Fans and gear motors for solid fuel heating systems 05-2014 by ebm-papst

More catalogs by ebm-papst | Fans and gear motors for solid fuel heating systems 05-2014 | 112 pages | 2016-08-07

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Page 103 of Fans and gear motors for solid fuel heating systems 05-2014

sure level of a fan is approximately 75 dba the level increase measured from the diagram is 9 db thus the overall sound level of the installation can be expected to be 84 dba 15 10 9 example 8 a3g800 axial fans are on a condenser according to the data sheet the sound pres 5 the noise values specified in the data sheet this is shown in the diagram opposite 0 the noise characteristics of multiple identical fans can be determined in advance based on [db [dba adding 2 noise sources with the same level results in a level increase of approx 3 db increase in sound pressure sound power level combined level of multiple same-level sound sources 1 2 3 4 5 6 7 8 9 10 15 20 25 point and an axial fan a3g710 with 71 dba in a ventilation unit the level difference is 4 db the level increase can now be read in the diagram as approx 1.5 db this means that the overall sound level of the unit can be expected to be 76.5 dba 3 2 1,5 example there is an axial fan a3g800 with a sound pressure level of 75 dba at the operating 1 levels given in the data sheet this is shown in the diagram opposite 0 the acoustic performance of two different fans can be predetermined based on the sound increase in sound pressure sound power level combined level of two different-level sound sources [db [dba number of sources of sound with identical level 0 4 8 12 16 20 sound power level is independent of distance to the sound source in contrast to this sound -10 pressure level decreases the further away the noise source is the adjacent diagram shows the 0 [db [dba distance laws 24 [db [dba difference in level with two sources of sound decrease in level under far sound field conditions far sound field conditions apply whenever the the near field of the fan other correlations apply and the decrease in levels can be considerably smaller the following example only applies to far sound field conditions and can vary strongly depending on the installation effects with an axial fan a3g300 a sound pressure level of 65 dba was measured at a distance of 1 m according to the adjacent diagram at a distance of 20 m we would get a reduction by -20 -26 -30 this complex topic per doubling of distance the level in the far sound field decreases by 6 db in -40 be considered for more information on far sound field please consult the relevant literature on decrease in sound pressure level distance between microphone and fan is big when compared to fan diameter and wavelength to 1 distance 2 5 10 20 50 100 [m 26 db i.e a sound pressure level of 39 dba 103