How to Distinguish Between Centrifugal Fans and Axial Fans?

Before installing and using centrifugal fans, it is essential to understand the differences between centrifugal and axial fans, the relationship between flow rate and pressure in centrifugal fans, and the specific operating conditions that dictate which type of fan to select.

I. Understanding the Differences Between Centrifugal and Axial Fans:

Centrifugal fans utilize centrifugal force (dependent on speed and outer diameter) to increase air pressure, generating higher pressure than mixed-flow or axial fans.

Their air volume is lower than that of mixed-flow or axial fans. Axial fans draw air axially through the inlet and discharge it axially via blade angles, utilizing thrust (lift) to perform work. Therefore, at identical sizes (and speeds), they generate significantly lower pressure than centrifugal fans. Their axial structure provides a much larger flow area than centrifugal fans, resulting in higher air volume.

II: When selecting a fan, the system ductwork configuration and system resistance must be considered to match the fan's internal characteristics (pressure, flow rate, speed).

If system resistance is high and structural dimensions are small, a centrifugal fan must be chosen. This is because the fan's overall performance process prioritizes airflow volume to overcome system resistance while generating pressure.

For cooling applications, if the airflow volume (flow rate) is excessive, the surplus volume will consume energy inefficiently through the fan. reducing motor efficiency. Conversely, if system resistance is low and structural dimensions are large, an axial fan must be selected. Since the low pressure generated by axial fans is sufficient to overcome system resistance, they can discharge large air volumes.

Finally, note: When a fan is operating, if the pressure it generates cannot overcome system resistance, the resulting air volume is zero. In this operating state, the fan is performing useless work.