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Residential Fire Alarm Protection:
Is your family ready??
Residential fires have become a significant problem throughout the world. The National Fire Protection Association (NFPA) of United States of America estimates that residential fires in the United States kill 4,000 to 5,000 persons annually and result in injury to 20,000 more. According to the Federal Emergency Management Agency, in its National Fire Incident Reporting System, the leading causes of residential fires in one- and two-family dwellings were heating (31%), cooking (15%) and incendiary or suspicious (10%).
In residential properties, cigarettes are still the leading cause of accidental multiple-death fires (those fires that are fatal to three or more persons) by a factor of two to one. Fires resulting from fixed or portable heating equipment—wood stoves, kerosene heaters, gas or electric cooking stoves, etc.—are the second most common cause of accidental multiple-death fires in residential properties.
When and Where Fires Start
An NFPA study of 1982 multiple-death fires shows that residential fires accounted for nearly 90% of the fires and 85% of the deaths. This study also showed that 83% of the fires originated in the living room, 20.8% in the bedroom, 11.7% in the kitchen, 7.6% at exits, 5.1% in a structural area, 1.5% in a heating equipment room, and 3% in other areas. About 81% of the multiple-death fires occurred between 8 p.m. and 8 a.m., when people are asleep and unaware of the development of a fire until it is too late.
Fire officials estimate that at least 50% of lives lost due to residential fires could be saved by installing early warning fire detection devices and developing and practicing an evacuation plan.
Early Warning Systems
To protect the purchaser and establish criteria for the manufacture and installation of residential fire detection systems, the National Fire Protection Association has developed NFPA No. 74, Standard for Household Fire Warning Equipment.
Types of Early Warning Systems
There are two types of residential fire detection systems: heat and smoke detectors. The basic residential detection system, according to NFPA No. 74, relies primarily on the use of smoke detectors. The standard does not require the use of heat detectors as part of the basic protection scheme, but it recommends that heat detectors be used to supplement the basic smoke detector system.
Smoke detectors consist of a sensing chamber, alarm sounding device and a means of electrical power transmission. There are two kinds of residential smoke detectors: ionization and photoelectric.
The ionization smoke detector uses a radioactive source (typically americium-241, an alpha-emitting radionuclide) to ionize the air within the sensing chamber. The ionization of air by the radioactive particle causes a very small flow of electrical current. When smoke from a fire enters the chamber, its presence causes a reduction in the current's flow. The electronic circuitry senses the reduced flow and triggers the alarm horn.
Photoelectric smoke detectors use the principle of scattered or reflected light to indicate the presence of visual smoke. They work much like the automatic eyes used to open doors. When there's no smoke, the chamber is dark. The light shines across the chamber and is received in a light trap on the far side. When smoke is present in the chamber, a photocell located at right angles to the light source senses the light scattered off the smoke particles and, at a certain level of illumination, triggers the alarm horn.
Both detectors sense the presence of smoke. The photoelectric detector senses the large, visible smoke particles. The ion chamber detector senses the small, invisible particles.
If a fire starts and slowly smolders in upholstery without visible flame, a good photoelectric unit would be superior to a good ion chamber detector in terms of detection time. But if the fire has flames, a good ion chamber will detect it faster than a good photoelectric detector. For this reason, it's a good idea to use both types in your detection system.
Recently, manufacturers have begun to introduce and market smoke detectors that combine ionization and photoelectric sensors in the same unit. These units should combine the advantages of both sensors into an advanced unit that will detect smoke from a broader spectrum of fires (smoldering or flaming). As the demand for these units increases, the cost should decrease to a competitive level.
A residential fire detection system may also include a heat detector. There are two types of heat detectors: fixed temperature and rate-of-rise.
Fixed temperature detectors are set to sound an alarm when the air temperature exceeds the fixed temperature. The most popular fixed temperature detectors used in homes are preset to sound an alarm when the temperature exceeds 135(F. Other units are available to be preset up to temperatures of approximately 200 to 225(F. These detectors may be used in an attic where summer temperatures normally may reach 135(F. Rate-of-rise heat detectors sound an alarm when the temperature in the immediate vicinity rises higher than the preset rate per time factor (minutes, etc.).
