from the Private department...
Natural Gas Density
Engineering and workplace issues. topic
Posted by Keven on 13 January, 2013 - 6:58 am
Hello friends;

Please help me to calculate the gas density of the natural gas for the data acquisition.

I have Molecular weight of the gas is 19.0
Pressure of the Fuel is 150 PSIg
Temperature of the fuel is 80 Deg F.
Compressibility factor is 0.978
R=10.7316 psi-cft/lb-mol-R

when i calculate by the given formula it gives me
P in psia
T in R

It gives me 0.5676

But the gas density is 0.047 lb/scf

I can not understand how it comes? and how i calculate the exact gas density to convert volumetric flow to mass flow?


Posted by Arthur Mayclin on 18 January, 2013 - 1:34 pm
Your density calculation is correct, for a gas density at the stated temperature and pressure. Your second answer is at STP (SCF, not CF), and if you perform a conversion to 60F and 14.69 psig (STP conditions), you will obtain the other answer.

Posted by Kelvin on 20 January, 2013 - 1:08 pm
Thanks for help me. But what u suggest that on this running fuel pressure and temperature calculated density is used to convert volumetric to mass flow or at standard condition calculated density to use for convert volumetric and mass flow?


Posted by Carl Burgess on 21 January, 2013 - 3:45 pm
You need compressibility at line conditions - your quoted value for z looks to be one at base / standard conditions. AGA8 is the standard to refer to. Z varies with temperature and pressure.


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