In order to legalize a second dwelling basement apartment a DUCT SMOKE DETECTOR would be used to provide extended security for your property and tenants. Check your local municipality’s fire code to determine whether or not this device is required to safely and properly legalize your basement apartment.
Purpose of Duct Smoke Detection National and local safety standards and codes recognize the ability of air duct systems to transfer smoke, toxic gases, and flame from area to area. Sometimes smoke can be of such quantity as to be a serious hazard to life safety unless blowers are shut down and dampers are actuated. The primary purpose of duct smoke detection is to prevent injury, panic, and property damage by reducing the spread (recirculation) of smoke. Duct smoke detection also can serve to protect the air conditioning system itself from fire and smoke damage, and can be used to assist in equipment protection applications, for example, in the ventilation/ exhaust duct work of mainframe computers and tape drives.
Perhaps more important is the identification of what duct smoke detection is not intended for rather than what it is.
• It is not a substitute for an area smoke detector. • It is not a substitute for early warning detection.
• It is not a replacement for a building’s regular fire detection system.
NFPA 90A, 2012, A.6.4 supports this by stating: “Protection provided by the installation of smoke detectors and other related requirements is intended to prevent the distribution of smoke through the supply air duct system and, preferably, to exhaust a significant quantity of smoke to the outside. Neither function, however, will guarantee either early detection of fire or the detection of smoke concentrations prior to dangerous smoke conditions if smoke movement is other than through the supply air system.”
NFPA 72, 2013 126.96.36.199 and section 907.3.1 of the 2015 edition of the International Fire Code states, “Detectors that are installed in the air duct system shall not be used as a substitute for open air protection.” Area smoke detectors are the preferred means of controlling smoke spread:
• Duct smoke detectors can only detect smoke when smoke laden air is circulating in the ductwork. Fans may not be running at all times, such as during cyclical operation or during temporary power failure.
• Duct smoke detectors sample great volumes of air from large areas of coverage. They cannot be expected to match the detection ability of area detectors.
• Dirt contaminated air filters can restrict air flow causing a reduction in the operating effectiveness of the duct smoke detectors.
Typical Scenarios Duct smoke detection may be useful in preventing injury and property damage in instances such as the following:
A heating, ventilating, or air conditioning (HVAC) fan motor overheats and resulting smoke is sensed by the duct smoke detector installed in the main supply duct. The duct smoke detector is equipped with an auxiliary relay that immediately cuts power to the fan motor before significant amounts of smoke can be distributed to the occupied areas.
Product Documentation / Drawings
D4120 (4-wire photoelectric low-flow duct smoke detector)
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