There is no best detector, only a best match, and two facts about the situation decide it. First, what the first few minutes of the likely fire look like: a slow smouldering ignition in bedding or wiring insulation produces large smoke particles and almost no heat, while a fast flaming fire in solvent or paper produces small particles, radiation and a rapid temperature rise. Detection technologies respond to different ones of those signatures, and a device excellent for one is late for the other. Second, what else is in the room: the nuisance sources that set how sensitive you may be, the ceiling height and airflow that decide whether anything reaches the device, the dirt and humidity it must survive, and who is present — sleeping occupants, nobody at all, or a crew who can respond themselves. The rule is to name the credible first fire, name the nuisance sources, name the response time you need, and only then choose. The devices themselves and how each works are covered elsewhere in this path; this is the selection rule that uses them. After this Concept you can defend a detector choice for a stated room and fire scenario.
This concept covers the physical detection principles underlying the two dominant smoke-alarm technologies used in fire safety: ionization detection, which relies on smoke particles disrupting a radi…