TABLE OF CONTENTS

1. CERTIFICATE……………………………………………………………………………22. DECLARATION………………………………………………………………………….33. ACKNOWLEDGMENT………………………………………………………………….44. ABSTRACT……………………………………………………………………………….55. LIST OF TABLES………………………………………………………………………...66. LIST OF FIGURES……………………………………………………………………….77. LIST OF COMPONENTS………………………………………………………………...88. CHAPTER 1-INTRODUCTION…………………………………………………………9

1.1 LIQUIFIED PETROLEUM GAS…………………………………………………….91.2 FIRE RISK AND MITIGATION……………………………………………………..91.3 HAZARDS…………………………………………………………………………...101.4 SAFETY PRECAUTIONS…………………………………………………………..101.5 PROBLEM……………………………...……………………………………………111.6 MAJOR GAS LEAK TRAGEDIES…………………………………………………121.7 SOLUTIONS AVAILABLE…………………………………………………………14

9. CHAPTER 2-SCHEME OF PROJECT………………………………………………….152.1 IDEA OF PROJECT…………………………………………………………………152.2 FLOW DIAGRAM…………………………………………………………………..152.3 WORKING OF DEVICE……………………………………………………………18

10. CHAPTER 3-IMPLEMENTATION OF DEVICE………………………………………193.1 BLOCK DIAGRAM DESCRIPTION………………………………………………203.2 WORKING WITH PROGRAM…………………………………………………….213.3 CIRCUIT DIAGRAM……………………………………………………………….243.4 CIRCUIT DESCRIPTION…………………………………………………………..25

11. CHAPTER 4-RESULT AND CONCLUSION………………………………………….2912. REFERENCES…………………………………………………………………………..3013. APPENDICES

APPENDIX A……………………………………………………………………………31APPENDIX B……………………………………………………………………………32APPENDIX C……………………………………………………………………………33APPENDIX D……………………………………………………………………………34

1

CERTIFICATE

This is to certify that Project Report entitled “Fully Automatic LPG Detection and

Checking in a Hostel Mess” which is submitted by Mansi Gupta, Sandhya Singh, Vinay

Kumar, and Yogesh Kumar in partial fulfillment of the requirement for the award of degree

B. Tech. in Department of Electronics Engineering of U. P. Technical University, is a

record of the candidates’ own work carried out by them under my supervision. The matter

embodied in this thesis is original and has not been submitted for the award of any other

degree.

2

Date: Supervisor:

DECLARATION

We hereby declare that this project report titled “Fully Automatic LPG Detection and Checking in Hostel Mess” submitted towards the completion of Project in Final year of B.tech (EC) in Institute Of Engineering and Technology, Lucknow is an authentic record of our work carried out under the guidance of Dr. V.K Singh, Head, Department of Electronics Engineering, Institute of Engineering and Technology, Lucknow.

Signature Signature

Name Name

Roll No. Roll No.

Date Date

3

Signature Signature

Name Name

Roll No. Roll No.

Date Date

ACKNOWLEDGEMENT

It gives us a great sense of pleasure to present the report of the B. Tech Project undertaken during B. Tech. Final Year. We owe special debt of gratitude to Dr. V. K. Singh, Head, Department of Electronics Engineering, Institute of Engineering and Technology, Lucknow for his constant support and guidance throughout the course of our work. His sincerity, thoroughness and perseverance have been a constant source of inspiration for us. It is only his cognizant efforts that our endeavors have seen light of the day.

We also take the opportunity to acknowledge the contribution of Dr. Neelam Srivastava, Assistant Professor, Department of Electronics Engineering, Institute of Engineering and Technology, Lucknow for her full support and assistance during the development of the project.

We also do not like to miss the opportunity to acknowledge the contribution of all faculty members of the department for their kind assistance and cooperation during the development of our project.

Signature Signature

Name Name

4

Roll No. Roll No.

