The flow unit of the PSA nitrogen generator is Nm3/h, which is different from the ordinary volume unit M3. Nm3 refers to the standard gas volume, which is the volume of the gas at 0 degrees Celsius and 1 standard atmosphere. Its basis comes from the "Petrochemical Automation Instrument Selection and Design Specification" P8 and the standard state defined by the 10th International Conference on Metrology (CGPM) in 1954 - 0 degrees Celsius, 101.325kPa;

According to the ideal gas equation of state PV=nRT, we know that the volume of gas is related to pressure and temperature. Using Nm3 as the flow unit of the nitrogen generator can reflect the size of the volume in the actual state. For example, the same air compressor, At different altitudes, the atmospheric pressure will be different. If m³/h is used, it will not reflect the impact of pressure and temperature on gas volume; the final gas production will be significantly different. Therefore, considering the pressure and temperature, the flow unit of the PSA nitrogen generator is not m3, but Nm3.