Cylinder Volume ( Technical Detail )

[JohnN]

this is nice answer but at the all the volume equal to 2000 and it`s should be 2000 , 3000, 4000 if wrong correct me .thank yo johnN

You're correct, my bad. Too early here

200 2000/1.0326 = 1937 l
300 3000/1.0669 = 2812 l
400 4000/1.1089 = 3607 l

 

[Storker]

at 20°C you will have about 2700l of air @ 300bar and about 3100 @ 400bar

Yep. There are slight variations with temperature, but not very significant.

Up to 232 bar, the compressibility is more or less negligible, at least for air and recreational nitrox. So a 200 or a 232 bar tank pretty much holds its nominal capacity. A 300 bar tank suffers roughly a 10% loss compared to nominal capacity. So topping up after the tank has cooled down is more important for getting the most out of your tank's capacity for a 300 bar tank than it is for the lower pressure tanks. Even more in cold water, where you easily "lose" some 20 bar or so from a 300 bar tank between rigging and submerging due to the cooling of the gas in the tank.

Despite the disadvantages of compressibility and getting decent 300 bar fills, I prefer the 10x300 over a 12x232 or a 15x200 (all three have roughly the same nominal capacity) due to the lower tank volume. a 12 needs 2kg more ballast, and a 15 needs 5kg more ballast to become neutral. When you're already carrying well north of 10kg of weights and the whole rig weighs more than 30kg in total, those kilos make a difference. At least they do to me. YMMV, of course.

 

[xxrebelxx3]

Well, i did not account for the compressibility factor but I made this neat little app that estimates roughly the amount of airtime in a tank depending on volume, pressure, mrv, and desired depth. Actually the first web app I've ever built

Streamlit

tank-air-time-calculator.herokuapp.com