|Number of air changes/hour in an area is
= Total Room Airflow In CFM x 60
For calculating Total Room Airflow in CFM, first calculate air flow of individual filter. Formula is given below.
Air flow (in cfm) = Avg.air velocity in feet/Minute x Effective area of filter
Total Air flow = Sum of air flow of individual filter.
Air flow Velocity can be measured with the help of Anemometer.