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The Quest for Smoke Detection Perfection

An effort to reduce nuisance alarms and better detect smoldering fires has led to the development of a new type of algorithm-assisted alarm. Learn how the device differs from standard photoelectric and ionization devices and how it might advance life-safety measures.




Technology that increases the speed at which smoke and fire is accuratelyMost smoke detectors work either by optical detection (photoelectric) or by physical process (ionization), while others use both detection methods to increase sensitivity to smoke. Right: inside a basic ionization smoke device. The black, round structure at the right is the ionization chamber. Photography ©istockphoto.com/powerofforever detected, as well as eliminates nuisance alarms, can have profound benefits. According to NFPA, nuisance alarms are the leading cause for home dwellers to intentionally disable their smoke alarms. About two-thirds of fire deaths occur in homes without a functioning smoke alarm.

How to End the Smoke Detection Debate

In 1991, a recommendation was made to the NFPA Steering Committee for Smoke Detection Technology for a tighter test regimen that (if detectors could pass) would eliminate the controversy surrounding photoelectric and ionization technologies. The assessment proposed two changes to the UL 217 large-scale fire tests: shorten the UL smoldering fire test time allowed to less than 40 minutes from the current 75 minutes; and light the paper fire test from the top, not the bottom.

Detector technology at that time could not pass both of these revised tests. The photoelectric devices would not have enough visible smoke in the paper test, and the ionization devices would not have enough time in the smoldering test. The purpose of the recommendations was to set a standard of excellence that manufacturers would have to work diligently to meet. New technology would have to be developed, but at least there would have been a target.

While the recommendations were not adopted at the time they may still come to fruition. They would establish a new category of detectors capable of equaling detection times in flaming fires and substantially improving detection times in smoldering fires. Additionally, these new detectors could be set with lower sensitivities making them less susceptible to nuisance alarms. These devices can be set with lower sensitivities because they do not have to be set to high sensitivities to detect smoldering fires any longer. False alarms will be reduced.

Photoelectric detectors may not survive this test regimen, but there are accounts of multiple flaming fires (residential and commercial) during which the ion detectors went off quickly. Had it not been for the speed of the ion detector activation, the negligible damage would have been much worse.

Furthermore, when these fires were detected there was hardly any visible smoke and what damage there was would have resulted in little to no financial loss. Thus, it is reasonable to conclude that a photo detector would not have alarmed until these fires were much larger and considerably more damage was done.

Once detectors are required to pass these two revised tests, not only would the controversy finally be put to bed but the following benefits would result:

  • Faster fire detection over a broader range of types of fires
  • Fewer nuisance alarms than with current ion detectors because sensitivities can be set lower
  • Lower cost than photoelectric or combo detectors
  • Fewer models stocked by stores
  • Less confusion for fire officials and buyers

Instituting a more stringent test protocol would revitalize fire protection efforts anew with the ultimate goal of saving more lives.

Fred Conforti is former CEO of the Pittway Systems Technology Group (PSTG). He can be contacted at fl.conforti@yahoo.com.

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Article Topics
Fire/Life Safety · Fire/Life Safety 2 · Features · Ionization · Photoelectric Detectors · Smoke Detection · Smoke Detectors · All Topics
Features, Ionization, Photoelectric Detectors, Smoke Detection, Smoke Detectors


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