Duct Liner Specification Improvement

Specification of Heating-Ventilation-Air Conditioning (HVAC) system acoustic treatment via duct liner material is driven by sound absorption performance. The ASTM C1071: Standard Specification for Fibrous Glass Duct Lining Insulation (Thermal and Sound Absorbing Material), currently requires the duct liner products to meet a minimum level of sound absorption performance per ASTM C423: Standard Test Method for Sound Absorption and Sound Absorption Coefficients by the Reverberation Room Method1. However, the true measure of duct liner and board material acoustic performance can be measured directly per ASTM E477: Standard Test Method for Laboratory Measurements of Acoustical and Airflow Performance of Duct Liner Materials and Prefabricated Silencers2. This standard covers the laboratory testing of acoustical properties of sound attenuating duct liner materials used in building system ventilation. Certainly, it is less difficult to perform sound absorption testing on these types of materials than test them in situ. The differences between the two measurements has been outlined in a previous paper. In this paper, additional data and analysis will provide support to justify changing the ASTM C1071 standard to better represent how materials perform in the actual duct environment.