Underwater pressure demonstration using water bottle - GIF

[Altair]

Underwater pressure demonstration using water bottle.




Previously:

Underwater explosion ultra slow motion - GIF
Ocean depth comparison - GIF

[IntheGroove]

Those poor souls...

[Frank S]

Looks like PADI free dive training or certification

[Karl_H]

It would be fun to see (vital info for the diving students) to fill the collapsed bottle with air at depth, then watch the bottle (analogous to the divers lungs if he holds his breath) explode as it comes back up to 1 atmosphere of pressure.

[hemmjo]

Yep. your lungs do the same thing if you are free diving.

Most PET bottles can hold a lot more than 1 atm 14-15 psi. But you lungs sure cannot!!!

I used to do an activity with my students making rockets. We used 2 liter PET pop bottles with compressed air for propulsion. We typically used 75-80 psi in class. As I developed the activity, I tested a lot of bottles to assure safety. Many bottles that held in excess of 100psi. The only one that burst below 70 psi is one that I found along the road that had been out in the sun for an unknown length of time.

[Philip Davies]

Is this speeded up? If so, by how much? To what depth did the diver descend, do you think?

[hemmjo]

The tank similar to that I was in was 40 ft deep. Pressure increases about 1 atm every 33 ft this varies according to water density and altitude. But 33 ft is a general rule of thumb.

The video looked real time to me.

[Frank S]

If it is a Padi freedivers training exercise, then the descent depth would be 25 meters or 80 feet One of the first things you learn is how to hyper oxygenate your lungs descend then slowly expel your breath on the way back up. even in free diving you try not to ascend faster than your bubbles and never expel all of your breath before surfacing, just most of it.

[hemmjo]

Hyper-oxygenation is a common but also risky process to prolong your time under water. You have to be VERY disciplined, aware of your limits and the subtle signals your body sends you. Our normal breathing is triggered by CO2 level in the lungs. When you oxygenate, you purged the CO2 from your lungs. It is then possible to depleted too much of the O2 before you body tells you to breathe. You can easily pass out from O2.

If you pass out on land your body will soon begin breathing again. If you pass out underwater the outcome is much worse.

[Frank S]

Hyper-oxygenation is a common but also risky process to prolong your time under water. You have to be VERY disciplined, aware of your limits and the subtle signals your body sends you. Our normal breathing is triggered by CO2 level in the lungs. When you oxygenate, you purged the CO2 from your lungs. It is then possible to depleted too much of the O2 before you body tells you to breathe. You can easily pass out from O2.

If you pass out on land your body will soon begin breathing again. If you pass out underwater the outcome is much worse.

Military diving instructors used to purposefully have their class to take rapid too deep breaths until everyone hyperventilated and felt lightheaded dizzy and or passed out while sitting in the classroom, once everyone came around, they would go into the spiel of why that happened how to recognize the symptoms and to imagine what would have happened had they dove with the onset of the symptoms. Then stress the point of never taking more than three moderate deep quick breaths before your dive breath.
Not sure how they do things now days its been over 50 yeasrs ago for me.