Theme for 2014: Smoke alarms save lives!
Not all fires are the same. There are two kinds of smoke alarm technologies in common use: ionization and photoelectronic. They detect two different types of fire, say the experts at smokesign.com.
Ionization Smoke Alarms are the most popular kind sold in the United States. They monitor the electrically charged particles in the air. Smoke particles entering the sensing chamber change the electrical balance of the air. When combustion particles enter the smoke alarm, they obstruct the flow of the current. An alarm is pre-programmed to sound when the current gets too low.
Ionization smoke alarms respond first to fast flaming fires. A flaming fire devours combustibles extremely fast, spreads rapidly and generates considerable heat with little smoke. They are best suited for rooms, which contain highly combustible material such as:
1, Cooking fat/grease. 2, Flammable liquids. 3, Newspaper. 4, Paint. 5, Cleaning solutions.
Photoelectronic Smoke Alarms contain a light emitting diode (LED) which is adjusted to direct a narrow infrared light across the unit's detection chamber. When smoke particles enter this chamber they interfere with the beam and scatter the light. When a pre-set level of light strikes the photodiode, the alarm is activated.
Photoelectronic smoke alarms respond first to slow smoldering fires that generate large amounts of thick smoke with little heat and may smolder for hours before bursting into flames.
They are best suited for living rooms, bedrooms and kitchens. This is because these rooms often contain large pieces of furniture, such as sofas, chairs, mattresses and counter tops, which will burn slowly and create more smoldering smoke than flames. They are also less prone to nuisance alarms in the kitchen area than ionization smoke alarms.