In the event of an emergency, audible and visual warning signals are the critical final link in
an automatic detection or monitoring system to warn the occupants of protected premises of
the need to take action. In the majority of commercial and industrial premises, the
building’s fire system is the most likely initiator of a warning about a potential threat to the
occupants, however in today’s ever increasingly safe world, security alerts are becoming
more common for other types of dangers as well.
Indeed, buildings and infrastructures are becoming more complex and their safety
increasingly hard to manage. In public buildings, for example the majority of users will be
unfamiliar with the layout of the building. In commercial premises, streams of customers,
constantly changing numbers of employees, outside contractors and suppliers – different
people move through buildings every day. Not everyone will be familiar with the building or
the significance of specific emergency signals let alone escape routes. If a serious incident
occurs there is a high risk that people will not be able to safely escape the danger zone.
There is often a considerable delay, primarily caused by uncertainty and the fear of looking
foolish, before people respond to a genuine warning signal. Voice alarms can supplement
audible and visual warning signals with clear and informative warning messages in the
event of an emergency.
People tend to be more responsive to voice alarms than to audible signal only such as bells
or electronic sounders; an intelligible voice command can help people react in a timely and
orderly manner compared to bells sounding an alarm tone. Following fire detection, for
instance, automated messages control the flow of people in stair wells and corridors,
allowing an orderly evacuation without panic. Installing a voice alarm speeds evacuation
and avoids the “false alarm” mentality, reducing the risk of death from fire. Voice messages
inform occupants exactly what to do in an emergency; people respond more quickly and are
more likely to take the correct action during an evacuation if voice messages reinforce tone
sounders. Despite the evidence reporting the greatly increased response times and
improved evacuation, installations of voice alarms are still relatively low in number,
although increasing rapidly. For general applications in larger projects such as arenas,
shopping malls and high rise buildings voice alarm (VA) systems are growing steadily
however, in smaller buildings, they are still fairly uncommon.
In onshore and offshore hazardous area environments, audible and visual warnings can be
triggered by a number of different safety systems: fire detection, gas alarm, process control
alarm and many others. With a number of different alarm sources generating different
tones, even personnel who are regularly trained in emergency procedures can be subject to
many potentially confusing warning messages. For example, on an offshore oil rig, everyone
present is very well aware of, and is trained to react to, the three main PFEER (Prevention
of Fire and Explosion, Emergency Response) audible warnings: evacuate facility, toxic gas
or fire. In normal conditions other warning signals will frequently sound and background
noise is high. In onshore high risk facilities such as petro-chemical plants, there will be a
significant number of office-based personnel who will not necessarily have received the
same high degree of training as those whose work gives them direct involvement with the
plant areas themselves. In industrial facilities, the combination of immediate danger,
visibility reduction for the presence of smoke or other gases and possible reduced
illumination from emergency lighting systems can lead to fear and uncertainty in even
highly-trained personnel.
Appello voice annunciators play a critical part in the Philippines’ tsunami warning
systems. Image courtesy of E2S Warning Signals.
Irrespective of the type of facility or building where automatic detection systems are
installed, the reinforcement of the audible and visual alarms with voice messages can help
the occupants to respond to the emergency and remove uncertainty as to what they should
do. For example, if phased evacuation from a building or area during an emergency such as
a fire is required, a “standby” warning in areas not directly affected can be augmented with
a voice message such as “This is a fire alert. Await further instructions.” Close to the
location of the fire, the evacuate tone could be followed by the voice message “Please
remain calm and evacuate the building immediately.”
Clearly, the technical and performance requirements of the warning devices and the nature
of the warning signals will vary. In fire systems, some countries, such as Germany, France,
Holland and Australia have a defined evacuate tone; many other countries do not.
Whatever the application, the key consideration for the system designer is how to produce
clear and effective audible warnings throughout the protected areas in the event of an
emergency; voice alarms can help considerably. Broadly, there are two approaches: for
public and commercial premises, a separate VA system can be linked to an automatic
detection system that overrides the system’s normal use as a feature-rich public address
(PA) system, broadcasting background music and general messages. For industrial facilities,
it is more appropriate to use voice messaging sounders, either as stand-alone units or
combined with a beacon, as an integral part of the detection system. Both approaches
normally use pre-recorded messages stored in the sounders to broadcast the warning.
E2S Warning Signals, the world’s leading independent manufacturer of warning signals for
use in industrial, marine and hazardous area environments designs and produces a series of
intelligent voice annunciators ideally suited for VA systems. The Appello X range of user
recordable voice annunciators is available as stand-alone sounders or as combined units
with a LED or Xenon tube beacon in 10 different designs. Appello X is the company’s latest
generation of voice annunciators and can store up to 2 minutes of user-recordable content
in four 30-second segments. These devices can record, store and play back with
unsurpassed clarity user-defined voice messages, music or sounds stored directly to nonvolatile memory. All units feature low current consumption and CD quality audio
reproduction.
Appello X is available in either a UL94-V0 flame retardant ABS moulded enclosure or a
marine grade aluminium housing, both environmentally sealed to IP66. All versions have
four stages with 45 UKOOA/PFEER compliant alarm tones and the recorded content can be
reproduced repeatedly, alternating with or without one of the built-in alarm tones. Both
types are available as stand-alone sounders or as combined AV units with either a 5 Joule
Xenon beacon or an array of 24 high output LEDs. Depending on the model, the content
output varies from 101 to 111 dB(A) @ 1 m and the tones from 102 to 126 dB(A) @ 1 m. The
recorded output and the tones have independent volume controls, enabling the output levels
to be characterised to the location to ensure audibility without ‘drenching’ the area with too
high a SPL.
User generated content can be easily recorded using the built-in microphone or line-in audio
input. Once the recording process on a single unit is finalised, it can be used as a master
unit to program all the other units in a multiple unit installation, guaranteeing
synchronisation during playback. Alternatively, factory recording of user content is available
if required. The available standard tones are listed below, but non-standard tones for
specific application can form part of the user-recorded content if necessary.
The research evidence supports the use of voice annunciators in conjunction with traditional
tone warnings to improve the effectiveness of warning signals. The Appello X has been
successfully employed for a Tsunami Early Warning System in the Philippines and you can
find more information about this success story on www.e2s.com. The Appello range is
available in a variety of enclosure types and sizes and provides an easy to use combination
of industry standard tones and user recordable messages, with integral beacons available as
a standard option.
For more information, go to www.e2s.com
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