Loudness [dB] |
Noise |
10 |
quiet whispering |
20 |
rustling leaves, ticking clock |
30 |
whispering |
40 |
quiet conversation |
60 |
offending noise |
80 |
loud shouting |
|
The flow of air at the fans produces a level of noise which may easily be perceived as a disturbance, especially in office environments. The decisive factor is the velocity of the air flow, which causes the noise as it passes over mechanical structures.
The air throughput of the fans is the product of the area of the opening through which the air passes and the velocity of the flow, i.e. a quiet fan runs at a slow speed and produces a lower flow velocity, whereby a greater opening is necessary to achieve a high throughput.
In industrial applications the noise level is generally unimportant. The chosen flow velocities are higher, in order to permit smaller openings. Typical fans (100 - 500 m³/h
air throughput) produce a noise level between 40 and 70 dB. |
