MINOR PROJECT (I)

On

GAS DETECTION AND ALERT SYSTEM

Under the guidance of

Dr. Malti Bansal

Assistant Professor, Department of Electronics and Communication

Delhi Technological University

BY-

Arpit Bhateley (2K12/EC/036)

Anngad Singh (2K12/EC/030)

Apaar Singhal (2K12/EC/034)

Angad Singh (2K12/EC/026)

B. Tech. (Electronics and Communication Engineering), DTU

Department of Electronics and Communication Engineering,

Delhi Technological University

2

CERTIFICATE

This is to certify that the report entitled “Gas Detection And Alert System” is a

bonafide record of Minor Project (I) Report submitted by

Arpit Bhateley(2K12/EC/036)

Anngad Singh (2K12/EC/030)

Apaar Singhal(2K12/EC/034)

Angad Singh (2K12/EC/026)

as the record study undertaken by them under my guidance. It is being accepted in

partial fulfillment of the requirements for the award of degree of fifth semester

Minor Project (I) course of Bachelor of Technology in Electronics and

Communication Engineering, Delhi Technological University, Delhi.

Mentor

Dr. Malti Bansal

Assistant Professor

Department of ECE

Delhi Technological University

3

ACKNOWLEDGEMENT

We express our deepest gratitude to our mentor, Dr. Malti Bansal,

Department of Electronics and Communication Engineering, Delhi

Technological University, whose encouragement, guidance and support

enabled us to undertake this Minor Project successfully and to get the

maximum output of understanding from the subject.

We also take this opportunity to thank my friends, who encouraged us

and cleared our doubts during the course of my Minor Project. We

extend my gratitude to our families whose efforts were crucial in the

successful completion of this project.

4

INDEX S. No. Title Page No.

1 Introduction 6

2 Microcontroller-Arduino 7

3 Gas Sensor Module 15

4 SIM 900 GSM Module 21

5 Servo Motor 27 6 Buzzer 28

7 Circuit Diagram 29

8 Code 30

9 Working 33

10 Applications 39

11 Cost Comparison 41

5

FIGURE INDEX S. No. Title Page No.

1 Block Diagram 6

2 Microcontroller-Arduino 7

3 Schematic & Reference Design-Arduino 8

4 Arduino Mega 2560 PIN diagram 9

5 Gas Sensor 15

6 Wiring-Gas Sensor 16 7 SIM 900 GSM Module 21

8 SIM 900 GSM Module-Pin Diagram 23

9 Interfacing the Modem to microcontroller (Basic connection)

24

10 Interfacing the Modem to ARDUINO 24

11 Servomotor 27

12 Circuit Diagram 29

13 Application of Gas Detection System 39

14 Practical System 40

6

Servo

Motor

Introduction

The presence of dangerous LPG leakage in the cars, service station or in the

storage tank environment can be detected using the Ideal Gas Sensor.

The objective of this project is to detect any leakage of LPG/CNG in gas based

cars, small scale factories or in home appliances also. It will detect the leakage and

will close the knob of the system to stop the supply of the gas. Stepper motor is

there that could be attached with the knob and will close the supply by rotating it.

An alarm is also there to alert the user as soon as leakage is found. There shall be

an automatic call/sms from the system if any gas is detected. Hence the user gets

automatic information as soon as some problem occurs at the station.

BLOCK DIAGRAM FOR LPG GAS LEAKAGE DETECTOR

Arduino

Microcontroller

Gas Sensor

Module GSM Module

LED ALARM

7

BLOCK DIAGRAM DESCRIPTION

1). MICROCONTROLLER-Arduino Mega

It is the heart of the project. It is used to control the Servo Motor, LED and Buzzer

when LPG leakage occurs. The input/ output ports of the microcontroller are used

for this purpose.

8

Overview

The Arduino MEGA ADK is a microcontroller board based on the ATmega2560.

