Frequency [50Hz/60Hz]


Most AC fans can operate on two frequencies: 50 or 60 Hz. This frequency is determined by the power source and affects the fans speed. A fan running on 60 Hz will spin faster than if it were running on a 50 Hz frequency. A faster spinning fan generates more airflow, static pressure, and noise. To account for these differences, a fans data sheet usually includes a set of specifications for each frequency. Note that the power from an electric outlet in North America has a 60Hz frequency.

Static Pressure

             Fans create positive static pressure when moving air. The environment the fan operates in has a negative static pressure that resists air movement. In an enclosed space, the tightly packed air generates high amounts of negative static pressure which will reduce the fans airflow. A fans static pressure rating, measure by mm-H2O reflects how well it will operate under negative pressure. The higher the number, the better it will perform. Not all fans require a high static pressure rating; it depends on the application and operating environment.

Power [W]


All fans have to consume power in order to operate. The power a fan consumes is measured in watts or W. The higher the watt rating, the more power it uses. Large and high-speed fans typically consume more power than smaller and lower speed fans.

Rotations Per Minute [RPM]


The RPM rating represents how fast a fan is spinning per minute. Holding all other specifications constant, a faster spinning fan will generate more airflow and noise. When designing a fan, many engineers will reduce a fans speed so that it delivers an acceptable airflow while minimizing the noise level.