GAS LEAKAGE DETECTION SYSTEM FOR CORPORATE INDUSTRIES

Arduino-Based LPG Leakage Detection with Automatic Gas Shut-Off | Smart LPG Monitoring System with Real-Time IoT Alerts | LPG Leak Detection with Servo-Controlled Regulator and Alarm | MQ-2-Based LPG Leakage Detection and Warning System Using Arduino | Integrated LPG Safety System with Leak Detection and Automatic Regulator Control.

GAS LEAKAGE DETECTION AND AUTOMATIC ENGINE SHUTDOWN SYSTEM FOR CORPORATE INDUSTRIES USING ARDUINO UNO R3 AND GSM

Complete Project Documentation Arduino UNO R3 Embedded Systems / IoT

This project documentation is designed for an engineering final-year project, diploma project, or academic mini-project. It includes the project abstract, objectives, working principle, hardware and software requirements, circuit connections, block diagrams, flowcharts, Arduino program, testing procedure, advantages, applications, and conclusion.

The proposed system uses an Arduino UNO R3 instead of the AT89S52 microcontroller. It monitors gas leakage and temperature, activates an alarm, sends an SMS through a GSM modem, and switches OFF a low-voltage demonstration motor when dangerous conditions are detected.

Important safety note: The circuit and code below are for an educational prototype. Do not connect an ordinary Arduino relay directly to a real vehicle ignition, fuel system, industrial gas valve, or safety interlock. Actual LPG/CNG installations require certified gas detectors, appropriately rated shutdown equipment, fail-safe control circuits, and installation by qualified professionals. An MQ sensor is not a certified life-safety detector.

1. PROJECT ABSTRACT

The Gas Leakage Detection and Automatic Engine Shutdown System is an embedded-system-based safety monitoring project designed to detect LPG/CNG gas leakage and abnormal temperature conditions in vehicles, small-scale industries, factories, and other gas-utilizing environments.

Gas leakage is one of the major causes of industrial accidents, fire hazards, and explosions. In many situations, leakage remains undetected until the gas concentration reaches a dangerous level. Therefore, an automatic monitoring and warning system is required to detect leakage at an early stage and take appropriate safety measures.

This project uses an Arduino UNO R3 microcontroller as its main processing unit. A gas sensor detects the presence of LPG/CNG gas, while a temperature sensor continuously monitors the surrounding temperature.

The sensors provide signals to the Arduino. The controller compares the measured values against predefined threshold limits. When any parameter exceeds its configured limit, the system performs the following operations:

1. Activates a buzzer to provide an immediate warning.

2. Displays the gas and temperature readings on a 16×2 LCD.

3. Sends an SMS alert through a GSM modem to a predefined authorized mobile number.

4. Disconnects the demonstration motor through a relay module.

5. Keeps the alarm condition active until the system is safely reset.

The proposed system demonstrates the use of embedded technology for automatic gas leakage monitoring, remote notification, and safety-oriented equipment shutdown.

2. INTRODUCTION

Gas leakage is a serious safety problem in industries, vehicles, laboratories, commercial kitchens, and domestic environments.

LPG (Liquefied Petroleum Gas) and CNG (Compressed Natural Gas) are widely used as alternative fuels. Although these fuels are useful and economical, accidental leakage can result in fire, explosions, and damage to human life and property.

Traditional gas detection systems generally provide only an audible warning. However, modern safety requirements demand more intelligent systems that can monitor multiple parameters, communicate warnings remotely, and initiate automatic safety actions.

The proposed project addresses these requirements using an Arduino-based embedded monitoring system.

The system continuously monitors:

• LPG/CNG gas concentration (using an appropriate gas sensor).

• Ambient temperature (using a temperature sensor).

• System operating status.

• Alarm and motor-control status.

When a dangerous condition is detected, the system generates a local alarm and communicates the event to an authorized person through GSM technology.

2.1 Existing system

In conventional gas detection systems:

• Gas sensors detect leakage.

• A buzzer produces an alarm.

• A display may indicate the leakage condition.

• Human intervention is usually required to take corrective action.

Disadvantages of the existing system

1. Limited remote monitoring.

2. No automatic notification to authorized personnel.

3. Delayed human response.

4. Limited monitoring of multiple parameters.

5. No integrated demonstration of automatic equipment shutdown.

2.2 Proposed system

The proposed system combines gas detection, temperature monitoring, GSM communication, LCD display, and automatic motor control.

The Arduino UNO R3 acts as the central controller and processes all sensor inputs.

When gas concentration or temperature exceeds the configured threshold:

• The controller identifies the abnormal condition.

• The LCD displays the readings and warning.

