Saturday, February 21, 2009

Nm3 Conversions

One of the frequent conversion problems encountered in our industry is to convert from or to Nm3. We all know that the volume of gases change according to pressure. So, the conventional unit of m3/hr cannot be used to measure volumetric gas flow rates. Nm3 simply provides a standard of gas flow measurement. Nm3 is the equivalent flow at a standard temperature and pressure.
Temperature standard can be either at 0 °C, 15 °C or 25 °C. Pressure standard is mostly taken at 1 atm.
Suppose, to convert 1 Ton of Nitrogen into Nm3, we can safely use the ideal gas law for all practical estimates:

The volume, V is the volume in Nm3 as it is the volume under defined conditions of 1 atm and 0 °C.

Again, to convert 1 litre of Liquid Nitrogen into Nm3, we can use the same method:

3 comments:

Pramod Mathew said...

Can we safely accept the ideal gas equation PV=nRT ?
Why would it not be better to use the van der vaals correction factors?

Why is the gas expected to show ideal gas behaviour?

Is the calculation of van der vaals constants a cumbersome process?

n@vneet said...

As the pressure is near atmosspheric pressure, (up to 2 atm) ideal gas law can be tried out.

Again, the rule is to make things simple. This is the very basic mistake I encountered in college days. People unnecessarily complicate simple things. If you look up the Bernoulli's equation in our textbooks you'll faint.

Unknown said...

very helpful. thanks!