How to select fan
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How to select the right fan
Selecting the right fan is important for designing an appropriate cooling solution. All the computers and electric equipments using cooling fans to realize the airflow required from the system heat dissipation, and also to consider the following listed parameters.
• Superb air flow efficiency (CFM)
• The fittest dimension (mm)
• Lowest acoustic noise (dBA)
• Smallest power consumption (W)
• Highest reliability and sufficient life expectancy (hours)
• Reasonable cost ($)
• Superb air flow efficiency (CFM)
• The fittest dimension (mm)
• Lowest acoustic noise (dBA)
• Smallest power consumption (W)
• Highest reliability and sufficient life expectancy (hours)
• Reasonable cost ($)
Three important steps to select right fans and blowers are listed below.
Step 1
Define the equipment’s specifications and conditions.
Base on the input and output currents, make sure the temperature rise and the total heat generated.
The common voltage inputs are 5VDC, 12VDC, 24VDC, 48VDC, and 115-220VAC powered. Make sure your system can provide the required amount of current for the fan to start
Step 2
Calculate the airflow to dissipate the heat. The basic formula for heat transformation of airflow:
Step 3
Select the fan
“System operating point”, the meeting point of system impedance curve and fan flow performance curve is the must-know when selecting a fan. It is the best working point for fan in the system. In general, the maximum fan flow rate is 1.5 to 2 times of operating flow rate for fan’s performance. (See below diagram).
Operating point of system impedance and fan
Example of fan selection
As right diagram shown, curve M and curve L are the curves of the airflow and static pressure in medium speed and low speed for fan 80x80x25mm. The meeting points of the two curves and system impedance are operating point M (15CFM/1.3mmAq) and operating point L (10CFM/1.0mmAq). If the operating point L just meets the system cooling requirement, we need to make choices from following three statuses.
1. If considering the power consumption and noise level priority, select the low speed fan.
2. If considering for additional control circuits insert priority after system sold, such as game cards, graphic cards, or disc floppy (CD ROM, etc.), select higher speed fan.
3. If considering both above, select variable speed fan. Please contact us for details.
2. If considering for additional control circuits insert priority after system sold, such as game cards, graphic cards, or disc floppy (CD ROM, etc.), select higher speed fan.
3. If considering both above, select variable speed fan. Please contact us for details.
Relationship between fan flow performance and system impedance