Smoke detectors for use in the home have been around for over 35 years. During that time, fire related deaths in the United States have reduced from approximately 12,000 in 1974 to less than 4,000 in 2009. The single most important reason for this drop in fire deaths has been the introduction of smoke detectors into nearly everyone’s home. Yet seventy percent of all home fire deaths still occur in homes with no smoke detectors or no working detectors. Nearly one in four smoke detectors present in reported fires is not working.
Fires usually are categorized into two groups: fast flaming fires or slow smoldering fires. When smoke detectors were first marketed in the 1970’s the only type available used ionization sensors that detected extremely small fire particles associated with fast flaming fires. The ionization type uses a minute quantity of americium 241 that shoots electrons across a positive and a negatively charged plate in the small chamber within the detector. The alarm sounds when these small fire particles interrupt the flow of electrons. Because this technology needed only a small amount of electricity, ionization detectors could easily use a power source as small as a 9 volt battery.
Later technology introduced photoelectric sensors into commercial grade smoke detectors that were hard-wired for use in offices or factories. Photoelectric sensors shoot a small beam of light across two sensors. When this beam of light is scattered, the alarm sounds. Photoelectric sensors were deemed better suited to react to slow smoldering, smoky fires, such as those that may occur in some mattresses or upholstered furniture. Initially photoelectric sensors needed 110 volt electric power to operate the light source, and were not available for those who used only battery powered smoke detectors.
The most recent developments in residential smoke detectors now incorporate both ionization and photoelectric technology into the same 9 volt battery operated detector. These new detectors respond equally well to both fast flaming and slow smoldering fires. Several manufacturers have begun marketing these models that cost between $ 20 and $25 each, and are available at most retail or hardware stores. Be sure that the manufacturer you choose has the Underwriter’s Laboratory “UL” seal. Manufacturers are also recommending that all smoke detectors should be replaced every 10 years to assure they are operating efficiently. If your smoke detectors are nearing this 10 year mark, or you would like the protection of this newer dual-sensor technology available for your home, you may wish to investigate and change your home alarm system to use these new smoke detectors. For more information contact Wyoming Fire Chief Robert Rielage at 513.842.1357.