Published November 14, 2025 © CC BY-SA

Arduino Gas Leakage and Flame Detection With Alert System

For the detection of flame I have added the flame sensor and for the detection of gas I have added the MQ2 gas sensor modules!

IntermediateFull instructions provided2 hours4

Arduino Gas Leakage and Flame Detection With Alert System

Things used in this project

Hardware components

Arduino UNO Wifi Rev.2

Software apps and online services

Arduino IDE

Hand tools and fabrication machines

3D Printer (generic)

Story

By the name itself you might have already know what is this project all about.

Well let me also quickly tell you what this project is actually about and what made me to build this project.

Most of us have already seen the gas detection system that is found in the ceiling of the office! Well that works in the similar way when it gets exposed to flame the fuse inside it breaks and it sprays water.

This project was inspired from that but here instead of spraying water I will use LED to show you the workings and not to mention you can also connect to other components like for example the water pump also when the sensor detects the flame or gas.

To make the device more sensitive considering the safety I have added 2 separate here in this project.

For the detection of flame I have added the flame sensor and for the detection of gas I have added the MQ2 gas sensor modules.

Both of these sensor really does a great job when it comes to preactical use cases.

To make the device interactive I have added LCD module that shows the values in real time, and the best part is there is 2 seperate rows to mention if the sensor detects the flame or gas.

Now in short let me tell you how this project works, as soon you connect this to power supply the project is ready for using.

The flame sensor is sensitive to fire and if it detects it immediately triggers the buzzer accompanying the led and also the same is shown in the LCD module, and the same is for gas sensor also.

I strongly recommend you to build this project as you can learn a lot about sensor and circuits.

The circuit is simple and dont panic by seeing the cable connections! I will make the circuit simple by breaking down the steps one by one component wise.

To begin with there are 5 components and I will go with connections of every one

Flame sensor

This has 3 pins and the signal pin is connected to D2

Whereas the power and ground is connected to 3v and GND pins respectively

Gas sensor

Here also the Ground and Power pins are connected to GND and 5v Pins of the Uno board

The signal pin that is A0 on the gas sensor is connected to A0 on the Uno board

Buzzer and LED

Sinec we have limittaion of the GND pins of the Uno board I have connected the ground of both componnets into one

Whereas the positive pins from LED is connected to D13 and the Buzzer is connected to D8

LCD module

Scl and Sda is connected to A5 and A4 pins whereas the Positive and Gnd is connected to 5v and the ground pins respectively.

This completes the connection, Now open your IDE and use the below file for program, You may need to install drivers if it shows errors.

Select proper port and board type and click on upload button and now we can move ahead with next steps.

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I will use battery supply to power this project, I used 2 lithium ion batteries connected to holder and then to a DC pin.

This is then connected directly to the uno board power supply, After you connect this to uno you should see the message on LCD screen and all the components will be active.

Allow few seconds for the gas sensor to work efficiently since it has a gas sensing filament cased inside mesh that will be ready to use after heating.

Now you can test the project, I used lighter for flame and when you bring it near to the flame sensor the red led glows along with buzzer and the LCD shows flame detected as Yes.

Now I only passed some gas from the same lighter to the gas sensor and like the previous one here also you can see the alert system getting active.

Also did you know not only one but you can expose both flame and gas sensor together and see the device working properly.

Untill the sensor stops sensing the gas or flame the buzzer will beep, You can take this project one step further by connecting water spray pump also instead of LED.

Code

gas_and_flame_sensor_arduno.ino

#include <Wire.h>
#include <LiquidCrystal_I2C.h>

#define flamePin 2
#define gasPin A0
#define buzzer 8
#define ledPin 13 

LiquidCrystal_I2C lcd(0x27, 16, 2); // Change to 0x3F if needed

void setup() {
  pinMode(flamePin, INPUT);
  pinMode(buzzer, OUTPUT);
  pinMode(ledPin, OUTPUT);
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Fire & Smoke");
  lcd.setCursor(0, 1);
  lcd.print("Detector Ready");
  delay(2000);
  lcd.clear();
}

void loop() {
  int flame = digitalRead(flamePin);
  int gasValue = analogRead(gasPin);
  int gasThreshold = 300; // Adjust based on environment

  lcd.setCursor(0, 0);
  lcd.print("Flame: ");
  lcd.print(flame == LOW ? "YES " : "NO  "); // For active LOW sensors

  lcd.setCursor(0, 1);
  lcd.print("Smoke: ");
  lcd.print(gasValue > gasThreshold ? "YES " : "NO  ");

  if (flame == LOW || gasValue > gasThreshold) {
    // Danger detected
    digitalWrite(buzzer, HIGH);

    // Flash LED
    digitalWrite(ledPin, HIGH);
    delay(150);
    digitalWrite(ledPin, LOW);
    delay(150);
  } 
  else {
    // Normal condition
    digitalWrite(buzzer, LOW);
    digitalWrite(ledPin, LOW);
    delay(300);
  }
}

Credits

Jeev

2 projects • 0 followers

Arduino Gas Leakage and Flame Detection With Alert System

Things used in this project

Hardware components

Software apps and online services

Hand tools and fabrication machines

Story

Flame sensor

Gas sensor

Buzzer and LED

LCD module

Schematics

circuit diagram

Code

gas_and_flame_sensor_arduno.ino

Credits

Jeev

Comments

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Arduino Gas Leakage and Flame Detection With Alert System

Arduino Gas Leakage and Flame Detection With Alert System

Things used in this project

Hardware components

Software apps and online services

Hand tools and fabrication machines

Story

Flame sensor

Gas sensor

Buzzer and LED

LCD module

Schematics

circuit diagram

Code

gas_and_flame_sensor_arduno.ino

Credits

Jeev

Comments

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