Nm3/h stands for Normal cubic meters per hour. It's a unit used to measure the flow rate of gas, specifically at standard conditions of 0 degrees Celsius (273.15 Kelvin) and 1 atmosphere pressure (101.325 kPa).

Here's a breakdown of the term:

• Nm3: Normal cubic meter - This refers to the volume of the gas at the standard conditions mentioned above.
• h: Hour - This indicates the rate of flow, which is the volume of gas passing a specific point in one hour.

This unit is commonly used in industries that deal with gases, like oil and gas drilling, air filtration systems, and natural gas transportation. It allows for easy comparison of flow rates even if the gas is at different temperatures and pressures during operation.

It's important to note that Nm3/h doesn't account for the actual conditions the gas is in at the time of measurement. If you need to know the flow rate at the actual temperature and pressure (often referred to as "actual cubic meters per hour"), you'll need to convert Nm3/h using the gas properties and relevant formulas.