You know what a doctor is, and what a surgeon does, but that is lots of dangerous stuff you don't know about....yet. Suff like what drugs cannot be use together or where or where not to cut.

 

[san diego diver]

check out the march issue of "scuba diving" magazine, it disscusses the shallow water expansion problem and dangers !! you should be able to pick one up at your local dive shop !! if not p.m. me before you try to breath compressed air at any depth and i will send you my copy !! there are very real dangers with what you are suggesting !! an open water course explains theese dangers and could save your life !! at least talk to an instructor before you buy the spare air !! also i don't think the hose idea will work because pressure on the hose will make it collapse !!
steve m