March 8, 2009

Emergency Preparedness: Smoke Alarms

Smoke alarms operate on one of two basic principles: ionization or photo electronic. For maximum protection, you should understand the advantages and disadvantages of both types.

Keep in mind only smoke alarms that are ULC approved should be used.

The ionization alarm uses a small amount of radioactive material to make the air within a sensing chamber conduct electricity. When very small smoke particles enter the sensing chamber, they interfere with the conduction of electricity, reducing the current and triggering the alarm. The particles to which the alarm responds are often smaller than can be seen with the human eye. Because flaming fires produce the greatest number of these invisible particles, ionization detectors respond slightly faster to open flaming fires than do photo electronic alarms.

Photo Electronic
The photoelectric alarm uses a small light source - either an incandescent bulb or light-emitting diode (LED) - that shines its light into a dark sensing chamber. The sensing chamber also contains an electrical, light-sensitive component known as a photocell. The light source and photocell are arranged so that light from the source does not normally strike the photocell. When smoke particles enter the sensing chamber of the photoelectric alarm, the light is reflected off the surface of the smoke particle, allowing it to strike the photocell and increase the voltage from the photocell. When the voltage reaches a predetermined level, the alarm activates.

Power Supply
Batteries or household current can power residential smoke alarm. Battery-operation detectors offer the advantage of easy installation - a screwdriver and a few minutes are all that are needed. Battery models are also independent of house power circuits and will operate during power failures. It is critical that only the specific battery recommended by the alarm manufacturer be used for replacement.

Smoke Alarm Location
A smoke alarm in every room will provide the fastest detection. 85% of all fire deaths and injuries occur in homes where there are no working smoke alarms. Remember, only a working smoke alarm can save your life! Most fatal fires occur at night when people are asleep. Often, victims never wake, due to carbon monoxide poisoning. A working smoke alarm will alert you, giving you precious time to escape.

Installing a smoke alarm on every level of the living unit provides good all-around protection. Because smoke rises, they should be placed on or near the ceiling, according to your users manual.

It's The Law!
Under the Ontario Fire Code, every home in Ontario is required to have working smoke alarms installed between sleeping and living areas. Homeowners must ensure that smoke alarms are installed on every level of a home and are required to maintain the smoke alarms in working order.



Smoke alarms should be tested regularly. It is recommended that you vacuum out the dust and change the batteries every spring and fall when you adjust your clocks for daylight savings time.

Note: Smoke alarms do not last forever; they should be replaced after ten years. Replace smoke alarms that malfunction in any way.