• The buzzer produces an audible alarm.

• The GSM modem transmits an SMS notification.

• The motor demonstration circuit is switched OFF.

This provides an integrated safety-monitoring prototype.

3. AIM OF THE PROJECT

To design and develop an Arduino UNO R3-based gas leakage detection and automatic shutdown system for monitoring LPG/CNG leakage and abnormal temperature conditions in vehicles and small-scale industrial environments using GSM communication.

4. OBJECTIVES

The major objectives are:

1. To detect LPG/CNG gas leakage using a gas sensor.

2. To continuously monitor environmental temperature.

3. To process sensor readings using Arduino UNO R3.

4. To compare sensor readings against predefined threshold values.

5. To provide an immediate warning through a buzzer.

6. To display sensor readings on a 16×2 LCD.

7. To send emergency SMS notifications through GSM.

8. To switch OFF a low-voltage demonstration motor when dangerous conditions are detected.

9. To develop an economical and easily understandable embedded-system prototype.

10. To demonstrate the possibility of remote industrial safety monitoring.

5. BLOCK DIAGRAM

The following block diagram explains the overall architecture of the project.

hackster.io

5.1 Proposed block diagram

GAS SENSOR (MQ-6 / MQ-2)

Detects LPG/CNG-related combustible gases

TEMPERATURE SENSOR (DHT22 / LM35)

Measures surrounding temperature

ARDUINO UNO R3 MICROCONTROLLER

Reads sensors, compares thresholds and controls outputs

16×2 LCD

Live readings

GSM MODEM

SMS notification

BUZZER

Audio warning

RELAY + MOTOR

Motor demonstration shutdown

Power supply: regulated 5V for Arduino and compatible peripherals; separate appropriate supply for GSM modem and motor.

6. HARDWARE REQUIREMENTS

The following components are required to construct the prototype.

Sl. No.	Component	Quantity	Purpose
1	Arduino UNO R3	1	Main controller
2	MQ-6 gas sensor module	1	LPG detection
3	DHT22 temperature sensor	1	Temperature measurement
4	16×2 LCD with I2C module	1	Display
5	GSM modem	1	SMS communication
6	5V-compatible relay module	1	Motor switching
7	DC demonstration motor	1	Shutdown demonstration
8	Active buzzer module	1	Audio alarm
9	Start switch	1	System activation
10	Regulated power supply	1	Power
11	Connecting wires	As required	Connections
12	Breadboard/PCB	1	Circuit assembly

6.1 Gas sensor – MQ-6

MQ-6 Gas Sensor

The MQ-6 is commonly used for detecting LPG and butane-related combustible gases. It provides an analog output proportional to the sensor response.

Functions:

• Detects combustible gas.

• Provides an analog signal.

• Connects to Arduino analog input.

• Supports threshold-based monitoring.

Note: MQ-6 readings are not automatically calibrated in ppm. Proper calibration against known gas concentrations is necessary for quantitative measurements.

6.2 Temperature sensor – DHT22

DHT22

The DHT22 measures surrounding temperature and relative humidity and sends digital data to the Arduino.

Functions:

• Measures ambient temperature.

• Measures relative humidity.

• Provides digital output.

• Suitable for educational environmental monitoring.

6.3 Arduino UNO R3

Arduino UNO R3

It is the main controller responsible for collecting sensor information and controlling the LCD, buzzer, GSM modem, and relay.

Main specifications:

• Microcontroller: ATmega328P.

• Operating voltage: 5V.

• Digital I/O pins: 14.

• Analog input pins: 6.

• Flash memory: 32 KB.

• Clock frequency: 16 MHz.

6.4 GSM modem

GSM/Cellular communication module

The modem transmits SMS alerts to an authorized mobile number whenever an abnormal condition occurs.

A suitable LTE-capable module with SMS support is recommended where 2G service is unavailable. SIM800L is a 2G option, but network availability must be checked before selecting it.

Important: Cellular modules often need a separate power supply capable of handling their peak current. Never power a high-current modem directly from the Arduino 5V pin. Follow the particular module's voltage and logic-level requirements.

6.5 LCD display

16×2 LCD

Displays gas sensor readings, temperature values, system status, and alarm messages.

6.6 Other components

• Buzzer: Generates an audible warning.

• Relay: Demonstrates automatic motor disconnection.

• DC motor: Represents a vehicle engine in the educational prototype.

• Start switch: Arms the monitoring system.

• Power supply: Supplies regulated power to the controller and peripherals.

7. CIRCUIT CONNECTIONS

The following connections are proposed for the Arduino UNO R3 prototype.

