Centrifugal fans play a crucial role in many industries. Properly selecting a fan can improve work efficiency and effectively reduce energy consumption. Below are five key factors that affect the selection of a centrifugal fan:

1. Airflow Calculation
   Airflow is one of the most basic parameters in selecting an industrial centrifugal fan. The airflow is defined as the product of airspeed (V) and the cross-sectional area of the fan’s duct (f). By using an anemometer, airspeed can be accurately measured, and the airflow can be calculated using the formula:
   $Q=V\times f$
   Fan manufacturers typically calculate the required airflow based on the ventilation rate required for the building, and select the appropriate number of fans accordingly.

2. External Residual Pressure
   External residual pressure is the difference between the total pressure of the fan and the resistance of each section of the air handling unit. When selecting a fan, it’s necessary to consider the resistance of the return air duct, which is typically calculated as 7~8 Pa/m, and 10 Pa per 90-degree bend. Proper pressure calculations ensure the fan operates efficiently and avoids insufficient airflow due to lack of pressure.

3. Specific Application Requirements
   Choosing the appropriate fan depends on the working environment and task. Below are fan selection recommendations for different places and needs:

   • Heat or Steam Removal: For heat or steam removal, it is recommended to use roof exhaust fans, which efficiently expel hot air and steam.
   • Heating, Cooling, or Supplying Fresh Air: If the task involves heating or cooling air, it’s best to transport the air through the area where personnel are located. In this case, duct fans or sidewall fans are suitable.
   • Fire Smoke Exhaust: For fire smoke exhaust, roof ventilation or suspended ducting is commonly used, with duct fans being a popular choice.

4. Warehouse Ventilation
   Ventilation requirements for warehouses depend on the type of goods being stored:

   • Flammable and Explosive Materials: For storage of flammable items, such as paints, explosion-proof fans must be used for ventilation to ensure safety.
   • Noise Requirements: If noise control is critical, roof ventilation fans or environmental centrifugal fans can be selected.
   • Airflow Requirements: Based on the required airflow for the warehouse, conventional axial fans (e.g., SF type) or exhaust fans (e.g., FA type) can be chosen.

5. Kitchen Exhaust
   Kitchen exhaust requirements are unique, especially for handling grease:

   • Direct Indoor Grease Exhaust: SF axial fans or FA exhaust fans are suitable, depending on the amount of grease.
   • Heavy Grease Kitchens: For kitchens with high levels of grease, centrifugal fans are recommended, and exhaust can be directed through long ducts with bends. Centrifugal fans have higher pressure and effectively prevent grease from reaching the motor, reducing maintenance frequency.

6. Special Venue Fan Selection
   For special places such as hotels, tea houses, cafes, and game rooms, fan selection is more critical:

   • Small Room Ventilation: Small plastic or aluminum axial fans are ideal. These fans are low noise, high airflow, and suitable for connecting to central ventilation ducts.
   • Noise Control: For venues with high noise requirements, fans with soundproofing material in the fan box can be used. These fan boxes not only reduce noise but also improve ventilation performance.
   • Gymnasium Ventilation: Large airflow industrial fans are necessary. Traditional SF rear axial fans should not be used due to the high ventilation requirements of gyms and the need to ensure aesthetics and safety.

Summary
When selecting industrial centrifugal fans, multiple factors such as airflow, external pressure, application environment, equipment type, and noise control should be considered. Choosing the appropriate fan equipment based on specific needs can improve work efficiency, reduce energy consumption, and enhance safety.