lindab | acoustic solutions Rectangular straight silencer DLD/DLDR The following table can be used for own manual calculations in accordance with the example on the previous page. Designing table for DLD and DLDR With mm Height mm Length mm Location Insertion attenuation Sound power level before silencer Attenuation from table page 42 – 45 Sound power level after silencer without self generated noise 63 Hz 125 Hz 250Hz 500Hz Resis- Self gene- 1000Hz 2000Hz 4000Hz 8000Hz tance num- rated noise ber number inlet Pressure drop Area m² Air flow l/s Graph on page 39, use resistance number, area and air Air velocity m/s Pressure drop Pa velocity Correction at disturbance according table on page 40 Factor Pressure drop Pa after correction Self generated noise 63 Hz 125 Hz 250Hz 500Hz 1000Hz 2000Hz 4000Hz 8000Hz Graph on page 41, use resistance number and air velocity Correction for gross cross section area Self generated noise Sound power level after the silencer (Logarithmical addition of self generated noise and sound power level after the silencer without self generated noise) 38 We reserve the right to make changes without prior notice 2017-12-11
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