The LWF Blog

Fire Engineering Design and Risk Assessment – Types of Fire Alarm Detector – Part 16

September 14, 2016 11:32 am

In this blog series for architects and those with an interest in Fire Engineering Design and Risk Assessment, we have been looking recently at types of fire alarm detector. Different types of detector are used for particular purposes and environments and are often combined within the same system to provide tailor made fire protection. In today’s blog, we are going to begin by looking at Video Smoke Detection.


Video Smoke Detection (VSD) systems have the same appearance and much of the same equipment as a standard CCTV system, the main difference being that a VSD system has an additional processor which is programmed with the characteristics of smoke. This means that it can monitor live situations through a camera and identify smoke patterns which raises the alarm. The algorithms involved in recognising smoke are sufficiently accurate that they would not, for instance, mistake the steam rising from a boiling kettle for smoke.


VSD can be of its best use when it is placed in large open areas, as smoke patterns cannot be predicted in such an area. It is not reliant on smoke rising to detector level and so can cover a much wider area per camera. Such a high-tech system is most likely to be found where the installation of a traditional smoke detection system might prove unattractive or inappropriate, or where there is a large area with valuable equipment or items.


As it is software-based, it is possible to ‘tweak’ the settings to pick up on a very low threshold (perhaps the smoke from a cigarette) or to up the level so that false alarms are not an issue.


Cabling for such systems must be able to operate in a fire situation and in addition, the area must be lit for the cameras to be able to work, this means that each of those two power requirements must be backed up. Some cameras can work in infrared lighting, but this also would need to be sustained in a fire situation.


In terms of cost and maintenance, the cost of the system can seem prohibitively high, but as such a system can also be used for security, that can make it worth the extra initial outlay. Any person involved in maintaining the building and system must be made aware that it is not simply a CCTV system and any changes must be avoided in order to maintain fire protection in the building.


In our next blog we will look at the siting and spacing 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 for over 25 years to produce innovative and exciting building projects. If you would like further information on how LWF and fire strategies could assist you, please contact Peter Gyere on 020 8668 8663.


Share this post