Attenuation of cylindrical silencers in HVAC systems.

In this study, we have tested more than 80 silencers of different sizes (from O 250 to 1250), length, insulating thickness and with or without central pod. The attenuation, measured at several velocities between 0 - 8 m/s, was compared to some literature estimations and has shown strong differences. They induce that literature estimations should be used only in the same conditions they were made and, not too widely, as it is currently done because real knowledge of the influence of parameters is lacking. The influence of construction parameters such as insulation material, thickness and density, has been shown and correlations between attenuation and free area were found on the full range of silencers.