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Selecting the operating point of the fan for the ventilation system
When determining the speed of the fan, we must know the maximum air flow for ventilation
and pressure drop caused by the pipeline. In Diagram 1, find the desired air flow and draw
a vertical line, then draw a horizontal line at the pressure drop that you have calculated
(based on the existing pipeline). Select the fan characteristic curve that lies the closest to
the point where the lines cross.
Example of selecting the aerodynamic characteristic
In diagram 3 at air flow of 150 m³/h draw a vertical line. The pipeline represents 70 Pa of
pressure drop, which is added to the below (red) line**. Total pressure drop is thus 90 Pa.
Draw a horizontal line at the pressure drop of 90 Pa. The point where the lines meet lies on
the curve that corresponds to 60% speed of the fan. This is the standard setting of the fan
that has also been preset by the manufacturer.
Note:
**Line, represents the internal static pressure drop created by the evaporator.
Diagram 3: Example of determining aerodynamic characteristic
