Smoke Detectors and Your Home

How to buy a smoke detector, with smoke alarm types and features, the number needed for a home, combination detectors and fire alarm manufacturers.
Every year in the United States, more than 3,500 people die in home fires and another 18,000 are injured. Additionally, house fires cost almost $8 billion in property damage annually. Many victims do not die of burns but rather smoke inhalation, because fires often occur at night when victims are asleep. Smoke detectors are the best way to prevent these catastrophic results. The risk of dying from a home not protected by a smoke detector is twice that of a protected home. Of course, it is essential that the detector is operational: Approximately 95% of U.S. homes have at least one smoke detector, yet 20 percent of fire fatalities occur in homes with broken or disabled detectors. A smoke detector stands guard around the clock, and when it first senses smoke, it sounds an alarm, often buying a family the precious time it takes to escape. The most common alarm is a beeping noise that is piercing and persistent enough to alert homeowners to danger.
Other types of alarms include a voice detector, which has verbal commands pre-recorded in addition to an alarm. Examples of the pre-recorded commands are ”Fire, get out!” or “Smoke alert!” or Low-battery alert.” One version of this type may even have a parent’s voice pre-recorded (studies indicate that children are more likely to respond quickly to a parent’s voice).
Strobe detectors are smoke alarms that are designed to meet the needs of the hearing-impaired. These smoke alarms use strobe lights that flash or vibrate to alert those who are unable to hear standard smoke alarms. There are also detectors that respond with tactile stimulation such as bed shaking.

Battery and Hardwired Smoke Detectors
Most smoke detectors are battery powered, but some, particularly those installed during house construction, are wired into a home’s electrical system. Most of the ones that run on line voltage (household current) have a battery backup in case a fire knocks out the house’s electrical power. Battery-powered detectors are easier to install. Smoke detector batteries insider both battery-operated and hard-wired smoke detectors last approximately 6 months. When they need replacing, the detector will chirp every minute or so to indicate that the batteries are expiring.
The main problem with battery-powered smoke detectors is that people don’t maintain them. All battery-operated detectors are supposed to signal a low battery, but you have to make sure they’re working; newer models won’t close if the battery is removed. New lithium battery models last up to 10 years; the entire unit is disposable.

Smoke Detector Types
There are many brands of smoke detector on the market, but they all fall under two basic types—ionization chamber detectors and photoelectric detectors. Both types have two basic parts: a sensor to sense the smoke and a very loud electronic horn to alert people.

Ionization detectors use a radioactive source that produces electrically charged molecules (ions). This sets up an electrical current within the detector chamber. When smoke enters the chamber, it attaches to the ions and reduces the flow of electrical current, which sets off the alarm. Ionization detectors are better at detecting the smaller amounts of smoke produced by fast, flaming fires.

Photoelectric detectors use an optical detector sensor (a photo beam) and go off when smoke from a smoldering fire is dense enough to deflect that beam of light.

Dual detectors Because homeowners cannot predict the type of fire that might start, a combination smoke detector—called a dual-sensor smoke alarm—is actually the wisest choice.

Smoke Detector Features
Depending upon quality of smoke detectors, some also offer:
• A remote-control mute button that can be linked to a television remote control to silence nuisance alarms.
• Safety lights to provide illumination during an alarm.
• Silence buttons that will quiet the alarm for a few minutes at a time. Detectors with this feature are commonly placed in kitchens.
• Transmission of a signal to a central monitoring station as part of a security alert system.
• Intercommunication of hardwired smoke detectors that guarantees if one alarm in the house goes off, they all go off. Even if the fire is detected in the basement, people upstairs will hear an alarm.

Addressable Smoke Detector Systems
Addressable smoke detection systems provide knowledge of the exact location and status of every device. The alarm decision is generally made by control equipment rather than an individual detection device.
Addressable system features include:
• The alarm can be investigated before a fire service is called.
• The system can tell you which device needs maintenance.
• Each detector is uniquely identified, and the exact location of each unit is displayed at the fire control panel.
• Any cut wires or short circuits do not generate nuisance alarms.
• Each sensor can be adjusted to its own unique environment.
• Nuisance alarms are less likely because the system uses multi-sensor detection
• Many incorporate strobe lights as a means of alerting the hearing impaired.

Combination Smoke-CO Detectors
Combination detectors are gaining in popularity because they combine smoke and carbon monoxide detection. They are available as CO and ionization alarms and CO and photoelectric alarms.
By purchasing these combo alarms, you would have fewer alarms to place in your home (except that many CO alarms mount in the typical wall outlet placed low on the wall while the optimum smoke alarm placement is on or near the ceiling).
Interconnecting CO detectors warn you of problems in remote areas of the house—especially important in multi-level homes. They can be linked through hard wires or wirelessly and set off all the alarms if any one goes off.

Source: www.hometips.com