fire alarm system basiscs

7/28/2019 Fire Alarm System Basiscs

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Importance of Fire DetectionSystem



Calcutta Hospital

Jaipur Oil

Rajghat Power Plant



Fire safety plans and practices are designed to protect:

People

Information

Property

Time

Fire Safety



Overview of Fire & Life Safety

• Code Background

• Fire Alarm Systems

• Fire Detection

• Fire Suppression

• Conducting a Basic Assessment



Standards and Codes

• Component tests by nationally recognizedlabs

–Underwriters Laboratories

– Factory Mutual

• Codes

– NFPA 70, National Electrical Code

– NPFA 72, The National Fire Alarm Code

– Local codes and ordinances



Fire Detection and

Signaling Systems

The early detection of a fire and the signaling

of an appropriate alarm remain the most

significant factors in preventing large losses

from occurring.



Basic Fire

Let’s examine the components that

make a basic Fire Alarm Control

System.



Main Controller

• The brains of thesystem

• Provides power to thesystem, monitors inputs

and controls outputsthrough various circuits

• Performs otherfunctions as required

by the appropriate code



Secondary(DC(12Vx2))

Requires two Power Sources

Elements of a Control Panel

Primary (AC)



Smoke Detector

Manual Pull Station

A fire alarm

system can havea variety of input devices.

Inputs




Inputs

• Initiating Device: A system component thatoriginates transmission of a change of statecondition, such as a smoke detector, manual firealarm box, supervisory switch, etc...

• Initiating Device Circuit (IDC): A circuit to whichautomatic or manual initiating devices are connected

where the signal received does not identify theindividual device operated




Horns

Strobes

Outputs



Outputs

• Notification Appliance: A fire alarm systemcomponent such as a bell, horn, speaker, light,or text display that provides audible, tactile, or

visible output, or any combination thereof.

• Notification Appliance Circuit: A circuit orpath directly connected to a notificationappliance.



The Basic System

Secondary

DC (12Vx2)

Outputs

InputsMain Controller

Primary AC



Basic Fire Alarm Technology

• Signal Initiation/Initiating Devices

– Need to understand stages of fire and what

technology works best for each



The Stages of a Fire

• Stage One

– Incipient: Products of Combustion particles are

produced (<0.3 microns). No visible smoke or

detectable heat. May occur for milliseconds ordays.

• Use ionization detectors




• Stage Two

– Smoldering: Visible smoke particles are produced

(>0.3 microns). Little visible flame or noticeable

heat.• Use Photoelectric Detectors




• Stage Three

– Flame: Rapid combustion produces radiant energy

in the visible, and invisible (IR, UV) spectrums.

Heat begins to buildup at this stage• Use Spark or Flame Detectors




• Stage Four

– High Heat: Uncontrolled combustion is caused by

the heating of nearby combustibles to their

ignition point.• Use Heat Detectors

– Note! Major disadvantages of using thermal

energy for fire identification are

• Takes a while for a fire to be recognized

• The toxic gases that are produced before an alarm

point is reached



Types of Fire Alarm Systems

• Selection factors

– Level of life-safety hazard

– Structural features of the building

– Level of hazard presented by the contents of

the building

–

Availability of fire suppression resources – State and local code requirements

(Continued)



Conventional System….



Addressable System



Type of Cables used and why



Importance of Proper Ground



Importance of proper input source

fire alarm system basiscs

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