The 2007 edition of NFPA 72® includes some of the most significant changes made in the National Fire Alarm Code® in many years. This article will present an overview of some of the more important changes that will impact the design of fire alarm systems.
Probably the most significant changes to the Code address the application of mass notification systems (MNSs) and their relationship to fire alarm systems. An MNS, as defined by NFPA 72 is "a system that is used to provide information and instructions to people, in a building, area, or other place." This broad definition can include systems used to initiate evacuation, relocation or to provide information to occupants for such things as fire emergencies; weather emergencies; terrorist events; biological, chemical, or nuclear emergencies; or any combination of these. Annex E, Mass Notification Systems, is new in this edition of NFPA 72 and has been developed to provide nonmandatory guidance for the design and installation of these systems.
An MNS can be installed as a separate system or as a system integrated with a fire alarm system. Several changes have been made in the mandatory chapters of NFPA 72 for correlation and to avoid having conflicting or competing signals with fire alarm systems.
The scope of NFPA 72 has been revised to include "emergency warning equipment," and the term "fire" has been removed in several locations throughout the Code so that specific requirements apply generally – not to just fire alarm systems.
The requirements for combination fire alarm systems have been modified to address MNSs, establish signal priorities, and specifically allow MNS signals to take priority over other signals, including fire alarm signals.
22.214.171.124* In combination systems, fire alarm signals shall be distinctive, clearly recognizable, and, with the exception of mass notification inputs, take precedence over any other signal even when a non-fire alarm signal is initiated first and shall be indicated as follows in descending order of priority unless otherwise permitted by this Code:
Signals associated with life safety
Signals associated with property protection
Trouble signals associated with life and/or property protection
The requirements for notification appliances in Chapter 7 have been modified to address wide area (outdoor) signaling applications to prohibit use of the word "FIRE" or any fire symbol on appliances used for non-fire signaling purposes in and to coordinate "color" requirements for visible signaling appliances.
Other significant changes to the Code include a number of new or updated requirements reflecting either new technology or new and evolving research. Several of these changes involve requirements for automatic fire detection devices.
The requirements for heat detectors have been modified to require the detectors to be marked with their response time index (RTI) and to include this information in related product documentation by July 1, 2008. This information will be of special value to those involved with performance-based detection designs.
The prescriptive requirements for location and spacing of smoke detectors in level joist and beam ceiling applications have been completely revised and now specifically address "waffle or pan-type" ceilings, corridors and small rooms. These changes were based in part on research performed under the auspices of the Fire Protection Research Foundation1 and will provide needed relief for common applications that would have otherwise required the installation of a greater number of detectors for compliance with the requirements of earlier editions of the Code.
126.96.36.199.4.2 For level ceilings the following shall apply:
For ceilings with beam depths of less than 10 percent of the ceiling height (0.1 H), smooth ceiling spacing shall be permitted.
For ceilings with beam depths equal to or greater than 10 percent of the ceiling height (0.1 H) and beam spacing equal to or greater than 40 percent of the ceiling height (0.4 H), spot-type detectors shall be located on the ceiling in each beam pocket.
* For waffle or pan-type ceilings with beams or solid joists no greater than 600 mm (24 in.) deep and no greater than 3.66 m (12 ft.) center-to-center spacing, the following shall be permitted:
(a) Smooth ceiling spacing including those provisions permitted for irregular areas in 188.8.131.52.2, substituting "selected spacing" for "listed spacing" (b) Location of spot-type smoke detectors on ceilings or on the bottom of beams
* For corridors 4.5 m (15 ft.) in width or less having ceiling beams or solid joists perpendicular to the corridor length, the following shall be permitted:
(a) Smooth ceiling spacing including those provisions permitted for irregular areas in 184.108.40.206.2, substituting "selected spacing" for "listed spacing" (b) Location of spot-type smoke detectors on ceilings, sidewalls, or the bottom of beams or solid joists
For rooms of 84 m2 (900 ft2) area or less, only one smoke detector shall be required.
