Photoelectric and Ionization Smoke Detectors

 Introduction:

There are two types of residential smoke alarm detectors; ionization and photoelectric smoke detectors. The vast majority of smoke detectors in private homes today are the ionization type, but there is doubt that they are a valid smoke alarm detector because they give so many false alarms. In some states they are no longer allowed as the only type of residential smoke alarms. 

The major problem with ionization smoke detectors is that they give off too many false alarms from cooking and showers.  When a smoke detector goes off every time someone cooks bacon, people usually remove the battery or take down the smoke alarm. Manufacturers recommend that they be installed away from kitchens and bathrooms to avoid these false alarms.

Another problem with ionization smoke detectors is that they take a long time to respond to a smoldering fire. They are much slower than photoelectric detectors.   Estimates show that at least one third of home fatal fires involve a significant smoldering period before the actual fire breaks out.  This is the reason that there is such a push to replace ionization detectors with photoelectric detectors. 

In a smoldering fire, a photoelectric smoke detector will outperform an ionization type detector.  So you may ask why we even have ionization type detectors. The primary reason is cost.  Photoelectric smoke detectors typically cost about twice as much as the ionization type.  Another reason is that ionization smoke detectors outperform photoelectric detectors in the event of a fast moving fire.  The faster reaction time can be measured in tenths of seconds, but in the event of a fast moving fire, these are precious seconds. There is a third type of detector that incorporates both ionization and photoelectric technology.   

To determine which type of detector you have, take it down and look at the back.  Ionization detectors all contain a trace amount of a radioactive material, Americium 241.  They’ll all have a warning about this on the back side.   

Fire safety officials recommend installing both photoelectric and ionization detectors, or detectors that use both technologies called dual alarms. These smoke detectors are the best detectors for protecting your home and your family.   

Related sartcles:

Installing a Security Camera

Installing Motion Sensor Lighting

Installing Motion Detectors

Installing a Home Security System