There are several different types of vent fans, each designed for specific airflow and pressure needs in buildings, factories, tunnels and underground mines. At the most basic level, vent fans are divided by how they move air and how they are used in a ventilation system. Understanding the main types helps you choose the right fan for exhaust, supply, booster or local ventilation duties.
The two most common categories are axial vent fans and centrifugal vent fans. Axial fans move air parallel to the shaft, like a propeller. They are typically used for high-volume, low to medium pressure applications such as wall-mounted exhaust fans, tunnel fans, mine main fans and large industrial hall ventilators. Axial fans are often compact and efficient where airflow is high and system resistance is moderate.
Centrifugal vent fans, sometimes called radial fans, move air radially outward from the impeller into a scroll casing. They are better suited to higher pressure systems, where air must be pushed through long ducts, filters, heat exchangers or scrubbers. In industrial plants, centrifugal fans are common in dust collection, fume extraction, process exhaust and boiler draft systems. Their ability to handle higher static pressure makes them ideal when the ventilation system includes significant resistance.
A third group is mixed flow vent fans, which combine features of axial and centrifugal designs. Air enters the fan axially but leaves at an angle, and the fan develops higher pressure than a pure axial fan with similar size. Mixed flow fans are used where space is limited but higher pressure is needed than standard axial fans can provide, such as in some building shafts, tunnels and plant rooms.
Vent fans are also classified by their role in the ventilation system. Exhaust fans are installed to remove hot, humid or contaminated air from spaces. Supply fans push fresh air into buildings, ducts or mine intakes. Booster fans increase pressure and airflow within long duct runs or ventilation circuits, which is common in tunnels and mines. Local ventilation fans, including portable fans and small ducted units, provide spot ventilation for specific work areas or temporary tasks.
In addition, vent fans can be differentiated by mounting and construction. There are wall-mounted fans, roof fans, in-line duct fans, tube axial fans, portable blowers and explosion-proof or flameproof designs for hazardous areas. Each combination of fan type, mounting and safety rating addresses a particular set of conditions, such as corrosive environments, flammable gases or restricted spaces.
In summary, the main types of vent fans are axial, centrifugal and mixed flow designs, configured as exhaust, supply, booster or local ventilation units. Choosing the right type depends on required airflow, pressure, duct layout, environment and safety requirements in your building, industrial plant or mine.
