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Results from a Full-Scale Smoke Alarm Sensitivity Study



Thomas G. Cleary


A series of 24 full-scale experiments was conducted to examine the effects of alarm type (photoelectric, ionization, and dual sensor), alarm location, fabric type (100% cotton and 100% polyester), polyurethane foam density, ignition scenario, and room configuration, on smoke alarm performance. A two-level, fractional factorial design of eight experimental configurations was developed around the five factors: fabric type, foam density, fire location, ventilation, and ignition scenario. A structure, designed to represent a single-story home or apartment, was constructed inside the Large Fire Laboratory at the National Institute for Standards and Technology for the experiments. The fire source was a chair mockup consisting of a seat and back cushion of a specific cover fabric and foam density, weighing between 5.5 kg and 8.3 kg. It rested on a metal frame and was subjected to a small propane gas flame, or an electric cartridge heater to initiate smoldering. Each experimental configuration was replicated three times. Smoldering fires were allowed to progress until they naturally transitioned to flaming fires except for one test that was terminated early due to time constraints. The smoldering to flaming transition times ranged from (81 to 182) min. Each fire progressed for a time sufficient to produce multiple hazards (smoke, heat, and toxic gases). All alarms tested were purchased from retail outlets and activated at their preset levels. Photoelectric, ionization, and dual photoelectric/ionization alarms were co-located at multiple locations to facilitate comparisons of each alarm type, and different designs of the same type of alarm. For smoke alarms in the room of fire origin, it was observed that each of the five factors had an effect on the measured alarm times that was primarily a result of fire growth rate (fabric type, foam density, and ignition scenario), or smoke dilution and transport (fire location and ventilation).
Fire Technology


Smoke alarms, Smoldering, Full-scale fire tests


Cleary, T. (2010), Results from a Full-Scale Smoke Alarm Sensitivity Study, Fire Technology (Accessed April 20, 2024)
Created April 9, 2010, Updated February 19, 2017