Converting liters to cubic feet

[Sascha314]

We have the possibility for 300 bar, but I just know 1 person who uses it.
More expensive in equipment, and buyoncy change larger. Also not possible to fill everyhwere, if you are for instance on vacation.
So the benefit betweeen 230 and 300 bar is too small to justify it for the applications here.

 

[inquis]

I dont know, why you make complicated. In metric you do not need to know the tank factor.
Lets assume you have 200 bar.
With a 12l its 12x200 = 2400 l (approx)

Perhaps I didn't explain it well. 12 IS the value of the tank factor in metric units. Inherently, it's a ratio, but the denominator is 1. The vessel holds 12 L gas per 1 atm of pressure. (Sure, you approximate an atm as a bar, but no one cares.)

The equivalent ratio in imperial units has a denominator other than 1. No big deal, I can remember that tank specific value (e.g. 3 cuft per hundred psi for my LP85s), just as you remember "12 L per bar" for your 12L.

The process from there is identical. You multiply your pressure (in bar) by 12 and get liters. I multiply my pressure (in hundreds of psi) by 3 and get cuft.

As was stated above, imperial is very easy when one has the tank factor. This is the same thing a metric diver does without even realizing it.

 

[Duglum]

I don't know much about the rest of Europe, but over in my neck of the woods we seem have new tanks being sold that are rated to 300, 232 or 230 bar. Older tanks tend to be 200 bar. Mostly Steel in various sizes. AL tanks are sold mainly for deco / stage use. So it would seem that 300 and 232 are (sort of) becoming the new standard, but there are plenty of older 200 bar tanks being used and I don't see them going away very soon.

Our club compressor does a nice job of filling my 300 bar tanks and the lighter 200 bar that my youngest daughter uses. There is a selector switch I use to tell it what the cut off pressure is supposed to be. I know quite a few other clubs have a similar set up. I haven't used commercial filling places, but the few I know, do cater 300 bar clients.

Same here basically.. but i haven't seen a pure 200bar tank in a looong while now. Basically everything since the shift to M25 tank threads in the nineties (or earlier?) has been 232bar.

Aluminium is only used for stages, everything else is steel. I'd say the 12L long is becoming the new standard.. it's a great tank with a nice weight distribution, especially the concave bottom version. Many people still (rent and) use the short fat 12L tanks though, those are absolutely horrible.

And apart from rebreather tanks almost noone uses 300bar.. doesn't make any sense for most applications since the tanks are more expensive and so much heavier for not that much more useable gas (ideal gas laws and all that).

 

[Sascha314]

Perhaps I didn't explain it well. 12 IS the value of the tank factor in metric units. Inherently, it's a ratio, but the denominator is 1. The vessel holds 12 L gas per 1 atm of pressure. (Sure, you approximate an atm as a bar, but no one cares.)

The equivalent ratio in imperial units has a denominator other than 1. No big deal, I can remember that tank specific value (e.g. 3 cuft per hundred psi for my LP85s), just as you remember "12 L per bar" for your 12L.

The process from there is identical. You multiply your pressure (in bar) by 12 and get liters. I multiply my pressure (in hundreds of psi) by 3 and get cuft.

As was stated above, imperial is very easy when one has the tank factor. This is the same thing a metric diver does without even realizing it.

I am sorry to say, but physically you are just wrong. And thst confusion comes exactly from this imperial interpretation of gas content.

A volume is a quantity defined as a cubic.in a length dimension, be it meter or feet. It happens that liter is a customary alias for 0.1m x 0.1m x 0.1m. That is independent of any pressure or whatever material is inside.
The ideal gas equation just states, that for a given volume, Pressure and Temperature you have an amount of gas molecules. Thats it.


What this reference to 1 bar actually means is, that you calculate something with a unit pressure x volumen (bar x liter or psi x cubic feet). Then you assume you have a pressure of 1 bar, so you just omit the pressure factor in your equation but keeping it in mind. Thats something like a "natural" unit. You redefine something or know in the end you have to multiply by a factor.

That is alright, no problem. But you cannot then just state you redefine the volume and the volume is pressure dependent. Thats just not how units work.

 

[Edward3c]

I know I’ve put a few posts on this thread, but in reality use whatever system works for you.

Next some one will say one computer is better than another; does it matter.

 

[34109411]

shall we just all go diving !

 

[JuLe]

shall we just all go diving !

I wish I could, but got this nasty headcold. All blocked up at the moment, so no diving for now.