I am trying to calculate a cost per hour use of a gas we buy in a cylinder. The details I have been working with are:
Gas used CP-grade N2 material number: 110628-L can
- Gas:
N
, density =1.251 g/L @ 0.101 MPa
M (molar mas) =14.007
- Gas cylinder: Pressure =
200 bar
or20 MPa
Cylinder volume9.45 m3
or9450 L
- Operating pressure of gas from cylinder =
4.5 bar
or0.45 MPa
and flow rate =60 cL/min
I have been applying the ideal gas law to PV=nRT
to figure out how many total litres of N are in the can at 4.5 bar pressure to then get a rough estimate of how many hours of flowing gas I get. However I seem to be getting unreasonable numbers, potentially from me using the equation or reasoning incorrectly:
When I apply the gas law under isothermal V2=V1/(P2/P1)
conditions to see how much the internal gas volume expands from the 20 MPa pressure, as a sanity check I wanted to see how many L at 1 atm came out. The result was 1.89 ML which makes little sense as the conversion of 1.89 ML N2 to mass = 2.364 Mg.
Similarly it equates to 420 kL @ 0.42 MPa.
Where am I going wrong?
Maybe the specifications mean that its 9.45m3 or 9450 L of compressed gas to 200 bar?