FOCUS
Better protection James Hall explores the potential issues
associated with ionisation smoke alarms and the latest technologies being developed to provide the greatest levels of protection
next few years due to concerns over its use of radioactive materials and sensitivity issues, ionisation sensing technology continues to be less popular with safety manufacturers and specifi ers. Yet for many years, ionisation sensing
C
technology was a popular choice for specifi ers and installers. Its low price point, combined with its outstanding ability to detect fast flaming fires, saw it being installed in all types of properties across the country. In recent years, the popularity of ionisation sensing technology has begun to wane, primarily for two reasons. Firstly, it contains a small amount of radioactive material (Americium 241) within the alarm which gives off low levels of radiation in the form of alpha particles. This presents environmental issues in respect of safe disposal, as a result of the radioactive materials present. The emitted radiation
44 JUNE 2018
www.frmjournal.com
URRENTLY ILLEGAL in a number of European countries and set to become illegal in the UK within the
ionises air in the detecting chamber. When smoke enters the detecting chamber, some of these ionised air molecules react with the smoke and cause a change in electrical behaviour which the alarm electronics can detect and trigger the alarm to sound. This makes the alarm sensitive to small
particles of smoke produced by fast fl aming fires, such as those produced by paper or wood, successfully providing early detection of fi re. However, the problem is that this also causes the alarm to be extremely sensitive to some spurious sources such as cooking fumes and dust, and this can lead to false alarms being created. The technology, therefore is unsuitable for installation in circulation areas, for instance in hallways or close to kitchens, where cooking fumes are frequently present. Such nuisance alarms can often
result in residents removing or damaging alarms, meaning that they are no longer protected. Specifiers and installers should therefore consider other technologies that will not provoke the tenant or homeowner
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