Automatic Alarm System

8/10/2019 Automatic Alarm System

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Dr. Eng. Walid Abdelghaffar

[email protected]
mailto:[email protected]:[email protected]


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Dr. Walid Abdelghaffar2Detectors

Why alarm system?

A security and safety system is an investment for

your peace of mind. In general, a system is available

for any budget. Costs do vary and largely depend onwhich security features chosen and the protected

area.

Detect fire

Initiate alarms

Activate fire isolation devices and / or fire suppression

systems

Protect life and property


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Detection System

Detection system selection must fulfill two

requirements:

1. It must be sensitive enough to detect combustion withinan acceptable and required time frame.

2. It must be reliable enough to not respond to non-fireactivation sources


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A determination of the proper detection system

depends on:

A basic knowledge of the function of the different

detectors.

The hazard characteristics.

The stages of combustion.

Detection System


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The Stages of Combustion

1.1. Incipient stageIncipient stage

2.2. Smoldering stageSmoldering stage

3.3. Flame stageFlame stage

4.4. Heat stageHeat stage


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1. Incipient stage

where invisible products of combustion areproduced

At this stage, smoke is not visible, nor has the

heat of combustion developed.


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2. Smoldering stage

The smoldering stage

occurs when the combustionhas developed to the point where combustion

products are visible as smoke, but flame and heat

are not yet a factor.


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3.Flame stage

The flame stage is an intermediate stage whereconsiderable heat is not yet being produced by

the combustion , although this stage very quickly

moves into the next, the heat stage.In this stage there may be a clean flame, but little

or no smoke.


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4.Heat stage

The heat stage combines all theelements of combustion-invisible products as

well as visible smoke, flame, and heat.

Classification of fi e detecto s


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Classification of fire detectors(EN 54 1976)

Detectors can be classified based on:

Fire phenomena

Response ModeResettability

Configuration

Detachability


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Fire phenomena:

Heat

Smoke

Gas

Flame


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Response Mode

Static

Differential

Rate of rise


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Resettability

Resettable

Self

Remotely Locally

Nonresettable

With exchangeable elements

Without exchangeable elements


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Configuration

Point

Multi-point

Line


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Detachability

Detachable

No detachable

i ili


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Fire Detectors Families

FireFire

Turbulent FlowTurbulent Flow

Laminar FlowLaminar Flow

Ultra-VioletUltra-Violet

VisibleVisible

Infra-RedInfra-Red

VisibleVisible

InvisibleInvisible

GaseousGaseous

AerosolAerosol

ConvectionConvection

RadiationRadiation

SuspensionSuspension

ResidualResidual

Thermal EnergyThermal Energy

Conservation

Of Matter

Conservation

Of EnergyFlame

Detector

Heat

Detector

Smoke

Detector

1 S k


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1.Smoke Detectors

1. Photoelectric Smoke Detector

2. Ionization Smoke Detectors

1.Photoelectric Smoke Detectoruses the light-reflection principle to detect smoke.

A) spot type detector

B) beam/line type detector

C) duct type detector


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. o o-e ec r c smo e e ec or


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. o o e ec r c smo e e ec orA) spot type detector

Ph t l t i S k D t t


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Smoke free chamber light

beam travels straight

through

Smoke particles in

chamber deflect some

light rays

Photoelectric Smoke Detector

Ph t l t i S k D t t


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The refractory photocell uses a light beam that passesthrough a small chamber at a point away from the light

source. Normally, the light does not strike the photocell,

and no current is produced. When a current does notflow, switch in the current remains open.

When smoke enters the chamber, it causes the lightbeam to be refracted (scattered) in random directions. A

portion of the scattered light strikes the photocell causing

current to flow. This current closes the switch andactivates the alarm signal




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A photoelectric smoke detector is activated by visible smokeparticles entering the detector.

The photoelectric detector responds to the thicker, heavier,visible smoke that develops when slow-developing andsmoldering combustion is presented.

A slow-burning or smolder fire is typical of combustion ofmaterials found in the office, home photoelectric, hotels, andhospitals.

