What are Ionization and Photoelectric Smoke Alarms?

What are Ionization and Photoelectric Smoke Alarms?

Smoke alarms save lives! Having working smoke alarms in the home cut the risk of dying in fires in half. According to a 2011 study released by the National Fire Protection Association, between 2005-2009, smoke alarms were present in 72% of reported home fires and sounded in only 51% of the home fires that were reported during that time. It is important and recommended to have smoke alarms on every floor and in each bedroom of the home. In order to have the best protection for your family, interconnect the smoke alarm into a network, so when one alarms goes off, the rest of the alarms in the home go off.

Ionization Smoke Alarm

There are generally two types of smoke alarms: ionization smoke detectors and photoelectric smoke detectors. They both will detect a fire differently. Ionization smoke alarms are responsive to flaming fires, such as grease fires or paper. They work by having a small amount of radioactive material between two electrically charged plates, which ionizes the air and allows the current of ions to flow – thus the name “ionization”. When smoke enters the area, it disrupts the flow of the ions, which then activates the alarm. Ionization smoke detectors sense small particles, which are produced by greater amount of hot flaming fire.

Photoelectric Smoke Alarm

A photoelectric smoke detector is more responsive to smoldering fires or fires that begin with a long period of smoldering. These alarms aim a light source into a sensing chamber at an angle away from the sensor. Smoke will enter the chamber, reflect the light into the sensor and trigger the alarm. Photoelectric smoke detectors are more sensitive at detecting larger smoldering fires, such as a cigarette burning in a couch or bed, before they burst into flame.

Both the ionization and photoelectric alarms will give sufficient time for a person to escape the home and one type is not better than the other. The two types of smoke alarms detect different types of fires, so it is crucial to have both types in your home, because no one can know what type of fire will start in their home. There are also combination ionization and photoelectric alarms, called dual sensor alarms, available for use in the home which come highly recommended by the National Fire Protection Agency and the United States Fire Association.

Whichever smoke alarm you decide upon, it is important to properly install and maintain the alarm for continual use.  Test your smoke alarm on a monthly basis. You can use a smoke detector test, which is basically smoke in an aerosol can that mimics the smoke produced by fires. This product is commercially available online or in home improvement stores. If you have a 9-volt battery smoke alarm, make sure to change your batteries at least once a year. The time change in the fall or spring is a great reminder when to change your smoke alarm batteries. Replace the entire smoke alarm unit every 8-10 years.  Having a properly working smoke alarm and fire escape plan is key to keeping your family and home safe.

 

Sources:

http://www.nfpa.org/~/media/Files/Research/NFPA%20reports/Fire%20Protection%20Systems/ossmokealarms.ashx

http://www.nfpa.org/safety-information/for-consumers/fire-and-safety-equipment/smoke-alarms/ionization-vs-photoelectric

http://www.usfa.fema.gov/campaigns/smokealarms/alarms/index.shtm