Duct detectors are usually required on systems with a capacity over which value?

Duct detectors are usually required on systems with a capacity over which value?

• A. 1000 cfm
• B. 1500 cfm
• C. 2000 cfm
• D. 2500 cfm

Answer: (C)

Duct detectors are used to catch smoke in the airflow of the building’s HVAC system, so you can control or isolate the spread of smoke before it reaches other areas. They’re typically required when the air-handling capacity is large enough that smoke could be rapidly distributed through the ducts. The common threshold you’ll see is about two thousand cubic feet per minute. If the system moves air at or above that level, a duct detector is usually mandated to provide early detection and to enable automatic smoke-control actions (like signaling the fire alarm and potentially closing dampers or stopping fans). For smaller systems with lower air movement, detectors in the occupied spaces or on the general fire alarm circuit are generally considered sufficient.

Duct detectors are used to catch smoke in the airflow of the building’s HVAC system, so you can control or isolate the spread of smoke before it reaches other areas. They’re typically required when the air-handling capacity is large enough that smoke could be rapidly distributed through the ducts. The common threshold you’ll see is about two thousand cubic feet per minute. If the system moves air at or above that level, a duct detector is usually mandated to provide early detection and to enable automatic smoke-control actions (like signaling the fire alarm and potentially closing dampers or stopping fans). For smaller systems with lower air movement, detectors in the occupied spaces or on the general fire alarm circuit are generally considered sufficient.