Unsourced material may be challenged and removed. Nfpa 92a pdf free download notification appliance may use audible, visible, or other stimuli to alert the occupants of a fire or other emergency condition requiring action. Audible appliances have been in use longer than any other method of notification. The primary function of the notification appliance is to alert persons at risk.
Several methods are used and documented in industry specifications published by UL. Used in many current notification devices. Used in newer notification devices. The majority of audible notification appliances installed prior to 1996 produced a steady sound for evacuation.
In general, no common standard at that time mandated any particular tone, or pattern for audible fire alarm evacuation signals. While less common than a steady sound, differing signaling methods were used for the same purpose. Today these methods are confined to applications intended to trigger a response other than evacuation alone. The pattern is uniform without regard to the sound used. To ensure that audible public mode signals are clearly heard, unless otherwise permitted by 7. 5 dB above the maximum sound level having a duration of at least 60 seconds, whichever is greater, measured 1.
Older Simplex 4051 fire alarm signal with an incandescent light. The majority of visual signals throughout the 1970s and 1980s were white or red incandescent lights. In the 1980s, most new installations began to include visual signals, and more strobes started to appear. Audible notification appliances would now have to include strobe lights with higher brightness intensity to alert the hearing impaired. This made incandescent lights inadequate for the purposes of the ADA. Many existing installations that did not include visual signals were retrofitted with strobe plates.