The LWF Blog

Fire Safety Engineering for Design – Fire Detection & Alarm Systems – Part 157

November 6, 2023 11:44 am

LWF’s Fire Safety Engineering blog series is written for Architects, building designers and others in the construction industry to highlight and promote discussion on all topics around fire engineering. In part 156, LWF talked about flame detectors and the advantages of carbon monoxide detectors over other types of detector. In part 157, we continue by discussing the disadvantages of gas combustion detectors (for the advantages, see our previous blog) before beginning to look at video smoke detection.

The main disadvantages of carbon monoxide detectors are threefold. Firstly, carbon monoxide does not remain static in the atmosphere but diffuses throughout the atmosphere. Within a building, this can mean that the detector responding to the level of carbon monoxide gas may not be the one closest to the fire and it may not even be on the same floor or zone.

Secondly, a carbon monoxide detector is designed to detect gases rather than smoke or a rise in temperature, therefore it may not respond when there is a fire emitting a lot of smoke which has a good oxygen supply.

Finally, maintenance of carbon monoxide detectors can feel onerous. The sensing element in most CM detectors has a finite life and must be replaced regularly as part of the maintenance regime for the system. It is possible to source long-life alternatives, however, they are very expensive in comparison.

When carbon monoxide detectors are used as a part of a fire detection and alarm system, ideally they should be used alongside smoke and heat detectors rather than instead of them to ensure a robust fire detection provision.

Video Smoke Detection

Are you looking for an effective fire detection system but also a security system? Video smoke detection may be the way forward. A VSD system makes use of conventional closed-circuit television (CCTV). A processing unit is connected to the CCTV which is able to detect smoke on the feed. It monitors the live images for smoke patterns which can be identified at an early stage and the alarm raised.

The video smoke detection systems can even tell the difference between smoke and water vapour. The VSD can monitor a number of cameras at once, meaning that the costs of processing equipment can be kept to a minimum.

In part 158 of LWF’s series on fire engineering, we will continue to talk about video smoke detection, before considering the siting and space of detectors. In the meantime, if you have any questions about this blog, or wish to discuss your own project with one of our fire engineers, please contact us.

Lawrence Webster Forrest has been working with their clients since 1986 to produce innovative and exciting building projects. If you would like further information on how LWF and fire strategies could assist you, please contact the LWF office on 0800 410 1130.

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.

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