American and english units

[sarcon]

Hi,

we use a metrical units and i would like to know, what volume unit do you use on your tanks. For the pressure is clear for me: PSI but for the Volume????? What do you see on your tanks graved???
Thank You very much

 

[rakkis]

cubic feet

 

[Leadking]

Hi,

we use a metrical units and i would like to know, what volume unit do you use on your tanks. For the pressure is clear for me: PSI but for the Volume????? What do you see on your tanks graved???
Thank You very much

We use psi and most tanks are stamped (graved?) with the cubic feet. Calculation for example is a 3000 psi 80cf tank is 2000 psi is .66 x 80= 53 cf or for a quick calculation underwater is .7x80=56 cf. It's quick and crude but works.

I know those that work in the metric system say our system is more difficult but I disagree because it is more of a mathamatical language problem, neither system is better or worse, it's just different. Tring to learn a new "language" only applying to diving mathematics would create more problems than it would solve.

Just my opinion, not looking for a debate.

 

[sarcon]

it is strange :huh: , because 80 cuft is a great volume, so it means the air volume with a 1 atm pressure but not the water capacity in the cylinder :huh:

 

[SparticleBrane]

Correct, it is not water volume. In the US, the "volume" of a tank is how much air you've jammed inside the tank at the working pressure. Or if you want to look at it another way, if you fill the tank to working pressure and let all the gas escape, that's how much air would come out at sea level and 70ºF.

 

[Walter]

It makes more sense to me. An 80 cu ft tank is an 80 cu ft tank. When it's full you know exactly how much air it holds. One might be full at 3000 PSI, another at 3500 PSI, yet another at 2400 PSI, but it doesn't matter, they all have the same amount of air when full. With an 11 liter tank, you have to know the working pressure to know how much air is available to you. I don't care how much air a tank holds when it's empty, I want to know how much it holds when it's full.

 

[Nemrod]

I was trained as a scientist and fully understand the metric system and all of it's disadvantages, that is why in the USA despite having it jammed down our throats rejected it. Our system is better for everyday use, for science and math the metric system is better.

The tank volume such as 80 cubic feet is the amount of air in the tank at rated pressure and it is easy to work with because for example, at 1500 psi that same tank will now have 40 cf, who cares what the water volume is? N

 

[grazie42]

Originally posted by Nemrod
The tank volume such as 80 cubic feet is the amount of air in the tank at rated pressure and it is easy to work with because for example, at 1500 psi that same tank will now have 40 cf

But the above is only true if the tank is rated for 3000psi!
According to Walter it could be rated to 3000/3500/2400 psi (I´ve personally seen tanks in the states pressureized to 4000 psi too), so you´d still need to know the rated pressure to know how much gas is in the tank! (just like in metric)
It seems that the only difference is that we dont "pretend" that you don´t need to know the rated pressure...

 

[Marcin2005]

I was trained as a scientist and fully understand the metric system and all of it's disadvantages, that is why in the USA despite having it jammed down our throats rejected it. Our system is better for everyday use, for science and math the metric system is better.

Not to take of topic but what are the disadvantages of metric system for every day use?

 

[Leadking]

None for me.

I wish the U.S. would go metric, as a manufacturer it is difficult to manufacture two different products, one for the U.S. and another for the rest of the world. It makes everything cost more. It would be difficult to learn at first (because we all work daily with pounds and ounces, inches and feet) but would get over it within a few years.