Squirrel cage fans are fans with a blade arrangement that makes them resemble a large hamster exercise wheel. They are also known as centrifugal fans or squirrel cage blowers.
Squirrel cage fans generally consist of a fan housing, inlet and outlet ducts, an impeller and a drive motor. The motor spins the impeller, drawing air or gas into the fan housing through the inlet duct, increasing its pressure and expelling it through the outlet duct. The increased pressure enables air or gas streams to move against resistance generated by ducts, dampers or other ventilation or gas flow components. They are commonly used in central heating and cooling systems, as well as in gas transportation, industrial processes and air pollution control systems.