It has a USB host interface to connect with Android based phones, based on

the MAX3421e IC. It has 54 digital input/output pins (of which 15 can be used as

PWM outputs), 16 analog inputs, 4 UARTs (hardware serial ports), a

16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a

reset button.

The MEGA ADK is based on the Mega 2560.

Similar to the Mega 2560 and Uno, it features an ATmega8U2 programmed as a

USB-to-serial converter.

Schematic & Reference Design

9

ATmega2560-Arduino Pin Mapping

Arduino Mega 2560 PIN diagram

10

Summary

Microcontroller

ATmega2560

Operating Voltage 5V

Input Voltage (recommended) 7-12V

Input Voltage (limits) 6-20V

Digital I/O Pins 54 (of which 15 provide PWM output)

Analog Input Pins 16

DC Current per I/O Pin 40 mA

DC Current for 3.3V Pin 50 mA

Flash Memory 256 KB of which 8 KB used by bootloader

SRAM 8 KB

EEPROM 4 KB

Clock Speed 16 MHz

USB Host Chip MAX3421E

11

Power

The Arduino MEGA ADK can be powered via the USB connection or with an

external power supply. The power source is selected automatically.

External (non-USB) power can come either from an AC-to-DC adapter (wall-wart)

or battery. The adapter can be connected by plugging a 2.1mm center-positive plug

into the board's power jack. Leads from a battery can be inserted in the Gnd and

Vin pin headers of the POWER connector.

The board can operate on an external supply of 5.5 to 16 volts. If supplied with less

than 7V, however, the 5V pin may supply less than five volts and the board may be

unstable. If using more than 12V, the voltage regulator may overheat and damage

the board. The recommended range is 7 to 12 volts.

The power pins are as follows:

VIN. The input voltage to the Arduino board when it's using an external power

source (as opposed to 5 volts from the USB connection or other regulated power

source). You can supply voltage through this pin, or, if supplying voltage via the

power jack, access it through this pin.

5V. This pin outputs a regulated 5V from the regulator on the board. The board can

be supplied with power either from the DC power jack (7 - 12V), the USB

connector (5V), or the VIN pin of the board (7-12V). Supplying voltage via the 5V

or 3.3V pins bypasses the regulator, and can damage your board. We don't advise

it.

3V3. A 3.3 volt supply generated by the on-board regulator. Maximum current

draw is 50 mA.

GND. Ground pins.

IOREF. This pin on the Arduino board provides the voltage reference with which

the microcontroller operates. A properly configured shield can read the IOREF pin

voltage and select the appropriate power source or enable voltage translators on the

outputs for working with the 5V or 3.3V.

12

Memory

The MEGA ADK has 256 KB of flash memory for storing code (of which 8 KB is

used for the bootloader), 8 KB of SRAM and 4 KB of EEPROM (which can be

read and written with the EEPROM library).

Input and Output

Each of the 50 digital pins on the MEGA ADK can be used as an input or output,

using pinMode(), digitalWrite(), anddigitalRead() functions. They operate at 5

volts. Each pin can provide or receive a maximum of 40 mA and has an internal

pull-up resistor (disconnected by default) of 20-50 kOhms. In addition, some pins

have specialized functions:

Serial: 0 (RX) and 1 (TX); Serial 1: 19 (RX) and 18 (TX); Serial 2: 17 (RX)

and 16 (TX); Serial 3: 15 (RX) and 14 (TX). Used to receive (RX) and transmit

(TX) TTL serial data. Pins 0 and 1 are also connected to the corresponding pins of

the ATmega8U2 USB-to-TTL Serial chip.

External Interrupts: 2 (interrupt 0), 3 (interrupt 1), 18 (interrupt 5), 19

(interrupt 4), 20 (interrupt 3), and 21 (interrupt 2). These pins can be

configured to trigger an interrupt on a low value, a rising or falling edge, or a

change in value.