7.1 Arduino pin configuration

Component	Component pin	Arduino UNO pin
MQ-6 gas sensor	AO	A0
DHT22	DATA	D2
Start switch	One terminal	D3
GSM modem	TX	D10 (RX)
GSM modem	RX	D11 (TX), through suitable level shifting
Relay module	IN	D7
Buzzer	Signal	D8
LCD I2C	SDA	A4
LCD I2C	SCL	A5
All compatible modules	GND	Common GND

Power connections:

Component	Supply
Arduino UNO	USB or regulated input
MQ-6 module	According to module rating, commonly 5V
DHT22	3.3V or 5V according to module
LCD I2C	According to module rating, commonly 5V
Relay module	According to module rating
GSM modem	Dedicated regulated supply specified by modem
DC motor	Separate suitable motor supply

Important: Check the exact GSM module pinout and voltage before connecting it. Arduino TX is 5V logic; many cellular modules require lower-voltage UART logic. Use a suitable logic-level converter.

7.2 Schematic diagram

docs.cirkitdesigner.com

The following is the simplified connection schematic for the academic prototype:

ARDUINO UNO R3

ATmega328P Microcontroller

A0

MQ-6 Gas Sensor

D2

DHT22 Temperature

A4 / A5

I2C LCD Display

D10 / D11

GSM Modem

D7

Relay Module

D8

Buzzer

D3 – Start / Arm Switch

All signal connections refer to the educational low-voltage prototype. Use suitable drivers, current limits and separate supplies where required.

7.3 Motor relay connection

For the demonstration, use a small low-voltage DC motor.

The relay should be configured so that the motor receives power only when the controller energizes the relay:

• Motor supply positive → relay COM.

• Relay NO → motor positive.

• Motor negative → motor supply negative.

• Relay coil/control → compatible relay module and Arduino output.

• The relay is de-energized during startup, alarm, or loss of controller power.

This is an educational demonstration arrangement, not a certified vehicle-engine shutdown circuit. A real vehicle engine or fuel system must not be controlled using this general-purpose relay circuit.

7.4 Power supply diagram

AC MAINS

Laboratory power source

ISOLATED AC-DC POWER SUPPLY

Appropriately rated and protected

5V REGULATED

Arduino and compatible sensors/display

SEPARATE SUPPLY

GSM modem and motor as specified

For a student project, an isolated certified DC adapter is preferable to constructing an exposed mains transformer/rectifier circuit on a breadboard.

8. WORKING PRINCIPLE

The proposed system operates through continuous monitoring and comparison of sensor readings.

Step 1: Power ON

When the power supply is switched ON, the Arduino UNO R3 starts executing the program.

The LCD initializes, and the GSM modem is prepared for communication.

Step 2: Sensor initialization

The Arduino initializes:

• Gas sensor analog input.

• Temperature sensor.

• LCD display.

• GSM serial communication.

• Relay output.

• Buzzer output.

The gas sensor is allowed to warm up and stabilize before normal operation. The manufacturer's specified warm-up and calibration requirements must be followed.

Step 3: Parameter monitoring

The MQ-6 gas sensor continuously senses the surrounding air.

The DHT22 measures the ambient temperature.

Both readings are sent to the Arduino controller.

Step 4: Threshold comparison

The Arduino compares the readings against predefined limits.

For the academic prototype, example limits may be:

Parameter	Demonstration threshold
MQ-6 analog reading	350 (0–1023 scale)
Temperature	55°C

These are example software settings only. They are not certified safety limits, gas concentration values, or appropriate industrial trip settings.

Step 5: Normal condition

When readings are below the configured limits:

• LCD displays normal status.

• Buzzer remains OFF.

• No emergency SMS is sent.

• The motor demonstration may operate when the system is armed.

Step 6: Gas leakage or high temperature detected

If the gas reading or temperature exceeds its threshold:

• The controller identifies the abnormal condition.

• The motor demonstration relay is de-energized.

• The buzzer activates.

• The LCD displays an alert.

• An SMS notification is sent to the configured mobile number.

• The system enters a latched alarm state.

Step 7: Reset

After the cause of the alarm has been investigated and the environment is confirmed safe, the prototype can be restarted.

A real gas safety installation must use an approved manual-reset procedure and must not automatically restart hazardous equipment simply because the sensor reading falls.

9. FLOWCHARTS

9.1 Main system flowchart

START

Initialize Arduino, LCD, GSM and sensors

Warm up and stabilize gas sensor

Read gas and temperature values

Compare readings with threshold values

Are readings within limits?

