FIRE
HLARM
PHYSICS.PROJECT
FIRE ALARM...
SUBMITTED BY:
NAME:
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certificate
This is to certify that project entitled
FIRE ALARM SYSTEM
has been completed under the guidance and supervision of
NAME
SUBJECT: PHYSICS
SESSION: 2023-2024
SUBMITTED TO: SIGNATURE
Internal
External
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INDEX
SL. NO
1
PAGE NO
INTRODUCTION
5
THEORY
6
2
3
5
COMPONENTS REQUIRED
CIRCUIT DIAGRAM AND
WORKING MODEL
PROCEDURE
7
8-9
10
11
67
8
WORKING PRINCIPLE
OBSERVATIONS
APPLICATIONS
9
10
11
FEATURES OF THE MOST
ADVANCED FIRE ALARMS
CONCLUSION
12
13
14-15
16
PRECAUTIONS
17
12
BIBLIOGRAPPHY
18
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INTRODUCTION
An automatic fire alarm system is designed to detect the unwanted presence of
fire by monitoring environmental changes associated with combustion. In general,
a fire alarm system is either classified as automatic, manually activated, or both.
Automatic fire alarm systems can be used to notify people to evacuate in the
event of afire or other emergency, to summon emergency services, and to
prepare the structure and associated systems to control the spread of fire and
smoke. Fire alarm systems have become increasingly sophisticated and
functionally more capable and reliable in recent years. They are designed to fulfill
two general requirements: protection of property and assets and protection of
life. As a result of state and local codes, the life-safety aspect of fire protection
has become a mnajor factor in the last two decades. There are a number of
reasons for the substantial increases in the life-safety form of fire protection
during recent years, foremost of which are
1. The proliferation of high-rise construction and the concern for life safety within
these buildings.
2. Agrowing awareness of the life-safety hazard in residential, institutional, and
educational occupancies.
3. Increased hazards caused by new building materials and furnishings that create
large amountsof toxic combustion products (i.e., plastics, synthetic fabrics, etc.).
4. Vast improvements in smoke detection and related technology made possible
through quantum advances in electronic technology.
5. The passing of the Americans with Disabilities Act (ADA), signed into law on
July 26, 1990, providing comprehensive civil rights protection for individuals with
disabilities. With an effective date of January 26, 1992, these requirements
included detailed accessibility standards for both new construction and
Renovation towards the goal of equal usability of buildings for everyone,
regardless of limitations of sight, hearing, and mobility. This had a significant
impact on fire alarm system signaling devices, power requirements, and device
locations.
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THEORY
Afire alarm system has a number of devices working together to detect
and warn people through visual and audio appliances when smoke, fire,
carbon monoxide or other emergencies are present. These alarms may
be activated automatically from smoke detectors and heat detectors or
may also be activated via manual fire alarm activation devices such as
manual callpoints or pull stations. Alarms can be either motorized bells
or wall mountable sounders or horns. They can also be speaker strobes
which sound an alarm, followed by a voice evacuation message which
warns people inside the building not to use the elevators. Fire alarm
sounderscan be set to certain frequencies and different tones including
low, medium and high, depending on the country and manufacturer of
the device.
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COMPONENTSREQUIRED
1X Bread board
>1X 1Ok Thermistor
1X4.7k Resistor
>1XLM358 Op-Amp
1X 10k Pot
>1X9VBattery
1X Buzzer
>Connection wires, as required
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CIRCUIT DIAGRAI
10K Thontg
POT
2NANA LM358
oND
TNg
TNGH
1OK
Buzzey
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WORKING MODEL
Wati
W
HWatt
on
aENERAL PURPosr
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PROCEDURE
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 NTCThermistor. PTC stands for Positive
Temperature Coefficient and NTCstands 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. In
this project, we have used a 10 KQ Thermistor with NTC. LM358 is a Dual
Operational Amplifier (Op-Amp) IC. All the functional modes of the typical
operational amplifier can be implemented using LM358 IC. In this project though,
we willbe using the LM358 Operational Amplifier in the Comparator Mode where
the input signals on inverting and non-inverting terminals are compared and
corresponding output is produced. Siren sound is simple. First, connect the 4.7 KQ
Potentiometer to the inverting terminal of the LM358 Op-Amp. One end of the
POT is connectedto +9V, other end is connected to GND and the wiper terminal is
connected to Pin 2 of Op-Amp. We will now make a potential divider using 10K
Thermistor and 4.7 KQ resistor. The output of this potential divider i.e. the
junction point is connected to the non-inverting input of the LM358 Operational
Amplifier. We have chosen a smallbuzzer in this project to make the alarm or
siren sound. So, connect the output of the LM358 Op-Amp to the buzzer directly.