PWM: 2 to 13 and 44 to 46. Provide 8-bit PWM output with

the analogWrite() function.

SPI: 50 (MISO), 51 (MOSI), 52 (SCK), 53 (SS). These pins support SPI

communication using the SPI library. The SPI pins are also broken out on the ICSP

header, which is physically compatible with the Uno, Duemilanove and Diecimila.

USB Host: MAX3421E. The MAX3421E comunicate with Arduino with the SPI

bus. So it uses the following pins:

o Digital: 7 (RST), 50 (MISO), 51 (MOSI), 52 (SCK). NB:Please do not use Digital pin 7 as input or output because is used in the

comunication with MAX3421E

o Non broken out on headers: PJ3 (GP_MAX), PJ6 (INT_MAX), PH7 (SS).

13

LED: 13. There is a built-in LED connected to digital pin 13. When the pin is

HIGH value, the LED is on, when the pin is LOW, it's off.

TWI: 20 (SDA) and 21 (SCL). Support TWI communication using the Wire

library. Note that these pins are not in the same location as the TWI pins on the

Duemilanove or Diecimila.

The MEGA ADK has 16 analog inputs, each of which provide 10 bits of resolution

(i.e. 1024 different values). By default they measure from ground to 5 volts, though

is it possible to change the upper end of their range using the AREF pin and

analogReference() function.

There are a couple of other pins on the board:

AREF. Reference voltage for the analog inputs. Used with analogReference().

Reset. Bring this line LOW to reset the microcontroller. Typically used to add a

reset button to shields which block the one on the board.

Communication

The Arduino MEGA ADK has a number of facilities for communicating with a

computer, another Arduino, or other microcontrollers. The ATmega2560 provides

four hardware UARTs for TTL (5V) serial communication. An ATmega8U2 on

the board channels one of these over USB and provides a virtual com port to

software on the computer (Windows machines will need a .inf file, but OSX and

Linux machines will recognize the board as a COM port automatically. The

Arduino software includes a serial monitor which allows simple textual data to be

sent to and from the board. The RX and TX LEDs on the board will flash when

data is being transmitted via the ATmega8U2/16U2 chip and USB connection to

the computer (but not for serial communication on pins 0 and 1).

A SoftwareSerial library allows for serial communication on any of the MEGA

ADK's digital pins.

14

The ATmega2560 also supports TWI and SPI communication. The Arduino

software includes a Wire library to simplify use of the TWI bus; see the Wire

library for details. For SPI communication, use the SPI library.

The USB host interface given by MAX3421E IC allows the Arduino MEGA ADK

to connect and interact to any type of device that have a USB port. For example,

allows you to interact with many types of phones, controlling Canon cameras,

interfacing with keyboard, mouse and games controllers as Wiimote and PS3.

Physical Characteristics and Shield Compatibility

The maximum length and width of the MEGA ADK PCB are 4 and 2.1 inches

respectively, with the USB connector and power jack extending beyond the former

dimension. Three screw holes allow the board to be attached to a surface or case.

Note that the distance between digital pins 7 and 8 is 160 mil (0.16"), not an even

multiple of the 100 mil spacing of the other pins.

The MEGA ADK is designed to be compatible with most shields designed for the

Uno, Diecimila or Duemilanove. Digital pins 0 to 13 (and the adjacent AREF and

GND pins), analog inputs 0 to 5, the power header, and ICSP header are all in

equivalent locations. Further the main UART (serial port) is located on the same

pins (0 and 1), as are external interrupts 0 and 1 (pins 2 and 3 respectively). SPI is

available through the ICSP header on both the MEGA ADK and Duemilanove /

Diecimila.

15

2). Gas Sensor Module

This sensor is used to sense the leakage of LPG. In normal conditions the output of

this sensor is ‘high’ and it goes ‘low’, when the LPG is sensed.

Introduction

The MQ series of gas sensors use a small heater inside with an electro-chemical

sensor. They are sensitive for a range of gasses and are used indoors at room

temperature.

