1. System Impedance

The range between the air inlet and air outlet of an enclosure accounts for 60% to 80% of the total system impedance. In addition, the greater the air flow, the higher the noise. The higher the system impedance, the greater the airflow required for cooling, so in order to reduce the noise, the system impedance must be reduced to a lower level.

2. Air flow disturbance

Disturbance caused by obstacles encountered along the air flow path will generate noise. Therefore, any obstacle, especially in the key air inlet and outlet range, must be avoided to reduce noise.

3. Fan speed and size

Since the high speed fan makes more noise than the low speed fan, try and select the low speed fan as far as possible. A fan with larger size and lower speed is usually quieter than a fan with lower size and higher speed when delivering the same air volume.

4. Temperature rise

In a system, the air volume required for cooling is inversely proportional to the allowable temperature rise. If the temperature rise is allowed to increase slightly, the required air volume can be greatly reduced. Therefore, if the imposed limit on allowable temperature rise is slightly relaxed, the required air volume will be reduced, and the noise will also be reduced.

5. Vibration

In some cases, when the weight of the whole system is very light or the system must operate in a specified way, it is particularly recommended to use soft isolation equipment to avoid the transmission of fan vibration.

6. Voltage variation

Voltage variation will affect the noise level. The higher the voltage applied to the fan, the greater the vibration and the greater the noise due to the increased speed.

7. Design considerations

Every part of the fan is designed to affect the noise level. The following design considerations can achieve noise reduction: size of winding iron core, design of fan blade and outer frame, and accurate manufacturing and balance.