82 SAFETY & SECURITY
Just because you have specified a multi-sensor, don’t assume it will perform better than all single-sensor detectors
detectors have been configured (or can be configured by the installer) to be less sensitive, which is a compromise that is not always acceptable or ideal.
It should also be noted that not all known causes of false alarms could be tested by the BRE. False alarm tests covering long-term dust build up, condensation, cigarette smoke, synthetic smoke and insect ingress were not possible due to difficulties with developing repeatable tests.
E-cigarettes have proven particularly problematic. They generate water vapour which, in an enclosed space where there are a number of people vaping, can have the same effect as steam i.e. can cause a sensor to go into false alarm. A standard multi- sensor will struggle to identify this.
Sensor combinations
While smoke and heat sensors are the most common combination, there are others available, including some that include carbon monoxide sensors and some that use more than two technologies. One of the less well- known combinations, but highly effective, is a heat sensor and two optical sensors, albeit each using very different sensor technologies. Some multi-sensors feature dual optical
alarm technology plus a heat sensor. The dual optical alarm technology is based on particle light scattering theory, but instead of just using the standard infra-red light found in optical alarms, it also employs blue LED to provide a more accurate measurement of particles within the chamber. Using a complex algorithm to calculate the ratio of these light sources, which operate at different wavelengths, the detector can determine the particle size and thus distinguish between smoke and non-combustion products such as steam, aerosols and dust. As we have seen above, this is where most typical multi- sensors struggle. Using this method, there is no need to lower the devices’ sensitivity to actual combustion products. So, what can we learn from this? multi- sensors can indeed be a good solution, especially in areas prone to false alarms, but only if you buy sensibly. Look for devices from reputable manufacturers that have specific features designed to improve false alarm immunity, rather than units that simply contain two sensors that essentially work separately from each other.
Barry Sargent is product support manager at Nittan
Advanced’s new EvacGo makes meeting the BS 8629 Code of Practice easy
meet the recommendations of BS 8629:2019, relating to buildings containing flats with a storey over 18 metres above ground level. Available to the UK market from
F
November 2nd, EvacGo has been designed to support any evacuation strategy chosen by the fire and rescue service. The panel, developed alongside fire industry leaders, combines EN54-2 and 4 approved MxPro 5 technology with clear, easy-to-use manual controls to ensure firefighters can quickly and effectively identify and operate alert sounders to support the safe evacuation of tall residential buildings. EvacGo provides a simple, at-a-glance overview of a building’s evacuation alert zones, along with LED indication and manual toggle-switch controls for operating evacuation alert devices in each zone. The panels are available in 8, 16, 24 or 32 ‘fire
ire protection solutions manufacturer, Advanced, has launched EvacGo, its evacuation alert system designed to
fighter evacuation alert area’ variants and are expandable from 1 to 4 loops – or even further, when using Advanced’s highly robust, fault-tolerant network. The EvacGo panel is housed inside a
robust, security-rated enclosure meeting the STS 205 class BR2 security rating with patented BS EN 1303-compliant lock. This minimises tampering and restricts access to fire and rescue service personnel only, who
are able to access the controls using a patented key, as stipulated in the BS 8629 code of practice. Ken Bullock, Advanced’s Business Development Manager – Emergency Evacuation Systems, said: “We appreciate that new standards can be confusing, so we’ve carefully designed EvacGo to take away the hard work for building owners, end users and, importantly, frontline fire and rescue services. Our system provides a robust, effective and reliable evacuation management system that can be trusted to work as intended at all times.” Advanced, owned by FTSE 100 company
Halma PLC, protects a wide range of prestigious and high-profile, high-rise buildings across the globe – from London’s Shard to Dubai’s Landmark Group HQ and Miami’s Sands Pointe development.
0345 894 7000
uk.advancedco.com
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ADF FEBRUARY 2021
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