Fire Alarm Systems

Is Fire Really a Problem?

According to the National Fire Protection Association (NFPA) a fire department responded to a fire somewhere in the US every 19 seconds in 2002. In 2002, there were 3,380 civilian fire deaths. In 2002, there were 389,000 reported home fires in the United States, resulting in 2,670 deaths, 13,650 injuries and $5.9 billion in direct property damage.

Are Smoke Detectors Effective?

Only one-fifth of the home fire deaths from 1989-1998 were caused by fires in which a smoke alarm was present and operated. The US Consumer Product Safety Commission (CPSC) recommends consumers place a smoke alarm that meets the requirements of a professional testing laboratory, such as Underwriters Laboratories (UL), on each level of multi-story homes outside sleeping areas, and inside bedrooms. CPSC has worked to strengthen smoke alarm performance and installation requirements and is now studying audibility to see if there are ways to make the alarms more effective in waking children and alerting older people.

The US Fire Administration has the following to say about smoke alarms “In the event of a fire, a smoke alarm can save your life and those of your loved ones. They are the single most important means of preventing house and apartment fire fatalities by providing an early warning signal — so you and your family can escape. Smoke alarms are one of the best safety features you can buy and install to protect yourself, your family and your home.”

FEMA Review Of Deadly Florida House Fire Reflects Importance Of Working Smoke Alarms

A technical review of a 2001 Florida house fire that killed six people – five of them children under age seven – has been released by the Federal Emergency Management Agency (FEMA). According to the review, the lack of a working smoke alarm allowed the fire to become so intense that rescuing the victims was impossible. The tragedy is all the worse because it might have been prevented if there was a working smoke alarm in the home. The local fire department had an aggressive public education program that included free smoke alarms and batteries, but demand was not great; interest in the items increased significantly after the fire. Smoke alarms are inexpensive and easy to install, and easy to check and keep operational. They are the closest thing to having a firefighter on duty in your home 24 hours a day. A copy of the full report can be downloaded by going to: www.usfa.fema.gov/fire-service/techreports/tr142.shtm.

Are Fire Systems Required?

Your local fire marshal may require a fire alarm system based upon the occupancy of the building. The occupancy of a building is determined by how the building or portion of the building is used. There are different requirements for schools, offices or other types of uses. Check with your local fire marshal or your alarm company to determine the requirements for your application.

If I Have Smoke Detectors Why Do I Need a Fire System?

There are two major categories of fire alarms: self-contained units, as exemplified by the single-station residential smoke detector unit (battery-operated or hard-wired to building electrical power) which produces an alarm signal at the fixture itself when activated by an integral sensing device, and building-wide systems, integrated (often zoned) alarms whose local signals are remotely initiated, either automatically from detectors or manually from pull stations spread throughout a facility.

Fire detection is often available as part of a complete burglar alarm system. The smoke/heat detectors may be hardwired back to a control unit which can be used to activate a number of reporting devices. Wireless systems are also available.

This type of alarm system has many advantages to protect your life and property including:

  • The ability to summon the Fire Department for immediate action whether you are at home or away.
  • In a fire alarm system all the component are powered from a control panel that has backup battery power to operate the system in the event of a power failure.
  • If one fire sensor picks up a fire all of the notification devices activate to make sure that you know a fire has been detected.

Alarm Initiating Devices and Detectors

Selecting the right detector for the job requires defining the hazard(s) and level of detection required. Among the variables to be considered are speed, sensitivity, accuracy, ambient conditions of the device location, integration with controller and device packaging as well as code requirements.

A variety of types of detectors can be used to form a complete fire system including:

  • Heat Detectors
    • fixed temperatures fusible element
    • linear detection/heat sensitive cable
    • rate of rise detector
    • rate compensation detector
  • Smoke Detectors
    • ionization
    • photoelectric
    • high sensitivity air sampling
  • Optical Flame Detectors
    • ultraviolet (UV)
    • infrared (IR)
    • combination ultraviolet/infrared (UV/IR)
    • multi-spectral
  • Manual Stations
  • Water flow Switches

Types of Smoke Detectors

A smoke detector warns of fire when it senses the products of combustion in the atmosphere. As anyone who has a smoke detector too close to the kitchen knows, a smoke detector goes off very quickly, even in small amount of smoke. There are slight differences between the two types of smoke detectors, but they both operate by detecting the products of fire combustion.

Some smoke detectors are self contained with a sensor to sense the smoke and a very loud electronic horn to wake people up. Self contained smoke detectors can run off of a 9-volt battery or 120-volt house current. Some models run off of house current and change to battery backup if the house current fails.

Others, known as system detectors are powered by a central source and connect to a control panel to sound the alarm.

Smoke detectors use two types of technology, photoelectric detectors and ionization, to sense a fire.

Photoelectric Detectors

Photoelectric smoke detectors use light and how it is reflected to detect smoke. Normally light is projected into a smoke sensing chamber inside the detector assembly. The light hits a black background of the chamber and is absorbed. When enough smoke enters the chamber it reflects the light on to a sensor inside the chamber. This causes the sensor to indicate an alarm. Photoelectric detectors are better at sensing smoky fires, such as a smoldering mattress.

