The LWF Blog

Fire Safety for Facilities Management Personnel – Fire Detection & Fire Alarms – Part 184

January 16, 2023 12:13 pm

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 183, LWF discussed the different types of fire alarm classification. In part 184, we begin to look at the components of fire alarm installations.

A fire alarm installation will be comprised of various parts, common to most systems:

• Trigger devices or sensors, may be automatic fire detectors or manual call points or both
• Control and indicating equipment – ie. The control panel with necessary power supply
• Alarm devices – bells, electronic sounders etc.
• Wiring to connect elements where connection is not via radio signals

In addition, the following elements may be incorporated:

• A transmitter to send the signal to an alarm receiving centre off site
• Interfaces with other systems such as aircon or ventilation, gaseous extinguishing installations, plant shutdown facilities, door release units, electronic locks etc.

Manual Call Points

Manual call points are often seen usually small red boxes placed on walls in accessible locations where building occupants can ‘break glass’ in case of fire. They include a frangible element such as glass which can be broken upon operation of the device. The single action required is not reversible and if there is the potential for casual malicious operation, a hinged plastic cover may be included to ensure a person must first lift the cover to operate the manual call point.

BS 5839-1 recommends that manual call points be placed at storey exits and final exits, so that they may be triggered by a person beginning to evacuate the building.

They are commonly placed adjacent to the storey exits to staircases on each floor, but BS 5839-1 would permit them to be sited on staircase landings in buildings other than those with phased evacuation in place.

A person at any point within a building should not be more than 45 metres away from a manual call point, unless the building is likely to contain a significant proportion of mobility-impaired occupants, such as in some residential care homes and in any building where rapid fire development is likely. In these cases the manual call point must be within 25 metres.

Manual call points should also be sited near to specific hazards in a building and additional manual call points may be necessary in buildings using phased evacuation to ensure the correct area(s) are evacuated.

In part 185 of this series, LWF will continue to look at the elements of a fire alarm installation by discussing automatic detectors. 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.