Pins 8 and 4 of the LM358 IC i.e. V+ and GND are connected to +9V and GND
respectively. We will now see the working of the simple Fire Alarm Circuit. First
thing to know is that the main component in detecting the fire is the 10K
Thermistor. As we mentioned in the component description, the 10 KThermistor
used here is a NTC type Thermistor. If the temperature increases, the resistance
of the Thermistor decreases. In case of fire, the temperature increases. This
increase in temperature will reduce the resistance of the 10 KThermistor. As the
resistance decreases, the output of the voltage divider will increase. Since the
output of the voltage divider is given tothe non-inverting input of the LM358 Op
Amp, its value will becomne more than that of the inverting input. As a result, the
output of the Op-Amp becomes high and it activates the buzzer
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WORKINGPRINCIPLE
The fire alarm working principle is based on thermistor used in the fire
alarm circuit. This fire alarm circuit is used to identify and indicate an
increase in temperature beyond certain value (temperature of an
enclosed area). The increase in temperature is indicated byturning ON
the LED (cooling system can be used to bring the temperature to its
normal value). Thus, if the temperature exceeds a certain value, then
the cooler or load turns ON automatically without any monitoring
system. To actuate the relay instead of LED, operational amplifier along
with negative coefficient thermistor can be used. In this fire alarm
project circuit, thermistor is used as a temperature sensor because
thermistor is very economical compared to all other temperature
sensors.
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OBSERVATIONS
We have seen that initially there was no buzzer sound as none of the
fire was detected. When we bring amatch stick near the fire switch
with a time lag of 5-10 seconds the buzzer starts giving sound as the fire
is detected and the circuit is completed by the action of bimetallic strip.
When we remove the burning match stick away from switch, the buzzer
continues to give the sound for some time due to actionof capacitor
and time is required by switch to return toroom temperature.
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APPLICATIONS
Fire Alarm Circuits are very useful in homes, offices, schools, labs,
etc. to detect and prevent any disasters due to fire.
Fire Alarm Systems can work as stand-alone devices or be a part
of acomplex home security system with other security features
like smoke detection, intruder alert, motion detection, etc.
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features of the most
advanced fire alarms
)
Smart Home
SAMSUNS
0
Most advanced fire alarm systems use wireless technology and smart devices to
protect and manage automated buildings from aremote control panel, typically a
mobile app that can be downloaded, installed and managed from a smartphone.
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Modern fire alarm systems use a control panel from a mobile app
The computerized logic of the control panel analyzes multiple detectors at the
same time to decide on the most appropriate course of action. These
modern smart fire alarm systems are more sensitive than classic models and are
better at avoiding false alarms. With better design and stronger resistance, they
can be placed in areas difficult to reach and give instructions about the best
escape route to the people in the building. Smart fire alarm systems can perform
integrated automatic actions, for example, discharge fire-suppression systems in
closed designated areas; and vary the notifications to support people on their way
out, while protecting expensive electronicequipment inside.
Smart wireless detectors use long-life batteries that can last up to 7 years. That is
the shelf life of the smart unit itself. The smart sensor is activated by connecting it
to a mobile account via a sim card. Users can activate, deactivate and assign fire
alarm functions to each sensor from anywhere. Two big bonuses of most
advanced fire alarms systems are the sleek design and the more pleasant audio
warnings that don't build upon the panic that's already there.
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Conclusion
The objective of our project was to build a fire alarm system. The key component
of the circuit is the thermistor, which has been used as fire detector or fire sensor.
Our project was successfully completed. The performance of the project met the
original technical problem,which was to build a circuit that would sound an alarm
when the heat in the atmosphere would reach a hazardous temperature. Also,
the cost of the project was well under the overall project cost projected, making
the project a good product since the application was successfully demonstrated
and the circuit price was reasonable.
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PRECAUTIONS
1. Components of the circuit should be handled carefully.
2. Care should be taken while soldering as it may burn the skin.
3. Connecting wires should be insulated to prevent disturbance.
4. Connections shouldbe tight as it may break easily.
5. Soldering must be done carefully as it may burn the PCB board.
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BIBLICGRAPHY
1) NCERT textbook class 12
2) NCERT physics lab Manuel
3) INTERNET
4) www.yahoo.com
5) www.scribd.com
6) www.google.com
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