 Cubic feet per minute (CFM)

• ### What is airflow and how is It measured?

• Airflow can also be described in terms of air changes per hour (ACH), indicating full replacement of the volume of air filling the space in question. The instrument that measures airflow is called an airflow meter. Anemometers are also used to measure wind speed and indoor airflow.

• ### How do you measure air velocity and flow rate?

• Some instruments can measure both air velocity (air speed) and air flow rate (air quantity). Air flow rate is measured by calculating an average velocity for the conduit of interest, and then, multiplying this velocity by the cross sectional area of the duct at the measurement location.

• ### How do you measure air flow in Conduit?

• Definition of Air Flow Measurement. Air flow rate is measured by calculating an average velocity for the conduit of interest, and then, multiplying this velocity by the cross sectional area of the duct at the measurement location. The air velocity value may estimated using a single reading, or a survey across the duct at a station.

• ### How many air flow measurements are taken per radius?

• Three air flow measurements are taken per radius: on the edge; one-third toward the center; twothirds toward the center. Note the air most affected by friction is seemingly over-represented. A total of eighteen readings accurately describes the air flow rate.