smoke alarms save lives

The majority of fatal home fires happen at night when people are asleep. Contrary to popular belief, the smell of smoke may not wake a sleeping person. The poisonous gases and smoke produced by a fire can numb the senses and put you into a deeper sleep.

Inexpensive household smoke alarms sound an alarm, alerting you to a fire.

By giving you time to escape, smoke alarms cut your risk of dying in a home fire nearly in half. Smoke alarms save so many lives that most states have laws requiring them in private homes.

 

Fire experts agree that 40 to 50 percent of the 6000 lives lost in residential fires in the country last year could have been saved if the families had used smoke detectors.

We’re pleased that you’ve taken the first step to making your home safer for your family by learning about smoke detectors and home fire safety.

why do i need a smoke detector in my home?

Most fire fatalities occur between 2am and 6am—when people are asleep and their natural “fire sensing equipment” is least effective. These deaths are caused by the inhalation of poisonous gases or smoke, which reach victims before the flames.

 

Many suffocate without ever waking or even becoming aware of the fire. They die because they had no warning.

 

A smoke detector can sense a fire and sound a alarm while there is time to escape safely.  

choosing an alarm

Be sure that the smoke alarms you buy carry the mark of an independent testing laboratory. Several types of alarms are available. Some run on batteries; others run on household current.  All approved smoke alarms, regardless of type, will offer adequate protection provided they are installed and maintained properly.

Tests conducted by the National Bureau of Standards showed ionization detectors to be slightly more effective in detecting flaming fires and photo electronic models are slightly more effective in detecting smoldering fires. Both offer effective protection.

For the best coverage of all types of fires, select one of each type or the combination ionization-photo electronic model.

A very important thing to look for in purchasing a detector of either type is a listing mark from a licensed testing laboratory. The Underwriters Laboratories (UL) listing will assure you of a quality product.

Many hardware stores, general merchandise stores and home improvement centers carry smoke detectors. If you are unsure where to buy them, call your local fire department for suggestions. Some fire departments offer smoke detectors for little or no charge. Do not purchase used smoke detectors. The price you pay for them new is cheap considering the value they offer. Most detectors cost between $5.00 to $15.00.

differences between ionization and photo electric smoke detectors

There are two types of residential smoke alarms currently in use - ionization and photoelectric alarms. But which type should you install in your home?

You should have more than one smoke alarm, including at least one each of the two kinds of smoke alarm technology.

This is a critical decision, because smoke alarms sound out the all-important warning that could mean the difference between life and death.

These days, everyone accepts that it is important to have the warning provided by a working smoke alarm. However, since the early days of smoke alarm technology, there has been a tendency to promote the generally less expensive "ionization" type product as a 'general purpose' smoke alarm. This is incorrect. There is no such thing as a general purpose smoke alarm.

But what most people don't realize is that there are two different types of smoke alarm technology which can help overcome any such limitations, thus increasing your chances of surviving a fire. These two types of technology are "ionization" and "photoelectric". It is also a fact that you can dramatically increase your chances of escaping from a fire alive if you have one of each type of smoke alarm installed in your home.

Here is an important fact. Not all house fires are identical. The slow smoldering fire resulting from a cigarette dropped onto a rug will have totally different characteristics to a fast burning fire resulting from an electrical short circuit. Both types of smoke alarms have sensing chambers which operate in different ways to sense products of combustion given off by a developing fire. It is important to know that an ionization type smoke alarm will be more sensitive to a rapidly burning fire whilst a photoelectric alarm is more effective in detecting a slow smoldering fire.


Ionization smoke alarms

The ionization alarm is designed to detect invisible particles of combustion, as small as .01 micron. Particles this small cannot be seen by the human eye. Ionization alarms, because of their sensing mechanism, cannot tell the difference between particles of combustion, dust, very small bugs, and possibly even paint fumes and steam.
So opening a gas oven, cooking toast, a new gas heater or an open fireplace can quite easily result in causing a false alarm in an ionization unit. This is not a problem with the alarm, it is doing what it is designed to do.
Ionization alarms respond very quickly to hot, fast flaming fires.

A basic ionization chamber consists of two electrically charged plates and an Americium 241 source for ionizing the air between the two plates.

The positively charged ions are attached to the negatively charged electrical plate and the negatively charged ions are attracted to the positively charged plate.

As particles of combustion (i.e smoke) enter an ionization chamber, ionized air molecules collide and combine with them.

Electronic circuitry monitors both a sensing chamber and a reference chamber and compares their current and voltage outputs for imbalalances, which ultimately sets off the alarm.

