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must be within 2 to 3 psi of ambient pressure anymore and you can't do it.
Breathing from a 30ft. snorkel
- Thread starter costi
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well, I just ran through my kid's PADI manual. A lot ot of "what happens", but not why.
Boulder John, my hat is off to you.
The regulator was the last piece of gear discussed and all the book says is "it reduces air pressure to the surrounding water pressure". No Boyles law that I can see.
I guess a lot of divers did not get Carl Brashear's frstration in "Men of Honor". Oh well, the bar is lowered again. LOL
In any event, this might be of interest to some:
Phys
Boulder John, my hat is off to you.
The regulator was the last piece of gear discussed and all the book says is "it reduces air pressure to the surrounding water pressure". No Boyles law that I can see.
I guess a lot of divers did not get Carl Brashear's frstration in "Men of Honor". Oh well, the bar is lowered again. LOL
In any event, this might be of interest to some:
Phys
Although it is not necessarily named as such, it is the focus of the earliest chapter. Students have to complete a chart on the effects of pressure on gases at different depths on Knowledge Review 1. They have to know the atmospheres of pressure to answer questions on the final exam. For example, they are told a tank lasts a certain amount of time at the surface, and they are asked how long it will last at a certain depth. They are asked about the effects of changing pressure on a glass of water as it is raised or lowered in the water column. They have to know the effect of depth on wet suit thickness. It is a critical part of the course.
Long snorkels, I admit, are not mentioned.
stacy e
Guest
I made my first dive in about 15' of water with a garden hose when my brothers bet i could not they were right you can not inhale with enough force ! that was 30 years ago iwould bet i can not now either.
You are kidding right??
IIFRC that is an RSTC requirement ....
That means everyone has to do it as part of EVERY major agency's certification process. You must be able to inflate and adjust your buoyancy despite a potential malfunction of the power inflator.... ORAL Inflation?? taking your inflator and breathing into it?? bringing back any memories from your OW course?? if you were PADI trained: doing the fin pivot without using the "pssshhht" button to fill your BCD?? ANY memory hits coming back to you??
If not, I suggest you practice it a few times in a controlled environment because the day you need to disconnect the Low Pressure inflator hose from your BC, due to it sticking on, is not the day you want to re-familiarize yourself with this skill
not trying to be rude... but this is kind important to:
A) know about
B) be able to do (while stressed)
hbhobby
Contributor
you guys kill me how does one go from sucking air down go to sucking water up? way different. but since it was brought up, even some of the best vaccume pumps in the world can only pull water up about 30-40 feet or so, much more and the pressure on the water becomes so low that it will start to boil. also to all of you that think it is possible to sit at the bottom of the pool and use a 8 foot snorkle please try it and film it and post it here it will be quite humerous to watch for the rest of us!
Guba
Contributor
NEWS FLASH!!! Empirical data, hot from the laboratory!
Yesterday afternoon, my competitive science team and I performed a few experiments just to see what kind of raw data we could obtain, and we had an "aha" moment or two.
Setup: 2.5 meters of .170 in (ID) clear hose, extended straight up from an open container of distilled water.
Experiment: attempt to draw a water column as far up the tube as possible using lung power alone.
Results: On first attempts, students (ranging in age from 14-17, four males and two females) were able to pull the fluid the ENTIRE 2.5 meters.
HOWEVER, here is the "aha" moment. Upon close observation, it was discovered that the students were using classic "sucking" effort, which uses the mouth and throat muscles. At this point we amended the experiment, instructing the students to INHALE the air from the tube. This effort uses only the diaphram and breathing muscles.
Amended Results: Upon using the inspiration method, the students were able to pull the water an average 1.4 meters up the tube.
Conclusions: The average distance a healthy young adult can pull fluid up a small tube using LUNG power is about 1.4 meters, which is far less than the distance achieved when using "sucking" effort. This, I hypothesize, helps to explain the anecdotal evidence provided by posters describing their experiences with siphoning, etc...I believe those people were utilizing their "suck" instead of their "inhale" abilities.
However, I realize that this data does not conclusively settle the issue concerning the long snorkel. (We did not, for example, use another tube of larger diameter for comparison...not available at the time, and we didn't do the reverse, which is to sit at the bottom of a pool and attempt to pull air down.) It does, however, support the statements describing the limitations of lung power in drawing fluids (air included) through a tube against pressure.
Hope this helps in some way.
Yesterday afternoon, my competitive science team and I performed a few experiments just to see what kind of raw data we could obtain, and we had an "aha" moment or two.
Setup: 2.5 meters of .170 in (ID) clear hose, extended straight up from an open container of distilled water.
Experiment: attempt to draw a water column as far up the tube as possible using lung power alone.
Results: On first attempts, students (ranging in age from 14-17, four males and two females) were able to pull the fluid the ENTIRE 2.5 meters.
HOWEVER, here is the "aha" moment. Upon close observation, it was discovered that the students were using classic "sucking" effort, which uses the mouth and throat muscles. At this point we amended the experiment, instructing the students to INHALE the air from the tube. This effort uses only the diaphram and breathing muscles.
Amended Results: Upon using the inspiration method, the students were able to pull the water an average 1.4 meters up the tube.
Conclusions: The average distance a healthy young adult can pull fluid up a small tube using LUNG power is about 1.4 meters, which is far less than the distance achieved when using "sucking" effort. This, I hypothesize, helps to explain the anecdotal evidence provided by posters describing their experiences with siphoning, etc...I believe those people were utilizing their "suck" instead of their "inhale" abilities.
However, I realize that this data does not conclusively settle the issue concerning the long snorkel. (We did not, for example, use another tube of larger diameter for comparison...not available at the time, and we didn't do the reverse, which is to sit at the bottom of a pool and attempt to pull air down.) It does, however, support the statements describing the limitations of lung power in drawing fluids (air included) through a tube against pressure.
Hope this helps in some way.
Last edited:
Guba
Contributor
you guys kill me how does one go from sucking air down go to sucking water up? way different.
Not as different as one might think. Both are attempting to draw air against a pressure, assuming that the only thing in the tube at the beginning of the test is air. The only true differences are that in pulling the air UP the tube, the resisting pressure is provided by the weight of the water in the tube. In pulling the air DOWN (while submerged) the pressure is provided by the weight of the water surrounding the person, and therefore the lungs. In both cases, the lungs must exert enough force to overcome the pressure. Since the lungs can by no means provide the pressure differential needed to vaporize the water, the experimental results will be similar.
Not as different as one might think. Both are attempting to draw air against a pressure, assuming that the only thing in the tube at the beginning of the test is air. The only true differences are that in pulling the air UP the tube, the resisting pressure is provided by the weight of the water in the tube. In pulling the air DOWN (while submerged) the pressure is provided by the weight of the water surrounding the person, and therefore the lungs. In both cases, the lungs must exert enough force to overcome the pressure. Since the lungs can by no means provide the pressure differential needed to vaporize the water, the experimental results will be similar.
2degrees
Contributor
Actually we do not suck the water up the straw. We remove the air pressure from the inside of the straw and the atmosphere forces the water up the straw. If you tried the same experiment with the cup being pressurized the results would be different
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