Smoke alarms are designed to detect the presence of smoke as it passes through the device. Once smoke is detected the alarm will sound.
Types of Smoke Alarms
There are many types of alarms, but they are generally broken up into two categories: Ionization and Photoelectric.
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-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 the alarm.
Dual Sensor Smoke Alarms
Both types of alarms have their strengths, and it is up to you to decide which type of alarm you prefer. To make the decision easy, alarm manufacturers have created dual sensor smoke alarms that have photoelectric and ionization detecting capabilities.
United States Fire Administration Recommendation
The United States Fire Administration recommends that every residence and place where people sleep be equipped with one of the following:
- Both ionization and photoelectric smoke alarms
- Dual sensor smoke alarms
After you have decided on what type of alarm you would like, there are a variety of sounding mechanisms to choose from. Some devices simply loudly beep, while others will talk to you and direct you to evacuate. If you are hearing impaired, manufacturers have designed detectors that use strobe lights and/or vibrate in order to alert the occupant. Smoke alarm technology has come a long way and there are many alarms on the market today to suit the needs of every customer.