They can be calibrated more or less (see the section about "Load-resistor" and

"Burn-in") but a know concentration of the measured gas or gasses is needed for

that.

The output is an analog signal and can be read with an analog input of the Arduino.

16

Wiring

The preferred wiring is to connect both 'A' pins together and both 'B' pins together.

It is safer and it is assumed that is has more reliable output results. Although many

schematics and datasheets show otherwise, you are advised to connect both 'A' pins

together and connect both 'B' pins together.

In the picture, the heater is for +5V and is connected to both 'A' pins. This is only

possible if the heater needs a fixed +5V voltage.

The variable resistor in the picture is the load-resistor and it can be used to

determine a good value. A fixed resistor for the load-resistor is used in most cases.

The Vout is connected to an analog input of the Arduino.

17

The Heater

The voltage for the internal heater is very important.

Some sensors use 5V for the heater, others need 2V. The 2V can be created with a

PWM signal, using analogWrite() and a transistor or logic-level mosfet.

The heater may not be connected directly to an output-pin of the Arduino, since it

uses too much current for that.

Some sensors need a few steps for the heater. This can be programmed with an

analogWrite() function and delays. A transistor or logic-level mosfet should also in

this situation be used for the heater.

If it is used in a battery operated device, a transistor or logic-level mosfet could

also be used to switch the heater on and off.

The sensors that use 5V or 6V for the internal heater do get warm. They can easily

get 50 or 60 degrees Celcius.

After the "burn-in time", the heater needs to be on for about 3 minutes (tested with

MQ-2) before the readings become stable.

18

Load-resistor

The sensor needs a load-resistor at the output to ground. It's value could be from

2kOhm to 47kOhm. The lower the value, the less sensitive. The higher the value,

the less accurate for higher concentrations of gas.

If only one specific gas is measured, the load-resistor can be calibrated by applying

a know concentration of that gas. If the sensor is used to measure any gas (like in a

air quality detector) the load-resistor could be set for a value of about 1V output

with clean air.

Burn-in

Some datasheets use the term "preheat", but it is the time to burn-in the sensor.

This is meant to make the sensor readings more consistent. A time of 12 or 24

hours is usually used for the burn-in time.

The Burn-in is achieved by applying normal power to the sensor (to the heater and

with the 'A' and 'B' pins connected, and with a load-resistor). In some special cases

a specific burn-in is needed. See the datasheet if the sensor needs such a specific

burn-in.

19

List of sensors

MQ-2

Sensitive for Methane, Butane, LPG, smoke.

This sensor is sensitive for flamable and combustible gasses.

The heater uses 5V.

MQ-3

Sensitive for Alcohol, Ethanol, smoke

The heater uses 5V

MQ-4

Sensitive for Methane, CNG Gas

The heater uses 5V.

MQ-5

Sensitive for Natural gas, LPG

The heater uses 5V.

20

MQ-6

Sensitive for LPG, butane gas

The heater uses 5V.

MQ-7

Sensitive for Carbon Monoxide

The heater uses an alternating voltage of 5V and 1.4V.

MQ-8

Sensitive for Hydrogen Gas

The heater uses 5V.

MQ-9

Sensitive for Carbon Monoxide, flammable gasses.

The heater uses an alternating voltage of 5V and 1.5V. It depends on the gases how

to use that alternating voltage. If only Carbon Monoxide is tested, the heater can be

set at 1.5V.

21

3.) SIM 900 GSM MODULE

The SIM900 is a complete Quad-band GSM/GPRS solution in a

SMT module which can be embedded in the customer applications.

Featuring an industry-standard interface, the SIM900 delivers

GSM/GPRS 850/900/1800/1900MHz performance for voice, SMS,

Data, and Fax in a small form factor and with low power

consumption. With a tiny configuration of 24mm x 24mm x 3 mm,

SIM900 can fit almost all the space requirements in your M2M

application, especially for slim and compact demand of design.