The engineer may, in order to provide reliable combustiondetection, recommend the installation of both ionization andphotoelectric detectors if the type of fire potential cannot be

readily determined




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In an effort to obtain a sensitive, early warningdetection system where ionization detectors appear tobe the best selection, it is imperative that the general

environment be considered because these detectorswill react to many non-fire invisible particles, includingexhaust fumes, welding operations, kitchen odors, andpilot lights.

Maintenance is a prime consideration with detectionsystem.

Dust and contamination can affect the sensitivity of anydetector, either by making it more sensitive to non-fire

detection sources, or by reducing the sensitivity


Signal Conditioning Circuit for


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g gPhotoelectric Smoke Detector



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ReceiverLight Source

Light Beam

Clean Air

ReceiverLight Source

Light Beam

Smoke Particle

Linear Beam Smoke Detector


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The linear beam smoke detector basically operates on the sameprinciple as the photoelectric smoke detector with a light sourcedirected on a photo-sensitive receiver.

The difference is that the linear beam smoke detector consists of

two separate units. The light source is one piece of equipment,and the light beam receiver is a separate piece of equipment.

The linear beam smoke detector light source, or transmitter,emits an invisible infrared beam over open area distances of 35'

to 300' on to the light receiver.

When no smoke interferes with this beam, the receiver acceptsthe beam at a specified voltage level, but when smoke interferes

with the beam, the infrared light reaching the receiver islessened, and when the beam intensity drops below thepredetermined sensitivity level of the receiver, it initiates a signalfrom the detector



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This type of smoke detector has many applications in

areas where spot-type smoke detector could not be

installed to operate efficiently,

Such as:

Airport terminals.

With very high ceilings.

Aircraft hangars.

Churches, and large open facilities.




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Duct detector


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Duct detector

Duct detectors are ionization photoelectric. They are usually installed on a return air duct close to the fan unit.

Duct detectors are installed on the exterior of the duct with longtubes extending into the duct .these tubes have holes that pick upproducts of combustion. In the air stream returning from the ventsin the facility, transmitting them into the detector unit on theoutside the Duct

When the detector is activated, one of the signals it actuates is anautomatic shut-down of the heating and air-conditioning fans toprevent the products of combustion from being sent back throughthe heating and air-conditioning system throughout the building.

Duct detectors provide an excellent function but always keep inmind that they should not substitute for a detection systemthroughout the facility

2. Ionization smoke detector


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2. Ionization smoke detector


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Ionization detector


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Ionization detector

In evaluating the hazard, the level of required detection

sensitivity, the environment in which the detector will function,and the type of combustion anticipated, it may be determinedthat the combustion should be detected in the incipient stagebefore there is appreciable heat and smoke in order to

prevent heat and smoke damage to delicate electronicequipment.

In such cases, ionization detectors should be seriously

considered because they react when invisible products ofcombustion are given off by the combustion before there isvisible smoke has developed.

The analysis of the combustibles present and the type of fire

that these combustibles will produce should be the firstconcern when making a detection selection.

Fire that develop rapidly into flaming stage without the

accumulation of heavy, visible smoke particles are detectedmost effectively by ionization detectors.

Photoelectric Verses IonizationS k D t t


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Smoke Detectors

Photoelectric

-Respond more quickly to smoldering fires

Ionization-Respond more quickly to flaming fires with smaller combustion

particles

-Less expensive-Less power requirements

Limitation is the radio active materialused in it.

2.Heat Detectors


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2.Heat Detectors

1. Fixed temperature heat detectorsResponds to changes in ambient temperature

a) Spot type

b) Bimetal

2. Rate-of-rise heat detectors

Respond to the sudden change or Rateof rise inambient temperature from a normal baselinecondition

a) Rate compensated detectors

b) Rate of rise detectors

3. Combination detectors

Thermal detection systems
http://en.wikipedia.org/wiki/Ambient_temperaturehttp://en.wikipedia.org/wiki/Baselinehttp://en.wikipedia.org/wiki/Baselinehttp://en.wikipedia.org/wiki/Baselinehttp://en.wikipedia.org/wiki/Ambient_temperature


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Thermal detection systems

The operation of thermal detectors is the leastsophisticated of all the detectors

Thermal detectors are designed to actuate at apredetermined fixed temperature.

