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    What’s That Sound?
    Code Changes to Life Safety Audible Notification

    By Mark Conroy

    There are various audible devices that are used by fire alarm systems to notify building occupants. When an alarm condition occurs, these systems may use horns, chimes, or speakers to initiate that building’s appropriate emergency response. Codes and regulations determine the type of device to be used, depending on the building construction, occupancy, and use. While there are many code books that govern the fire protection industry, the one most referenced is NFPA 72, National Fire Alarm and Signaling Code.

    In the 2010 edition of NFPA 72, Chapter 18 requires that after January 1, 2014, three-beat low-frequency (520 Hz) audible alarms be provided in sleeping areas to notify building occupants of a fire alarm condition. A 520 Hz audible alarm tone was decided upon after a 2006 study showed this frequency was most effective at waking a variety of participants. This study, commissioned by NFPA, demonstrated success with the low-frequency tone in some of the more difficult groups to notify and wake, such as: children under 10 years of age, the elderly, individuals with hearing loss, deep sleepers, and persons impaired by alcohol or medications. The most common applications of this 520 Hz tone are hotel rooms, college/university dormitories, apartments, and possibly some assisted-living facilities.

    NFPA 72 (2010) is a referenced standard in Chapter 80 of the 2012 International Fire Code (IFC) and Chapter 35 of the 2012 International Building Code (IBC), both codes providing respective minimumrequirements for new and existing construction. These two referenced chapters point to section 907.2 of the IFC/IBC, which requires a fire alarm system to be installed in new buildings in accordance with NFPA 72 (2010). While indirect, both publications now require low-frequency (520 Hz) alarm notification in sleeping areas of newly constructed buildings. As with all codes, there are exceptions and special applications to be considered against the general rule. Provisions set by the Authority Having Jurisdiction (AHJ) may guard against two different audible tones being heard in an area or apply a retroactive enforcement of code on existing systems. It is important to investigate the local requirements prior to a project in order to maintain compliance efficiently.

    Stepping outside of code-speak, the changes can be summarized as follows: Going forward, the 520 Hz audible tone is replacing the high-pitched 3 KHz tone in sleeping areas (where audible devices are required). For fire alarm notification, the tone will sound in a three-beat temporal pattern. Where carbon monoxide notification is required, the same 520 Hz tone will sound in a four-beat temporal pattern. Notification can be accomplished by providing two devices - one each for fire and carbon monoxide (CO) events or providing one device that can provide both audible tones. When using one audible device to annunciate both events (fire and CO), make sure that the alarm panel equipment has the capability to provide both the three-beat and four-beat temporal audible patterns.

    The fire industry can be challenging when it comes to code changes and code conformance. A change that is updated today may not be mandated in some jurisdictions for two or more years. NFPA updates code every three years, but AHJs may not yet enforce the latest edition. It is important to check yearly with your local AHJs to find out which editions of the codes are being used, and when compliance with the next edition is planned.

    1. “Low Frequency Requirements Sound Confusing, But They’re Necessary.” LifeSafety Magazine. System Sensor, Mar. 2014. Web. 19 Feb. 2015.

    In life safety code, NFPA 72 is parallel with NFPA 720: Standard for the Installation of Carbon Monoxide (CO) Detection and Warning Equipment. NFPA 720 was first published in 1998,updated in 2000, and has proceeded forward with the NFPA standard 3-year update since. The 2012 edition of NFPA 720 expanded on how low-frequency notification tones were applied.It states that where CO detectors are required, a four-beat low-frequency audible tone (one additional beat over the fire alarm notification) is required to warn occupants of the detection ofcarbon monoxide, and sets a deadline of implementation for January 1, 2015. It is important to note, NFPA 720 is an installation and maintenance standard, and the required location(s) of devicesare set forth by IFC/IBC section 908.7.

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