SIM900 is designed with a very powerful single-chip processor integrating

AMR926EJ-S core

Quad - band GSM/GPRS module with a size of 24mmx24mmx3mm

SMT type suit for customer application

An embedded Powerful TCP/IP protocol stack

Based upon mature and field-proven platform, backed up by our support

service, from definition to design and production

22

General features

Quad-Band 850/ 900/ 1800/ 1900 MHz

GPRS multi-slot class 10/8

GPRS mobile station class B

Compliant to GSM phase 2/2+

– Class 4 (2 W @850/ 900 MHz)

– Class 1 (1 W @ 1800/1900MHz)

Dimensions: 24* 24 * 3 mm

Weight: 3.4g

Control via AT commands (GSM

07.07 ,07.05 and SIMCOM enhanced AT

Commands)

SIM application toolkit

Supply voltage range 3.4 ... 4.5 V

Low power consumption

Operation temperature:

-30 °C to +80 °C

Specifications for SMS via GSM/GPRS

Point-to-point MO and MT

SMS cell broadcast

Text and PDU mode

Drivers

MUX Driver

Interfaces

Interface to external SIM 3V/ 1.8V

analog audio interface

RTC backup

SPI interface

Serial interface

Antenna pad

I2C

23

GPIO

PWM

ADC

Compatibility

AT cellular command interface

Approvals in planning

CE

FCC

ROHS

PTCRB

GCF

AT&T

IC

TA

Pin Assignment

24

INTERFACING THE GSM MODEM

Interfacing the Modem to microcontroller (Basic connection)

GSM Modem Interfacing with Microcontroller

The Modem can be directly interface with 5V microcontrollers like PIC,AVR,

8051 Derivatives, Arduinos and 3V3 Microcontrollers like ARM ,ARM Cortex

XX etc. Make ensure V_INTERFACE pin is supplied with same voltage level as

the microcontroller VCC. As per the Fig there is only 2 connections are required to

use the modem. Connect RX pin of the modem to the TX pin of the

Microcontroller and TX pin of the modem to microcontroller’s RX pin. The

connected power supply (4.2v to 12v dc) should be capable of handling current up

to 1 A.

Interfacing the Modem to ARDUINO

25

GETTING STARTED

1) Insert SIM card. Open the SIM cardholder by sliding it as per the arrow mark

and lift up. Insert the SIM card , so as to align the chamfered corner suits in card

holder .After inserting the SIM card, lock the holder by sliding it to theopposite

direction of arrow mark.

2) Connect the antenna.Fix the supplied RF antenna to the SMA Antennae

connector and tighten it by rotating the nut

3) Connect the pins connect the GSM modem as per the circuit diagram provided

4) Power the modem power the modem from suitable power supply, which is

having enough current capacity (>1A).

5) Check the Status of the LEDs

PWR LED - Red LED will lit immediately

STS LED - Green LED will lit after 1-2 seconds

NET LED -Blue LED will starts to blink in fast for few seconds(Searching For

Network) and becomes slow blinking once the Modem registers with the Network.

6) Network LED

The Network LED indicates the various status of GSM module eg. Power on,

Network registration & GPRS connectivity. When the modem is powered up, the

status LED will blink every second. After the modem registers in the network

(takes between 10-60 seconds), LED will blink in step of 3 seconds. At

this stage you can start using Modem for your application.

7) Baud rate

The Baud rate supported by the modem is between 9600 and 115200. Make sure

the host system is set to the supported baud rate. The modem automatically sets to

the baud rate of the first command sent by the host system after it is powered up.

User must first send “A” to synchronize the baud rate. It is recommended to wait 2

to 3 seconds before sending “AT” character. After receiving the “OK” response,

Your Device and GSM Modemare correctly synchronized. So there is no need for

setting the baud rate using commands. Before You Start using the modem, please

make sure that the SIM card you inserted support the needed features and there is

enough balance in SIM.

