g
Forward Curved Centrifugal Fan
static pressure
input power
% 
$
airflow | g IE |
|
cwx tuutr2 °—
types of nonoverloading fans would not be as significant when “riding the fan curve.”
Additionally, when the BI and AF fans surge, undesirable noise and vibration result. Care must be taken to establish a modulating range that does not take these fans into the surge area. The FC fan, on the other hand, may be operated in the surge area, provided the operating point enters the surge area at a relatively low static pressure.
A satisfactory modulation range may be achieved by selecting a fan that is two to three sizes (fan wheel diameter) smaller than one that would be selected for a
Finally, “riding the fan curve” is used most successfully when the system’s airflow modulation range is small. If the fan is required to modulate over a wide range of airflows, the increased static pressure experienced at reduced airflow may overpressurize the VAV terminals, resulting in
caQ3caM6793O[ | :7 |
