As can be seen in the image, inside of the graph appear a series of characteristic curves, each associated with a different number of revolutions of the fan. To the point of operation, using other parametric curves shown in the graph, you can associate:
- The sound power emitted at maximum efficiency (Lp, measured in dB)
- The system efficiency (η)
- The input power (in kW)
The fan chosen is optimal if in operating point ensures good performance, so if it is close to the maximum efficiency points, which are typically found in the central areas of the same curves.