26

Testing GSM module with arduino using AT commands

AT commands are instructions used to control a modem. AT is the abbreviation of ATtention.

Every command line starts with "AT" or "at". That's why modem commands are called AT

commands. Many of the commands that are used to control wired dial-up modems, such as ATD

(Dial), ATA (Answer), ATH (Hook control) and ATO (Return to online data state), are also

supported by GSM/GPRS modems and mobile phones. Besides this common AT command set,

GSM/GPRS modems and mobile phones support an AT command set that is specific to the GSM

technology, which includes SMS-related commands like AT+CMGS (Send SMS message),

AT+CMSS (Send SMS message from storage), AT+CMGL (List SMS messages) and

AT+CMGR (Read SMS messages).

Note that the starting "AT" is the prefix that informs the modem about the start of a command

line. It is not part of the AT command name. For example, D is the actual AT command name in

ATD and +CMGS is the actual AT command name in AT+CMGS. However, some books and

web sites use them interchangeably as the name of an AT command.

There are two types of AT commands: basic commands and extended commands.

Basic commands are AT commands that do not start with "+". For example, D (Dial), A

(Answer), H (Hook control) and O (Return to online data state) are basic commands.

Extended commands are AT commands that start with "+". All GSM AT commands are

extended commands. For example, +CMGS (Send SMS message), +CMSS (Send SMS message

from storage), +CMGL (List SMS messages) and +CMGR (Read SMS messages) are extended

commands.

27

4.) Servomotor

A servomotor is a rotary actuator that allows for

precise control of angular position, velocity and

acceleration. It consists of a suitable motor

coupled to a sensor for position feedback. It also

requires a relatively sophisticated controller,

often a dedicated module designed specifically

for use with servomotors.

Servomotors are used in applications such

as robotics, CNC machinery or automated

manufacturing.

Here we are using the servomotor to close the

knob of the gas cylinder in case of any leakage.

Mechanism

Servo motors have three wires: power, ground, and signal. The power wire is

typically red, and should be connected to the 5V pin on the Arduino board. The

ground wire is typically black or brown and should be connected to a ground pin

on the Arduino board. The signal pin is typically yellow, orange or white and

should be connected to a digital pin on the Arduino board. Note that servos draw

considerable power, so if you need to drive more than one or two, you'll probably

need to power them from a separate supply (i.e. not the +5V pin on your Arduino).

Be sure to connect the grounds of the Arduino and external power supply together.

28

5.) BUZZER

A buzzer or beeper is an audio signalling device,which may be mechanical,

electromechanical, or piezoelectric. Typical uses of buzzers and beepers

include alarm devices, timers and confirmation of user input such as a mouse click

or keystroke.

Here we are using the buzzer to detect the

leakage of LPG. It is 12 V DC operated buzzer

which sounds an alarm as soon as it detects

LPG leakage.

29

Circuit Diagram

30

Code

#include <Servo.h> // Header File

Servo myservo; // create servo object to control a servo

/*--------------Variables-------------------------------*/

int gas=0;

int pos = 0;

const int analogInPin = A0; // Analog input pin that the gas sensor is attached to

int sensorValue = 0; // value read from the gas sensor

int timestosend=1;

int count=0;

char phone[]="9716946367"; // registered phone number

/*--------------------------------------------------------*/

void setup()

{

Serial.begin(9600); // initialize serial communications at 9600 bps:

myservo.attach(9); // Servo attached to PWM pin 9

Serial.println("AT+CMGF=1");

delay(200);

31

}

void loop()

{

sensorValue = analogRead(analogInPin); // read the analog in value:

Serial.print("sensor = " );

Serial.println(sensorValue);

if (sensorValue >= 900)