The evolving technology of video image smoke and flame detection has prompted the addition of new requirements to address this technology. This technology may be of particular interest in certain applications where equipment can be used for dual purposes, such as video surveillance as well as fire detection. The new requirements place the primary responsibility for these systems on the manufacturer, listing organization and the system designer. The Code requires these systems to be listed for the purpose of smoke- or flame-detection and designed in accordance with the performance-based design requirements established in the Code.
Revisions have been made to better address the performance requirements for combination, multicriteria, and multisensor detectors. All of these detectors involve the use of more than one sensor, and combination detectors are not new. However, the function(s) performed by detectors that use multiple sensors vary, and the Code now includes requirements to address selection, location and spacing of these detectors depending on the function(s) they perform. Requirements were added to specify how the individual sensors must be tested.
Updated guidance for the installation and location of duct detectors has been included based on work sponsored by the Fire Detection Institute.2 The revised guidance no longer recommends that detectors be located between 6 and 10 duct-equivalent diameters of straight uninterrupted run, and guidance for obtaining a representative sample has been brought up to date.
Significant changes have also been made to reflect new technology or new and evolving research in other areas of the Code.
New requirements have been added to address the use of exit-marking audible notification appliances. These are audible notification appliances that mark building exits and areas of refuge by the sense of hearing for the purpose of evacuation or relocation. The sound of these appliances actually draws the listener to the location of the exit – an advantage where the presence of smoke could cause occupants to become disoriented. These appliances are not intended to replace appliances used for traditional occupant notification.
Fire extinguisher monitoring devices are now available and are intended to replace the routine inspections needed for portable fire extinguishers. Requirements have been added to address the use of these monitoring devices. These devices are located in close proximity to fire extinguishers and transmit a supervisory signal to the fire alarm control unit when conditions adverse to the operation and use of the fire extinguisher are detected. These devices monitor the fire extinguisher in accordance with the requirements of NFPA 10, Standard for Portable Fire Extinguishers.
Two-way radios are being more commonly used by the fire service in lieu of the two-way telephone communications service normally provided in buildings. Two-way in-building radio communications enhancement systems (bidirectional antenna systems) are often needed so that these radio systems will operate reliably throughout the building. New requirements have been added to permit the fire alarm system to monitor these enhancement systems. Testing requirements and guidance are provided.
Visible signaling in large ("big box") warehouse and distribution spaces is often a challenge for fire alarm system designers. New guidance based on research conducted under the auspices of the Fire Protection Research Foundation3 has been provided to help designers with this difficult application.
Although not prompted by new technology or research, a handful of other significant changes have been made that will impact the design of fire alarm systems.
The definitions associated with protected premises (local) fire alarm systems have been revised to include new subcategories of these systems. The terms "building fire alarm system," "dedicated function fire alarm system" and "releasing fire alarm system" have been added. The primary reason for these changes was to recognize that not all buildings are required to have a building fire alarm system, and the need to have a dedicated function fire alarm system, such as one that might be needed to supervise a sprinkler system, does not necessarily invoke requirements for a full building fire alarm system.
Revisions have also been made to clarify or update requirements for annunciation and annunciation zoning; combination systems; alarm and supervisory signal initiation; emergency voice alarm communications systems; two-way telephone communications systems, including a new requirement for circuit survivability; elevator recall; and visible appliance location.
Although not discussed in detail here, it is worth noting that other important changes have also been made in the chapter for Public Fire Alarm Reporting Systems regarding the use of fiber optic communications, and in the chapter for Single- and Multiple-Station Alarms and Household Fire Alarm Systems addressing new coverage requirements for larger dwelling units and allowances for voice messages in smoke alarms, among other changes.
Lee Richardson is with the National Fire Protection Association.
1 O'Connor, D., et al., "Smoke Detector Performance for Level Ceilings with Deep Beams and Deep Beam Pocket Configurations – Research Project," Fire Protection Research Foundation, Quincy, MA, 2006. 2Cholin, J., "Investigation into the Application of Duct Smoke Detectors in Heating, Ventilating and Air Conditioning Systems," Fire Detection Institute, 2003. 3Schifiliti, R., "Direct Visual Signaling as a Means for Occupant Notification in Large Space – Research Project," Fire Protection Research Foundation, Quincy, MA, 2006.
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