Date Date

Signature Signature

Name Name

Roll No. Roll No.

Date Date

ABSTRACT

Purpose of Project:

We purpose to install a system which will help in detecting LPG leakage. The system can also be used in the household kitchen and other places where LPG is used and there is a potential risk of LPG leakage.

Inside View:

By changing the sensor type, the detector can be used for other gas types. We have used sensor HS-133 for LPG detection. It can also be used for methane and natural gas detection.

The detector is based on the commercial gas sensor from Figaro Company. The electronic circuit needs to evaluate change in the internal sensor resistance.

We have used ATMEGA-32 microcontroller because it makes the detector much simpler. It is in small DIP40 package with inbuilt analog to digital converter. The software is written in assembly language. The code is uploaded to the chip using bootloader method. This allows really low cost and easy development of any microcontroller application. The program measures voltage across

5

the sensor and compares it to the reference. If this value is higher than the threshold value for more than 15 sec, level 1 alarm is initiated. If the value exceeds the second threshold, level 2 alarm starts. Alarm levels are indicated by the LED diode and also relay contacts are closed. If the gas concentration falls down, alarm/indicator is stopped. With the memory function the detector will indicate alarm continuously if the gas concentration does not fall and the user will see potential risk of the gas leakage and need to check manually.

Significance of Project:

The software controls current consumption of the sensor heater and the value of the sensor resistance. If any of these values is out of limits, the detector indicates sensor malfunction. The software can be simply modified for other functions based on user wish.

Plan of Work:

In the past days we have followed following procedures to complete the project:

1. Inspection of hostel mess2. Power supply PCB construction3. Connection to sensor4. Programming of microcontroller5. Interfacing6. Circuit and software testing

LIST OF TABLES

Table 1. Pin description of HS-133

Table 2. Absolute maximum rating of ULN-2003

6

LIST OF FIGURES

Figure 1. Schematic of a hostel mess

Figure 2. Flow chart for LPG detection in cylinder room of a mess

Figure 3. Flow chart for LPG detection in cylinder room of a mess

Figure 4. Circuit schematic of LPG detection and checking in hostel mess using microcontroller

Figure 5. Circuit diagram of power supply

Figure 6. Model of inter-grain potential barrier (in the absence of gases)

Figure 7. Model of inter-grain potential barrier (in the presence of gases)

Figure 8. Pin outs of ATmega32 (PDIP)

Figure 9. Pin configuration of ULN-2003

7

CHAPTER 1

INTRODUCTION

Nowadays LPG is widely used in commercial as well as household purpose. Liquefied petroleum gas also called auto gas is a flammable mixture of hydrocarbon gases used as a fuel in heating appliances and vehicles, and increasingly replacing chlorofluorocarbons as an aerosol propellant and a refrigerant to reduce damage to the ozone layer. As low-polluting fossil fuel, LPG is recognized by governments around the world for the contribution it can make towards improved indoor and outdoor air quality and reduced greenhouse gas emissions.

LPG is a low carbon emitting hydrocarbon fuel available in rural areas, emitting 19 percent less CO2 per kWh than oil, 30 percent less than coal, and more than 50 percent less than coal-generated electricity distributed via the grid. Being a mix of propane and butane, LPG emits less carbon per joule than butane but more carbon per joule than propane. LPG is widely available and can be used for hundreds of commercial and domestic applications. Moreover, LPG is now being used alongside renewable technologies, as well as with decentralized electricity generation to help reduce carbon emissions on a local level.

LPG is synthesized by refining petroleum or "wet" natural gas, and is usually derived from fossil fuel sources, being manufactured during the refining of crude oil, or extracted from oil or gas streams as they emerge from the ground. It currently provides about 3% of the energy consumed, and burns cleanly with no soot and very few sulfur emissions, posing no ground or water pollution hazards. LPG has a typical specific calorific value of 46.1 MJ/kg However, its energy density per volume unit of 26 MJ at normal temperatures and pressures, LPG will evaporate. Because of this, LPG is supplied in pressurized steel cylinders. In order to allow for thermal expansion of the contained liquid, these cylinders are not filled completely; typically, they are filled to between 80% and 85% of their capacity.