{ gas=1;

pos=90;

digitalWrite(PinMode,HIGH); // Switching ON Alarm and LED

}

else

{ gas=0;

pos=0;

digitalWrite(PinMode,LOW); // Switching OFF Alarm and LED

}

32

myservo.write(pos); // Writing PWM signal to Servo Motor

if(gas==1)

{

/*-----------------Sending Message to Registered User------*/

while(count<timestosend)

{

delay(1500);

Serial.print("AT+CMGS=\"");

Serial.print(phone);

Serial.println("\"");

while(Serial.read()!='>');

{

Serial.print("gas is leaking ,please come,help!");

delay(500);

Serial.write(0x1A);

Serial.write(0x0D);

Serial.write(0X0A);

delay(3000);

33

}

count++;

}

}

else

count=0;

delay(10);

}

WORKING

Input Section:

MQ6 gas sensor: The sensor is capable of detecting different type

flammable gases on calibrated sensitivity. In this that is Lighter Gas.

This sensor can be calibrated using the two potentiometers fitted in the

breakout board of MQ6 Sensor. The sensor gives an analog output. The

value of this output is decided as follows-

34

Input 5 V is divided into 1024 equal levels

Sensitivity= 5V/1024=0.0048V

Sensor Output= Sensitivity*Analog value( 0-1024)

Eg: Analog Value =900( in case of Lighter Gas)

Sensor Output=900*5/1024=4.39V

This the Output Value that is sent to the Microcontroller.

Processing Section:

Microcontroller: Programmed by the user to monitor the input and

generate proper output for the output unit. In general this is the brain of the

system.

It reads the Sensor Output Value and compares them to the threshold

level.

If the reading exceeds the threshold level ie 4.39V in this case it

generates the required PWM signal (through the PWM pin) for the

working of the Servo motor which shuts out the supply of gas.

It then sends a digital high signal to both the LED and the Buzzer to

sound off an alarm and glow the LED.

It finally sends commands and the text message to the GSM Module(

through Tx and Rx pins) via AT Commands to send the emergency

message to the concerned person/ authority.

Output Section:

1. Servo Motor: It accepts the PWM signal from the microcontroller and input voltage from the external battery for its working. It subsequently turns off the knob to shut down the supply of gas.

35

2. Buzzer: It accepts the digital high signal from the microcontroller to sound

off the alarm. 3. LED: It accepts the digital high signal from the microcontroller to glow the

LED in case of any leakage. 4. GSM Module: It receives the required message ( through Tx and Rx pins)

from the microcontroller. Then it send the emergency message in case of any

leakage.

Code Description:

#include <Servo.h>- Header file of Servo Library which contains all the

functions necessary for the control and operation of the Motor. It has the following

2 functions-

1. Myservo.attach(pin)-This function tells the microcontroller that the given

pin is attached to the input of the motor. In our case it is the PWM 9 pin.

2. Myservo.write(value)-This function is used for writing the PWM signal on

the Motor. Value ranges from 0-180 degrees.

3. Servo myservo- Create servo object to control the servo

int gas=0-signifies no leakage of gas

int pos = 0-signifies the position of the Motor

const int analogInPin = A0- Analog input pin that the gas sensor is attached to

int sensorValue = 0- value read from the gas sensor

int timestosend=1-Number of times the message is to be sent

int count=0-flag variable

36

char phone[]="9716946367"-registered phone number

void setup()

{

Serial.begin(9600)-initialize serial communication between arduino and PC at

9600 bps

myservo.attach(9)- Servo attached to PWM pin 9

Serial.println("AT+CMGF=1")-It indicates text mode and tells the length of the

message signal in character set

delay(200)-provides a delay of 200 ms for the analog values to settle down

}

This function sets up the processing task.

void loop()

