Fonte (Source): Consulting-Specifying Engineer
Por (By): William E. Koffel, PE, FSFPE, Koffel Associates Inc., Columbia, Md.
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The edition of NFPA 72: National Fire Alarm and Signaling Code required for a project is typically determined by the edition of the standard referenced by the adopted building or fire code. Most jurisdictions are using the 2012 (or earlier) editions of nationally recognized building and fire codes, which reference the 2010 Edition of NFPA 72. Some jurisdictions, such as the state of Maryland, have recently adopted the 2015 edition of the International Building Code, in which the 2013 edition of NFPA 72 is the reference standard.
In addition, design professionals often consider the most recent edition of a reference standard because it typically includes the most recent technology and could be considered in determining the “standard of care.” Newer editions of a reference standard may be used when approved by the code official or authority having jurisdiction (AHJ) using the concepts of alternative methods or equivalencies. The purpose of this article is to provide an overview of NFPA 72-2013 for both wired and wireless fire alarm systems, including identifying some of the significant changes to the 2013 edition.
Documentation (Chapter 7)
Building on the reorganization that occurred with NFPA 72-2010, the 2013 edition contains a new chapter titled “Documentation.” The intent was to provide a central location for all the documentation requirements of the code. From the perspective of the design professional, Section 7.3 addresses the design documentation requirements. In many cases, the section refers the user to documentation requirements found elsewhere in the standard, such as identifying the acoustically distinguishable spaces (ADS) in accordance with 18.4.10 and specifying the rooms and spaces that will have visible notification in accordance with 18.104.22.168. Design documents are also required to include ambient sound pressure levels and audible design sound pressure levels in accordance with 22.214.171.124.3.
Fundamentals (Chapter 10)
Recognizing the confusion that has occurred regarding whether an initiating device should result in an alarm signal, supervisory signal, or trouble signal, the standard has been revised to define conditions that are detected. The conditions are a situation, environmental state, or equipment state of a fire alarm or signaling system. For example, a supervisory condition is defined as “an abnormal condition in connection with the supervision of other systems, processes, or equipment.” The resulting signal from a particular initiating device is “a message indicating a condition, communicated by electrical, visible,audible, wireless, or other means.”
There are times when the signal may be consistent with the condition detected or a signal that results in a higher level of response, such as an alarm signal. For example, while smoke detectors mounted in HVAC ducts are to initiate a supervisory signal, such detectors may also initiate an alarm signal under certain conditions (see 21.7.4). The actions to be performed upon receipt of a signal, referred to as the response, are based on the type of signal received.
Inspection, testing, and maintenance (Chapter 14)
Format-wise, the three tables from previous editions have been consolidated into two tables, one for inspection and one for testing. The methods that previously were in a separate table have now been included in the appropriate table associated with the component to be inspected or tested. However, the more significant change to Chapter 14 involves the deletion of requirements that are not related to the components of a fire alarm system. This change is in recognition of the new standard, NFPA 4: Standard for Integrated Fire Protection and Life Safety System Testing. NFPA 4 addresses the testing requirements for the integrated systems but not the individual fire protection systems.
For example, the fire alarm aspects associated with a smoke control system are tested in accordance with NFPA 72. The smoke control aspects (for example, air movement) of the smoke control system are tested in accordance with NFPA 92: Standard for Smoke Control Systems. However, the integration of the fire alarm system and smoke control system are tested in accordance with NFPA 4. These changes will obviously affect how a design professional develops the acceptance test protocols and commissioning plans for integrated fire protection and life safety systems.
Notification appliances (Chapter 18)
The use of the distinctive evacuation signal (the three-pulse temporal code) has been updated to extend to signals used for relocation and partial evacuation, not just complete evacuation as required by previous editions of NFPA 72. As such, this includes occupancies such as health care (Group I-2) and detention and correctional occupancies (Group I-3). Recognizing the expanded use of textual and graphical visible appliances, some provisions have been relocated from the chapter on emergency communications systems (Chapter 24). In addition, the provisions have been expanded to include fire alarm system applications and refined to include location, mounting, and performance requirements.
Emergency control functions (Chapter 21)
Consistent with the expanding use of occupant evacuation elevators, the requirements for such elevators have been revised to coordinate with changes in ASME A.17.1/B44: Safety Code for Elevators and Escalators. A waterflow switch may initiate elevator recall when sprinklers are installed in elevator pits.The waterflow switch is not permitted to have a time delay, and the piping shall be dedicated to the sprinkler in the elevator pit (see NFPA 72 21.3.3). Various updates also have been made for fire alarm systems interfacing with HVAC systems, for door and shutter release, and for electrically locked doors.