Ebm-papst centrifugal fans with backward-curved blades are used primarily for intake suction. Since most of the pressure build-up takes place in the impeller, there is generally no need for a scroll housing. The centrifugal fans have very good hydraulic efficiency and a low noise level and are ideally suited for high pressures. The centrifugal fans are used in applications such as central air conditioning units or building ventilation systems.