2 replies to this topic

[Olaniyi]

***sorry posted in the wrong section initially*

Hi all
This seems a basic question but its throwing me for a loop.
i have a gas composition, C1 to C10 in mol %, gas flow rate in both t/d and sm3/d
I'm told that I have a water content of 20 ppmv

How to I convert this to mol % water? Can I based on rule of partial pressures say 20 ppmv = 20 x 10-6 mol% of total..

Thanks!!

[breizh]

Let you try this resource :

http://www.air-dispe...m/formulas.html

Breizh

[paulhorth]

Ogeds,
In an Ideal Gas Mixture, volume fraction is indeed equal to mol fraction. In a natural gas at high pressure this is not strictly correct, because the non-ideality (as expressed by the compressibility factor Z) will be different for each component depending on its partial pressure. But for very dilute components like the water at 20 ppmv you can take it as pretty close to 20 ppm mol. The chances are that the analysis was done in the lab at low pressure anyway so then it will be exactly the same as mol fraction.
Paul