The terms "Nm^3/h" and "m^3/h" both refer to flow rates, but they represent flow rates measured under different conditions. Here's the difference between the two:

1. Nm^3/h (Normal Cubic Meters per Hour):

   • Nm^3/h represents the flow rate of a gas at "normal" conditions, typically defined as 0°C (32°F) and 1 atmosphere of pressure (101.325 kPa or 14.7 psi).
   • The "N" in Nm^3/h signifies that the flow rate is normalized to these standard conditions. It means that the volume of gas flowing per hour has been adjusted to what it would be at standard temperature and pressure.

2. m^3/h (Cubic Meters per Hour):

   • m^3/h represents the flow rate of a gas or liquid in cubic meters per hour without any normalization to standard conditions.
   • It does not consider temperature or pressure variations, so it simply represents the volume of gas or liquid passing through a given point in a pipeline per unit of time.

In summary, the main difference between Nm^3/h and m^3/h is that Nm^3/h is a normalized flow rate adjusted to standard temperature and pressure conditions, while m^3/h is the actual flow rate without any normalization. When comparing flow rates or specifying flow requirements, it's essential to consider whether the flow rates are given in Nm^3/h or m^3/h to ensure accurate measurements and calculations.