FIRE ALARM PROJECT

Princess Bamigboye
Aug 1, 2023
3 min read

Updated: Aug 4, 2024

The fire-detection project is a prototype fire alarm system.

Whenever a flame or a fire goes off, an alarm is raised.

COMPONENTS USED:

Flame sensor.
Active (piezoelectric) buzzer.
Arduino Uno Rev3 Board.
Liquid Crystal Display (LCD) module.
Female-to-male wire.
Male-to-male jumper wires.

WHAT IS A FLAME SENSOR?

A flame sensor is a type of detector that is used to detect as well as react to the occurrence of a fire or flame. They are usually used to verify whether the furnaces are functioning correctly, and also used in an ignition system to get precise actions otherwise to inform the operator.

Flame sensors use UV (Ultraviolet) or IR (Infra-Red) or UV-IR technology to identify flames below a second. These sensors react to a detected flame based on the installation, although it includes sounding an alarm, disabling a fuel line & activating a fire control system.

The flame sensor with UV technology works by simply sensing the UV radiation. Generally, all fires generate UV radiation at the ignition point so, in case of a fire, the sensor would become alert of it & generate a series of pulses that are changed by detector electronics and gives an alarm output.

The flame sensor with IR technology works by checking the IR spectral band for particular ornamentation that hot gases emit. But, this kind of device needs a flickering movement of the flame. Generally, infrared radiation is not only generated by flames but also radiated from lamps, ovens, etc. So, there is a high risk of a fake alarm

The sensor with UV-IR is capable of detecting both UV & IR radiations, thus it possesses both sensors. The combined sensor has a better rejection capacity for false alarms as compared to a separate UV/IR detector.

The flame sensor interfacing with a microcontroller like an Arduino is shown below.

Figure 1: Pin-Out for Flame Sensor

Here, the flame sensor used is an Infrared flame sensor.

This sensor is available in small size and is used to detect a source of fire or any other clear light source. Basically, this kind of sensor detects infrared light with 760 nm to 1100 nm range wavelength that is generated from the light source or fire or flame. This IR flame sensor includes a YG1006 phototransistor which has high sensitivity & high speed.

Infrared sensor modules are available in two types where one type includes three pins and the other type includes four pins. The main difference between these two modules is; the three-pin module provides only digital output whereas four pin module provides both analog and digital outputs. So, these two modules can be used easily with different microcontroller boards. Here, the 4-pin flame sensor is used in this interfacing.

This 4-pin flame sensor module includes different components like phototransistor, trimpot, LM393, power LED and output LED.

The three-pin flame sensor pin diagram is shown below.

Pin1 (VCC): This is a 5V power supply pin.
Pin2 (GND): This is a GND pin.
Pin3 (OUT): This is a digital output pin.
Pin4 (OUT): This is the analog output pin.

WORKING PRINCIPLE:

The working of the flame sensor module is simple. The theory behind it is that a hot body will emit infrared radiation. And for a flame or fire, this radiation will be high. We will detect this IR radiation using an infrared photodiode. The conductivity of the photodiode will vary depending on the IR radiation it detects. We use an LM393 to compare this radiation and when a threshold value is reached the digital output is changed.

We can also use the analog output to measure the IR radiation intensity. The analog output is directly taken from the terminal of the photodiode. The onboard D0 LED will show the presence of fire when detected. The sensitivity can be changed by adjusting the variable resistor on board. This can be used to eliminate false triggering.

Below is the circuit diagram for the project on Fritzing;