NFPA Code No. 74 requires that AC (home current) powered units meet the following conditions:
> Power supply must be sufficient to operate the alarm signal(s) of 85 decibels for at least four consecutive minutes.
>A visible “power on” indicator must be provided.
>All electrical systems designed to be installed by someone other than a qualified electrician must be powered from a source less than 30 volts. These systems should meet the requirements for power-limited fire-protective signaling circuits as defined in Article 760 of the National Electric Code No. 70.
> The power source for the unit must not be subject to loss of power by a wall switch.
> Neither loss nor restoration of the primary power should cause an alarm signal.
> A restraining means should be used at the plug-in of any cord connected installation.
> Single-station and multiple-station smoke detectors, powered from 120 VAC sources, should not be installed on circuits protected by a ground fault circuit interrupter. NFPA Code No. 74 requires that battery-operated units meet the following requirements:
> The alarm must be capable of producing an alarm signal of 85 decibels for four consecutive minutes.
> The batteries must meet all power requirements for at least one year, including routine testing.
> The alarm must be able to give a distinctive, audible trouble signal at least once per minute for seven consecutive days before the batteries are incapable of operating (from aging, terminal corrosion, etc.).
Battery-operated smoke detectors have two advantages and one disadvantage when compared with detectors operated from the dwelling's electrical power. One advantage of battery-powered units is that if the dwelling’s electrical power is off due to an interruption from the utility company or from a fire within the dwelling, the detector will still function. Some manufacturers are now making units with a battery backup in case power is lost.
The other advantage is that you can install a smoke detector in an existing dwelling even where no electrical outlet is available.
The major disadvantage is that the batteries need to be replaced once a year.
The basic (minimal) detection system should consist of one smoke detector outside of each sleeping area and one additional smoke detector unit on each additional living level, including the basement and excluding unfinished attics, crawl spaces, etc. If hallways are longer than 40 feet between the sleeping and living areas, use two smoke detectors.
A good system should include both types of smoke detectors, one plug-in smoke detector and one battery-operated smoke detector. You might consider installing a photoelectric unit in the bedrooms of any family members who smoke.
Heat detectors or additional smoke detectors can supplement the basic system. Consider these areas for heat detectors: kitchen, dining room, furnace room, attic, garage or utility room.
Follow the manufacturer's recommendations for mounting and servicing the detectors. Place the first unit in the center of the hallway ceiling between the bedrooms and the living area, not closer than 12 inches from the wall.
Determine additional locations according to your lifestyle. If you must wall-mount the detector, it should be mounted no closer than 6 inches and farther than 12 inches from the ceiling. This is to avoid the dead air space.
If you own a mobile home, you may want to consider wall mounting your units on an inside wall to avoid some of the problems of ceiling drafts.
Smoke detectors should not be located in the following areas:
>Kitchen, because of false alarms (burned food, etc.).
> Garage, because of temperature extremes and false alarms.
> In front of air registers, open windows or open doors, because of false alarms caused by high air velocities.
> In or near attics, bathrooms, inside air ducts, unheated buildings and unheated motor homes, because temperatures may exceed typical limits of 32 to 100F.
With the advent of modern electronic circuitry, the single-station smoke detector has become the subject of strong sales rivalry by several companies vying for the household market. The result is that some sales personnel are using high-pressure tactics. Therefore, it is wise for the potential buyer of a residential fire alarm system to be cautious. Here are some buying tips:
>Don't be frightened into a quick purchase. Some door-to-door sales personnel use films, pictures and tape recordings that play on your emotions. Get at least two or three price estimates from different manufacturers before purchasing.
> Test the units as you install them or, if you elect to have someone else install the units, request that the installer test the units in your presence.
> Request an instruction booklet that gives you information on operation, testing and maintenance of the alarms.
> Buy only fire alarms with labels showing they have passed the tests of the Underwriters' Laboratories (UL) or Factory Mutual (FM).
> Understand the guarantee or warranty with the unit you select, and be sure you understand who will repair or replace the unit if it is defective.
An Escape Plan:
Your job is not done, however, after you buy and install smoke detectors. There remains the task of training your family to respond properly when a fire is sounded.
.The first thing to do is to develop a family plan for escape. It is a good idea to make a floor plan with two escape routes.\
Basic floor layout:
> Make an outline of the entire floor area. Dimensions and details need not be exact.
> Now add each bedroom and label it.
