NATURAL VENTILATION SYSTEM The Complete Solution - Gilberts ...

Acoustic InformationExtensive acoustic testing has been carried outin order to establish the noise reduction valueswhich can be reasonably expected from eachcomponent of our Natural Ventilation assembly.Whilst heating/cooling coils give limitedreductions both the weather louvres anddampers do contribute to the overall noisereduction index.A slim 200mm deep acoustic silencer wasalso tested with the other key components toprovide a higher performance acoustic optionif required.The figures provided below illustrate the 1/3octave db reductions in sound pressure levelswhen measured in accordance with BS EN ISO140-3:1995 (sound reduction index) and BS EN20140-10 1992, ISO 140-10:1991 (elementalnormalised level difference).SOUND REDUCTION INDEX FIGURES (dB) forWEATHER LOUVRE + OPEN DAMPER (acoustically lined blades)Unit AreaMEAN FREQUENCY (OCTAVE BANDS) HzRwDn,e,w631 m 230.5 m 2 60.25 m 2 90.125 m 2 12125471013250369125004710131.0k5811142.0k6912154.0k1013161958121714172023AS ABOVE WITH DAMPER CLOSEDUnit AreaMEAN FREQUENCY (OCTAVE BANDS) Hz1 m 2 63121251225012500221.0k272.0k324.0k35Rw26Dn,e,w34AS ABOVE WITH DAMPER HALF OPENUnit AreaMEAN FREQUENCY (OCTAVE BANDS) Hz1 m 20.5 m 20.25 m 20.125 m 2 6336912125481013250379125004810141.0k71114172.0k101417204.0k14181926Rw8121520Dn,e,w16192225SOUND REDUCTION INDEX FIGURES (dB) for WEATHER LOUVRE + OPENDAMPER (acoustically lined blades) +200 WIDE TUBULAR SILENCERUnit AreaMEAN FREQUENCY (OCTAVE BANDS) HzRwDn,e,w631 m 230.5 m 2 60.25 m 2 90.125 m 2 1212547101325069121550091215181.0k141720232.0k202326294.0k242730331417202322252831NoteIf RW figures have beengiven on a reducedopening area they havebeen calculated backto a 1m 2 opening.29