There
are two basic types of smoke detectors:
- 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.
- Photo-electric
detectors - This type of detector contains 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 you want to protect, where fire would
be most dangerous, how many you will need, etc.
The
National Fire Protection Agency recommends that every home have a smoke
detector outside each sleeping area (inside as well if members of the
household sleep with the door closed) and on every level of the home,
including the basement. The National Fire Alarm code requires a smoke
detector inside each sleeping area for new construction. 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.
Installation
The placement of smoke detectors is very important. Sleeping areas need
the most protection. 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
you should put a smoke detector in your kitchen, be sure to keep it away
from cooking fumes or smoking areas.
It’s
important to properly mount a smoke detector. You can mount many detectors
by yourself, however those connected to your household wiring should have
their own separate circuit and be installed by a professional electrician.
If you mount your detector 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
It’s simple to keep smoke detectors in good condition. Always follow the
manufacturer's instructions. Be sure to replace the batteries every year
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.
Remember,
every three years to change the bulbs. Keep extras handy. Check
the smoke detector every month by releasing smoke or pushing the “test”
button. Clean the detector face and grillwork often to remove dust and
grease. Never paint a smoke detector as it will hamper its function. Check
your detector if you've been away from home.
Smoke
Detectors make great housewarming (or any time) gifts. It's an interesting
present that can save lives and it shows that you care.
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