> Locate windows, doors and stairways. On upper floors, shade in any rooftops that could be used as a fire escape.
> Go to each bedroom. Select the best window for an emergency escape.
> Test the window to see that it works easily and is large and low enough.
Complete escape plan:
> Black arrows show normal exits through hall or stairway.
> Colored arrows show emergency exits in case fire blocks hallway or stairs.
Every member of your family should have at least two escape routes from his or her bedroom. One usually will be by the door into the hallway; the other route usually will be by the window.
For two-story residences, it probably will be necessary to provide a chain ladder (the first choice) or a rope ladder to escape. Again, this requires training because the person using the ladder must make certain he or she is not going to be crawling past a life threatening fire on a lower floor and must know how to use the ladder.
“The first thing to learn is that no one should jump up out of bed and stand when the alarm sounds.”
Every member of your family should know exactly what he or she is expected to do in the event of a fire. This can be accomplished by holding family fire drills.
The first thing to learn is that no one should jump up out of bed and stand up when the alarm sounds. Instead, all family members should learn to crawl out of bed onto the floor. In the early stages of a fire, the toxic and super-heated fire gases lie in layers near the ceiling. It is very important to stay below these gases. There have been many cases where it appears that victims slept through the build-up of deadly gases only to die when they stood up and inhaled them.
All members of your family should crawl to their bedroom doors. If the door is closed, feel it. If it is not hot to the touch, it is probably safe to place your body weight against the door and open it slowly to see if smoke and flames have filled the hallway. Use your body weight to keep the door from opening quickly in the event that there is heavy smoke or fire in the hallway or an explosion of fire gases.
If the hallway appears clear, the first member of the family into the hallway can then crawl from one bedroom to the next to make certain that all family members are awake. Use the hallway and nearest outside door for escape only if you are very certain that no flames are visible and there is little or no smoke along the path you must travel.
Select a meeting place for all family members outside the home near a tree, mailbox, etc. Everyone should go immediately to this meeting place. When everyone is accounted for, someone can be selected to go to a neighbor's home to call the fire department. When calling the fire department, speak slowly and distinctly so that you are sure the fire department understands whose house is on fire and where it is located. In fact, you should practice giving directions to your home, the same directions you would give to a visitor who had never been there before. Stay outside! Once everyone is out of the house, no one should return. More than one person has been killed by going back into a fire to save a few dollars worth of keepsakes. Obviously, learning the fire escape plan is like learning anything else—you get better at doing it if you practice. Periodically, Residential Fire Protection Section 13.7 Page 8 The Disaster Handbook 1998 National Edition Institute of Food and Agricultural Sciences University of Florida preferably once a month, someone in the family should sound the alarm in the middle of the night and then monitor the actions of other family members to see that they comply with the fire drill plans. Remember, installation of an early warning fire alarm system combined with a well-rehearsed plan for escape may save the lives of you and your family
Addressable Fire Alarm Systems
Rather than being limited to a general zone information (see conventional alarm system), addressable alarm systems can identify individual alarms and can therefore pinpoint the location of the fire or of any errors much better. A wider range of devices can be deployed.
Addressable Fire Alarm Panel:
Addressable fire alarm panels use an intelligent programming system that allow you to assign an "address" to each detector and device that has been installed on the system. Unlike conventional systems that indicate the zone, addressable fire alarm panels identify the exact detector or device that has been activated, helping to save valuable time in the event of a fire or suspected false alarm.
The Syncro AS single loop addressable fire alarm panel from Kentec is capable of running up to 126 Apollo devices, with each given a unique address for ease of identification when the system has been activated. Its large graphical display and clear control button layout allow for installers, engineers and end users to easily configure and maintain the addressable panel when needed. The Kentec Syncro AS panel offers a range of configuration options as well as a number of programmable inputs and relays, giving the fire alarm system the flexibility to adapt to various commercial applications.
Addressable Smoke and Heat Detectors
To operate with an addressable fire alarm panel, smoke, heat and multi-sensor detectors require specially designed bases that give each detector an "address" for the fire alarm panel to recognise. As well as the Apollo XP95 and Apollo Discovery smoke and heat detectors, we offer a range of standard, isolating, beacon and sounder beacon mounting bases that allow the detectors to form part of the addressable system.
