Different between Nm3/h = m3/h ?

[JohnS]

Originally Posted by Unregistered

What is the conversion factor between Nm3/h and m3/h

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It depends. m³/h generally refers to a measurement at actual temperature and pressure. The volume of a gas is a meaningless concept unles the temperature and pressure are clearly stated explicitly or by convention. Nm³/h is a convention. The volume, regardless of actual conditions, has been adjusted to what the gas would occupy at 0 °C, 101.325 kPa. Unless those ARE the conditions, it won't be the actual volume.

The adjustment is usually taken via the ideal gas law. Compressibility or a better equation of state may be used if the gas pressure/temperature/volume relationship departs significantly from the ideal gas law.