This document discusses fire detection and alarm systems. It describes why such systems are required, including to detect fires, notify occupants, summon assistance, and initiate suppression systems. It provides a block diagram of system components, including input devices like manual pull stations and detectors, as well as output devices like audible alarms and visual strobes. The document discusses various types of detectors in detail, including heat, smoke, flame, and gas detectors. It also covers conventional and addressable microprocessor-based fire alarm systems.

1. FIRE DETECTION & ALARM SYSTEM
FIRE DETECTION & ALARM SYSTEM
RAVI SHANKAR SINGH
(E6S304)
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2. 2
Why are fire detection and alarm systems
required?
 Detect fire in the areas.
 Notify building occupants to take evasive action to escape the
dangers of a hostile fire.
 Summon organized assistance to initiate or assist in fire control
activities.
 Initiate automatic fire control & suppression systems & to sound
alarm.
 Supervise fire control & suppression systems to assure operational
status is maintained Initiate auxiliary functions involving
environmental, utility & process controls
 Systems may incorporate one or all of these functions

3. Block diagram of FDA system
Block diagram of FDA system
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Input
Devices
Output
Devices
Control
Panel

4. 4
InputDevices
 Fire Box (Manual Pull Station)
 When shorted trips an alarm (usually fire)
 Installed in the normal exit path
 Types of Fire Box
 Single Action
 Pull handle once
 Glass Break
 Glass rod or plate is broken
 Double Action
 Lifting of a cover or opening a door

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3.1) Heat detectors
1. fixed temp type heat detector
2. rate-of-rise type heat detector
3.2) Smoke detectors
1. Photoelectric
2. Ionization
3.3) Flame detectors
1. Ultraviolet light (UV)
2. Infrared (IR)
3.4) Fire-gas detectors
FIRE DETECTORS
Input Devices
Heat Detectors
Smoke Detector

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7. Fixed temp. heat detectors
Fixed temp. heat detectors
 Detect heat by one or more of 3 primary principles of physics:
 Expansion of heated material
 Melting of heated material
 Changes in resistance of heated material

8. Rate-of-rise heat detectors
Rate-of-rise heat detectors
 Operate on the principle that the temperature in a room will
increase faster from fire than from atmospheric temperature
 Will initiate an alarm when the rise in temp. exceeds 12-15F (7-8C)
per minute
 Alarm can be initiated at a temp. far below that required for a fixed-
temp. device
◦ Reliable devices, not subject to false activations
◦ But if not properly installed, they can be activated under non fire
conditions (eg. detector located too close to doorway and subject to
extreme fluctuations in temperatures)
 Pneumatic rate-of-rise spot detector
 Pneumatic rate-of-rise line detector
 Thermoelectric detector

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Photoelectric smoke detector
Uses a photocell coupled with a specific light source.
Basically smoke entering the smoke detector chamber disrupts the
light beam causing an alarm signal to be initiated
More sensitive to smoldering fires
1: optical chamber
2: cover
3: case moulding
4: Photodiode (detector)
5: infrared LED

10. 10
Circuit of Photoelectric Smoke Detector

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Ionization smoke detector
Invisible products of combustion enter the chamber
decreasing the current between the –ve & +ve plates, thereby
initiating an alarm signal.
Generally responds faster to flaming fires versus smoldering
fires
Automatically resets when the atmosphere clears

12. Fire-gas detectors
Fire-gas detectors
 Monitors levels of carbon dioxide and carbon monoxide
(common to all fires)
 More discriminating than other detectors – can be designed to
be sensitive only to gases produced by specific types of hostile
fires and ignores gases produced by friendly fires
 Not many in use – very specialized applications

13. Combination detectors
Combination detectors
 Single device can be designed to have more than 1 function eg.
heat/smoke, smoke/carbon monoxide detectors
 Different combination make the detectors more versatile and
more responsive to fire conditions

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S.No PLANT AREA TYPE OF DETECTORS
1. Main control room, Computer
room, Electronic cubicle
room and control rooms in
outlying areas.
Combination of -
Ionisation smoke detector
Optical type smoke detector
2. Switchgear rooms in main
Plant and outlying areas,
battery charger room, record
and shift-in-charge engineers
room
Ionisation type smoke detector.
3. Office rooms / storage rooms Ionisation type smoke detector
4. Battery rooms and
chemically corrosive areas.
Corrosion resistant, Rate of rise of temperature heat
detector with fixed temperature setting.
5. Cable gallery Combination of Optical type smoke detectors and Linear
heat sensor running above all HV and LV power cable trays.
Unless the vertical distance between cable tray is less than
500 mm in which case alternate trays (in addition to the top
and bottom trays). The optical smoke detector and LHS
detectors along with necessary number of interface units in
the cable gallery will be cross zoned to actuate the water
spray system
6. Station building / Plant area Infrared flame detectors (where oil tanks are located), spray
tanks rate of rise of temp. detector with fixed element
Selection of Detectors for different Area

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7. Coal Conveyors Analogue Linear heat sensor cable, infra red spark / ember
detectors and manual call points. If water spray system is
provided the LHS cable and IR detector will be cross zoned
to actuate the same
8. Dusty areas in coal handling
plants like crusher house
Flame proof manual call points
9. Junction towers Flame proof heat detectors, flame proof manual call points
10. Conveyor tunnels Flame proof infrared detectors, flame proof MCPs, LHS
cables
11. Hazardous plant areas such
as fuel oil / lube oil, DG
houses, H2 generating plants
and hydrogen storage areas.
Flame proof rate of rise of temperature detector with fixed
element and flame proof MCP

