|Advances in Fire Alarm Technology|
Issue 2: Advances in Fire Alarm Technology
By Ralph Transue, P.E.
With thanks to several members of Technical Committees of the National Fire Alarm Code for their contributions
Fire alarm systems, and the technology that supports them, have
broadened substantially from the earliest systems that were manually
activated notification systems. To cover the range of the latest
developments, it is best to consider the two primary functions of
today's fire alarm systems: detection and notification.
Video Smoke Detection
Unlike "combination detectors" of past decades, which were part of a
horsepower race for faster detection, the new developments use the
combination of technologies to provide more reliable fire detection –
less prone to unwanted alarms yet no less effective to detect real
fires. Sources of aerosols that may have caused nondiscriminating smoke
detectors to alarm, such as steam, are not falsely identified as fire
because one or more components of the fire profile are missing.
These developments are establishing a new standard of performance for stability in automatic fire detection systems.
Joists, Beams, and Confined-Dimension Spaces
Research sponsored by the Fire Protection Research Foundation2 has shown that a companion to the reservoir effect is the effect to increase the optical density, temperature rise, and gas velocities as a beam pocket fills and the smoke collected spills into adjacent pockets. For small beam pockets, "waffle" pan-type ceilings, and corridors with ceiling beams, these results have justified proposed changes to NFPA 72 that will permit smoke detector locations on the ceiling or bottoms of the beams using the same spacing as for smooth ceilings, where the solid joist or beams are less than 600 mm deep and spaced no more than 3.66 m center to center.
Quantifying Detector Response for Modeling
Fire Service Interface
Conceptually, the technology employed will permit touch-screen
inquiries to inform a fire commander of conditions at selected locations
in the building. Digital network technology would permit the interface
to be located at several points within a building or complex or at a
The information available is intended to enable the fire service response to be smarter and safer.
Visible Notification Appliance Applications
The majority of the hearing-impaired community has been well served by
several iterations of improvements in the standards and products used to
notify people of a fire threat using visible notification appliances –
strobe lights. Practices are in common use related to awakening sleeping
people and to alerting people who are awake.
Research presented by Dorothy Bruck at the 10th Fire Suppression & Detection Research Application Symposium has shown that some minority hearing-impaired populations may not yet benefit from the practices which serve the majority. These populations include the very young, very old, and even the majority when in certain environments such as large, high-ceiling spaces – for example, discount retail stores. Real-world testing has commenced to understand the related characteristics of the very young and very old, which may be addressed by notification technologies. The NFPA 72 Technical Committee on Notification Appliances is addressing the large-enclosure application.
New Horizons in Notification
Amendments to NFPA 72 proposed for the 2006 edition will
permit fire alarm systems to be a portion of a mass notification system
and will permit a mass notification message to override a fire alarm
The technologies to be applied will include digital network interfaces, which will require greater contact with equipment that is not a part of the listed fire alarm system. This challenge, to meet society's larger need for broader information, will include the necessity to permit system interconnections that have not been permitted under traditional fire alarm system codes and standards.
Exit-Marking Directional Sounders
Changes Affecting Alarm Transmission
For supervising station and protected premises systems, continued
developments in the use of nonfire data networks and Internet-friendly
technologies must be pursued while continuing to assure society that the
level of integrity expected of code-conforming protective signaling
systems is maintained.
Ralph Transue is with Rolf Jensen & Associates, Inc.
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