Holding your Breath

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HKGuns

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Simple, probably stupid question.

Why is it ok to hold your breath while free diving but not while Scuba diving? I'm sure there is a simple answer, but I guess I am lacking some fundamental knowledge.
 

tbone1004

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@HKGuns if you freedive you have say 4l of gas in your lungs at 1ata which is a "normal" breath. At 4ata you have 1l of gas which then expands back to 4l when you get back to the surface.
When you are on scuba at 4ata you take that 4l of gas in, but when you hit the surface that gas expands to 16l which is much larger than your lung capacity and they explode
 

agilis

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Simple, probably stupid question.

Why is it ok to hold your breath while free diving but not while Scuba diving? I'm sure there is a simple answer, but I guess I am lacking some fundamental knowledge.
Boyle's Law, the first thing I was taught in basic scuba certification. You lungs are only able to stretch about 20% Holding a full breath of compressed air from a scuba tank and surfacing from just two atmospheres (33 feet) will pop parts of your lungs and possibly kill you. People have died from surfacing with a full breath of compressed air from the bottom of a 15 feet deep pool. Surface breath holds compress in your lungs as you dive and return to only their original volume as you surface.
 

James79

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Just to add, popping a lung isn't the only risk for the SCUBA diver. The over-pressure if you hold your breathe ascending can also force air directly into the blood-stream causing an embolism (AGE). I think the technical term is "no bueno."
Respectfully,
James
 

HKGuns

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Thanks everyone. Hopefully this helps someone else. Basic physics that I knew, but for some reason was having a hard time understanding.

Filling at the surface was the key point I wasn't thinking about.
 

tbone1004

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Boyle's Law, the first thing I was taught in basic scuba certification. You lungs are only able to stretch about 20% Holding a full breath of compressed air from a scuba tank and surfacing from just two atmospheres (33 feet) will pop parts of your lungs and possibly kill you. People have died from surfacing with a full breath of compressed air from the bottom of a 15 feet deep pool. Surface breath holds compress in your lungs as you dive and return to only their original volume as you surface.

people have died from the shallow end of the pool, it doesn't take much
 

BlueTrin

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The ballon is what would happen to your lungs if you held your breath, except they can’t expand so much without damage.

 

Hank49

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Simple, probably stupid question.

Why is it ok to hold your breath while free diving
If you don't hold your breath free diving, you'll drown. :D:D
 
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