A duct smoke detector is required in the supply for units that exceed what airflow rate?

The correct answer is based on the guidelines established in the National Fire Alarm and Signaling Code, specifically NFPA 72 and relevant standards concerning fire safety within HVAC systems. A duct smoke detector is an essential device for monitoring airflow in air ducts. It plays a crucial role in identifying smoke within the ductwork of HVAC systems.

Units with an airflow rate exceeding 15,000 cubic feet per minute (cfm) necessitate the installation of duct smoke detectors within the supply air ducts. This requirement is due to the increased risk of smoke transport throughout larger airflow systems, which can result in significant challenges for fire safety if undetected. By installing detectors in these high-capacity ducts, it ensures a prompt response in the event of a fire, enhancing the safety of the occupants and the property.

In contrast, lower airflow rates, such as 2,500 cfm, 5,000 cfm, and 10,000 cfm, do not trigger the same requirement for duct smoke detectors because the risk of smoke being dispersed throughout a building at these levels is comparatively lower. Hence, the standard mandates the installation of detectors only for the higher capacity systems to effectively manage risks related to smoke detection in ducted environments.