{

sensorValue = analogRead(analogInPin)-read the analog in value

Serial.print("sensor = " )-prints the given text on serial monitor

Serial.println(sensorValue)- prints the value on serial monitor

37

if (sensorValue >= 900)-checks if sensor value is above threshold or not

{ gas=1-indicates leakage of gas

pos=90-inidcates position of Servo Motor

digitalWrite(PinMode,HIGH)- Switching ON Alarm and LED

}

else

{ gas=0- indicates no leakage of gas

pos=0-indicates rest position of Servo Motor

digitalWrite(PinMode,LOW)-Switching OFF Alarm and LED

}

myservo.write(pos)- Writing PWM signal to Servo Motor

The following code segment is used for sending the text message

if(gas==1)-checks if gas is leaking

{

while(count<timestosend)-loop to determine number of times the message is

to be sent

38

{

delay(1500);

Serial.print("AT+CMGS=\"")- This command sends a short message

from the modem to the network

Serial.print(phone)-indicates the phone number to which message is to be

sent

Serial.println("\"")-

while(Serial.read()!='>')-checks if GSM Module is connected or not

{

Serial.print("gas is leaking ,please come,help!")-content of the

text message

delay(500);

Serial.write(0x1A)- Setting up control word registers of gsm module.

Serial.write(0x0D)-

Serial.write(0X0A)-

delay(3000);

}

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count++-Increments flag counter

}

}

40

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APPLICATIONS

Safety plays a major role in today’s world and it is necessary that good safety

systems are to be implemented in places of education and work. The LPG or

propane which is flammable mixture of hydrocarbon gases used as fuel in many

applications like homes, hostels, industries, automobiles, vehicles because of its

desirable properties which include high calorific

value, which produce the less smoke, produces

less soot, and does not cause much harm to the

environment. Natural gas is another widely used

fuel in homes. Both gases burns to produce clean

energy, however there is a serious problem about

their leakage in the air. The gases being heavier

than air do not disperse easily and may lead to

suffocation when inhaled also when gas leakage

into the air may lead to explosion. Due to the

explosion of LPG gas the number of deaths has

been increased in recent years. To avoid this

problem there is a need for a system to detect and also prevent leakage of LPG.

Gas leak detection is the process of identifying potentially hazardous gas leaks by

means of various sensors. The advantage of this automated detection and alerting

system over the manual method is that it offers quick response time and accurate

detection of an emergency and in turn leading faster diffusion of the critical

situation.

The gas detection and alert system that we have designed is a very cost effective

system to detect leakage of any gas. It not only detects leakage of gas, it also

sounds an alarm and has a motor attached to it that can be used to close the knob of

the leaking cylinder. It has its applications in various fields like

Schools, Colleges, Universities

Homes

Industries

It is especially useful in the case when leakage takes place when there is no one

around. In this case the motor installed would close the source of the leakage and

the concerned person would get an alert by SMS.

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One of the incidents that everyone can closely relate to is the Bhopal Gas tragedy.

With this system in place not only would a timely alert been useful for evacuation,

but the source of gas leakage could also have been stopped and a lot of lives would

have been saved.

ADVANTAGE

It is used in house as LPG leakage detection.

It also detects alcohol so it is used as liquor tester.

The sensor has excellent sensitivity combined with a quick response time.

DISADVANTAGES

It is little sensitive to smoke, then in kitchen it is not perfectly response for

LPG gas leakage.

It works only when at 5V power supply is given.

Its sensitivity depends on Humidity and temperature.

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COST COMPARISON

S.No Hardware Component Cost

1) Arduino 800

2) Mq-6 400

3) GSM Module 900

4) Servo Motor 200

5) Wires 30

6) Battery 15

7) Buzzer 40

8) Miscellaneous 100

Total Cost 2485

Our Gas Detection And Alert System was designed for a cost of 2,485/-. The same

product is available in the market for an approximate cost of about 8,000/- to

9,000/- .

Serving almost the same purpose it can be seen easily that our system is much

more cost effective than any other system that is commercially available and can

be used easily in households, automobiles, schools, colleges, industries etc.