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Audible Output Devices
 An audible alarm signal lets people know the
alarm system has been activated
 Devices may be mounted inside or outside
based on level of protection required
 May consist of:
 Sirens
 Bells
 Buzzers
 Horns
 Voice Drivers
Output Devices

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Visual OutputDevices
 A visual signal lets users know the status of
the alarm system if activated
 Visual devices may be mounted inside or
outside
 May consist of...
 Strobe lights
 LED’s
 On / Off site printer
Output Devices

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Criteria to determine layout of the fire detectors
 The design, construction and operational features of all types of
detectors shall be in accordance with relevant standards.
 The number of fire detectors to be installed is governed by
 total area to be protected
 type of building construction
 air movement & air velocity
 ceiling obstructions
 concentration of equipment in the area covered
 sensitivity required
 Area is divided into zones to be protected
 The zones of individual detectors should overlap and no blind zone
should be left.

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 Areas above false ceiling and below false flooring shall be
considered as separate zones.
 Under ideal conditions of smooth ceiling and average room size, one
detector is recommended to protect the area.
 Ionisation type detectors should be located where the largest
combustible gas concentration can be expected.
 In the air conditioned areas both ionisation and optical type smoke
detectors are used.
 Detectors must always installed at the highest point of the ceiling
and minimum coverage indicated by manufacture shall be
considered.
 The number of detectors and their location should be so selected that
complete coverage is obtained

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Initial quantity estimation of smoke / heat detectors
 35 to 40 sq.m per detector for general application.
 20 to 25 sq.m per detector for main control room, electronic
cubicle room, computer room, etc., in view of high valve
concentration
 The exact requirement shall calculated based on relevant
IS/NFPA standard

21. TYPES OF FIRE DETECTION SYSTEM
TYPES OF FIRE DETECTION SYSTEM
A. Conventional FDA System
C. µ-P Based Addressable FDA System
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22. CONVENTIONAL FIRE DETECTION AND ALARM SYSTEM
CONVENTIONAL FIRE DETECTION AND ALARM SYSTEM
 Conventional fire sensors and manual call points shall provide for continuous
surveillance the area.
 Main fire alarm panel shall derive signals from the zone indicating panels and
audible and visual annunciation shall be provided in the event of fire.
 Repeater panel shall be located in security house / fire station to alert fire
fighting / security personnel.
 Fire detectors shall be selected depending on the type of fire expected in a
particular area.
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 All the fire alarm circuits shall be of modular design using
electronic printed card circuits to facilitate easy replacement.
 The system design shall be such that operation / resetting of
alarms for one zone / detector will not block availability of alarm
for any other zone.
 the alarm / system resetting shall be by common push button and
not by individual switches for different zones / detectors.

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Addressable Fire Detection & Alarm
System
It is an automatic fire detection & alarm system consists of fire
detectors & manual call points positioned in Zones/ loop through
out a building(Area).
These are wired to control & indicating equipment which shows
the location of alarm call, & actuates audible alarm sounders.
 Industrial/ Non Industrial Buildings
 Institutional Buildings
 Residential Apartments
 Hotel & Hospitals
 All Industries
 Mall & Multi Storied Complexes
 Offices & Control Rooms

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Addressable µ-P based FDA system
 Addressable I/P devices
 Addressable O/P devices
 Control panel
 Constant power supply
 Emergency Battery supply

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Microprocessor Based control Panel
 Processor(CPU)
 Adequate number of loop modules for detector loops
 A coloured VDU monitor with keyboard
 Output modules for alarm
 Output control & interlocks
 Communication modules for interfacing

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 Continuous supervision of the detector connecting lines, individual
detector performance / operation and disconnection / removal of
detectors.
 Discrimination between a real fire and false fire conditions by
incorporating signal verification and other features.
 Individual detector addressing capability.
 Detection of over / under sensitive detectors and automatic calibration by
increasing or decreasing their sensitivity levels based on environmental
conditions like air movement, fumes, humidity, etc.
 Pre-alarm in case of any detector / detectors requiring maintenance.
 Facility shall be provided for alteration programme according to needs.
BENEFITS OF µ-P BASED ADDRESSABLE FDA
SYSTEM

28. CLEARANCE AND APPROVALS
CLEARANCE AND APPROVALS
All detectors and sensors shall be approved by any of the
following bodies as applicable :
A. Under writers’ Laboratories (UL) – USA
B. Fire Officers Committee (FOC) – UK
C. Any other internationally recognised body acceptable to
Purchaser / Consultant. Approval certificates shall be
furnished with the bid.
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29. The Contractor shall be solely responsible for obtaining the
required approval and clearance for the different components
and systems of the fire detection and alarm system from the
following authorities as applicable.
A. Tariff Advisory Committee (TAC) of the Insurance Association of
India.
B. Dept. of Atomic Energy (DAE) Certification of safety from
radioactivity.
C. Central Building Research Institute (CBRL), Roorkee
D. Central Mining Research Station (CMRS), Dhanbad.
E. Local Fire Authority.
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30. SOME APPLICABLE STANDARDS
SOME APPLICABLE STANDARDS
 Code of practice for selection, installation & maintenance of
automatic fire alarm & detection system-IS-2189,BS-5839
PART1,ANSI-NFPA-72,FOC RULES
 Code of practice for fire safety of buildings - IS-1646
 Smoke detectors for use in automatic fire alarm system-IS-11360,
BS-5445 PART-7, ANSI-UL268
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