Fires are categorized by how fast they burn: fast-flaming and slow-starting smoldering fires. Google Nest Protect can detect both.
According to the National Fire Protection Association (NFPA), home fires are categorized as either fast-flaming or slow-starting smoldering fires. Nest Protect has been tested to work in both types of fires, and is tested to meet US, Canadian, and European safety standards.
Slow-smoldering fires
Slow-starting smoldering fires most often occur when smoking materials, such as cigarettes, are left unattended. These fires produce a large amount of thick smoke, which can contain toxic chemicals like carbon monoxide and cyanide.12
Fast-flaming fires
Fast-flaming fires result from the ignition of flammable liquids, wood, paper, or open flames that ignite other items. These fires produce large quantities of flames with smaller amounts of smoke and are the most common types of home fires. A smoldering fire can also become a flaming fire, as the fire moves through the home and ignites different materials.
Fires can also vary dramatically based on several other factors: the source of the flame, the amount and type of things surrounding the source, as well as weather conditions. For instance, kitchen fires are the most common type of fire in the US, which causes nearly half of home fires,1 and are a major source of fires in other countries as well. Kitchen fires can include grease fires, oven fires, and appliance fires. Dryers clogged with lint, overloaded electrical outlets, chimneys with excessive soot, and incorrectly installed appliances can all lead to home fires as well.
1st and 2nd generation Nest Protects can both detect fast-flaming and slow smoldering fires. 2nd gen Nest Protects feature a Split-Spectrum Sensor that uses two beams of light to detect each type of fire.
Nest Protect's Split-Spectrum Sensor
1National Fire Protection Association (NFPA)
2 http://fireengineering.com/articles/print/volume-162/issue-8/features/toxicology-of-smoke-inhalation.html