The LWF Blog

Fire Safety for Facilities Management Personnel – Fire Detection & Fire Alarms – Part 196

April 11, 2023 10:49 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 195, LWF looked at the necessary sound pressure levels required in different types of environment. In part 196, we begin to discuss voice alarm systems.

A typical fire alarm system has sounders which clang like bells (although they are usually electronic sounders not actual bells).  An increasing number of fire alarms have an alternative to the usual bell sounders and warning of fire is delivered by a specially designed public address system, known as a voice alarm system.

BS 5839-8:2013 – Fire detection and fire alarm systems for buildings – Code of practice for the design, installation, commissioning and maintenance of voice alarm systems is the standard pertaining to voice alarm systems and gives recommendations for the design, installation, commissioning and maintenance of voice alarm systems that automatically broadcast speech or warning tones in response to signals from their associated fire detection and fire alarm systems.

The standard also covers systems that allow for the manual transmission of live voice messages in addition to automatically generated messages for emergencies.

As it is the eighth part of the standard that deals with the voice alarm system element in particular, it should be noted that the first part – BS 5839-1 – deals with the fire detection and fire alarm systems themselves.

Voice alarm systems are most commonly seen in large places of gathering, such as sports stadiums, assembly buildings such as air and rail terminals, shopping centres and complexes, auditoriums etc. and also in buildings with a phased evacuation system in place.

The use of a voice alarm system means that specific directions can be given to the building occupants. This negates some of the (often significant) delay experienced when standard alarm sounders are used and people are expected to evacuate a building. Research has shown that this delay is significantly reduced in situations where the warning of fire is given by voice messages rather than alarm sounders.

While the emergency evacuation messages are usually standard and pre-recorded, as mentioned above, it is possible to install a system where live messages can be relayed to the occupants of a building which can prove useful in certain environments.

In part 197 of this series, LWF will begin to look at the wiring of a fire alarm system. 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.