Air flow measurement in ducts is a process used to measure the amount of air that is passing through a duct. This measurement is important for many reasons, including determining the efficiency of air conditioning systems, ensuring proper ventilation, and preventing the spread of contaminants. Air flow measurement in ducts is typically done using an airflow meter, which measures the velocity of air as it passes through the duct. This velocity is then converted into a volumetric flow rate, which is the amount of air that is passing through the duct per unit of time. This volumetric flow rate is then used to calculate the total air flow through the duct. Additionally, air flow measurement in ducts can also be used to measure the pressure drop across the duct, which can be used to determine the amount of air that is being lost due to friction. By accurately measuring the air flow in ducts, engineers can ensure that air conditioning systems are operating at their peak efficiency and that ventilation systems are providing adequate air flow.