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Wednesday, September 15, 2010

System Sensor Duct Detector Applications

System Sensor Duct Detector Applications

NFPA 90A2, “Standard for the Installation of Air Conditioning and Ventilating Systems”, specifies that “Smoke detectors listed for use in air distribution systems shall be located as follows:

(1) Downstream of the air filters and ahead of any branch connections in air supply systems having a capacity greater than 2,000 cfm (944L/sec).

(2) At each story prior to the connection to a common return and prior to any recirculation or fresh air inlet connection in air return systems having a capacity greater than 15,000 cfm (7080 L/sec), and serving more than one story.”

Exception Number One:

“Return system smoke detectors are not required when the entire space served by the air distribution system is protected by a system of area smoke detectors.” (NFPA 90A, 2002, 6.4.2.2)

Exception Number Two:

“Fan units whose sole function is to remove air from inside the building to outside the building.” (NFPA 90A, 2002, 6.4.2.3)

Application Documents

There are several important documents that provide guidance concerning the performance, application and installation of System Sensor duct smoke detectors:

• U.L. Standard 268A, Standard for Smoke Detectors for Duct Applications

• NFPA Standard 90A, Installation of Air Conditioning and Ventilating Systems

• NFPA 92A, Standard for Smoke-Control Systems Utilizing Barriers and Pressure Differences Nfpa 92A: Recommended Practice for Smoke-Control Systems (Gl-92a-88)

• NFPA 92B Standard for Smoke Management Systems in Malls, Atria, and Large Spaces NFPA 92B: Standard for Smoke Management Systems in Malls, Atria and Large Spaces (2009)

• NFPA Standard 72, National Fire Alarm Code

• NFPA Standard 101, Life Safety Code

• ASHRAE Handbook and Product Directory, “Fire and Smoke Control”