Smoke Detector

Smoke detectors are devices that are mounted on the wall or ceiling and automatically sound a warning when they sense smoke or other products of combustion.

Although everyone likes to feel safe at home, about two-thirds of our nation's fire deaths happen in the victim's own home. The home is where their is the greatest risk and where residents take the most precautions. Most deaths occur from inhaling smoke or poisonous gases, not from the flames.

Most fatal fires occur in residential buildings between 11 p.m. and 6 a.m. when occupants are more likely to be asleep. More than 90 percent of fire deaths in buildings occur in residential dwellings.

A John Hopkins University study, funded by the United States Fire Administration, found that 75 percent of residential fire deaths and 84 percent of residential fire injuries could have been prevented by smoke detectors.

There are two basic types of smoke detectors:

1. Ionization detectors - Ionization detectors contain radioactive material that ionizes the air, making an electrical path. When smoke enters, the smoke molecules attach themselves to the ions. The change in electric current flow triggers the alarm. The radioactive material is called americium. It's a radioactive metallic element produced by bombardment of plutonium with high-energy neutrons. The amount is very small and not harmful.

2. Photoelectric detectors - these types of detectors contain a light source (usually a bulb) and a photocell, which is activated by light. Light from the bulb reflects off the smoke particles and is directed towards the photocell. The photocell then is activated to trigger the alarm.

Choosing a smoke detector
When choosing a smoke detector, there are several things to consider. Think about which areas of the house that need protection. Where would fire be most dangerous? How many detectors are needed?

The Sni Valley Fire District recommends that every home have a smoke detector in the hallway, and each bedroom of a home. On floors without bedrooms, detectors should be installed in or near living areas, such as dens, living rooms or family rooms. Smoke detectors are not recommended for kitchens.

The safest bet is to have both kinds or a combination detector with a battery back up. Be sure to check for a testing laboratory label on the detector. It means that samples of that particular model have been tested under operating conditions. Check to see if it is easy to maintain and clean. Make sure the batteries are common and easy to replace.

Installation
The placement of smoke detectors is very important. Sleeping areas need the most protection. A smoke detector should be located in each bedroom of the home. One detector in a short hallway outside the bedroom area is usually adequate. Hallways longer than 30 feet should have one at each end. For maximum protection, install a detector in each bedroom.

Be sure to keep the detector away from fireplaces and wood stoves to avoid false alarms. Place smoke detectors at the top of each stairwell and at the end of each long hallway. Smoke rises easily through stairwells. If a smoke detector is installed in the kitchen, be sure to keep it away from cooking fumes or smoking areas.

Proper mounting of a smoke detector also is important. Many detectors can be mounted by the resident, but those connected to your household wiring should have their own separate circuit and be installed by a professional electrician. If a detector is mounted on the ceiling, be sure to keep it at least 18 inches away from dead air space near walls and corners. If you mount it on the wall, place it six to 12 inches below the ceiling and away from corners. Keep them high because smoke rises.

Never place them any closer than three feet from an air register that might re-circulate smoke. Don't place them near doorways or windows where drafts could impair the detector operation. Don't place them on an un-insulated exterior wall or ceiling. Temperature extremes can affect the batteries.

Maintenance
Keeping smoke detectors in good condition is easy. Always follow the manufacturer's instructions. Be sure to replace the batteries every six months or as needed. Most models will make a chirping, popping or beeping sound when the battery is losing its charge. When this sound is heard, install a fresh battery, preferably an alkaline type.

Important Smoke Alarm Information and links

Smoke Alarms: What You Need to Know

US Fire Administration

Children and Smoke Alarms

Smoke and Carbon Monoxide Alarms for Manufactured Homes