1. According to the cooling principle of the negative pressure fan, the negative pressure fan uses the gas pressure effect in the air to promote the heat convection effect of the gas. The warm air in the factory is dismantled to achieve the cooling effect. All the problems of poor natural ventilation can be dealt with through this plan, and the effect of cooling ventilation can reach more than 90%.

3. According to the material of the negative pressure fan made, it can be divided into the following four categories: glass steel plate negative pressure fan, stainless steel plate negative pressure fan, shell negative pressure fan, and galvanized steel plate negative pressure fan.

4. According to the bearing of the cyclone formed by the negative pressure fan, it can be divided into four categories:

Loose flow negative pressure fans, oblique and mixed flow negative pressure fans, axial flow fans negative pressure fans, centrifugal negative pressure fans.

At present, negative pressure fans in the market can be moderately divided according to the above types. The cooling effect of different types of negative pressure fans is also different. Generally, negative pressure fans are purchased in factories according to the living environment of the factories, the geographical location of the factories, the situation of the factories and the size of the factories.