YES

Display normal values

Buzzer OFF

Motor enabled only if armed

NO

Activate alarm

Motor OFF

Send GSM SMS

Repeat monitoring until power is switched OFF or system is reset

9.2 Gas leakage detection flowchart

text

       START
         |
         v
 Initialize Arduino
         |
         v
 Read MQ-6 Sensor
         |
         v
 Get Analog Gas Value
         |
         v
 Compare With Threshold
         |
    +----+----+
    |         |
    v         v
  NORMAL    LEAKAGE
    |         |
    v         v
 Display   Motor OFF
 Reading   Buzzer ON
    |       SMS Alert
    |         |
    +----+----+
         |
         v
   Continue Monitoring

9.3 GSM notification flowchart

text

       ABNORMAL CONDITION
               |
               v
       Identify Alarm Type
               |
               v
       Initialize GSM Modem
               |
               v
       Check Network Status
               |
               v
       Prepare SMS Message
               |
               v
       Send SMS to Authorized
          Mobile Number
               |
               v
       Display Alert Status
               |
               v
        Continue Monitoring

9.4 Motor shutdown flowchart

text

         SYSTEM START
               |
               v
       Relay Initially OFF
               |
               v
       Sensor Warm-up Complete?
               |
               v
       Is System Armed?
               |
          +----+----+
          |         |
          NO        YES
          |         |
          v         v
       Motor OFF  Check Parameters
                    |
               +----+----+
               |         |
             SAFE      UNSAFE
               |         |
               v         v
           Motor ON   Motor OFF
                         |
                         v
                    Alarm Latched

10. SOFTWARE REQUIREMENTS

The project uses the following software tools.

Software	Purpose
Arduino IDE	Writing and uploading program
Embedded C / Arduino C++	Programming
Arduino libraries	Sensor and LCD interfacing
ExpressPCB / KiCad	PCB design
Serial Monitor	Debugging and monitoring
USB driver	Arduino communication

10.1 Required Arduino libraries

Install these libraries through Arduino IDE Library Manager:

1. DHT sensor library by Adafruit.

2. Adafruit Unified Sensor.

3. LiquidCrystal_I2C.

The SoftwareSerial library is included with the standard Arduino AVR core.

11. COMPLETE ARDUINO UNO R3 SOURCE CODE

The following program implements the educational prototype.

Program features:

• MQ-6 gas sensor monitoring.

• DHT22 temperature monitoring.

• 16×2 I2C LCD display.

• GSM SMS notification.

• Buzzer warning.

• Automatic low-voltage demonstration motor shutdown.

• Start/arm switch.

• Latched alarm condition.

• SMS notification when an abnormal condition is first detected.

Arduino program

cpp

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

// ---------------- PIN CONFIGURATION ----------------

#define GAS_PIN       A0
#define DHT_PIN       2
#define START_PIN     3
#define RELAY_PIN     7
#define BUZZER_PIN    8

// GSM: Arduino RX = 10, Arduino TX = 11
SoftwareSerial gsm(10, 11);

// ---------------- SENSOR CONFIGURATION ----------------

#define DHTTYPE DHT22

DHT dht(DHT_PIN, DHTTYPE);

// Change 0x27 to 0x3F if required by your LCD.
LiquidCrystal_I2C lcd(0x27, 16, 2);

// ---------------- THRESHOLD SETTINGS ----------------

// Demonstration values only.
// MQ analog reading is NOT a calibrated ppm value.

const int GAS_THRESHOLD = 350;
const float TEMP_THRESHOLD = 55.0;

// Demonstration warm-up period.
// Follow the actual sensor manufacturer's instructions.
const unsigned long WARMUP_TIME = 60000UL;

// ---------------- GSM SETTINGS ----------------

// Replace with an authorized recipient number.
// Include the appropriate country code.

const char PHONE_NUMBER[] = "+91XXXXXXXXXX";

// ---------------- SYSTEM VARIABLES ----------------

bool alarmLatched = false;
bool smsSent = false;

unsigned long startupTime;

int gasValue = 0;
float temperature = 0.0;
float humidity = 0.0;

String alarmReason = "UNKNOWN";

// ---------------- GSM SMS FUNCTION ----------------

void sendSMS(String message)
{
  gsm.println("AT");
  delay(500);

  gsm.println("AT+CMGF=1");
  delay(500);

  gsm.print("AT+CMGS=\"");
  gsm.print(PHONE_NUMBER);
  gsm.println("\"");

  delay(1000);

  gsm.print(message);

  gsm.write(26);  // CTRL+Z to submit SMS

  delay(5000);
}

// ---------------- ALARM FUNCTION ----------------

void activateAlarm(String reason)
{
  if (alarmLatched)
  {
    return;
  }

  alarmLatched = true;
  alarmReason = reason;

