Initiating Devices- A system component that originates transmission of a change of-state
condition, such as in a smoke detector, manual fire alarm box, or supervisory switch. (SIG-IDS)
72 (2013), 909 (2013), 914 (2010), 731 (2011)
Notification Devices- A fire alarm system component such as a bell, horn, speaker, light, or text
display that provides audible, tactile, or visible outputs, or any combination thereof. (SIG-NAS)
Discuss the differences/similarities between Ionization smoke alarms and Photoelectric
Use illustrations to assist with the discussion. (4 pts)
Ionization smoke alarms are generally more responsive to flaming fires.
How they work: Ionization-type smoke alarms have a small amount of radioactive material
between two electrically charged plates, which ionizes the air and causes current to flow between
the plates. When smoke enters the chamber, it disrupts the flow of ions, thus reducing the flow of
current and activating the alarm.
Photoelectric smoke alarms are generally more responsive to fires that begin with a long period
of smoldering (called “smoldering fires”).
How they work: Photoelectric-type alarms aim a light source into a sensing chamber at an angle
away from the sensor. Smoke enters the chamber, reflecting light onto the light sensor; triggering
For each type of smoke alarm, the advantage it provides may be critical to life safety in some