1. The control parameters for selecting duct ventilation fans include air volume, total pressure, efficiency, noise level, and motor power.
2. Select ventilation fans for different applications based on the physical and chemical properties of the gas being transported. For example, general-purpose fans should be selected for transporting clean air; explosion-proof fans should be selected for transporting flammable or explosive gases; and corrosion-resistant fans should be selected for transporting corrosive gases.
3. When selecting a ventilation fan, leakage losses in the pipeline system, calculation errors, and negative deviations in the actual air volume and pressure of the fan should be considered. Generally, a safety factor of 1.05–1.1 for air volume and 1.10–1.15 for pressure is used. However, excessively large safety factors should be avoided to prevent the fan from operating in a low-efficiency zone for extended periods.
4. Pay attention to the matching relationship between the pipeline resistance characteristics and the fan characteristics. To ensure stable operation, the fan should operate near its highest efficiency point. The operating point of the fan should be located to the right of the peak total pressure point on the performance curve (i.e., the high air volume side, and generally at 80% of the peak total pressure).
5. For ventilation systems requiring noise reduction, high-efficiency fans with low impeller circumferential speeds should be selected first, and they should be operated near their peak efficiency. Appropriate noise reduction and vibration damping measures should also be taken based on the propagation patterns of noise and vibration generated by the ventilation system.
6. Duct fans, by altering the blade shape, create a combination of axial and centrifugal forces upon airflow entering the fan, thus their performance falls between that of axial and centrifugal fans.
7. Duct fans can provide medium air pressure and medium air volume, making them suitable for ventilation systems in high-rise residential buildings.
