Ionisation Smoke Detector

An ionisation smoke detector is a type of smoke detector and is an alarm initiating device designed to detect the presence of smoke.

An ionisation smoke detector operates on the principle that, under normal circumstances, air in a chamber is ionised by the radioactive element (Americium 241) which causes the free and equal flow of electrons between two adjacent electrodes.  When smoke particles enter the chamber between the electrodes, the normal flow of electrons is interrupted causing an alarm that is received by fire detection control and indicating equipment ("FDCIE").