Not all fires are the same. There are two kinds of smoke alarm technologies in common use-- ionization and photoelectric--that detect two different types of fire.
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. Ionization models are best suited for rooms which contain highly combustible materials. These types of materials include: cooking fat/grease flammable liquids newspapers paint cleaning solutions.	Photoelectric smoke alarms respond first to slow smoldering fires. A smoldering fire generates large amounts of thick, black smoke with little heat and may smolder for hours before bursting into flames. Photoelectric models 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, counter tops, etc. which will burn slowly and create more smoldering smoke than flames. Photoelectric smoke alarms are also less prone to nuisance alarms in the kitchen area than ionization smoke alarms
The use of both ionization and photoelectric alarms will provide a home with maximum protection and an ample warning in the event of a fire.