They should be used when the protected hazard areahas the potential to produce considerable combustionheat, or at least sufficient combustion heat to activate

the detector before considerable damage is donepassing through the early stages of the combustion.

A sprinkler head is actually a thermal detector, when

combustion heat reaches the temperature setting of thefusible element of the sprinkler head, the fusible elementmelts, or softens sufficiently to release the head linkage,thereby releasing the discharge. The water movement in

the piping actuates a device that transmits an alarm

Thermal detection systems(cont,)


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y ( ,)

The sprinkler head is a good example of a non-restorabledetector.

Once the head is activated, it must be replaced.

A thermal element melts at a predetermined temperature,

releasing a mechanical arrangement such as a spring or aplunger which makes or breaks an electric circuit, activatingthe alarm system.

Other thermal detectors are available that activate at a

predetermined fixed temperature, but are self- restoring.After the detector has been activated and the combustionheat removed, the detector returns to room temperature andautomatically resets it self

When designing a detection system that activates asuppression system, and the detectors are self-restoring,always determine what may be required to maintain thesuppression system in an operating condition should thedetector reset

1.Fixed temperature heata) Spot type


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a) Spot type

Detect heat by one or more of 3 primaryprinciples of physics:

1. Expansion of heated material

2. Melting of heated material

3. Changes in resistance of heated material

Spot type


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p yp

Has a detecting element or elements that respond to

temperature conditions at a single point or in a small area.

Designed for one-time operation, and the whole device or the

element needs to be replaced.

Usually 57C to 62C or 85C to 92C

Fixed-temperature devices


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Fixed temperature devices

That melt employ soft metal alloys or thermoplasticresins to hold together a two-piece link or latchingmechanism. A frequently used metal alloy is solder.

When the solder melts, the link separates or the latch isreleased, causing an alarm signal to sound.

Another type of fixed-temperature device actuatesthrough the expansion of heated solvents. In this type ofdevice, small glass bulbs contain solvents; the bulbs aremanufactured to break at predetermined pressures.

When the solvent is heated, it vaporizes. The resultingvapor pressure breaks the glass bulb, which has beenholding two electrical contacts apart. the contacts close,

causing an alarm signal to be send.

1.Fixed temperature heata) Bimetal type


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a) Bimetal type

Contact

Metal A

Metal B

WiringTerminal

Uses 2 metals with different thermal expansion

characteristics, when heated, 1 metal expands faster than

the othercausing the strip to bend or arch, Deflection of

strip makes or breaks alarm circuit, initiating an alarm

Automatically when cooled

2.R-O-R heat Detector


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a) Rate-compensateddetectors b) Rate-of-rise detectors

-When temp rate of r ise increase the pressure change rate

increase, at low rates the high pressure air allowed to escape

through an air breather and at high rates it affects a bellowdiaphragm and causes the alarm

Rate of Rise Detector


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The rate of rise detector responds to a rate oftemperature rise of 15 C per minute regardless of the

room's ambient temperature. This feature gives the

rate of rise detector an advantage over thermal

detectors because it is not affected by thermal lag.

The rate of rise detector is activated by the very rate

of temperature rise that is lost with a thermal detector.

If the temperature rises at the rate of 15 C per minute,

the rate of rise detector will activate.

Rate of Rise Detector


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There are certain disadvantages of the rate of risedetector:

1. Slow-burning or smoldering combustion may produceconsiderable heat, and the ceiling where the detector is

located may rise to a very high temperature, but unless

the rate of heat rise is rapid enough to produce a 15 Cper minute increase, the detector will not activate.

2. It is for this reason that combination fixed temperatureand rate of rise detectors are used to overcome the rate

of temperature rise disadvantage

Rate-of-rise detectors


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Respond to quick changes in temperature rather thanactivating at a fixed temperature.

