Fans are fluid-flow machines used for the continuous conveyance of gases through equipment and installations. This mode of operation is achieved by transferring mechanical energy to the respective gas by means of a rotating fan wheel. The energy is transferred via the impeller blades arranged in a lattice structure. The drive is regarded as a component of the fan. The energy mechanically supplied to the gas is converted into potential and kinetic energy. For this reason, fans are classified as working machines.
When conveying the volume flow through a system, pressure losses must be overcome which occur in the device or system components. The calculation and design of fans requires extensive knowledge in the field of fluid mechanics as well as mathematics and is reserved for specialists, especially if high efficiencies are to be achieved.