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TRG-TRC013-EN 15
period one
Fan Performance
notes
A surge line is established during the fan test procedure to indicate the area on
a fan performance curve where surge occurs. As long as the fan’s operating
point falls to the right of this line, the fan will operate in a stable manner. If the
fan is operated at a point that falls to the left of this line, the fan will surge.
Finally, to serve as a guide for selection, curves are established to indicate the
percentage of wide-open airflow being delivered by the fan at various operating
points.
This completes the typical fan performance curve. It shows the relationship
between pressure and airflow, and can be used to graphically represent the
fan’s interaction with the system.
airflow
airflow
static pressure
static pressure
surge
line
surge
surge
line
line
Fan Surge Line
Figure 22
airflow
airflow
static pressure
static pressure
50%
50%
60%
60%
70%
70%
80%
80%
90%
90%
% wide-open
airflow
% wide-open
% wide-open
airflow
airflow
100%
100%
Percent of Wide-Open Airflow
surge
line
surge
surge
line
line
Figure 23