lindab | acoustic solutions Rectangular curved silencer BDLD The following table can be used for own manual 1 calculations in accordance with the example on the previous page. Designing table for BDLD 2 With mm Height mm 3 Leg lengh mm Location 4 5 Insertion attenuation 6 63 Hz 125 Hz 250Hz 500Hz 1000Hz 2000Hz 4000Hz 8000Hz Resistance number Self generated noise number inlet Sound power level 7 before silencer Attenuation from table page 80 – 82 8 Sound power level after silencer without self generated noise 9 Pressure drop 10 Area m² Air flow l/s 11 Graph on page 77, use resistance number, area and air Air velocity m/s Pressure drop Pa velocity Correction at disturbance according table on page 78 Factor Pressure drop Pa after correction 12 13 Self generated noise 63 Hz 125 Hz 250Hz 500Hz 1000Hz 2000Hz 4000Hz 8000Hz Graph on page 79, use resistance number 14 and air velocity Correction for gross cross section area Self generated noise 15 Sound power level after the silencer (Logarithmical addition of self generated noise and sound power level after the silencer without self generated noise) 16 17 18 76 We reserve the right to make changes without prior notice 2017-12-11
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