Protect Your Family From Fire:
 | Purchase one or more smoke detectors. |
| Install smoke detectors near where individuals sleep. |
| Take care of your smoke detector. |
| Develop and rehearse an escape plan so when your detector sounds,
family members react appropriately. |
Where Should I Install Smoke Detectors?
| Where you place smoke detectors depends on the size and layout of your
home, and where people sleep in your home. Since the primary job of a
smoke detector is to awaken sleeping persons and warn them of urgent
danger, put your detector as close as possible to the bedrooms or other
places where people frequently sleep. If two sleeping areas are separated,
each should have its own detector. The hallway next to the bedrooms or
other sleeping areas should be a priority location for detectors. |
| If bedroom doors are normally closed at night, detector locations
within each bedroom might be considered, particularly if the occupant
smokes in bed. Closed doors usually offer some protection against both
fire and smoke from outside the room. However, they may make it more
difficult to hear a detector alarm outside the bedroom. More
significantly, they can keep smoke produced by a fire in a bedroom from
reaching a detector in the hall. |
| In single floor homes, the detector should be placed in the hallway
near the bedrooms. In a house where the bedrooms are upstairs, one
detector should be near the top of the stairs to the bedroom area. The
simplest rule for locating one smoke detector in your home should be
"between the bedrooms and the rest of the house, but closer to the
bedrooms." If you are installing multiple detectors, put one near each
sleeping area. It is also a good idea to make certain there is one on each
level of the house. The basement ceiling, near the steps to the rest of
the house, is another good location. |
| Don't put detectors within six inches of where walls and ceilings
meet, or near heating and cooling ducts. Detectors located in these areas
may not receive the flow of smoke required to activate the alarm. |
| In homes with more than one sleeping area on the same level or on
different levels, a smoke detector should be installed to protect each
separate sleeping area. In a one-floor plan with only one sleeping area,
the smoke detector should be placed between the sleeping area and the rest
of the house. |
(In a one-floor plan (top) with only one sleeping area, the smoke detector
should be placed between the sleeping area and the rest of the house.
In homes with more than one sleeping area on the same level or on different
levels (top), a smoke detector should be installed to protect each separate
sleeping area.)
How to Take Care of Your Smoke Detector:
| Smoke detectors don't need much attention. Regular testing and prompt
replacement of batteries or bulbs is generally all that is needed.
However, if you neglect these few requirements, your detector won't do its
job if a fire starts. |
Monthly Testing:
|
At least once every
month, test your detector by holding a candle six inches under it. If
you're testing an ionization detector, let the flame burn. To test a
photoelectric unit, extinguish the candle and let visible smoke drift into
the detector. Heavy tobacco smoke also will work. The unit's alarm should
begin to sound within twenty seconds. To stop the alarm, fan the smoke
away from the detector. Soon the detector will become silent, and you can
walk away knowing it's still on guard.
|
| Using real smoke is more dependable than pressing the "test" button
found on many older smoke detectors. In some older units, the button only
starts the warning sound, and does not tell you whether the detector
circuit itself is working. Some newer detectors have more refined test
systems that simulate the presence of smoke in the chamber. These don't
need to be tested with real smoke. Check the package or instructions of
your detector to see if it has this feature. |
| Some authorities suggest testing every two weeks. This should not
reduce battery life significantly. Testing more often than this may
shorten your battery's life. |
Replace Batteries and Lamps At Once:
| Batteries will last approximately one year. If your battery-powered
detector begins to emit its low-power warning sound, remove the weak
battery and replace it immediately with a fresh one. Have a new battery on
hand always. |
| Replacement lamps for photoelectric detectors also should be kept on
hand so no delay occurs in restoring their function. Owner neglect of
testing and part replacement has been a cause of smoke detector failure,
often resulting in tragedy. |
Don't Play "False Alarm":
| The detector is not a toy. Remind everyone in your family that it
should not be operated, or even touched, except to test, maintain, and
clean. Some authorities suggest using the detector test feature to operate
the alarm as part of a family "fire drill" on occasion. Operating the
alarm excessively draws heavily on battery power, and may cause a
malfunction when it's needed most. |
"Nuisance Alarms":
| Do not respond to "nuisance" alarms (cooking, fireplaces, etc.) by
disconnecting the battery. Either fan away the smoke or relocate the
detector. |
If It "Acts Up":
| Most manufacturers back their detectors with a service or replacement
warranty. If your detector begins to malfunction during the warranty
period, follow the warranty procedure listed in the use and care
literature. In some instances you can return the unit to the store from
which it was bought. You may be instructed to send the unit directly to
the manufacturer. |
How to Shop for a Smoke Detector:
When shopping for a smoke detector, consider these
suggestions:
|
Look for a laboratory
seal of approval or a statement on the package or unit itself. A seal of
approval indicates that the detector has been tested and certified by a
recognized testing organization. Such a seal ensures that the unit meets
certain standards of operation and sensitivity. The seal from
Underwriter's Laboratories (UL) is a common seal.
|
|
Be certain that the
detector has clear and detailed instructions that tell you how to install
it, suggest where to place it, and provide directions for testing and
maintenance.
|
Types of Smoke Detectors:
Photoelectric Detectors:
|
Occasionally, you will
walk into a store and a bell will go off as you cross the threshold. If
you look, you will often notice that a photo beam detector is being
used. Near the door on one side of the store is a light (either a white
light and a lens or a low-power laser), and on the other side is a
photodetector that can "see" the light.
|
| When you cross the beam of light, you block it. The photodetector
senses the lack of light and triggers a bell. You can imagine how this
same type of sensor could act as a smoke detector. If it ever got smoky
enough in the store to block the light beam sufficiently, the bell would
go off. But there are two problems here: |
- It's a pretty big smoke detector.
- It's not very sensitive.
| There would have to be a LOT of smoke before the alarm would go off --
the smoke would have to be thick enough to completely block out the light.
It takes quite a bit of smoke to do that. |
Photoelectric smoke detectors therefore use light in a different way.
Inside the smoke detector there is a light and a sensor, but they are
positioned at 90-degree angles to one another, like this:
In the normal case, the light from the light source on the left shoots
straight across and misses the sensor. When smoke enters the chamber,
however, the smoke particles scatter the light and some amount of light hits
the sensor:
The sensor then sets off the horn in the smoke detector.
Photoelectric detectors are better at sensing smoky fires, such as a
smoldering mattress.
Ionization Detectors:
| Ionization smoke detectors use an ionization chamber and a
source of ionizing radiation to detect smoke. This type of smoke
detector is more common because it is inexpensive and better at detecting
the smaller amounts of smoke produced by flaming fires. |
| Inside an ionization detector is a small amount (perhaps 1/5000th of a
gram) of americium-241. The radioactive element americium has a
half-life of 432 years, and is a good source of alpha particles.
|
| Another way to talk about the amount of americium in the detector is
to say that a typical detector contains 0.9 microcurie of americium-241. A
curie is a unit of measure for nuclear material. If you are holding
a curie of something in your hand, you are holding an amount of material
that undergoes 37,000,000,000 nuclear transformations per second.
Generally, that means that 37 billion atoms in the sample are decaying and
emitting a particle of nuclear radiation (such as an alpha particle) per
second. One gram of of the element radium generates approximately 1 curie
of activity (Marie Curie, the woman after whom the curie is named, did
much of her research using radium). |
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