The LWF Blog

Fire Safety for Facilities Management Personnel – Voice Alarm Systems – Part 210

July 18, 2023 11:08 am

Lawrence Webster Forrest (LWF) is a specialist fire engineering and fire risk management consultancy whose aim is to give information on best practice in fire safety for facilities management personnel through this blog series. In part 209, LWF discussed the checks that should be performed on fire alarm systems. In part 210, we turn our attention to voice alarm systems.

In recent years, voice alarm systems have gained in popularity. A voice alarm system differs from a standard fire alarm system in that the warning sound is a voice which gives instruction, rather than a siren or bell tone.

Although such systems might seem a modern innovation, they have actually been in use in some form or another since the 1960s. The use of a public address system to give warning of fire and instigate evacuation was commonplace and some systems sounded the alarm bell and then further information was given ‘over the tannoy’ by a member of staff.

Changes to fire alarm system technology in the last 20-30 years means that fire detection systems may be integrated with a public address system. In other words, it is possible for the fire alarm to detect the fire and the public address system to automatically give warning of the fire and tell occupants to evacuate the building via a pre-recorded message.

Therefore, the term ‘voice alarm system’ now refers to a sound distribution system providing means for automatically broadcasting speech messages and/or warning signals. They are certainly able to satisfy current standards for fire alarm systems and potentially exceed them.

It is unlikely to be possible to convert an existing sound system into a voice alarm system, the installation would have to be complete.

The increase in take up of voice alarm systems is largely due to two developments since the 1980s. The first is the increasing use of phased evacuation in tall office buildings. The use of phased evacuation in such buildings means that when a fire alarm sounds, it avoids the total evacuation of the building in its entirety. A large number of people may be contained in such buildings and a full evacuation would require that there was a sufficient number of staircases or that the staircases provided were of suitable width to accommodate. Phased evacuation typically allows the design to be tailored to cater for two floors of personnel at a time.

With phased evacuation, generally the floor of fire origin and the floor above are evacuated, followed by other floors in twos as required. On other floors, an alert signal is given to ensure people are aware there may be a need to evacuate at a later stage and to reassure them there is no need to do so until asked. The reassurance is essential in a building with planned phased evacuation. Any element of panic might spread and if all occupants decided to evacuate simultaneously, the reduced number of staircases might lead to overcrowding and potential danger for all involved.

In part 211 of this series, LWF will look at the second factor in the prevalence of voice alarm systems. In the meantime, if you have any queries about your own facilities or wish to discuss this blog series, please contact LWF on freephone 0800 410 1130.

 

Lawrence Webster Forrest is a fire engineering consultancy based in Surrey with over 35 years’ experience, which provides a wide range of consultancy services to professionals involved in the design, development and construction and operation of buildings.

 

While care has been taken to ensure that information contained in LWF’s publications is true and correct at the time of publication, changes in circumstances after the time of publication may impact on the accuracy of this information.