Photoelectric smoke alarms

The photoelectric alarm detects visible particles of combustion from .3 micron. This is generally associated with smoke you can see. Photoelectric alarms respond better to slow smoldering fires, and because of their detection principles are better suited to some locations than are ionization alarms.

These locations include:

Near cooking areas, small confined apartments, open fireplaces, near heating devices, and in air-flow areas near kitchens.

Visible smoke produced by a fire affects the propagation of a light beam passing through air. At it's most basic, this is usually a light emitting diode combined with a photo-sensitive device such as a photo-diode

Smoke can block or obscure part of the beam.

How to minimize nuisance alarms

Never install ionization smoke alarms in areas where cooking fumes, open fires and products of combustion are present. Where these conditions occur and a smoke alarm must be installed, a photoelectric alarm is the best option .

is one enough?

Every home should have a smoke alarm outside each sleeping area and on every level of the home, including the basement. The National Fire Alarm Code, developed by the National Fire Protection Association (NFPA), requires a smoke alarm in each sleeping room for new construction. On floors without bedrooms, alarms should be installed in or near living areas, such as dens, living rooms, or family rooms.

Be sure everyone sleeping in your home can hear your smoke alarms' alarm. If any residents are hearing impaired or sleep with bedroom doors closed, install additional alarms inside sleeping areas. There are specially designed detectors for the hard of hearing or hearing impaired. These devices use bright strobe lights and vibrating alarms for notification.

There are special smoke alarms for the hearing impaired; these flash a light in addition to sounding an audible alarm.

For extra protection, the NFPA suggests installing alarms in dining rooms, furnace rooms, utility rooms, and hallways. Smoke alarms are not recommended for kitchens, bathrooms, or garages - where cooking fumes, steam, or exhaust fumes could set off false alarms - or for attics and other unheated spaces where humidity and temperature changes might affect a alarm's operation.

where to install

Because smoke rises, mount alarms high on a wall or on the ceiling. Wall-mounted units should be mounted so that the top of the alarm is 4 to 12 inches (10 to 30 centimeters) from the ceiling. A ceiling-mounted alarm should be attached at least 4 inches (10 centimeters) from the nearest wall. In a room with a pitched ceiling, mount the alarm at or near the ceiling's highest point.

In stairways with no doors at the top or bottom, position smoke alarms anywhere in the path of smoke moving up the stairs. Always position smoke alarms at the bottom of closed stairways, such as those leading from the basement. Dead air trapped near the door at the top of a stairway could prevent smoke from reaching an alarm located at the top.

Don't install a smoke alarm too near a window, door, or forced-air register where drafts could interfere with the alarm's operation.

installation and maintenance

Most battery-powered smoke alarms and alarms that plug into wall outlets can be installed using only a drill and a screwdriver by following the manufacturer's instructions. Plug-in alarms must have restraining devices so they cannot be unplugged by accident. Alarms can also be hard-wired into a building's electrical system. Hard-wired alarms should be installed by a qualified electrician. Never connect a smoke alarm to a circuit that can be turned off from a wall switch. If you are uncomfortable standing on a ladder, ask a friend or relative to help. Some fire departments will install a smoke detector in your home for you. Call your local fire department's non-emergency telephone number if you have problems, need advise or assistance.

Smoke detectors are relatively simple to maintain. Manufacturers recommend that the unit be tested once a week. This can be done by pressing the test button or blowing a small amount of pipe or cigarette smoke into the detector. A common tip for maintenance is to CHANGE YOUR BATTERY WHEN YOU CHANGE YOUR CLOCK. When you replace the battery, use a vacuum cleaner to pull any dirt, dust or debris that may be found underneath the detector cover.

 

 

Replace the battery every year in all battery operated smoke detectors. (The detector is designed to emit short “beeps” with increasing frequency when the battery is losing power).

 

other important considerations include

• Strategically locate detectors so they can be heard from the main bedroom. If only one detector is to be used, place it on the ceiling in the hallway outside the bedrooms.
• Mount the detector in the middle of the ceiling, or, if that is not possible, detectors should be placed on the wall at least three feet away from a corner and 4-6 inches away from the ceiling.
• Avoid placing detectors too near the kitchen stove and bathroom shower.
• Put smoke detectors at both ends of a bedroom hallway if the hallway is more than 40 feet long.
• Put basement detectors at the bottom of the basement stairwell.
• Read the manufacture installation guide

false alarms

Cooking vapors and steam sometimes set off a smoke alarm. To correct this, try moving the alarm away from the immediate kitchen area and bathrooms.

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