A smoke detector is a device that senses smoke, typically as an indicator of fire, usually housed in a disk shaped plastic enclosure roughly 125 millimeters across, and it detects smoke either optically, by a photoelectric method, or by a physical ionization process, with some detectors using both. Household smoke detectors, also called smoke alarms, sound an audible or visual alarm and may be interlinked so that any one unit detecting smoke triggers every connected unit, powered by a battery, by mains electricity, or by a combination of the two so a battery can back up the mains supply. Commercial smoke detectors typically send a signal to a fire alarm control panel as part of a larger fire alarm system rather than sounding an alarm on their own. According to the United States National Fire Protection Association, the risk of dying in a home fire is roughly cut in half in houses with working smoke detectors, which recorded 0.53 deaths per 100 fires compared with 1.18 deaths per 100 fires without them, in data covering 2009 to 2013. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/
Facts
YearSourced to the subject's own accountFirst low-cost smoke detector built for home use, by Duane D Pearsall and Stanley Bennett Peterson. Earlier stages: Francis Robbins Upton patented an automatic electric fire alarm in 1890; Walter Jaeger and Ernst Meili did ionization-detection research in the late 1930s; ionization smoke detectors were first sold in the United States in 1951, to commercial and industrial buyers only. SignificanceSourced to the subject's own accountCheap, reliable smoke detectors turned automatic fire warning from a costly commercial and industrial fitting into a standard household safety device required by law in homes across much of the world. 1 FAQs
Is an ionization or a photoelectric smoke alarm faster?
Ionization alarms tend to be faster for flaming fires and photoelectric alarms for smoldering fires.
It depends on the fire. The U.S. Fire Administration says ionization smoke alarms tend to respond faster to the smoke produced by flaming fires, while photoelectric smoke alarms tend to respond faster to the smoke produced by smoldering fires. In some full-scale fire tests the difference in time to alarm was trivial, and in others it was considerable.
Which type of smoke alarm does the U.S. Fire Administration recommend?
It recommends both types together or dual sensor alarms.
The U.S. Fire Administration says it cannot state that one type of alarm is better than another because every fire is different. Because no one can predict what type of fire might start in a home, it recommends that every home and place where people sleep be equipped with either both ionization and photoelectric smoke alarms, or dual sensor smoke alarms that contain both kinds of sensor.
Connections
In Field
Source Smoke detector (Wikipedia)
Sources
1. Smoke detector (Wikipedia)
WikipediaHistory section, para 2, low-cost domestic detector
In 1965, the first low-cost smoke detector for domestic use was developed by Duane D. Pearsall and Stanley Bennett Peterson.
History section, para 2, early commercial and industrial use
In the following years, they were used only in major commercial and industrial facilities due to their large size and high cost.
In Field: Electrical Engineering, Introduction
Smoke can be detected either optically (photoelectric) or by physical process (ionization).
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