An industrial centrifugal blower with different volutes is investigated numerically for its aerodynamic performance and flow characteristics. Towards this, six different volutes are designed from a combination of three cross sectional shapes (parallel, rectangular and circular) and two area ratios (ratio 4.0 and ratio 5.0). A detailed analysis is carried out at design and off-design mass flow rates. Parallel wall volutes not only perform better but also improve stage performance among all cross sectional shapes explored. Parallel and rectangular volutes with ratio 4.0 exhibit higher stage performance, while, circular volute performs better with ratio 5.0. Flow inside the volutes is characterized in terms of circumferential pressure distribution at volute inlet, pressure recovery coefficients and velocity distribution across different cross sections. This detailed flow field investigation revealed the underlying physics behind the loss mechanism inside different volutes. The overall investigations suggest that the parallel wall volute is most compact and efficient one. © 2019 Walter de Gruyter GmbH, Berlin/Boston 2019.