Most rate-of-rise detectors have a small chamber filled

with air.A small vent from the chamber allows for slow changes

in temperatures.

If rapid heating occurs, however, the air inside thechamber expands. The small vent cannot relieve thepressure, which forces a diaphragm out.

The movement of the diaphragm either opens or closes

a set of electrical contacts than initiate an alarm signal

Rate compensation detector


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The rate compensation detector, sometimes referred toas a rate anticipation detector, consists of two metallicstruts mounted inside of a steel elongated shell.

The stainless steel shell has a coefficient of expansion

greater than the two metallic struts mounted within it.When the shell is exposed to heat, it expands, and since

the ends of the two struts are attached to either and ofthe shell, the expanding shell pulls the struts and

stretches them until they make contact at the center ofthe struts.

Rate compensation detectors have a predeterminedfixed temperature set point, and when the two struts

make contact and activate the detector, it has reachedthis temperature set point.

Rate compensation detector


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Unlike the rate of rise detector that requires a minimum15 C per minute rate of temperature rise to operate, asmoldering fire producing a slow rise in temperature

heat both the outer and the struts equally until the setpoint of the detector is reached

When the combustion heat is rapid, the ratecompensation shell expands rapidly until the struts arestretched to the point of contact, thus eliminating thethermal lag that may prevent a fixed temperature

detector from operating when the surrounding air hasreached the set point of the detector.

Heat actuating Device (H.A.D)


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The heat actuating devise, commonly referred to as theH.A.D is a rate of the rise detectorthat has been on themarket and in service for many years

Basically, the H.A.D is a hollow cylinder connected to the

system operating devices through small copper tubing. When there is an increase in combustion temperature,

the air in the H.A.D expands and the pressure created istransmitted through the copper tubing to activate a

diaphragm, or equivalent device that reacts to increasepressure.

This detection system is pneumatic, and as a result, hasbeen used frequently in areas where flammable vapors

may be present and an electric spark from electricdetector activation could cause an explosion.

Heat actuating Device (H.A.D)


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The H.A.D pneumatic system copper tubing is connected to adevice called a mercury check

The mercury check acts as the environmental temperaturechange vent for a group of H.A.D's that connected to themercury check.

The mercury check prevents an increase in pressure in oneH.A.D in the group from being dissipated by pressurizing theother H.A.D's in the group

The mercury check is a retard device to prevent false alarms.

Thermostatic release


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There is detector on the market that operates on the rate of rise

principle when the detector is subjected to a temperature rate increaseof 15 C or more per minute.

This detector can also be equipped with a sprinkler head to serve as afixed temperature detector.

The detector can function as a pneumatic or hydraulic system.

The thermostatic release detector operates on the principle of two

metals expanding at different rates when subjected to temperaturechange. The tube expansion exerts a pulling force on the rod, which inturn mechanic operates a valve that releases pressure on diaphragm,which then raises a clapper and vents the system.

The valve is actually a Schrader valve, the same valve found on thetires of a car or bicycle. When the rod is pulled by the expanding tube,it depresses the stem of the diaphragm then opens the vent, releasingair when the system is pneumatic, and water when the system ishydraulic

om na on xe empera ure nrate of the rise detector


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The combination fixed temperature and rate of the risedetector are used to overcome the rate of temperaturerise disadvantage.

The combination fixed temperature and rate of the risedetectors are activated when the rate of the temperaturerise is 15 c or more per minute. it also has a fusibleelement with a predetermined operating temperature.

The combination electrical spot detector is hollow shellcontaining a diaphragm . When the shell is subjected to

combustion heat that is increasing in temperature at arate of 15 C per minute or greater, the air trapped in thedetector shell expands, thereby forcing the diaphragm upto make an electrical contact that closes a current and

activates the system.

Combination rate-of-rise/fixed temperature detectors


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p

Feature the quicker reaction rate of the rate-of-rise

detector coupled with the higher dependability of thefixed- temperature unit

Pilot heat system


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The pilot heat detection system is a thermal detection systemfrequently used to activate suppression system.