  // De-energize relay: demonstration motor OFF.
  digitalWrite(RELAY_PIN, LOW);

  // Activate audible alarm.
  digitalWrite(BUZZER_PIN, HIGH);

  // Prepare emergency message.
  String message = "GAS SAFETY ALERT!\n";
  message += "Condition: " + reason + "\n";
  message += "Gas ADC: " + String(gasValue) + "\n";

  if (!isnan(temperature))
  {
    message += "Temperature: ";
    message += String(temperature, 1);
    message += " C";
  }
  else
  {
    message += "Temperature sensor error";
  }

  message += "\nMotor demonstration OFF.";

  if (!smsSent)
  {
    sendSMS(message);
    smsSent = true;
  }
}

// ---------------- LCD FUNCTION ----------------

void displayReadings()
{
  lcd.setCursor(0, 0);

  lcd.print("Gas:");
  lcd.print(gasValue);
  lcd.print("       ");

  lcd.setCursor(0, 1);

  if (isnan(temperature))
  {
    lcd.print("Temp: SENSOR ERR");
  }
  else
  {
    lcd.print("Temp:");
    lcd.print(temperature, 1);
    lcd.print((char)223);
    lcd.print("C     ");
  }
}

// ---------------- SETUP FUNCTION ----------------

void setup()
{
  pinMode(GAS_PIN, INPUT);

  pinMode(START_PIN, INPUT_PULLUP);

  pinMode(RELAY_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);

  // Safe initial output state.
  digitalWrite(RELAY_PIN, LOW);
  digitalWrite(BUZZER_PIN, LOW);

  Serial.begin(9600);
  gsm.begin(9600);

  dht.begin();

  lcd.init();
  lcd.backlight();

  lcd.setCursor(0, 0);
  lcd.print("GAS DETECTION");

  lcd.setCursor(0, 1);
  lcd.print("SYSTEM STARTING");

  startupTime = millis();

  delay(2000);

  lcd.clear();

  gsm.println("AT");
}

// ---------------- MAIN LOOP ----------------

void loop()
{
  // Read gas sensor.
  gasValue = analogRead(GAS_PIN);

  // Read temperature and humidity.
  temperature = dht.readTemperature();
  humidity = dht.readHumidity();

  // Display sensor information.
  displayReadings();

  // Show warm-up status.
  if (millis() - startupTime < WARMUP_TIME)
  {
    digitalWrite(RELAY_PIN, LOW);
    digitalWrite(BUZZER_PIN, LOW);

    lcd.setCursor(0, 0);
    lcd.print("SENSOR WARMING  ");

    Serial.println("Sensor warming up");

    delay(1000);
    return;
  }

  // Check temperature sensor validity.
  if (isnan(temperature))
  {
    activateAlarm("TEMPERATURE SENSOR ERROR");
  }

  // Check gas threshold.
  else if (gasValue >= GAS_THRESHOLD)
  {
    activateAlarm("GAS LEAKAGE DETECTED");
  }

  // Check temperature threshold.
  else if (temperature >= TEMP_THRESHOLD)
  {
    activateAlarm("HIGH TEMPERATURE");
  }

  // Alarm condition.
  if (alarmLatched)
  {
    digitalWrite(RELAY_PIN, LOW);
    digitalWrite(BUZZER_PIN, HIGH);

    lcd.clear();

    lcd.setCursor(0, 0);
    lcd.print("DANGER ALERT!");

    lcd.setCursor(0, 1);
    lcd.print(alarmReason.substring(0, 16));

    Serial.println("ALARM ACTIVE");
    Serial.println(alarmReason);

    delay(500);
    return;
  }

  // Normal condition.
  digitalWrite(BUZZER_PIN, LOW);

  // Arm switch connected between D3 and GND.
  bool systemArmed = (digitalRead(START_PIN) == LOW);

  if (systemArmed)
  {
    // Relay energized: demonstration motor may run.
    digitalWrite(RELAY_PIN, HIGH);

    lcd.setCursor(0, 0);
    lcd.print("SYSTEM NORMAL   ");

    Serial.println("System armed - Normal");
  }
  else
  {
    // Motor remains OFF when disarmed.
    digitalWrite(RELAY_PIN, LOW);

    lcd.setCursor(0, 0);
    lcd.print("SYSTEM DISARMED ");

    Serial.println("System disarmed");
  }

  // Print monitoring data.
  Serial.print("Gas ADC: ");
  Serial.println(gasValue);

  Serial.print("Temperature: ");
  Serial.println(temperature);

