A suspended acoustical ceiling in which the board, perforated metal, or tile is provided with small, evenly distributed mechanical perforations through the material; designed to provide a desired flow of air from a pressurized plenum above.
A suspended acoustical ceiling in which the board, perforated metal, or tile is provided with small, evenly distributed mechanical perforations through the material; designed to provide a desired flow of air from a pressurized plenum above.