As a general estimation, a person will die in a house fire every three hours in the United States. In the year 2008 alone, there were over 403,000 house fires, which resulted in $8,550,000,000 in total damages. House fires can be an extremely catastrophic event for any homeowner, especially if your home insurance policy doesn’t cover certain types of fire damage. To protect your safety, as well as prevent fire damage in your home, it’s important to install high quality home smoke detectors.
How Do Home Smoke Detectors Work?
There are three different methods that a home smoke detector may use in order to detect a fire in your home.
Photoelectric Smoke Detectors
In a photoelectric smoke detector, the detector functions by seeing when a photoelectric beam of light in the device is blocked. This blockage occurs during a house fire, when smoke often first collects on the ceiling. However, the more sophisticated photoelectric devices will also be triggered to sound their alarm when the particles in the photoelectric light beam are scattered by a small volume of smoke. This diffusion of light will trigger the alarm on the smoke detector.
Ionization Smoke Detectors
An ionization smoke detector is considerably less expensive than a photoelectric smoke detector, but it does have a higher rate of “false” alarms. An ionization smoke detector has the ability to detect particles of smoke that are too small or too far dispersed to be seen with the naked eye. Ionization smoke detectors contain a very small amount of americanium 241, a radioactive synthetic element. The alpha radiation that is emitted from the americanium passes through a tiny ionization chamber, allowing for a small current to form between two electrodes. When smoke enters the ionization chamber, it absorbs the alpha particles in the chamber, which subsequently disrupts the current. This then sets off the smoke alarm. Since the element of americanium has a half-life of 432 years, it will not have to be replaced during the life of the smoke detector. It should be clarified that the radiation emitted from the smoke detector is alpha radiation, as opposed to harmful beta or gamma radiation.
Air-Sampling Smoke Detector
An air-sampling smoke detector is also able to detect particles of smoke that are invisible to the naked eye, much like an ionization smoke detector. However, air-sampling smoke detectors are most commonly aspirating smoke detectors, also called ASD’s. An ASD consists of a central unit that circulates air through a small network of pipes in order to detect any smoke in the air. A small nephelometer in the smoke detector is able to discern if there are any traces of smoke particles in the air. Air-Sampling smoke detectors are usually used in environments that require a high sensitivity of smoke detection, such as in labs, clean rooms and warehouses that contain valuable goods.
Which Home Smoke Detectors Are The “Best”?
Depending on your needs, you need to decide which home smoke detectors are best for you. Due to the high sensitivity of ionization and air-sampling smoke detectors, these types of detectors are usually not practical for use in residential homes. Optical, or photoelectric smoke detectors, are sometimes called “toast-proof” smoke detectors, since they are not prone to being triggered because of smoke from cooking food indoors. Optical smoke detectors are better for detecting smouldering, slow-burning fires (such as electrical fires in between walls), while air-sampling or ionization smoke detectors will have a faster detection rate for hot, fast-burning fires (such as a fire caused by arson, or with the use of a propellant).