Photoelectric vs. Ionization Smoke Alarms


Collection of Residential Smoke Alarm Research

This report was scanned from hardcopy. 

Gentex - Photoelectric and Ionization Smoke Alarms/Detectors:  Sleeping Room Applications


Gentex Manufactures Only Photoelectric Smoke Alarms

NFPA Study Indicates That About 1/3 of Smoke Alarms Installed in Homes Are Inoperative

Woodlands, TX Study Shows Over 91% of Nuisance Activation Are Ionization Alarms

Hilton Hotel Fire, Houston, TX 1982:  First Detector to Activate Was Photoelectric Located in Elevator Lobby 4 Floors Away When Guest Had Door Propped Open to Clear the Smoke From Her Room.

Prudential Building, Boston, MA: Ionization Detectors on Most Floors Never Activated During the 2+ Hour Incident Even Though Smoke Was Known to Be Thick in These Locations Within 4 Minutes of the Fire.

Ft. Lauderdale, 1984:  First Ionization Alarm Activated 68+ Minutes After Photoelectric Alarms.  First Ionization Alarm Activated After All Photoelectric Alarms Sounded

Norwegian Study, 1991:

First Ionization to Alarm Was 66+ Minutes After Photoelectric.  Ionization Alarm After All Room Did Not Respond


Ionization:  Is Many Times More Susceptible to Nuisance Alarms Caused by Cooking Odors Which Can Lead to Disabling of The Detectors - Especially in Residential Applications

Photoelectric:  Is Much More Immune to Nuisance Alarms Caused by Cooking Odors

When Determining the Type Of Detector for Sleeping Room Applications Consider:  NFPA and British Studies Conclude That the Vast Majority of Fatalities Occur in Slow Smoldering Fires.

Combination Ionization/Photoelectric Smoke Alarms: 
     Ionization Portion of Unit Is Still Susceptible to Nuisance Tripping
     To Keep Costs Reasonable, Many Manufacturers Utilize Less Expensive Ionization and Photoelectric Components.

See Page 19 of PDF






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