Fire Alarm System Components

It is well known that design of the fire alarm systems full located on power distribution engineer.
And also, it must be noted that the design of the fire system depends on the importance degree of the facility. and the accumulation degree of persons and also specific budget and other factors.

Fire Alarm System Components:

-Sensors
-Controllers
-Alarms
-Assistance equipment

-Sensors

Are the tools which detect the effects of the fire, It is divided into several types:

1-Smoke Detector

Theory of work based on the existence of optical ray. If there is a fire, Smokes rise and cross the optical ray, So that alarm work.
The number of used detectors depends on the dimensions of the place  so that the distance between each detector and another not more than 7.5 meters.

The following images for smoke detectors

The following figure shows the component parts of smoke detectors

2-Heat Detector

From its name,  it depends on a heat sensor (thermocouple) if the temperature of the place raise, The alarm work.
The number of used detectors depends on the dimensions of the place  so that the distance between each detector and another not more than 5.5 meters.
There are two types of heat detectors depending on the nature of the place:

a)Type works at 60 C degree, It is used in most applications.
b)Type works at 90 C degree, It is used in generators rooms, Where it is normal that the temperature exceeds 60 C degree.

The following images for heat detectors

Important note:

It is well known that the smoke detector better than heat detector, but you must use the heat detector in places where smokes is normal such as kitchens and parking garages.

3-Multi-sensor

This type is a mixture of the previous two types,  a smoke detector and heat detector ... And this type is more expensive in the price, but give better efficiency.

Very important note:

Multi-sensor works as an alternative to only smoke detector,  As if it is used as an alternative to heat detectors in a garage or the kitchens (where the smokes are normal) The device will operate even in the absence of fire.

The following images for heat detectors

4-Beam Detector

Used with highs more than 5 meters, It is the most expensive type.
Consists of "Transmitter and Receiver" 
 Receiver simply is a reflecting mirror reflects the signal from the transmitter.
If there is a fire, When the smokes cross the path between transmitter and receiver, the alarm work.

There is two types:

-1st Type, the distance between the transmitter and receiver should not exceed 50 meters.
-2nd Type, the distance between the transmitter and receiver should not exceed 100 meters (more expensive)

Notes:

-The beam detector is installed on the highs from  6 meters to 10 meters.  And if the height is more than 10 meters, the detectors do not operate when there is a fire.
-The horizontal distance between every two groups must not be more 7 meters.

The following images for beam detectors

-Controllers

Is the mediator between the sensors and the alarms.
Any controller contains fire alarm control panel (FACP)

Fire alarm control panel (FACP) consists of (Monitor - PCB - Battery)

-Monitor: To view the options and information
-printed circuit boards (PCB): Input/Output Electronic board.
-Battery: To extend the fire system with power even the main Power cut where, the fire alarm system is very important and must work even the main Power cut.

There are two types of the controller:

-conventional type
-Addressable type

1-conventional type:

Is used in open loop system where it cannot detect the fire source room but it can detect the zone which is consists of more than room.
The building is divided into some zones, Every zone consists of some rooms, If there is a fire in a room the controller cannot detect the room but it can only detect the zone which contains the room.

This type is less expensive.

Note that there are four zones every zone has a group of detectors, if one of zone 1 detectors detect a fire the controller show that there is a fire in zone 1 but it cannot show which detector.

2-Addressable type

Is used in closed loop system where it can detect in accuracy the fire source room in any zone in the building.
The building is divided into some zones, Every zone consists of some rooms, Every room has an address. So that, If there is a fire in a room the controller can detect in accuracy the room in any zone. Because, the address of the room is appear on the controller monitor with the help of micro processor. 

This type is more expensive.

-Alarms

There are two types of alarms:

1-Sound alarm only

Sound alarm is (bell - horn - sounder)

2-Sound and light alarm

Light alarm is (strobe light), Light like the flash of the camera.

Important note:

You must review catalog annex with any alarm to know the place to be installed exactly.

-Assistance equipment

1-manual call point (MCB)

There is always in subway cars, in the roads of the building and at the beginnings of the fire escape stairs.

It is used to turn on the alarm manually or open the doors manually.

The distance between two manual call points should not be less than 30 meters.

The installation height of MCB must be from 1.2 meters to 1.35 meters at the level of persons.

2-The cables used in fire alarm system

A custom type of cable is used called fire resistance cables, And there are two types:

1-Cables bears to 950 C degrees ( more expensive in price ) and does not require pipes contents it as, the cable is designed to withstand high temperature resulting from the fire.

2-Cables bears to 105 C degrees ( less expensive in price ) but it requires pipes to contents it as, the cables cannot withstand high temperature resulting from the fire.

Important notes: 

-If the distance is less than 3000 meters, use cables have cross section area 1.5 mm2.

-If the distance is more than 3000 meters, use cables have cross section area 2.5 mm2.

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Ahmad Mohammad

Hi. I’m Designer of Mawsoo3a Blog. I’m Electrical Engineer And Blogger Specializing In Electrical Engineering Topics. I’m Creative.I’m Working Now As Maintenance Head Section In An Industrial Company.

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