Smoke Alarms

smoke alarm

Widespread use of smoke alarms began in the 1970s, and have greatly reduced the number of home fire deaths. Prior to the 1970s, the average number of annual deaths by home fires was roughly 6,000. While there has been a dramatic decrease in home fire deaths, there is still more work to be done. Three out of every five home fire deaths occur in a home with no smoke alarms or no working smoke alarms. No smoke alarms were present in more than 1/3 of home fire deaths. In reported home fires where smoke alarms were present, but did not operate, almost half of the smoke alarms had missing or disconnected batteries. A quarter of the smoke alarm failures were due to dead batteries. NFPA estimates that there are about five million homes nationwide without smoke alarms.

In 2015, 3,280 civilians died in fires. Most fire deaths are not caused by burns, but by smoke inhalation. An individual can become incapacitated by smoke so quickly that they are overcome and can’t make it to an otherwise accessible exit. Having smoke detectors and alarms in your home and business can provide valuable time to evacuate, preventing injury and death.

A smoke alarm is a stand-alone device with a built-in sounder, a power supply, and a sensor. A smoke alarm is not connected to a fire alarm control panel, but may interconnect with other smoke alarms within the building. A smoke detector is part of a commercial fire protection system, it has only a built-in sensor and sends information to the fire alarm panel.

There are two main types of smoke detection technology used both in stand-alone devices and as the sensor in smoke alarms, ionization and photoelectric. Each has advantages, for best protection you should use both types of smoke detection technologies. There are units available which utilize both technologies in a single device for both detectors and alarms.

Ionization Smoke Detection
Ionization Smoke Detectors are generally more responsive to fires that have flames. The detectors have a small amount of radioactive material between two electrically charged plates, this 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 Smoke Detection
Photoelectric Smoke Detectors are more responsive to fires that begin with a long period of smoldering. Photoelectric-type detectors aim a light source into a sensing chamber at an angle away from the sensor. When smoke enters the chamber, it reflects the light onto the light sensor which triggers the alarm.

Smoke detectors have advanced technologically to be more user friendly. In addition to combination detectors which include both photoelectric and ionization technology, you can also get detectors that combine CO detection, or many have features for silencing nuisance alarms. Smoke alarms can be interconnected to allow an alarm to sound throughout the house or building when one unit detects smoke; some of these devices can be programmed to provide audio messages that state for which room the alarm has sounded.

A1 is a leading expert on the latest technology in life safety. To find out more information or to ask a question, click here or call us at 1-800-859-6198.

Jack Menke
Jack Menke

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Posted on: October 4, 2016

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