Results From a Full Scale Smoke Alarm Sensitivity Study.
Results From a Full Scale Smoke Alarm Sensitivity Study.
(219 K)
Cleary, T. G.
Suppression and Detection Research Application: A
Technical Working Conference, 13th Annual. SUPDET 2009.
Proceedings. Fire Protection Research Foundation.
Feburary 24-27, 2009, Orlando, FL, 2009.
Keywords:
smoke detectors; sensitivity; experiments; fire alarm
systems; scenarios; fire tests; chairs; smoldering
ignition; heat sources; electric batteries; smoldering;
low density foams; cotton fabrics; bedrooms; living
rooms; high density foams; polyurethane foams; cushions;
photoelectric detectors; ionization detectors
Abstract:
A series of 24 full-scale experiments was conducted
during the summer of 2008 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 conducted 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 (fire location and
ventilation). The photoelectric alarm responded quicker
on average than ionization alarm in two of four
smoldering fire configurations, responding before the
ionization alarm in all 6 trials, while the ionization
alarm responded before the photoelectric alarm in two of
three trials for the other two configurations. The
ionization alarm responded quicker on average than
photoelectric alarm in all four flaming fire
configurations, and responded before the photoelectric
alarm in all 12 flaming fire trials. One dual alarm had
the fastest average alarm time for all four smoldering
fire configurations, and responded first in 11 of the 12
trials. It also yielded faster average alarm times than
the other dual alarm in seven of eight configurations,
and was the first dual alarm to respond in 22 out of 23
trials where dual alarms were present.
