There are several types of booster fans, each designed to increase pressure and airflow in a particular part of a ventilation system. In mining and industrial applications, booster fans can be classified by both their aerodynamic design (axial, centrifugal, mixed-flow) and their position in the network (main-circuit, district, level or duct booster fans). Understanding these types helps engineers choose the right booster fan for each ventilation problem.
In underground mining ventilation, the most important types are:
- Main-circuit booster fans installed in major airways to add pressure to part of the primary ventilation circuit. They work in series with the surface main fan, usually on long declines, deep levels or remote branches where resistance is high.
- District or level booster fans located at the entrance to a mining district, panel or level. Their role is to raise pressure locally so that enough air flows through that district’s stopes, headings and return airways.
- Sub-level or sub-branch booster fans used in complex networks where specific branches require additional airflow. These are less common and must be carefully engineered to avoid recirculation and ensure safe, stable airflow patterns.
From an aerodynamic standpoint, mining booster fans are often axial fans (tube-axial or vane-axial) because they can deliver large volumes of air efficiently at the pressures typically required in mine airways. However, in some high-pressure or dusty applications, centrifugal booster fans may be used for their robust construction and higher pressure capability.
In industrial and commercial ventilation, booster fans are commonly referred to as inline duct booster fans. These can be:
- Inline axial booster fans, which fit inside circular ducts and are used to increase airflow to remote rooms or branches in HVAC systems.
- Inline centrifugal booster fans, which provide higher pressure for longer or more restrictive ducts, often in rectangular duct systems.
Some manufacturers also offer mixed-flow booster fans that combine axial and centrifugal characteristics, providing a compact option with moderate pressure capability for tight spaces such as tunnel niches or congested plant rooms.
Regardless of type, all booster fans share the same basic function: to add pressure and airflow at a strategic location within the ventilation system. The choice between mining main-circuit boosters, district boosters, inline axial boosters or centrifugal boosters depends on the required duty, system resistance, safety regulations and available installation space.