The pilot heat system uses regular sprinkler heads as the thermaldetectors

These heats are installed on pipe which is filled with compressedair.

When a heat fuses, the compressed air is released, and the release of

compressed air pressure activates the suppression system valve

The pilot head detection system is very reliable in that it is not subjectto false trips from non-fire sources, which can cause havoc with otherdetector that, operate on a principle other that heat.

Pilot heat detection systems are frequently used to activate coolingtower and outdoor transformer deluge suppression system.

3.flame Detectors


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A device which detects the infra-red, ultraviolet, or visibleradiation produced by a fire.

Ultraviolet

infra-red

UV/IR Visible sensors

detectors work according to wavelengths to detect fires and

explosions within mil liseconds

mRadiant Energy

0.1-0.35Ultraviolet

0.36-0.75Visible

0.76-220Infrared

Flame Detectors
http://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Wavelength


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Ultraviolet Infrared

Most sensitive to detect fires, but also easily activated by non-fire

conditions (e.g.. welding, sunlight etc.)

Must be positioned with an unobstructed view of the protected area and

will not activate if line of site is blocked.

IR detectors are designed to require the flickering motion of flame ,UV

detectors insensitive to sunlight so they can be used in areas not

suitable for IR detectors


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Carbon Monoxide detectors


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Advantages of Carbon Monoxidedetectors over any other detector:

improved the speed of detection from slow

smoldering fires.

reduced the possibility of false alarms thansmoke detectors.

Four types of sensorsIn

carbon Monoxidedetector1. Opto-Chemical

2. Biomimetic

3. Electrochemical

4. Semiconductor


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Detectors Summary

Type of Detector Advantage Disadvantage


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Type of Detector Advantage Disadvantage

Ionization Smoke Detector

Effective at sensing fast flaming

fire, low cost and simple to

manufacture

Sometime too expensivecausing nuisance alarms and it

contains radioactive element.

Also, not effect ive at sensing

slow smouldering fire.

Photoelectr ic Smoke Detector Effective at sensing slowsmoldering fire High cost and not effective atsensing fast flaming fire

Air Sampling Smoke DetectorVery sensitive and have

multiple methods of operation.

Complicate to design and have

high cost. Vulnerable to

nuisance alarms.

Fixed Temperature Heat

Detector

Very sensitive to manufacture

and the production cost is not

high.

Easier to give false alarmscomparing with other heat

detectors and it needs to be

well placed for it to operate

effectively.

Rate Compensating Heat

Detector

More flexible and reliable than

fixed temperature detectors.

For effective operation it needsto be well placed. Additionally,

more complicated to

manufacture hence, possibly of

high cost.

Rate of Rise Heat DetectorRelatively simple tomanufacture and are more

sensitive.

Also need to be placed

efficiently. Vulnerable to

sudden environmental changes

thus causing nuisance alarms.

System design
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Takes into account:1. Location of fire

2. Classes of fire

3. Stages of fire (incipient, smoldering, visible

flames and intense heat)

4. Products of fire at each stage (Flames, Heat

,Smoke, Toxic gases )

Alarm & detection
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Fire alarm systems:installed in occupied building such as schools, hospitals,

designed to detect fires and to warn occupants forevacuation and notify a monitoring station or a firedepartment.

Fire detection system:

installed in unoccupied building to monitor processesand equipment, Is set up to notify a control room ormonitoring station, is typically installed:

The system may be:


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1. An alarm system2. A suppression system

3. An equipment shut-down system

4. An equipment start-up system5. A combination of any of these systems

By closing the electrical circuit, the detector signals thecontrol panel which transmits a signal to the varioussystems.

System components


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Primary (AC)

Control panel

Secondary (DC) output

input

System components: (CPU)/controlpanel
http://news.thomasnet.com/images/large/027/27329.jpghttp://news.thomasnet.com/images/large/027/27329.jpghttp://news.thomasnet.com/images/large/027/27329.jpghttp://news.thomasnet.com/images/large/027/27329.jpg


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Main function Receives signals from initiation devices (contacts, motion

detectors, smoke detectors etc.) and activates appropriate

notification devices (dialer, horns, strobes etc.)

