Choosing a cooling fan size requires a number of factors to be considered, including the power of the fan, the airflow, and the amount of heat generated by the device. Airflow is the speed and volume of air flowing through the fan blades, while air pressure is the pressure created by pushing air through the blades. The larger the fan size, the greater the airflow will usually be, but at the same time the lower the air pressure. Conversely, the smaller the fan size, the higher the air pressure but the lower the airflow.

There are many factors to consider when sizing a cooling fan, including:

Equipment heat: Fan size needs to be selected based on the heat generated by the equipment. For example, a 1916667CFM airflow is required on a computer, and a 12250CFM airflow is required on a DC switching power supply.

Fan power: the higher the fan power, the fan size needs to be increased accordingly.

Equipment volume: the fan size needs to match the equipment volume to ensure that the fan can effectively dissipate heat.

Quietness: If quietness is required, a smaller fan size is needed.

Mountable size: The fan size needs to match the mountable size of the device.

When choosing the cooling fan size, you need to choose the right number of inches according to the actual needs and the use of the environment. For example, common sizes are 60, 70, 80, 92, 120 and other mm, and larger or smaller sizes are also available.

In actual application, it needs to be tested and adjusted according to the equipment and environmental conditions. For example, fan and radiator sizes need to be matched to ensure the best use.

In conclusion, the selection of cooling fan size needs to take into account factors such as the heat generated by the equipment, fan power, equipment volume, silence requirements and mountable size, etc., to ensure that the fan can effectively dissipate heat, while meeting the silence requirements and mountable size and other requirements.