Group I2 - What should be the sequence of operation for fire alarm systems operated by  using duct smoke detectors only in a zone.

Group I2 - Scenario - Duct detector zones are in place and shut down dampers in an area which stops airflow to other zones that also use duct detectors as notification. Is this considered area detection still? If air is isolated to a zone, and air is needed to activate a duct detector, how can it operate in that zone? Note, There is no below ceiling detectors avalible and other devices are not programmed to isolate system.

Group I2 - Your thoughts on using duct smoke detection devices in place of area smoke detection?