The performance of a fan can change due to the air flow on the inlet and outlet side. Thus, the fan under test must be installed with a specified test arrangement. This installation type refers to the arrangement of the airflow upstream and downstream of the fan. In ISO 13349, five different installation types have been defined and respectively designated as measurement categories A, B, C, D, E :
A: Installation with free intake and free blow-out
B: Installation with free intake and pipe-guided blow-out
C: Installation with pipe-guided intake and free blow-out
D: Installation with duct-guided suction and duct-guided discharge
E: Installation with free suction and free discharge without a separating wall
Figure 5.1: Fan Installation Types according to ISO 13349
In the technical document of a fan, in addition to the performance data, the type of installation or measurement category A-E must also be indicated. A fan can have different characteristic curves according to the measurement category. When designing the fan, the characteristic curves corresponding to the actual installation type must be used.