Ionization Detectors

Ionization smoke detectors use a small amount of radiation to detect smoke. A small amount of electrical current flows form one point to another inside the smoke chamber within the smoke detector. When smoke enters the chamber it disrupts the flow of current and generates an alarm.

What are Heat Detectors?

Heat detectors warn of fire when the temperature in the areaaround the smoke detector reaches a certain level. Heat detectors do not notice smoke. Some studies show that heat detectors may not provide early enough warning to aid escape from a life-threatening fire. However, a heat detector could be valuable additional protection in areas such as kitchens and attics, where smoke detectors are not recommended. They are not recommended for the use in bedrooms or sleeping areas. There are several types of heat detectors including:

  • Rate-of-rise heat detectors: If the temperature sensed by this type of detector increases faster than a specified rate, an alarm will be initiated. A typical rate may be 8.3 degrees Centigrade per minute. In most of these detectors, when the rate of rise element alone has been activated, the detector is self-restoring.
  • Fixed-temperature heat detectors: If the temperature at the detector rises to the detector’s rated temperature, an alarm is initiated. Often, when actuated by the fixed temperature element, the detector is non-restorable and must be replaced. A typical set temperature might be 57.2 degrees Centigrade.
  • Combined rate-of-rise/fixed-temperature heat detectors: Some heat detectors combine both features, providing warning when the rate-of-rise and/or the absolute temperature is exceeded.

What are Pull Stations?

Pull stations allow a building occupant to signal that a fire has been observed as they leave a building. Manual pull stations are located according to specific standards in each of the paths that people normally use to exit a building.

Types of Notification Devices

Fire alarm systems utilize an variety of devices to alert building occupants and fire authorities within the protected area as well as outside that an event or fault has occurred. These devices include:

  • audible alarms (horns, bells, buzzers, chimes, etc.)
  • visual alarms (strobes, etc.)
  • remote enunciators
  • communications systems
  • data display and output devices (CRT’s, printers, etc.)

What Are Visual Alarms?

Visual alarms are flashing lights used as fire alarm signals.

The terms visual alarm signal, visible signal device, and visible signaling appliance are used relatively interchangeably within the fire protection community; the National Fire Protection Association (NFPA) calls them visual notification appliances.{/slide}

{slide=”Why are Visual Alarms Required? “}One American in a hundred has a severe hearing loss; nearly one in ten has a significant loss. A visual alarm provides persons with hearing loss the same warning delivered to hearing persons by an audible alarm.

In passing the Americans with Disabilities Act in 1990, Congress specifically directed the Access Board to provide greater guidance regarding communications accessibility. Thus the ADA Accessibility

Guidelines (ADAAG) require that where emergency warning systems are provided in new or altered construction, they must include both audible and visible alarms that meet certain technical specifications.

What is a Voice Evacuation System

A voice evacuation System operates in conjunction with the Fire Alarm Control Panel in a building to provide automatic response to life safety emergencies.

Automatic evacuation, stay-in-place, or other public address messages can be played over speakers located throughout the building and fire authorities can make announcements as necessary to take command of evacuation or relocation procedures and emergencies.

Fire Fighter Phones or Warden Stations may be included as required.

Why Voice Evac.?

Why use a voice evacuation system rather than just a standard audible horn or bell notification? The Life Safety Code, NFPA 101, was changed in 1983 to require voice systems in assembly occupancies where the occupancy load is 300 persons or more. This change in the Code suddenly included structures such as theaters, auditoriums, nightclubs, restaurants and even churches.

With so many devices making alarm like sounds all around us, people have become complacent to alarm sounds and signals. Combining a signal with a voice message, instructing occupants what to do, has been proven to be much more effective in getting people to a safe area.

Do I Need A Fire Alarm If I Have Sprinklers?

The US Fire Administration says “Don’t Forget the Smoke Alarms

Even though fire sprinklers are effective life safety devices you still need smoke alarms. Some fires can begin as smoldering fires that produce smoke and gases but don’t generate enough heat to activate the sprinklers. Smoke alarms are needed to provide warning for these situations.”

How Many Smoke Detectors Do I Need?

Install smoke alarms on every level of your home, including the basement. Many fatal fires begin late at night or in the early morning. For extra safety, install smoke alarms both inside and outside the sleeping area. If all the bedrooms in your home share a single hallway, place the smoke detector in the hall outside the rooms. You should have an additional detector outside every bedroom that doesn’t share a common hallway. If you sleep with the door closed, put another detector inside the bedroom. On floors without bedrooms, place detectors in or near living areas. A good place for a smoke detector in a two-story house is at the top of the stairs since smoke from downstairs will rise along that path.

Also, smoke alarms should be installed on the ceiling or 6 to 8 inches below the ceiling on side walls. Since smoke and many deadly gases rise, installing your smoke alarms at the proper level will provide you with the earliest warning possible. Always follow the manufacturer’s installation instructions.

How Long Will My Smoke Alarm Last?

About eight-to-ten years, after which it should be replaced. Like most electrical devices, smoke alarms wear out. You may want to write the purchase date with a marker on the inside of your unit. That way, you’ll know when to replace it. Always follow the manufacturer’s instructions for replacement.

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