Electrically monitors system wiring and primary power

Supplementary functions Elevator capture

Equipment shutdown

Air handling shutdown

Event printing

Door holding devices

Display monitor interface

(CPU)/control panel
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CONVENTIONAL SYSTEMS


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Conventional system


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-A building is sectioned into zones.

Conventional detectors have two states, normal and alarm.

-Each zone is wired back to the fire indicator panel (FIP)

separately

Fire Alarm Control Panel

I Conventional Panels


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Have a small number ofcircuits, each circuit covering

a zone within the building. The main drawback with

conventional panels is thatone cannot tell which device

has been activated within acircuit.

They are no longer used

frequently in large buildings,but are still used on smallersites such as small schools orapartments.

I. Conventional Panels

I. Conventional Panels
http://upload.wikimedia.org/wikipedia/en/f/f2/Simplex_FACP.JPG


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Fire Alarm Control Panel

I. Addressable Panels


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Much more advanced

Panels usually have a numberof signaling line circuits (slcs)

within the range of one to thirtycircuits.

Each slc can have a number ofdevices connected to it. Each

device has its own address,and so the panel knows thestate of each individual deviceconnected to it.

A loop may have up to 200device

I. Addressable Panels

II. Addressable Panels

Common addressable input (initiating) devices include:


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Common addressable input (initiating) devices include:

Smoke detectors

Manual call points

Responders

Fire sprinkler system inputs Switches

Flow control

Pressure Isolate

Standard switches



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Addressable output devices are known as relays andinclude

(Warning System/Bell) Relays

Door Holder RelaysAuxiliary (Control Function) Relays

Relays are used to control a variety of functions such as

Switching fans on or off

Closing/opening doors

Activating Fire Suppression System

Activating notification appliances

Shutting down industrial equipment



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Addressable system

Connected in constant two-way communication with the


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y

control panel Continuously monitor the protected area for changes in temp.

or air clarity.

Any abnormal change communicated to the fire panel which- after analyzing the signals - then makes the decision totrigger the alarm and shows which detector is indicating a firein a specific part of the building

Control Module

Is a device connected to the addressable control panel


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Is a device connected to the addressable control panelbut it allowing an extension to another conventionalcircuit.

Is also connected with the fire control power supply

(FCPS)NOTE THAT: FCPS gives up to 4 amp current and uses about 24 volt

,and can be connected to more that one control modulewhich will not give out more than 1 amp to notificationdevices connected to it.

An isolator is put after every 20 digital components(detectors, control modules, call points,..) to avoid failure incase of shortcuts.

Control modules activate a conventional sound circuitaccording to the signal received from the control panelwhich can be programmed to activate all the sound circuitsin all floors.

System components: Mon tor ngsystem


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MonitoringIf an alarm being tr iggered the 24-hour monitoring station

immediately summons help from the police or fire

departments.

Arming StationsKey operated arming stations use a high security key to arm

and disarm the system. A more common type of arming

station is the digital key pad.

Types of keypads:

L-E-D

L-C-D


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Manually activated devices


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Fire alarm pull station Manual call point " break glass"

Automatically activated devices:Fire detectors


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Line-Type detectors:A device in which detection is

continuous along a path.Spot-Type detector:A device whose detecting element

is concerned at a particular location.

System components:

System output/ Fire-indicating devices


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g

A) Audible devices-Such as horns, bells, sounders, sirens, chimes and speakers. They

are designed to produce a very loud, hard to ignore sound whenactivated.

-They are available in many shapes and sizes.

System output/ Fire-indicating devices


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An average ambient sound level greater than 105 dB shallrequire the use of a visible signal appliance(s)

The total sound pressure level produced by combining the

ambient sound pressure level with all audible signaling

appliances operating shall not exceed 120 dB anywhere in the

occupied area.

Audible devices


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Strobes/flasher light can be used to visually indicate an alarmcondition. Various color lens can be used to differentiateseparate events.

