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Many businesses ignore a problem when purchasing cooling fans. That is, all motors and electronic products that need to use a cooling fan must choose a cooling fan with sufficient air volume for the system's heat dissipation. The amount of air volume depends on the power consumption of the system and whether it can take away enough heat. In daily life, The service life of motors and electronic products that require cooling fans is often reduced due to the lack of cooling systems, so companies should also understand that due to the lack of cooling fan cooling systems, the sales prices and sales of motors and electronic products are often not as good It is expected that, therefore, to select the correct cooling fan ventilation components, the following objectives must be considered as criteria:

First, the strongest air flow rate;
Second, the most suitable size;
Third, the quietest noise;
Fourth, the minimum power consumption;
Fifth, the greatest reliability and the strongest service life;
Sixth, a reasonable total cost.

Knowing the above target standards, we correctly select the cooling fan through the following four steps, which can help you achieve the above targets:

Step 1: Total cooling requirements
You must first understand three key factors to get the total cooling demand:
1. The heat that the cooling fan must convert (that is, the temperature difference DT)
2. The wattage (W) that the cooling fan offsets the converted heat
3. Air volume required by the cooling fan to remove heat (CFM)
The total cooling requirement is extremely important for the effective operation of the system. Efficient system operation must provide ideal operating conditions, so that all components in the system can play the maximum function and the longest service life.

The following methods can be used to select the general cooling fan motor:
1. Calculate the heat generated inside the equipment.
2. Determine the allowable temperature rise range inside the device.
3. The equation calculates the required air volume.
4. Estimate the system impedance of the equipment.
5. Select the required cooling fan according to the characteristic curve or specification of the catalog.
If the internal heat dissipation of the system equipment and the allowable total temperature increase are known, the air volume required for cooling the equipment can be obtained.

Step 2: All system impedance / system characteristic curve
When the air flows, the air flow will encounter the interference of the internal components of the system in its flow path, and its impedance will restrict the free flow of air. The change in pressure is the measured static pressure.
In order to confirm the cooling wattage between each slot, the design or manufacturer of the cooling fan system must not only have an effective cooling fan characteristic curve of the cooling fan to determine its maximum air volume, but also must know the wind resistance curve of the system. Parts inside the system can cause loss of wind pressure. This loss varies with the amount of wind, the so-called system impedance.

Step 3: Operating point of system operation
The intersection of the system characteristic curve and the cooling fan characteristic curve is called the system operating operating point, which is the optimal operating point of the cooling fan.

Step 4: Noise value
The noise of the cooling fan is measured in a non-reverberant room with a background noise below 15 dBA. The cooling fan to be tested runs in free air, and a noise meter is disposed one meter away from the air inlet.

The following seven guidelines provide the best way to use cooling fans to reduce noise to a minimum:
1. System impedance
The range between the air inlet and the air outlet of a chassis accounts for 60% to 80% of the total system impedance. In addition, the greater the airflow, the higher the noise. The higher the system impedance, the greater the airflow required for cooling, so in order to minimize noise, the system impedance must be minimized.

2. Airflow disturbance
The turbulence caused by obstacles encountered along the airflow path can generate noise. Therefore, any obstructions, especially in the critical air inlet and outlet areas, must be avoided to reduce noise.

3. Cooling fan speed and size
Since high-speed cooling fans produce more noise than low-speed cooling fans, you should try and choose low-speed cooling fans as much as possible. A large-size, low-speed cooling fan is usually quieter than a small-size, high-speed cooling fan when delivering the same amount of air.

4. Temperature rise
In a system, the air volume required for cooling is inversely proportional to the allowable temperature rise. Allowing the temperature rise to be slightly increased can greatly reduce the amount of air required. Therefore, if the restrictions imposed on the allowable temperature rise are slightly relaxed, the required air volume will be reduced and the noise will be reduced.

5. Vibration
In some cases, when the weight of the entire system is very light, or the system must be operated in a prescribed manner, it is particularly recommended to use soft insulation equipment to avoid the transmission of vibration of the cooling fan.

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

7. Design considerations:
The design of each part that constitutes the cooling fan will affect the noise level.