Ion Vs. Photo Smoke Detector

Types of Detectors

• The three types of smoke detectors available today are photoelectric, ionization and those that have both sensors. A photoelectric alarm is triggered when smoke enters the detector and light from a pulsating source is reflected off the smoke particles onto a light sensor. In an ion alarm, ionized air molecules attach to the smoke particles that enter the chamber, reducing the ionizing current and triggering the alarm.

Pros and Cons

• The ion detector reacts faster than the photoelectric in responding to flaming fires, and the photoelectric detector is more responsive to smoldering fires. Because an ion detector tests the air for small combustible particles, it can be fooled by chemical or paint particles in the atmosphere. The photoelectric detector, which needs to "see" the fire, can be fooled by dust, steam or even spider webs. Though both offer protection against undetected fires, ion detectors experience a higher incidence of nuisance alarms.

How Many To Have

• Underwriters Laboratories recommends installing at least one smoke alarm on each floor of your home and one outside all sleeping areas. Some fire safety professionals further recommend installing smoke detectors inside each sleeping area if the occupant sleeps with the door closed.

Regular Maintenance

• Smoke detectors should be tested once a month or in accordance with the manufacturer's recommendation. Batteries should be replaced at least once a year.

Fire Escape Planning

• Installing and maintaining smoke detectors will help keep your family safe, but developing a fire escape plan and practicing it several times a year with everyone in your household is equally important.