Strobe lights usually flash to save power and attract moreattention. Strobe lights can help authorities locate the site ofan alarm

Outputs


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Bells

Siren Flasher

Annuciator

System Control Wiring andconnections


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Signaling Line Circuits (SLCs Loops)

Control panel wiring


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Control panel wiring


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Control components wiring


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Control Module

SLC Loop


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24 VDC

Power FCM addressable control module control panels circuit to

control appliances (horns, strobes, speakers, act) by meansof a digital signal from FCP or to monitor telephone circuit.Addressability allows the FCM to be activated, either manuallyor through panel programming, on a selected (zone or area ofcoverage) basis.

Control Module


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Control Module


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Monitor module

It is a transducer for monitoring the status of analogue

devices like sounders and manual call points and transmit


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devices like sounders and manual call points and transmitdigital signal to the control panel.

Monitor module


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Relay module and contacts

Provides the system with dry-contact output for activating a

verity of auxiliary with device such s fans dampers control


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Normally Closed

Norma lly OpenCommon Normally Closed

Norma lly Open

Common

verity of auxiliary with device, such s fans, dampers, control

equipment, ect.



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Fault Isolator Module

Isolator Module should be spaced between groups ofsensor in loop to protect the rest of the loop Use to


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Isolator Module should be spaced between groups ofsensor in loop to protect the rest of the loop. Use to

isolate short circuit problems within a section of a loop so

that other sections can continue to operate normally.

The Isolator Module supports a maximumb f d i i b t i l t t



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The Isolator Module supports a maximumnumber of devices in between isolators, expect

when using relay bases.

Detectors wiring


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Power Sources

NFPA Code number 74 requires that AC powered units

meet the following conditions:


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meet the following conditions:

Power supply must be sufficient to operate the alarm

signals of 85 decibels for at least 4 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 not in excess of 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 number 70. The power source for the unit must not be subject to loss

of power by a wall switch.

Power Sources

A restraining means should be used at the plug-in


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A restraining means should be used at the plug inof 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 groundfault circuit interrupter.

Neither loss nor restoration of the primary powershould cause an alarm signal.

Battery-Operated Units

NFPA Code number 74 requires that

battery-operated units meet thef ll i i t


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y pfollowing requirements The alarm must be capable of

producing an alarm signal of 85

decibels for 4 consecutive minutes. The batteries must meet all power

requirements for at least one year,including routine testing.

A distinctive, audible trouble signalmust be given at least once per minutefor seven consecutive days before thebatteries are incapable of operating

(from aging, terminal corrosion, etc.). The unit must also be capable of

producing the alarm signal for 4consecutive minutes during the sevendays of trouble signal.

Photoelectric smoke

detector equipped with

strobe light for the hearing

impaired

System design requirements


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System design

requirement

Power supply

Smoke and heat

detector

installation

maintenance

Installation of detectors

Consideration should be followed in installation of

detectors: Wh i t lli th k l th t


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When installing the smoke alarm ensure that:

on the ceiling, ensure it is a minimum of 10cm fromany wall.

If wall mounting it is a minimum of 10cm below theceiling, but no lower than 30.5cm below the ceiling.

if it is more than 9 meters long install smoke detectors

at both ends of the room. Ideal location is on the ceiling in the centre of the

room.


In stairways install smoke alarms anywhere in the path of

smoke moving up the stairs.


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For sloped type ceilings, install the smoke alarm 10cm

below the peak.


Locations to Avoid:


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avoid dead air pockets.


Do not install a smoke alarm within 1 meterfrom kitchen,

bathroom, forced air ducts used for heating or cooling,til ti f i diti it


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ventilation fans, air conditioner units.

To avoid nuisance alarms: Install smoke alarms at least 30 cm away from

fluorescent lighting.

Avoid Dust particles, insects and dirties.

Do not install in areas where the temperature is

colder than 4.4C or hotter than 37.8C (100F)

Smoke Fire Detectors location andspacing

Locationconditions that shall be included according to


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conditions that shall be included according to

NFPA:

Ceiling shape Ceiling height

Configuration of contents

Burning characteristics Ambient environment

Smoke Fire Detectors

Detectors according to installation:

Spot Type Smoke Detectors


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p yp

Beam Type Smoke Detectors

Smooth Ceiling Spacing Spot type detectors. On smooth ceilings, spacing of

9.1 m shall be permitted to be used as a guide.


