1. Acoustic Of Duct : ( With Rigid Board )
With Fiberglass of specified thickness and density covered with RP Tissue / Perforated Al. coil of specified guage duly supported to the duct by means of suitable GI nut bolts & washers.
2. Acoustic of Duct (With Armasound)
Insulation of duct acoustic with Armasound & stuck by adhesive.