Facts About Smoke Detectors

When properly installed, smoke detectors provide early notification to occupants of potential fire hazards. Picking up a smoke detector is as easy as a short drive to a hardware or home supply store, or even your local fire department. You have two choices for residential devices: photoelectric and ionization chamber smoke detectors.

While both are made from the same basic materials (polyvinyl chloride (PVC) or poly-styrene plastic and electronic circuit boards) their functionality varies slightly.

Photoelectronic Devices

Photoelectronic alarms are triggered when smoke clouds an optical beam, causing a decrease in light intensity. This type of device reacts most quickly with fires containing large amounts of smoke.

Ionization Chamber

Ionization chamber smoke detectors (ICSD), the most common type of device in American homes, reacts quickly to flaming fires with small amounts of smoke. When the flow of radioactive material (Americium 241) fails to ionize the air between a pair of electrodes due to smoke, the alarm sounds.

The U.S. Fire Administration recommends installing devices on every level of your home, even the basement, and both inside and outside of sleeping areas. For both photoelectric and ICSD units, change batteries once annually and replace the unit every eight to 10 years. For hard-wired systems with battery back-up, check batteries monthly and replace the unit every 8 to 10 years.