Single and double inlet centrifugal fans
Standard fans are usually manufactured as Single Inlet Single Width designated SISW or alternatively SWSI (especially in Northern America).
Where a large volumetric flowrate is required, a Double Inlet Double Width fan designated DIDW or alternatively DWDI may be used. At a given speed for a given diameter approximately twice the flow can be handled at the same pressure and efficiency.
For a given flowrate and pressure the DIDW fan will be approximately 70% of the size at the same efficiency. It will also run faster, permitting the selection of a cheaper motor.
Posted in Fans Ventilation A Practical Guide