  Serial.print("Humidity: ");
  Serial.println(humidity);

  delay(1000);
}

11.1 Understanding the program

Function	Description
setup()	Initializes the hardware
loop()	Continuously monitors sensors
analogRead()	Reads gas sensor analog output
readTemperature()	Reads temperature
displayReadings()	Updates LCD
activateAlarm()	Activates alarm and sends SMS
sendSMS()	Sends GSM notification
digitalWrite()	Controls buzzer and relay

11.2 Important code configuration

Before uploading the program:

1. Change +91XXXXXXXXXX to the authorized recipient's mobile number.

2. Confirm the GSM modem baud rate.

3. Confirm the LCD I2C address (usually 0x27 or 0x3F).

4. Adjust the gas sensor demonstration threshold only after observing and calibrating sensor readings.

5. Verify the relay module's input polarity. The code assumes HIGH energizes the relay and LOW de-energizes it.

6. Check that the GSM modem supports SMS and is registered on a compatible network.

The code's 60-second warm-up is only a prototype startup delay, not a substitute for the MQ sensor's specified conditioning and calibration requirements.

Alarm reset: This program intentionally latches the alarm. To reset the educational prototype, remove the alarm cause, verify safe conditions, and restart the controller. A production installation needs a supervised manual reset and independent safety interlocks.

12. GSM SMS OUTPUT

When gas leakage is detected, the configured mobile number receives an alert similar to the following:

SMS notification

Emergency alert

Gas Safety Monitoring System

GAS SAFETY ALERT!

Condition: GAS LEAKAGE DETECTED

Gas ADC: 450

Temperature: 42.5 C

Motor demonstration OFF.

Illustrative SMS

For high-temperature conditions, the message will identify the temperature warning instead.

Note: The current program sends the first alarm SMS only. It does not verify delivery or automatically retransmit failed messages. A production version should monitor network registration, modem responses, SMS submission status, and communication failure.

13. IMPLEMENTATION PROCEDURE – STEP BY STEP

Follow these steps to build the prototype.

Step 1: Assemble the Arduino board

chegg.com

• Place the Arduino UNO R3 on the workbench.

• Connect it to the computer using a USB cable.

• Verify that the Arduino board is detected.

• Install the Arduino IDE.

Step 2: Connect the gas sensor

mdpi.com

• Connect MQ-6 VCC to its specified supply.

• Connect GND to common ground.

• Connect AO to Arduino A0.

• Upload a basic analog-reading program.

• Open Serial Monitor and observe the sensor values.

Step 3: Connect the temperature sensor

arduino-projekte.info

• Connect DHT22 VCC to its rated supply.

• Connect GND to common ground.

• Connect DATA to Arduino D2.

• Install the DHT library.

• Verify temperature readings.

Step 4: Connect the LCD

esroit.com

• Connect SDA to A4.

• Connect SCL to A5.

• Connect VCC and GND appropriately.

• Verify that the LCD displays text.

Step 5: Connect the GSM modem

arduino.stackexchange.com

• Connect modem TX to Arduino D10.

• Connect Arduino D11 to modem RX through a suitable level converter.

• Connect the modem to its dedicated power supply.

• Insert an activated SIM card.

• Verify network registration.

• Test SMS transmission.

Step 6: Connect the buzzer and relay

storage.googleapis.com

• Connect the buzzer signal to D8.

• Connect the relay control input to D7.

• Connect a low-voltage demonstration motor through the relay's normally open contact.

• Verify that the motor only runs when the system is armed and no alarm is active.

Step 7: Upload the complete program

• Open Arduino IDE.

• Select the Arduino UNO board.

• Select the correct COM port.

• Install the required libraries.

• Paste the complete source code.

• Enter the authorized SMS recipient number.

• Compile and upload the program.

Step 8: Perform testing

Test the system under controlled laboratory conditions using appropriate sensor test equipment. Do not release LPG, CNG, or other flammable gas into an ordinary classroom or laboratory to test leakage response.

14. TESTING AND OBSERVATION TABLE

The following table shows illustrative prototype test cases.

Test	Gas condition	Temperature	Expected response
1	Normal	30°C	Normal display
2	Above gas threshold	30°C	Buzzer, SMS, motor OFF
3	Normal	60°C	Buzzer, SMS, motor OFF
4	Above gas threshold	60°C	Alarm and motor OFF
5	Normal	35°C, system disarmed	Motor OFF
6	Temperature sensor disconnected	—	Sensor error alarm

14.1 Sample observation table

These are example values, not measured project results.

S.No.	Gas ADC	Temperature	System status
1	120	28°C	Normal
2	180	32°C	Normal
3	260	40°C	Normal
4	420	42°C	Gas alarm
5	150	60°C	Temperature alarm
6	500	65°C	Critical alarm

14.2 Expected result

The project is expected to detect abnormal gas sensor readings and high-temperature conditions.

