The discussion clarifies that static pressure decreases as CFM (Cubic Feet per Minute) increases on blower fan charts due to the inherent resistance in ductwork systems. As airflow increases, the pressure required to push air through the system rises, but fans operate differently; higher resistance results in lower airflow. Fan charts indicate the CFM a fan can deliver at specific resistance levels, measured in Pascals (Pa) or inches of water, but do not provide complete performance data without considering system resistance.
PREREQUISITESHVAC engineers, system designers, and anyone involved in optimizing airflow and pressure in ventilation systems will benefit from this discussion.
Yes, the fan curve alone won't tell you the performance of the fan, just the performance range. To find the actual performance you need to match the fan curve to the system resistance.hali24953 said:Does that mean that fan charts tell what CFM flow will the fan be able to give at a given resistance to its inflow?
The resistance coming from a pipe wall for example, a fan at the outlet will be able to suck the air out at a given CFM overcoming the wall resistance given in terms of Pa/inches of water ?