@Kapsyl I have a question about this, especially when you are going to buy a pre-filled tank. If the nitrogen is in a 40 cu ft tank, and that's just how they sell it to you, how do you know how much nitrogen you are getting? How could you possibly know how many "bars" of gas there are?
Also, how do we know how much nitrogen will be needed? If it's an on demand system, like SCBA, I would "guess," that you would need less gas.
Any explanation here about all this would be great.
The cylinder (tank) they sell to you should have the amount per the size.
They are usually color coded or have a sticker on them stating what they contain.
There might be data also labeled on it that states how much it has in it & the pressure it is at. Its all an industry standard.
The cylinders for nitrogen are made to hold it exclusively. You can't interchange gases in cylinders.
So a 40 cubic foot cylinder will have just about that...40 cf, which is about 1100 liters.
It will also be at about 2200 psi or more (pounds per square inch) of pressure in the US. (which is about 150 bar)
(Bars is the metric unit of pressure 100kPa. Used everywhere in the world except the US.)
40 cf is sufficient. It is equivalent to 5L cylinder metric. If they had normal air in them, they would last about 30-40 minutes in a scba system.
Because these are the same size cylinders & pressure that fire fighters use.