| Axial-flow fans | Propeller-type impeller moves air mainly parallel to the shaft. | General ventilation, equipment cooling, and air movement through low-resistance systems. | Blade profile, diameter, rotational speed, casing, and motor arrangement. | Required airflow, available pressure, noise, installation space, and operating point. |
| Centrifugal fans | Impeller draws air near its center and discharges it radially through a casing. | Ventilation and process systems that require ducted airflow or higher resistance handling. | Impeller geometry, casing design, inlet arrangement, balancing, and drive configuration. | Airflow and pressure requirements, system resistance, efficiency, and service access. |
| Backward-curved centrifugal fans | Centrifugal impeller with blades curved opposite to the direction of rotation. | Air-handling systems, industrial exhaust, and applications requiring efficient airflow. | Blade angle, wheel strength, clearances, balance quality, and operating speed. | Duty point, efficiency across the operating range, motor load, and noise. |
| Forward-curved centrifugal fans | Centrifugal impeller with blades curved in the direction of rotation. | Compact ventilation units and systems designed for relatively high airflow at lower pressure. | Blade spacing, wheel construction, cleanliness of the air stream, and drive protection. | Airflow, static pressure, dust or contaminant levels, and maintenance needs. |
| Mixed-flow fans | Combines features of axial and centrifugal airflow paths. | Ducted ventilation where space is limited and more pressure is needed than a typical axial arrangement provides. | Impeller and guide-vane geometry, casing transitions, vibration, and motor cooling. | Duct resistance, airflow, available space, sound level, and installation orientation. |
| Roof exhaust fans | Roof-mounted units, commonly using axial or centrifugal fan arrangements. | Exhaust ventilation for factories, warehouses, and other large buildings. | Weather-resistant construction, roof curb compatibility, discharge design, and access for maintenance. | Required exhaust rate, roof opening, weather exposure, backdraft control, and noise. |
| Explosion-protected fans | Fan assemblies designed for specified hazardous-area conditions and protection requirements. | Ventilation in locations where flammable gases, vapours, or combustible dust may be present. | Applicable protection certification, motor and electrical components, materials, and installation controls. | Hazard classification, required certification, gas or dust group, temperature class, and local regulations. |
| High-temperature fans | Fans configured with temperature-suitable materials, components, and, where needed, cooling arrangements. | Hot-air exhaust, ovens, kilns, and other elevated-temperature processes. | Temperature limits for the complete assembly, thermal expansion, bearings, seals, and motor location. | Continuous and peak temperature, exposure duration, gas composition, and cooling requirements. |
| Corrosion-resistant fans | Fans made with corrosion-resistant materials or protective surface systems selected for the process. | Exhaust or supply air containing corrosive moisture, fumes, or chemical vapours. | Material compatibility, coating selection, joints, fasteners, drainage, and inspection access. | Chemical composition, concentration, temperature, moisture, and expected service conditions. |
| Dust-handling fans | Fans configured to handle air containing particulate matter; suitable designs depend on dust properties. | Dust extraction, material handling, and industrial process exhaust. | Particle size and abrasiveness, impeller wear, buildup prevention, cleanout access, and dust hazards. | Dust loading, particle characteristics, required conveying or extraction duty, and safety requirements. |