A centrifugal fan is suitable when a specific pressure must be built up for a defined flow rate. Whether this design is appropriate for a given application depends on the required operating point, the system resistance, the fluid being moved, and the spatial conditions. We also take temperature, operating mode, and control range into account during the selection process. This ensures that the fan is designed to meet the actual process requirements and is not selected based solely on available connection dimensions.

We require the specified flow rate and total pressure, as well as information on the fluid being pumped, its temperature, and density. In addition, we determine the operating duration, control range, installation dimensions, connection geometry, noise specifications, and electrical supply. If there are special process or protection requirements, we also need reliable information regarding these. Only with this data can the impeller, housing, drive, and motor be properly designed.

In a direct-drive system, the impeller is mounted directly on the motor shaft journal. Coupling and belt drives provide greater structural separation between the motor and the impeller; a belt drive also allows for a speed reduction ratio. When making a selection, we consider power, speed, temperature, space constraints, maintenance access, and control requirements. The drive concept is therefore determined in conjunction with the fan and process requirements.

The temperature and composition of the pumped medium can affect density, power requirements, and the selection of suitable materials. Depending on the application, the housing, impeller, bearings, seals, motor configuration, and monitoring systems must also be taken into account. We therefore require reliable information about the medium as well as the normal and maximum operating conditions. Based on this information, we determine the project-specific design and the appropriate drive concept.

Re-engineering is advisable when an existing centrifugal fan is no longer available, documentation is missing, or the machine needs to be adapted to changed requirements. We assess the condition and continued serviceability of the housing, foundation, impeller, drive, and interfaces. If the new operating point and the required operational safety can be achieved at a reasonable cost, a modified solution may be appropriate. If the technical discrepancies or risks are too great, a complete rebuild provides a more reliable foundation.

The actual operating point results from the interaction between the fan characteristic curve and the system characteristic curve. If the system resistance changes, the airflow, pressure, and power consumption also change. We therefore take piping, dampers, filters, and other flow resistances into account in our evaluation. This allows us to determine whether the impeller, speed, and drive are suitable for the intended application.