Fire Alarm technology has come a long way since the introduction of the electric Fire Bell in 1860. For over 100 years the fire bell remained the most popular choice in sounding an alarm, except in areas with high-background noise which utilised the electro-mechanical siren.

With the introduction of electronic sounders in the late 70’s, the popularity of the fire bell began to decline. The electronic sounders were able to produce a range of sound outputs and consume much less power than their older, less flexible counterpart.

Continued progress and development of electronic sounders has meant that the number of products available on the market today is overwhelming. Wide voltage ranges cover almost any conceivable power supply and can be used in general purpose fire alarm applications to large industrial environments. Sounders used in these industrial applications require higher sound outputs of between 110dB (A) and 120dB (A) and a rugged construction to deal with harsh locations. Fire alarms are more likely to have a higher Ingress Protection rating, such as IP67, for protection against dust and water.

Visual Indicators

A great deal of time and effort has been spent in trying to find more effective ways of alerting and protecting the public from potential fire hazards. The enforcement of the Disability and Discrimination Act has emphasised the importance of visual indicators in addition to the audible alert in the workplace. As a result electronic sounders evolved with the integration of Xenon beacons at the same point.

High current consumption has been an issue long associated with beacon use, the xenon beacon draws excessive current that results in large current surges after each flash. When many units are working together, the cumulative effect can cause overloads in power supplies and cause disruptions to other parts of the system.

It has been a key objective in research and development to find an alternative way to accommodate visual signalling. In security and fire installations, low current consumption, reliability and synchronised beacon flashing is paramount. Now beacons are available using light emitting diodes as an alternative to the high consumption xenon. LED beacons can produce light outputs similar to that of their xenon equivalents for currents around 3mA. This allows the user to integrate these units with sounders, lowering installation costs and finally making loop-powered sounder beacons a real option.

The Voice Sounder

Although electronic sounders are able to effectively address most problems in the event of a fire, the alarm can still create confusion due to the absence of a common warning signal and lack of communicated information. Ambiguity leads to a delayed action and longer response time. The need for a clear unambiguous voice message to accompany a warning tone and combat confusion or complacency during an active alarm led to the development of the voice sounder.

In general, people tend to presume that when an alarm sounds, it is a false alarm. As a result, many warning signals are ignored. Many offices and work buildings have put in place evacuation procedures that employees must follow when a fire alarm sounds; training, practice and continual alarm testing leads to familiarity and a more effective and efficient response time. But in areas where there is a high volume of visitors, training is not possible and the public must rely on clear information and instructions from a reliable source.

Behavioural responses to fire alarms tend to show that people react in accordance to their peers. People observe what others are doing and, if no one else appears to be responding to the alarm, are reluctant to take action themselves. Often visitors wait for confirmation or instructions from an authority figure of member of staff before responding, which may lose valuable time; unfamiliar surroundings can increase stress and confusion when a warning signal sounds.

The introduction of the voice sounder provides a clear unambiguous warning message in the event of an emergency. Voice messages have proven to substantially improve evacuation response time to fire alarm or bomb alert situations; the voice alarm being the next ‘big thing’ in warning device technology. They have the added benefit of being able to promptly evacuate untrained personnel or visitors via clear and concise instructions. Klaxon Signals has expanded its Sonos and Nexus Range of fire alarms to include new voice enhanced variants - where normal sounder signals are combined with a clear, synchronised voice message to help reduce confusion and distress during an active alarm.

Sonos Voice

The Voice Enhanced Sonos is an entry level device designed to broadcast a single evacuation message in small to medium fire alarm installations. This message is preceded by a selectable fire alarm tone for clear, effective warning. Multi message variants are available for larger installations where both, ‘Alert’ and ‘Evacuate’ messages are required for staged evacuation. Up to four messages can be transmitted over two wires via an interface unit which monitors the sounder circuit outputs from the fire alarm panel. A test facility is available through a key switch mounted on the interface unit which emits an ‘All Clear’ message when the key switch is returned to its original position.

Both the single message and multi message Sonos units benefit from all the features of the existing range. Installation is quick and easy as heads are simply locked onto the base with a “twist and click” action, allowing fitting or removal at any time because the base is the only component that needs to be wired. Less cabling is required, resulting in reduced commissioning time and costs.

Nexus Voice

Single and multi message options are integrated into one unit with the Nexus voice sounder. Units can be configured as either single message devices for simple applications or as multi message 2-wire devices with an interface unit for retrofitting into existing fire alarm systems.

Gas extinguishant alarm

A pre-programmed Nexus interface directly linked to extinguishant control panels enable Nexus Voice sounders to function as a gas extinguishant alarms in gas systems.

Voice enhanced Nexus has been designed specifically to meet the requirements of gas extinguishant systems by supplying three stages of alarm, each with a separate and distinct warning message and tone. The integrated LED beacons can be configured to operate with either or all of the alarm stages. These devices come complete with an interface unit which monitors the outputs from the extinguishant panel and then consequently sends out the appropriate tone and message.

All Nexus voice sounders have a USB interface that allows special messages in WAV format to be downloaded onto the sounder from any PC, providing users with the flexibility of adding/removing messages in-house.

Both voice enhanced variants have a low current consumption and come with a choice of 32 (Sonos) and 64 (Nexus) tones including 3 British Standard tones and the Apollo evacuate and alert tones. Sonos units are available as sounders or sounder-beacons in a variety of colours, with shallow or deep base options for indoor and out. All Nexus units are rated to IP66.\ The added capability of voice to existing electronic sounders gives users the option of being able to select an extremely effective warning device for notification purposes. The fact that these units can be easily retrofitted to existing fire alarm systems makes them an even more attractive choice for specifiers.

Voice sounders are effective at reducing response time to an alarm signal by providing essential information about the type of alarm and the action required by those in the area. Having an understandable message in addition to a warning signal prevents confusion and provides the impetus for people to take action rather than waiting for confirmation.

Klaxon Signals Limited manufacture and supply the world’s largest range of sound and vision signalling equipment for fire and life safety, industrial and security applications. Part of Halma p.l.c., Klaxon offers an extensive range of fire alarm sirens, electronic sounders, buzzers, beacons and bells, in addition to innovative evacuation technology and software.