A booster fan is used whenever the main ventilation fan alone cannot deliver enough airflow or pressure to a particular part of a system. In industrial plants, tunnels and especially underground mines, friction losses in long ducts and roadways cause pressure drops that reduce air quantity at distant locations. A properly placed booster fan increases the pressure at an intermediate point, allowing more air to reach remote headings, production areas or process equipment.
In underground mining, booster fans are often installed in main or sub-main roadways between the surface main fan and deeper districts. As air travels further underground, resistance increases because of longer paths, more turns, ventilation doors and equipment. The booster fan raises the pressure in the intake or return airway so that the required volumes of fresh air still reach the faces and working places. Booster fans may be axial or centrifugal, depending on the pressure needed, and their operation is carefully coordinated with main fans to avoid instability or unwanted recirculation.
Booster fans are also used in long tunnels and underground transport systems. When a single portal fan cannot maintain the required airflow and smoke control over the full tunnel length, additional fans may be positioned along the route. These booster fans help maintain acceptable air velocities and support emergency ventilation strategies for fire or smoke events, working together with jet fans, dampers and control systems.
In industrial buildings and ducts, smaller duct booster fans are used to overcome pressure drops in especially long or heavily loaded duct sections. For example, a booster fan can maintain flow through a long extraction duct serving remote hoods, or help deliver supply air to a distant room at the end of a distribution network. In these cases, the booster fan must be selected to match the airflow and pressure of the main fan, and the added energy use must be weighed against alternatives such as larger ducts or repositioned equipment.
Because booster fans change the pressure distribution in a ventilation system, their use requires careful engineering and control. In mines, regulators may require detailed studies and monitoring to ensure that booster fans do not create recirculation loops or unsafe airflows. In industrial plants, booster fans must be integrated into the duct layout so that they assist rather than fight the main system. When properly designed and operated, a booster fan is a powerful tool to extend effective ventilation into areas that would otherwise be under-ventilated.
