Fan boxes are available in two types: smoke and exhaust prevention, and ventilation. They come in centrifugal and axial flow designs.

1. The control parameters for the fan housing selection include air volume, total pressure, efficiency, noise, and motor power, etc. Available in centrifugal and axial flow types.

2. The ventilation fan is designed with a fan housing, which is conducive to noise reduction.

When selecting a ventilator, consider the air leakage loss of the piping system, calculation errors, and the negative deviation of the actual airflow and pressure of the ventilator. Generally, a safety factor of 1.05 to 1.1 for airflow and 1.10 to 1.15 for pressure is adopted. However, avoid over-sizing to prevent the ventilator from operating in the low-efficiency zone for extended periods.

4. Note the matching relationship between the resistance characteristics of the pipeline and the fan characteristics. To ensure stable operation of the fan, it should operate near its high-efficiency point. The working point of the fan should be to the right of the peak total pressure point on the performance curve (i.e., on the high-airflow side, generally located at 80% of the total pressure peak).