Scuba Tank Sizes

[lottie]

Okay, I'm showing my dive naivety here.

What is the difference between the different sized tanks out there? - I'm just talking about the recreational tanks (not nitrox). Also is there a difference between Aluminium and Steel? (apart from the buoyancy aspect)

So for example: if a diver (okay, me) was at a steady 60fsw, not hoovering up my air with the tank filled to 3000psi. Would the different tank sizes make any difference to the length of time that i was under the water?

I just got back from doing a dive and took a smaller tank (normally used by the DMs/Instructors) rather than the normal (think they are AL80s - whatever that means) - so i was only under for 31 minutes instead of my average of 45 mins

Thanks

[hbh2oguard]

The size of the tank is how many cubic feet of air. So an 80cf tank has 80 1ft cubes of air(If that makes sense) The bigger the tank the more air you have, so the longer you can last under water. Steel tanks last A LOT longer than AL, I have one that has a hydro stamp of 1963. Also my AL tanks are at a working pressure of 3000psi, while there are numerous working pressures for steel like (2200,3000,3442,3500) and I'm sure there are more. Probably one of the nicest tanks is a high pressure steel tank.

[lottie]

Thanks for that.
let me get this straight - even if you have a small and a larger tank - both filled with 3000psi. Am i under the assumption that you will have longer underwater with the larger tank??

[acelockco]

Thanks for that.
let me get this straight - even if you have a small and a larger tank - both filled with 3000psi. Am i under the assumption that you will have longer underwater with the larger tank??

What dive shop do you use? How many dive shops are there in your area?

[lottie]

What dive shop do you use? How many dive shops are there in your area?

How is that relevant?

Most of the dive places here are attached to a resort. There are a couple that are independant (and they cost more), but they are up in the north (about a 90 min drive, to then have the boat come back down south to do the actual diving)

[acelockco]

Just wondering what shop you use?

I have a friend going to St. Lucia for a vacation shortly.

[hbh2oguard]

Thanks for that.
let me get this straight - even if you have a small and a larger tank - both filled with 3000psi. Am i under the assumption that you will have longer underwater with the larger tank??

I thought this would have been taught in OW, or for sure in AOW. Not to be mean but isn't this just common sense

[lottie]

I thought this would have been taught in OW, or for sure in AOW. Not to be mean but isn't this just common sense

It probably was mentioned in the OW book (will have to have another look to check) - maybe i didn't understand it as much as I do now and didn't take in the information.
And it probably is common sense...but i couldn't remember hence why I asked.

[Tigerbeach]

Thanks for that.
let me get this straight - even if you have a small and a larger tank - both filled with 3000psi. Am i under the assumption that you will have longer (time) underwater with the larger tank??

Lottie, there are too many variables at play to really answer your question.

The simple answer is; I think you are asking if all tanks that have a full working pressure of 3000 psi hold the same amount of air, the answer is "no".

In this case the tank with the larger capacity should last the longest time underwater. However, there are many other variables at play.

Such as: Are the two tanks going on the same dive with the same diver?
If a man has a bigger tank than his female buddy, he might suck up more air and finish sooner. What depth are you diving? How hard will you be working? What is the water temperature?
All these can impact the bottom time with a tank of any size.

[Papa Bear]

Lottie, there are too many variables at play to really answer your question.

The simple answer is; I think you are asking if all tanks that have a full working pressure of 3000 psi hold the same amount of air, the answer is "no".

In this case the tank with the larger capacity should last the longest time underwater. However, there are many other variables at play.

Such as: Are the two tanks going on the same dive with the same diver?
If a man has a bigger tank than his female buddy, he might suck up more air and finish sooner. What depth are you diving? How hard will you be working? What is the water temperature?
All these can impact the bottom time with a tank of any size.

Well said! A single 72 has as much air as a closet. If you close the door and just sit there you will have a long time, but if you jump up and down and run in place, it won't last so long. The best thing I can tell you about air consumption is just dive a lot and become comfortable and you will be bringing extra air back!