When selecting a centrifugal fan, airflow, static pressure, efficiency and noise are usually the first parameters considered. Impeller material, however, is often reduced to a simple assumption: metal is stronger, while plastic is lighter.
Cross-flow fans, also known as tangential fans, typically use a long cylindrical impeller. Air enters the impeller radially, passes across its interior, and then flows through the blades a second time before being discharged. This creates a broad, relatively uniform airflow pattern across the length of the fan.
Dry coolers and cooling towers are typically installed outdoors on rooftops, equipment platforms, or at industrial facilities
