The functional parameters of general negative pressure fans mainly include flow, pressure, power, efficiency and speed. The ratio of the fan's effective power to the shaft power is called efficiency. Negative pressure fan is based on the cooling principle of air convection and negative pressure ventilation. From the opposite of the installation site-the door or window naturally inhales fresh air, and the sultry gas is forced out of the room quickly. Any poor ventilation can be improved. Machine, cooling and ventilation effect can reach 90% -97%.

For the size of noise and vibration is also the main fan design index. Flow is also called air volume, which is expressed by the volume of gas flowing through the fan per unit time. Pressure is also called wind pressure, which refers to the increase in the pressure of the gas in the fan, which is divided into static pressure, dynamic pressure and full pressure; The input power is the shaft power.

The development of fans will further improve the aerodynamic efficiency, device efficiency and use efficiency of fans to reduce power consumption; replace large centrifugal fans with axial flow fans with adjustable blades; reduce fan noise; improve smoke and dust exhaust fan impellers and casings Wear resistance; realize variable speed adjustment and automatic adjustment.

The classification of fans can be divided into centrifugal, axial flow, diagonal flow and cross flow types according to the direction of gas flow. Fans are divided into axial flow fans, centrifugal fans, and oblique flow (mixed flow) fans according to the flow direction of the airflow after entering the impeller. Fans are divided into pressure type local fans and explosion-proof electric motors placed outside or in the flow channels, and explosion-proof electric motors are withdrawable local fans placed in explosion-proof sealed chambers.