Projected beam type detectors On smooth ceilings, a spacing of not more than 18.3 m between

j t d b


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projected beams


High Air-Movement Areas


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Heat-Sensing Fire Detectors locationand spacing

Location

Spot-type heat-sensing


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Spot type heat sensing

Line-type heat detectors

on the ceiling or on the sidewalls not more than(500 mm) from the ceiling.

Heat-Sensing Fire Detectors

Smooth Ceiling Spacing

The distance between detectors shall not exceed their


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listed spacing

detector shall be installed within a distance equal to

0.7 times the listed spacing (0.7S).



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High Ceilings


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Alarm detectors Maintenance


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Cleaning Alarm detectors

Alarm detectors testing

Replacing Outdated Alarms

Maintenance of Power Supply

Visible System Characteristics andlocation

Visible Characteristics

Light Pulse Characteristics


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The flash rate shall not exceed two flashes

per second (2 Hz) nor be less than one flashevery second (1 Hz).

light source color shall be clear or nominal

white and shall not exceed 1000 cd.

Visible System location


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Visible System location

If ceiling heights exceed 30 ft (9.14 m), visiblenotification appliances shall be suspended.


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Room spacing for wall-mounted appliances shall be

based on locating the visible notification appliance at the

halfway distance of the longest wall.

Spacing in Rooms


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Spacing in Corridors

The table shall apply to corridors not exceeding 20 ft (6.1

m) in width.


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Audible System Characteristicsand location

Audible CharacteristicsMechanical Equipment Rooms


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the average ambient sound level used for design

guidance shall be at least 85 dBA

Public Mode Audible Requirements

sound level of not less than 75 dBA at 10 ft (3 m) ormore than 120 dBA at the minimum hearing distancefrom the audible appliance

Audible System location

Location of Audible Notification Appliances

If ceiling heights allow, wall-mounted appliances shall

have above the finished floors not less than 90 in (2 30


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have above the finished floors not less than 90 in. (2.30

m) and below the finished ceilings not less than 6 in.

(152 mm).

Heat Detectors Installation

Heat Alarms are ideal for kitchens, garages, boiler rooms,attics and other areas where there are normally high levels


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of fumes, smoke or dust which preclude the use of Smoke

Alarms due to the risk of false alarms.

On sloped, peaked or gabled ceilings, install Heat Alarm

30cm from highest point.

If only wall placement is possible, install no further than

30cm from ceiling.

Do not install Heat Alarms directly over the cooker, stove

or oven or In areas with high humidity, like bathrooms or

shower rooms, or areas near dishwashers or washingmachines Install heat alarms at least 3m away from these

areas if possible.

According to NFPA Code number 72

Location: Spot-type heat-sensing fire detectors shall belocated on the ceiling not less than 4 in. (100 mm) from



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g ( )

the sidewall or on the sidewalls between 4 in. and 12 in.

(100 mm and 300 mm) from the ceiling.

Exception: In the case of solid joist construction,

detectors shall be mounted at the bottom of the joists. In the case of beam construction where beams are

less than 12 in. (300 mm) in depth and less than 8 ft

(2.4 m) on center, detectors shall be permitted to beinstalled on the bottom of beams.

Line-type heat detectors shall be located on the ceiling

or on the sidewalls not more than 20 in. (500 mm) fromthe ceiling.



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Exception No. 1: In the case of solid joist

construction, detectors shall be mounted at thebottom of the joists.

Exception No. 2: In the case of beam constructionwhere beams are less than 12 in. (300 mm) in depth

and less than 8 ft (2.4 m) on center, detectors shall be

permitted to be installed on the bottom of beams.


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Dr. Eng. Walid Abdelghaffar

[email protected]
mailto:[email protected]:[email protected]

Automatic Alarm System

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