Whenever the measured parameter crosses the configured threshold, the Arduino activates the buzzer, displays the warning on the LCD, sends an SMS through the GSM modem, and de-energizes the demonstration motor relay.

The system demonstrates the integration of sensor monitoring, embedded processing, wireless communication, and automatic equipment control.

15. ADVANTAGES

1. Automatic detection of abnormal gas conditions.

2. Continuous temperature monitoring.

3. Immediate audible warning.

4. Remote SMS notification.

5. Automatic demonstration motor shutdown.

6. Real-time parameter display.

7. Simple embedded-system architecture.

8. Relatively economical educational prototype.

9. Expandable to additional sensors.

10. Useful for demonstrating industrial safety automation.

16. APPLICATIONS

1. Industrial applications

Gas storage and industrial monitoring demonstrations.

2. Automotive applications

Gas leakage monitoring concepts for alternative-fuel vehicles.

3. Domestic applications

LPG leakage warning systems.

4. Chemical industries

Environmental parameter monitoring.

5. Warehouses

Gas and temperature monitoring concepts.

6. Small-scale factories

Remote safety notification and monitoring.

17. LIMITATIONS

The educational prototype has the following limitations:

1. MQ-6 sensor readings depend on environmental conditions and require calibration.

2. The sensor cannot independently provide certified gas concentration measurements.

3. GSM communication depends on network availability.

4. SMS delivery may be delayed or unsuccessful.

5. DHT22 is an ambient temperature sensor, not an industrial fire detector.

6. A single sensor cannot guarantee detection of every possible leakage location.

7. The prototype does not provide certified industrial safety protection.

8. Arduino and ordinary relay hardware are not suitable as standalone vehicle or industrial emergency shutdown controllers.

Important clarification about RTA: The prototype sends SMS to a configured authorized phone number. It does not automatically connect to the Regional Transport Authority (RTA). Sending notifications to an RTA requires an approved recipient, communication interface, and authorization.

18. FUTURE SCOPE

The project can be further developed with the following features:

• IoT-based remote monitoring through a web dashboard.

• GPS integration for vehicle location tracking.

• Multiple gas sensors for monitoring different locations.

• Additional industrial sensors for smoke, pressure, and humidity.

• Cloud-based data storage.

• Mobile application for live monitoring.

• Battery backup for power interruption.

• Event history and data logging.

• Industrial-grade certified gas detectors.

• Certified safety controller and engineered shutdown system.

• Authorized emergency notification integration.

18.1 Proposed advanced architecture

storage.googleapis.com

An advanced version could use a cellular IoT module to transmit sensor readings to a cloud server. Authorized personnel could view the gas concentration, temperature, alarm history, and device status through a web or mobile application.

19. PROJECT COST ESTIMATION

The following is an approximate student-project budget in Indian rupees. Actual prices depend on component quality and supplier.

Component	Approximate cost
Arduino UNO R3 compatible board	₹400–700
MQ-6 sensor module	₹100–200
DHT22 sensor	₹150–300
16×2 I2C LCD	₹150–250
GSM/LTE module	₹700–2,000+
Relay module	₹50–100
DC demonstration motor	₹100–200
Buzzer	₹20–50
Power supplies and converters	₹300–600
PCB, wires and accessories	₹200–400
Estimated total	₹2,170–4,800+

Budget estimate only. Cellular module selection, original components, and power supply requirements can substantially change the total.

20. RESULT

The proposed Gas Leakage Detection and Automatic Engine Shutdown System using Arduino UNO R3 demonstrates the monitoring of LPG/CNG-related gas sensor readings and environmental temperature.

The Arduino receives sensor data, compares the readings with predefined thresholds, and determines whether the system is operating normally or an abnormal condition exists.

When an abnormal condition is detected, the system:

• Activates an audible warning.

• Displays the abnormal parameter values.

• Sends an SMS through the GSM modem.

• Switches OFF the low-voltage demonstration motor.

Thus, the prototype demonstrates an integrated approach to gas leakage detection, temperature monitoring, remote notification, and automatic shutdown.

21. CONCLUSION

The Gas Leakage Detection and Automatic Shutdown System using Arduino UNO R3 and GSM is an embedded-system-based safety monitoring project.

The system is designed to detect abnormal gas conditions and high temperature through sensors. Arduino UNO R3 processes the sensor data and compares the values with predefined threshold limits.

Whenever an abnormal condition is detected, the system activates the buzzer, displays the readings on the LCD, sends an SMS notification to the authorized mobile number, and switches OFF the demonstration motor.

