Ventilators are divided into 2 categories:

1- Axial fans

2- Radial fans

Axial fans:

Fans are those that move around an axis and suck air from one point to the opposite. Single-blade axial fans are placed linearly in different models with their own angle and head, which has the ability to move high air volume with low pressure.

Radial fans:

Ventilators are those that suck air from one side  and give it from  90-degree angle of itself. According to their type of structure, these types of fans are divided into 3 categories: forward, flat blade and cardboard. Each of them has its own characteristics.

The main difference between axial and radial fans is that radial fans tolerate more pressure drop than axial fans and in places such as: duct length, elbow, filter and coil and any other factor that gets in the way of air that causes Pressure drop Axial fans have less pressure tolerance, in which case a radial fan is used.