Fire alarm notification appliance

A Wheelock MT-24-LSM electronic fire alarm horn and strobe.

A fire alarm notification appliance is an active fire protection component. A 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. Most of today's appliances produce sound pressure levels between 45 and 120 decibels at ten feet.

Methods 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.

Alerting methods include:

• Sound (audible signals)
  • usually around 3200 Hz due to component constraints
  • 45dB to 120dB A weighted for human hearing
• Light (visible signals)
  • 15 cd to 1000 cd candela output
  • 1 to 2 flashes per second

Coding

Coding refers to the pattern or tones a notification appliance sounds in and is controlled either by the panel or by setting jumpers or dip switches on the notification appliances. 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 signalling methods were used for the same purpose. These are named with respect to their distinctive structure and include, March Time (usually 120 pulses per minute but sometimes at 90 pulses or 20 pulses per minute, depending on the panel), Hi-Lo (repeatedly changing tone), Slow-Whoop (slow rising sweep upwards in tone) among others. Today these methods are confined to applications intended to trigger a response other than evacuation alone. In 1996, the ANSI and the NFPA recommended a standard evacuation pattern to eliminate confusion. The pattern is uniform without regard to the sound used. This pattern for smoke alarms is named the Code-3 temporal pattern (often referred to as T3) and produces an interrupted four count (three half second pulses, followed by a one and one half second pause). CO (carbon monoxide) detectors are specified to use a similar pattern using four pulses of tone (often referred to as T4).

Visual signals

In 1971, Space Age Electronics introduced the first visual notification appliance, the AV32 light plate (which was installed over an existing horn) and V33 remote light. Meanwhile, in 1978, Wheelock introduced the first horn/strobe notification appliances with its 700X series. 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. In the United States, the 1990 Americans with Disabilities Act (ADA) triggered changes in evacuation signaling methods to include the hearing impaired. Audible notification appliances would now have to include strobe lights 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. These retrofit plates would allow for the easy installation of a strobe without replacing the audible signal. The 1996 ADA also required that the strobe to be at least 15 candelas and have a flash rate of at least 60 flashes a minute. Companies such as Wheelock and Simplex discontinued their translucent strobes, and replaced them with new, clear, high-intensity strobes. Today, strobe synchronization is often used to synchronize all strobes in a uniform flash pattern. This is to prevent individuals with photosensitive epilepsy from potentially experiencing seizures due to unsynchronized strobes.

Voice evacuation

Voice evacuation systems, also called VACIE (Voice Alarm Control and Indicating Equipment) in Europe, and Voice Alarm Systems have become popular and in most countries are normally a mandatory requirement in Europe for rail and air transport, high-rises, schools, hospitals, and other large facilities. Voice-evacuation alarms typically are not as loud as horns or bells, and usually sound an alarm tone (typically either Slow Whoop or a Code-3 tone) and a voice message warning that an emergency has been reported and to evacuate the building (often also mentioning not to use elevators). Voice-evacuation systems can also be used by personnel to give specific information and/or instructions over the alarm system. Usually they are either tied into the building's public address system or are outfitted with their own speakers (usually also equipped with strobe lights). In 1973, the Autocall fire alarm company manufactured the first voice-evacuation fire alarm system , and starting in the 1980s, many other companies such as ASL, Application Solutions (Safety and Security) Ltd began producing voice-evacuation fire alarm systems. In the 1990s, voice evacuation started to become the standard for large facilities, and is still growing in popularity. The use, design, operation and installation of Voice evacuation systems is governed in Europe by CENELEC European Committee for Electrotechnical Standardization EN 60849 and in the UK by the British Standard BS 5839-Part 8] soon to be superseded by EN54-1:2008 and ISO 7240-16:2007.

Effectiveness

Initial research into the effectiveness of the various alerting methods is sparse. From 2005 to 2007, research sponsored by the NFPA focused on understanding the cause of a higher number of deaths seen in high risk groups such as the elderly, those with hearing loss, and those who are intoxicated. Research findings suggest that a low frequency (520 Hz) square wave output is significantly more effective in the high risk individuals at awakening. More recent research suggests that strobe lights are not effective at waking sleeping adults with hearing loss and suggest that a different alarm tone is much more effective. Individuals in the hearing loss community are seeking changes to improved awakening methods.

See also

• Fire protection
• Active fire protection
• Passive fire protection
• Fire alarm control panel
• Fire alarm pull station
• Fire drill
• False alarm
• Fire alarm system
• Smoke detector

Alarm manufacturers

• Cooper Wheelock
• Federal Signal
• General Electric (Edwards/EST)
• Gentex
• Honeywell (System Sensor)
• Notifier
• Siemens (formerly Cerberus Pyrotronics/Pyr-A-Larm)
• SimplexGrinnell

Further reading

• National Fire Protection Code, Article 72
• Underwriters Laboratories UL 217: Single and Multiple Station Smoke Alarms
• Underwriters Laboratories UL 1971: Signaling Devices for the Hearing Impaired

External links

• National Fire Protection Agency
• NFPA study press release July 26, 2007: Effectiveness of audible and alternative non-audible alarms
• Photosensitivity and Seizures resource at the Epilepsy Foundation
• Hearing Loss Association of America press release: Current Smoke Alarm Unable To Wake Millions Of Hearing People