How can air volume shrink as you go deeper, when the tank itself doesn't shrink?

[John C. Ratliff]

When the air in your tank is at 232bar, it is already 232 times compressed, but you don’t see the metal tank expanding when you fill it.

The tank is quite rigid so it can bear a certain amount of pressure.

Like others said, after the first stage, the gas you inhale will be at the ambiant pressure (which is function of your depth) but others explained better so I’ll leave it at this.

Actually, it is 232 times atmospheric pressure compressed. One bar is one times atmospheric pressure. (That's 1013.25 millibar times 232 bar, or 14.7 psi times 232, or 3410.4 psig.)

SeaRat

 

[lexvil]

im trying to understand why all of you are trying to convince the OP that the tank doesn’t shrink, all you have to do to witness this is find some very clear bright water, find a spot that is at least 50 feet deep and toss the tank overboard, now you can see how small it is! You can’t witness this by diving because you shrink too!


or believe all of these other people.


I waited until the OP got it before I posted, it been eating me alive having to wait

 

[BlueTrin]

im trying to understand why all of you are trying to convince the OP that the tank doesn’t shrink, all you have to do to witness this is find some very clear bright water, find a spot that is at least 50 feet deep and toss the tank overboard, now you can see how small it is! You can’t witness this by diving because you shrink too!


or believe all of these other people.


I waited until the OP got it before I posted, it been eating me alive having to wait

I wanted to post that too but after reading all the serious replies I felt a bit bad

 

[RXTdiver]

I think PADI intended to say you consume air faster, not your breath rate is faster.

I would like to clarify something that for some reason blocked my understanding a as a "D" average high school student taking SCUBA. When we reference breathing "compressed air" it's not because the air is compressed into the tank, it's because the air we inhale is compressed by the water pressure at depth.

See the highlighted part in the attached picture. I included parts before and after to show everything in context. Seems like they are saying that you would breathe faster if you breathe denser air, but maybe I'm misunderstanding?

 

[L13]

See the highlighted part in the attached picture. I included parts before and after to show everything in context. Seems like they are saying that you would breathe faster if you breathe denser air, but maybe I'm misunderstanding?

The are combining two ideas.

• The denser the air, the more energy you use breathing
• The faster you breath, the more energy you use breathing

To become:

• The denser the air and the faster you breath, the more energy you use breathing

 

[Scott G. Bonser]

See the highlighted part in the attached picture. I included parts before and after to show everything in context. Seems like they are saying that you would breathe faster if you breathe denser air, but maybe I'm misunderstanding?

…the same volume at every depth, however you consume more air molecules at increased depth.

giantfroginthepool