The key difference between a centrifugal fan and an axial fan is the direction in which air leaves the impeller and the pressure each type can develop. This has a direct impact on where each fan is used in industrial plants and mining ventilation systems.
In an axial fan, air enters and leaves roughly parallel to the shaft. The blades act like a propeller, generating lift in the direction of flow. Axial fans are best at providing high airflow at relatively low to medium pressure. They are compact for the volume they move and are very efficient when installed in straight, low-resistance air paths. For these reasons, axial fans are widely used as main mine fans, tunnel fans, auxiliary fans with flexible ducts, and as large supply or exhaust fans in factories and process plants.
In a centrifugal fan, air enters near the centre of a rotating wheel and is thrown radially outward into a scroll-shaped housing by centrifugal force. Inside the housing, some of the velocity is converted into static pressure. As a result, centrifugal fans can generate higher pressures than axial fans of the same size. They are therefore preferred when air must pass through long duct systems, filters, cyclones, baghouses, heat exchangers or other equipment with significant resistance, such as boiler draft systems and many dust collection applications.
The two types also differ in their ability to handle dust and harsh conditions. While there are axial fans designed for dirty air, centrifugal fans can be built with radial or backward-curved blades that tolerate heavy dust, chips and even abrasive particles better than most axial designs. In mines and mineral processing plants, centrifugal fans are common on dust collectors, mills, kilns and furnaces, where gas temperatures and particulate loading are too demanding for standard axial units.
From an engineering standpoint, axial fans are often chosen when space is limited and the system resistance is modest, such as in straight headings, shafts or large building exhaust systems. Centrifugal fans are chosen when higher pressure, dust handling and complex duct systems dominate the design. Efficiency, noise, maintenance access and explosion protection requirements are also considered when deciding between the two types.
In summary, axial fans move air along the shaft and are ideal for high volume, low to medium pressure ventilation, while centrifugal fans throw air radially and are better suited for higher pressure, dust-laden or complex systems. Both are essential in well-designed mining and industrial ventilation.
