What is CFM ? How to measure it ?
What is CFM? -CFM is short for cubic feet per minute (cu ft /min). - CFM determines how much Volume(cubic feet) can be moved or exchanged each minute. -In HVAC we use CFM to represent the capacity of equipment like Air Handling Unit. -It is measured by Anemometer. Anemometer - An anemometer is a device used for measuring wind speed and direction. -It provides Velocity of air in M/s or FPM. -It does not provide air quantity directly. Formula Air Quantity = The velocity of Air (FPM) X Area(Through which air is passing) …… Area will be in Sq. feet How to measure CFM across coil/Filter AVG Velocity across filter = (A+B+C+D+E)/5 Total CFM = Area( LxW ) X Avg Velocity Ex. AVG Velocity=60 FPM Area =2*2=4 SqFt Total CFM=4*60 =240 C ubic F eet per M inute Eg. AVG Velocity across filter = (A+B+C+D+E+F+G+H)/8 Total CFM = Area( LxW ) X Avg Velocity How to measure CFM across