The Apollo XP95 optical smoke detector has an LED alarm indicator. When in standby mode, the LED remains clear and turns red when in alarm condition. The optical smoke detector is designed to react quickly to slow smoldering fires which produce a lot of smoke. When installed using the XP95 series mounting baseor XP95 isolating base, the Apollo XP95 optical smoke detector can be used as part of an XFP or Kentec addressable fire alarm panel system.
Addressable Manual Call Points
If a fire is discovered before the fire alarm system is activated, the addressable manual call point allows occupants to trigger the system from a single location. As part of an addressable fire alarm system, each installed call point is assigned an "address". This allows for authorised personnel to quickly identify the exact device that has been activated, and in turn saves time for the emergency services to locate the origin of the fire.
The Apollo Discovery red manual call point features a built-in short circuit isolator and complies with EN54-11:2001. Providing a way to manually activate an addressable fire alarm system, the Apollo Discovery call point is supplied with a resettable element which negates the need to purchase replacement glass after each use. The manual call point has a bi-coloured LED indicator and is supplied with clip-on terminal blocks and a connector for ease of installation.
Addressable Sounders and Beacons
Forming an essential part of an addressable fire alarm system, sounders and beacons provide audible and visual warning in the event of an emergency. Typically, addressable sounders and beacons are installed inside a building; however, there are a number of applications such as hospitals, schools and garages where a weatherproof sounder or beacon may be required. Our sounder and beacon range include those that have an IP65 rating, making them weatherproof for open area environments.
The XP95 open area sounder beacon is wall mounted and designed to work as part of a XFP or Kentec addressable fire alarm panel system. The sounder beacon is weatherproof (IP65 rated) and is supplied with a built-in isolator. The nominal sound output is 100dB; however the sound can be adjusted to 92dB using the volume control feature.
Two wire (also known as Sav-Wire) conventional fire alarm panels allow sounders, beacons, detectors and call points within one zone to run on the same pair of wires, meaning there is no need for a separate sounder circuit. This reduces the wiring costs.
Designed for use with the range of C-Tec AlarmSense detectors, call points, sounders and beacons, this conventional 8 zone fire alarm panel is acceptable for BS 5839-1 and BS 5839-6 systems and fully complies with EN 54 Parts 2 and 4. Due to its two-wire setup the C-Tec CFP AlarmSense panel allows for detection and alarm devices to connect to the same pair of supply wires, making it less expensive and more flexible to install than other conventional fire alarm systems.
Conventional Smoke and Heat Detectors
Hard wired to the main fire alarm panel, conventional smoke, heat and multi-sensor detectors form an essential part of a fire alarm system. When triggered, the conventional smoke or heat detector signals the main panel, which then activates its other connected components and warns occupants of an emergency situation. Suitable for use with 2, 4 and 8 zone fire alarm panels, our range of conventional smoke, heat and multi-sensor detectors include Apollo Series 65, Veritas 2, AlarmSense and Rafiki Multipoint. Separate detector bases provide additional functionality, some enabling sounder and beacon presence and others enabling two wire compatibility from four wire.
This optical smoke detector for CFP and Kentec Sigma fire alarm systems is part of the Apollo Series 65 range. The detector is activated when smoke enters the chamber and causes an LED light pulse to scatter. At this point, the optical smoke detector changes in to the alarm state.
Conventional Manual Call Points
Conventional manual call points are typically installed at various fire escape route locations throughout a premises. Featuring bright red housing for ease of identification, the manual call point allows for occupants to manually activate the fire alarm system in the event of an emergency. Conventional manual call points are available with either a replaceable glass window or with a flexible plastic element that can be reset after each use.
Conventional Sounders and Beacons
To have an adequate amount of time to evacuate the premises in the event of an emergency, it is important to receive the earliest possible warning of danger. Designed for use as part of a two wire or four wire fire alarm system, conventional sounders and beacons provide audible and/or visual indication when the fire alarm system has been activated. Conventional sounders emit a high decibel output, whilst beacons are suitable for Disability Discrimination Act (DDA) compliant installations.
Fire alarm bells are a popular choice of audible warning for use in evacuation systems. Made of robust aluminium, these 24V alarm bells are available in two different sizes, with a choice of internal or external (weatherproof) suitability. Each bell has a high sound output with a low power consumption.