FIRE DETECTION AND
ALARM
PRESENTED BY: SANYA KUMARI
VIDHISHA GOUTHAMI
SPOORTHI M U
SWARNA RAJ ANAND
INTRODUCTION
• When a fire breaks out, the measures need to be taken to
evacuate the trapped people and contain the fire before it
spreads out of hand.
• to accomplish this we need a system that can detect fires
before it is too late.
• This fully automated Fire Detection and Alarm System is
equipped with a temperature sensor and a 555 timer IC.
This fire detection can sense changes in temperature and
sound an alarm in case of fires.
• Fire Alarm Circuits are very important devices to detect
fire in the right time and prevent any damage to people or
FIRE DETECTORS
These are designed to detect one or more
of the three characteristics of fire-smoke,
heat and flame. Besides it every fire
detection system must include manual call
points (break glass), so that in the event of
fire can be of immediate help.
During a fire importance of activation of
the occupants through alarm or bell is of at
most vital and this can performed through
alarm system.
FUNCTION OF FIRE DETECTORS
Microprocessor based addressable analogue type fire
alarm and detection system to be used for various
building/areas to detect and provide alarm signal in
the main fire alarm panel to be located in the central
control room. Fire alarm will be repeated in a
repeater alarm panel in the fire station.
Main fire alarm panel annunciation shall be located in
the control building. A repeater panel shall be
provided in the fire station. Total no of annunciation
shall be based on the specific plant requirement.
siren of 10 Km range is envisaged to provide warning
in the event of fire.
WHY FIRE DETECTION AND ALARM SYSTEM
REQUIRED
Fire detection and protection system is required for the following
reasons:
• To detect fire in the area during the initial stage.
• To alert occupants, so that they escape the building safely.
• Summon trained personnel to take charge of controlling
the fire as quickly as possible.
• To initiate automatic fire control and suppression system.
• To support and supervise the fire control and suppression
system.
HARDWARE USED
temperature Sensor
Resistors
Capacitors
Transistors
Cables and Connectors
Diodes
PCB and Breadboards
LED
Transformer/Adapter
Push Buttons
Switch
IC
IC Sockets
THERMISTORS
Thermistors are Temperature Dependent Resistors i.e. the
resistance of a Thermistor varies according to the ambient
temperature.
There are two types of Thermistors: PTC Thermistor and NTC
Thermistor. PTC stands for Positive Temperature Coefficient and
NTC stands for Negative Temperature Coefficient. In PTC
Thermistor, the resistance is directly proportional to the
temperature and in NTC Thermistor, the resistance is inversely
proportional to the temperature.
WORKING
The main component in detecting the fire is the 25 K Thermistor.
If the temperature increases, the resistance of the Thermistor
decreases.
At room temperature it had a resistance of 25kohms.Another
resistance is connected to the thermistor to form voltage divider
circuit and this is connected to the transistor through a diode .
Buzzer switches on only when the transistor is grounded. As the
temperature increase the buzzer sound also increases
WORKING
When the temperature increases above the set value, the
potentiometer arrangement produces a high voltage. This voltage is
then given to BC547 transistor in common emitter mode.
It is an NPN general purpose transistor. When the base is given a
high input, it gets turned on. When the transistor is turned on, its
collector voltage is reduced to low as the collector to emitter voltage
decreases.
The collector output voltage of the first transistor is given to the
base as an input to the second BC 547 NPN transistor. This transistor
too is in common emitter mode and as the input is low when the
temperature threshold is reached, the output at the collector will rise
high.
In this state, it will turn on the next transistor, i.e. BC107.
WORKING
This transistor will now act as a switch for the siren circuit. This transistor can
bear power quite larger than the BC547 and it is also equipped with a heat sink
for that purpose .
When the BC107 transistor turns on, it allows current to pass from power
supply to ground through collector thereby acting as an electronically
controlled switch.
When the current is passing, the siren circuit which is assembled as the load to
the circuit is turned ON. Then you can hear the siren sound through the buzzer.
The capacitors used in the circuit are the main components in producing the
siren effect.
The principle involved in generating the siren effect is to make an oscillator
with an envelope which periodically increases and decreases so as to generate
that effect.
ADVANTAGES DISADVANTAGES
Low cost
• Reliable
• Fast response
• Circuit can be easily constructed
• High level security
• Easy to design • False alarm
• Easy to modify • Blinded by thick smoke
• Low power consumption
• Senses near range heat(fire) only
• Early warning benefits
• Can easily be installed anywhere in commercial buildings
• Uses continuous power supply
• Early warning is essential to effective fire safety because
fires can occur at any timeany place
• Detection distance
• Speed of response
• Sensitivity
• Range of applications
CONCLUSION
Thus, we conclude from this
fire alarm is used for safety
and emergency purpose. This
is not only use in houses but
also in any type of buildings.
THANK YOU…
