Static Fire Dampers are approved for use in duct systems where the Air Conditioning and Heating system blower will be cycled off during the activation a fire alarm (usually turned off by an automatic fire detector)
Blades in Air Stream
Used the airflow interruption from the stack of blades in the fire damper frame is not a main requirement.
High Flow Blades Out of Air Stream
Used in applications where a fire damper with 100% free area is desired.