The project demonstrates how microcontrollers and wireless communication technologies can be integrated to improve monitoring and response in industrial and automotive safety applications.

The proposed system can be extended with IoT connectivity, GPS tracking, cloud storage, additional sensors, and certified industrial safety equipment.

22. BIBLIOGRAPHY / REFERENCES

The following references can be included in your project report:

1. Arduino UNO R3 official documentation – Arduino Documentation .

2. Arduino programming reference – Arduino Language Reference .

3. MQ-6 gas sensor datasheet – manufacturer-specific technical documentation.

4. DHT22/AM2302 technical datasheet – manufacturer documentation.

5. GSM/LTE modem AT command manual – selected modem manufacturer's documentation.

6. ATmega328P microcontroller datasheet – Microchip official documentation .

7. Embedded Systems: Introduction to Microcontrollers – reference textbook.

8. Digital Electronics and Microprocessor Systems – reference textbook.

23. VIVA QUESTIONS AND ANSWERS

These questions will help you prepare for your project presentation.

Q1. What is the main aim of this project?

To detect LPG/CNG gas leakage and abnormal temperature conditions, provide warnings through GSM, and switch OFF a demonstration motor automatically.

Q2. Why is Arduino UNO used?

Arduino UNO is used because it is economical, easy to program, and provides analog and digital interfaces for connecting multiple sensors and output devices.

Q3. What is the function of the MQ-6 sensor?

It detects combustible gases, particularly LPG and butane-related gases.

Q4. Why is a temperature sensor used?

It monitors environmental temperature and identifies abnormal temperature conditions.

Q5. What is the function of GSM?

GSM enables the system to send remote SMS notifications to an authorized mobile number.

Q6. What is the purpose of the LCD?

It displays real-time gas sensor readings, temperature, and system status.

Q7. What is the purpose of the relay?

It controls the low-voltage demonstration motor according to the controller's output.

Q8. What happens when gas leakage is detected?

The system activates the buzzer, sends an SMS, displays an alert, and switches OFF the demonstration motor.

Q9. What is the function of the ADC?

An analog-to-digital converter converts analog sensor signals into digital values that the microcontroller can process. Arduino UNO already has an internal 10-bit ADC, so a separate ADC0808 is not necessary for this design.

Q10. What is the difference between AT89S52 and Arduino UNO?

AT89S52 is an 8051-family microcontroller, whereas Arduino UNO R3 is a development board based on the ATmega328P. Arduino UNO includes built-in analog input capabilities and a convenient programming environment.

Q11. Can this project be used in industries?

The prototype demonstrates the concept, but real industrial installations require certified detectors, safety-rated controllers, suitable actuators, and professional engineering.

Q12. What happens if GSM communication fails?

The local buzzer and relay actions should still operate independently of GSM communication. A production system should additionally detect and report communication failures.

24. SUGGESTED FINAL-YEAR PROJECT REPORT STRUCTURE

You can organize your final documentation into the following chapters.

Chapter	Title	Content
1	Introduction	Background, aim, objectives
2	Literature Survey	Existing systems and proposed system
3	System Design	Block diagram and architecture
4	Hardware Description	Arduino, MQ-6, DHT22, GSM, LCD
5	Circuit Design	Circuit schematic and pin connections
6	Software Design	Flowcharts and Arduino code
7	Implementation	Assembly and testing
8	Results and Discussion	Observations and outputs
9	Advantages and Applications	Benefits and uses
10	Conclusion and Future Scope	Project summary and improvements
11	References	Datasheets and technical references

25. Final project demonstration – expected output

Your project demonstration should show three main operating conditions:

NORMAL

Condition 1 – Normal operation

• Gas reading below configured threshold.

• Temperature below configured threshold.

• LCD displays readings.

• Buzzer OFF.

• Motor can operate when armed.

WARNING

Condition 2 – Gas leakage

• Gas sensor reading exceeds threshold.

• Buzzer ON.

• LCD displays gas warning.

• GSM sends SMS.

• Demonstration motor OFF.

WARNING

Condition 3 – High temperature

• Temperature exceeds threshold.

• Buzzer ON.

• LCD displays temperature warning.

• GSM sends SMS.

• Demonstration motor OFF.

Final recommendation: For your project, retain the Arduino UNO R3, MQ-6, DHT22, LCD, GSM, buzzer, and relay architecture. It provides a clear and demonstrable final-year embedded-systems project without needing the older AT89S52, MAX232, or external ADC0808.

You can use this documentation as the foundation of your project report, then add your actual circuit photographs, measured test results, and implementation details after completing the prototype.