SMOKE ALARMS


SMOKE ALARMS - Part 1

Replacing your smoke alarms

  • Replace all smoke alarms when they are 10 years old. To determine the age of your smoke alarm, look at the back where you will find the date of manufacture. Smoke alarms should be replaced 10 years from the date of manufacture.
  • Immediately replace any smoke alarm that does not respond properly when tested.
  • Replace combination smoke-carbon monoxide alarms according to the manufacturer’s recommendations.

SMOKE ALARMS - Part 2

Smoke Alarm Placement

Proper placement of your smoke alarm can mean getting out safely or not getting out. It is a scary reality, but it is reality nonetheless. Properly placed smoke alarms save lives!!

As the illustration below shows, proper placement in single level and multi-level homes are different, but one thing remains the same. Place smoke alarms inside of each bedroom and outside of each sleeping area. This is more important if your alarms are not wired together, which we will discuss in a later post. 

In multi-level homes, in addition to the alarms inside each bedroom and outside of each sleeping area, you should also place an alarm on each level including the basement. This will allow you to be alerted to smoke and/or fire on a level that you may not be on. The living room is another important location place an alarm, either in or near by. 

You will notice that neither of homes in the illustration have smoke alarms in or near the kitchen. It is recommended that alarms are kept at least 10 feet away from the kitchen due to light smoke and steam from normal cooking operations. Also, do not place alarms in or directly outside of bathrooms due to steam from showers. 

Finally, do not place smoke alarms near heat or AC vents because air could move the smoke away from the alarm, causing the alarm not to alert when seconds count.

SMOKE ALARMS - Part 3

The Different Types of Smoke Alarms

The two primary types of residential smoke alarms contain either ionization or photoelectric sensors. Each type of smoke alarm detects distinctly different types of fires, so dual sensor alarms, which utilize both types of sensors, have risen in popularity.

Smoke detectors consist of two basic parts: a sensor to sense smoke and a loud electronic alarm. They can run off of a 9-volt battery or be hardwired into a 120-volt house current. The batteries, or backup batteries in a hardwired system, should be tested on a regular basis and replaced at least once each year.

Additionally, some smoke alarms are designed to meet the needs of people with hearing disabilities. These alarms use strobe lights and vibrations to alert anyone unable to hear standard smoke detectors.

  • Ionization
  • Photoelectric
  • Dual Sensor


Ionization

Ionization smoke detectors contain a very small amount of americium-241 within an ionization chamber. They create an electric current between two metal plates, which sound an alarm when disrupted by smoke entering the chamber. Ionization smoke alarms can quickly detect the small amounts of smoke produced by fast flaming fires, such as cooking fires or fires fueled by paper or flammable liquids.

This type of smoke detector, which is commonly used in kitchens, is prone to nuisance tripping. For example, we’ve all experienced the loud annoying chirping when we leave a cake in the oven too long or add oil to an extremely hot pan. When this happens, people are more prone to disable the alarms.

Photoelectric
Photoelectric smoke detectors contain a light source in a light-sensitive electric sensor, which are positioned at 90-degree angles to one another. Normally, light from the light source shoots straight across and misses the sensor.  When smoke enters the chamber, it scatters the light, which then hits the sensor and triggers the alarm.

Photoelectric smoke detectors typically respond faster to a fire in its early, smoldering stage – before the source of the fire bursts into flames. These detectors are more sensitive to the large combustion particles that emanate during slow, smoldering fires, which usually occur at night when people are asleep.

Dual Sensor
Dual sensor smoke detectors include both ionization and photoelectric sensors, so they should adequately alert homeowners of a smoldering fire or a fire with active flames. Some safety organizations have previously recommended these smoke alarms, because they should cover a broad range of fires.

However, there are no industry standards for setting the individual sensor sensitivity in dual sensor alarms. This means that a dual sensor alarm could have a non-functional ionization sensor, but as long as the photoelectric sensor works, it still meets the national standards developed by Underwriters Laboratories (UL).

(Source: www.asecurelife.com)

SMOKE ALARMS - Part 4

Facts and Figures about Smoke Alarms

  • In 2009-2013, smoke alarms sounded in more than half (53%) of the home fires reported to U.S. fire departments.
  • Three of every five home fire deaths resulted from fires in homes with no smoke alarms (38%) or no working smoke alarms (21%).
  • No smoke alarms were present in almost two out of every five (38%) home fire deaths.
  • The death rate per 100 reported home fires was more than twice as high in homes that did not have any working smoke alarms compared to the rate in homes with working smoke alarms (1.18 deaths vs. 0.53 deaths per 100 fires).
  • In fires in which the smoke alarms were present but did not operate, almost half (46%) of the smoke alarms had missing or disconnected batteries. 
  • Dead batteries caused one-quarter (24%) of the smoke alarm failures.

Source: National Fire Protection Association's "Smoke Alarms in U.S. Home Fires" report, September 2015

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