FOCUS
Tailored solutions
trays can be a challenge. A much less invasive solution uses wireless point detectors, which also come with most of the detection and technology options of their wired counterparts. Not only do wireless solutions result in
lower visual and physical impact, but also they are faster and cheaper to install. Thanks to two way communication with the panel, battery replacement and fault reporting can be worked into the ongoing maintenance schedule via the panel service tools, and they are increasingly popular.
Beams and aspirators
Where rapid warning is vital, such as a gallery space or archive store, aspirating detectors offer a highly effective solution. These continually sample the air several times a second, and can be set at various sensitivity levels. Although the associated pipework can be bulky and hard to conceal, they are a widely used option when located in less prominent, hard to access spaces such as cellars, service areas and attics. As point detectors are unsuitable for ceiling
heights over 10.5 metres, due to the way smoke dissipates in taller spaces, beam detectors can be used in larger rooms, such as great halls or chapels. They function on the basis of smoke obscuration of a beam of light. The need for a reflector or detector on the other side of the room can make them sensitive to movement, particularly in timber framed structures, but
32 OCTOBER 2018
www.frmjournal.com
some of the better beams self align, minimising the effects of building movement, and making installation simpler. A further option is video and charged coupled device (CCD) driven flame detectors, a technology that has developed rapidly in recent years. Although flames will often, though not always, be detected after smoke, these are useful devices where quickly visible flame fires are more likely. A final detector option, especially suited to sensitive installations, is linear heat or heat sensing cable, which can be run through any area. Even tiny changes in temperature cause the conducting cables to short, pinpointing the location and alerting the fire system. In London, the recreated Globe Theatre was able to overcome a 400 year old ban on thatched roofing using this system. The cables run through the thatch and connect directly to the fire panels, giving real time indication of any incident.
Prioritised protection
Another key to effective fire safety is to ensure that critical or high risk areas, such as kitchens, boiler rooms or gallery spaces, are specified for a higher level of detection, using single or multiple detector types so that incidents are confirmed as quickly as possible, and action can be taken without any delay. Fires can spread very quickly in historic structures, so measures to allow quick
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