Chemical Forums
Specialty Chemistry Forums => Chemical Engineering Forum => Topic started by: sania on July 07, 2007, 07:24:12 AM

I read in gas processing industry the term Normal Cubic meter is used (Nm3) of gas,From normal i got an idea that normal means
A Normal Cubic Meter of a gas (Nm3) is the volume of that gas
measured under the standard conditions of 0 degrees Celsius,
and 1 atmosphere of pressure. As volume of a gas is inversely proportional to its pressure, and proportional to absolute temperature. How can we convert it in to room or process temperature. By using pv = nrt or some other method. how can we find the volume of gas. Want a detail answer from you. Thankyou
with kind regards

PV = nRT will do.

One more thing where we use Compressibility factor in PV=nRT. I mean in which condition we use Z1 and Z2. Thankyou
With kind regards

Sania:
I understand you to say that you know the “Normal” volume of a gas and want to know the actual volume at a specific temperature and pressure (both different from “Normal” conditions). If that is what you mean, then you can use the Ideal Gas Equation PV = nRT – but only if you know the molecular weight of the gas. A more conventional method of converting the volume is to use the result of combing simultaneous equations:
V_{2} = V_{1} (Z_{2}/Z_{1}) (P_{1}/P_{2}) (T_{2}/T_{1})
Where,
V_{2} = gas volume at the new condition, m^{3};
V_{1} = “Normal” gas volume, m^{3};
P_{1} = 1.0 atm, absolute;
P_{2} = pressure at the new condition, atm., absolute;
T_{1} = 273 ^{o}K;
T_{2} = absolute temperature at new condition, ^{o}K.
The above equation is derived dividing one of the following equations by the other:
P_{2} V_{2} = Z_{2} n R T_{2}
P_{1} V_{1} = Z_{1} n R T_{1}
I hope this helps you out.

Sania:
Art Montemayor's equation is perfectly correct.
But I would caution you on assuming that Normal conditions are always 0 degrees Celsius and 1 atmosphere. There is no universally accepted set of Standard or Normal temperature and pressure conditions. I urge you to read this article:
http://en.wikipedia.org/wiki/Standard_conditions_for_temperature_and_pressure
For example, as you will see in the above article, the International Union of Pure and Applied Chemistry (IUPAC) defines the standard conditions of temperature and pressure as 0 degrees Celsius and 100 kPa which is 1 bar (not 1 atmosphere) and has done so for a good many years.

U can also refer my post
http://profmaster.blogspot.com/2007/07/suctionvsdischargegasflow.html (http://profmaster.blogspot.com/2007/07/suctionvsdischargegasflow.html)