1.2 Fire risk and mitigation

8

Since LPG turns gaseous under ambient temperature and pressure, it must be stored in special pressure vessels. LPG containers that are subjected to fire of sufficient duration and intensity can undergo a boiling liquid expanding vapor explosion .Due to the destructive nature of LPG explosions, the substance is classified as a dangerous good One of the main dangers is that accidental spills of hydrocarbons may ignite and heat an LPG container, which increases its temperature and pressure, following the basic gas laws. The relief valve on the top is designed to vent off excess pressure in order to prevent the rupture of the container itself. Given a fire of sufficient duration and intensity, the pressure being generated by the boiling and expanding gas can exceed the ability of the valve to vent the excess. When that occurs, an overexposed container may rupture violently, launching pieces at high velocity, while the released products can ignite as well, potentially causing catastrophic damage to anything nearby, including other containers .

Mitigation measures include separating LPG containers from potential sources of fire. In the case of rail transport, for instance, LPG containers can be staggered, so that other goods are put in between them. This is not always done, but it does represent a low-cost remedy to the problem. LPG rail cars are easy to spot from the relief valves on top, typically with railings all around.

1.3 Hazards of LPG

LPG is approximately twice as heavy as air when in gas form and will tend to sink to the lowest possible level and may accumulate in cellars, pits, drains etc.

LPG in liquid form can cause severe cold burns to the skin owing to its rapid vaporization.

Vaporization can cool equipment so that it may be cold enough to cause cold burns.

LPG forms a flammable mixture with air in concentrations of between 2% and 10%.

It can, therefore, be a fire and explosion hazard if stored or used incorrectly.

Vapour/air mixtures arising from leakages may be ignited some distance from the point of escape and the flame can travel back to the source of the leak.

At very high concentrations when mixed with air, vapour is an anaesthetic and subsequently an asphyxiate by diluting the available oxygen.

9

A vessel that has contained LPG is nominally empty but may still contain LPG vapour and be potentially dangerous. Therefore treat all LPG vessels as if they were full.

1.4 Safety Precautions

Action in an Emergency

Sound the alarm and summon the fire fighting services. Evacuate all personnel, except those necessary to deal with the emergency, from the

danger area (particularly if in path of any cloud). Always approach fire or leak from upwind and ONLY if safe to do so.

In case of a leak without fire

Isolate the leaking cylinder(s) and if possible stop the source of the leak. If the leak cannot be stopped remove the cylinder(s) to an isolated area i.e. clear of

people, buildings, drains and sources of ignition. The point of leakage should be kept uppermost.

In case of a leak with fire

A small fire from a bottle may be smothered with a wet cloth or dry powder extinguisher, ONLY if it is possible to stop the leak.

Cool with water any adjacent cylinder, which cannot be moved to a safe place. Always approach any fire or leak from upwind and using all protection available. It is best to control gas fires and not to extinguish them until the sources are cut off. Due regard should be taken of the possibility of exploding bottles and jets of flame from

relief valves.

1.5 Problem

Since LPG is a highly inflammable, various precautionary measures should be taken to handle it. Besides these precautions, various incidents had occurred in past years due to improper handling or storage of LPG. Such events led to a mass destruction of property and a large number of human casualties. Not only LPG other gases possessing similar characteristics can be similarly

10

dangerous and can bring devastating effects if not maintained or handled properly while their use. A large number of Chemical Industries use these types of gases. Various preventive measures are employed in the industries to check such ___.LPG is also used widely used for household cooking purpose. Various incidents have occurred due to leakage of LPG from cylinders used in kitchens. Thus gas leakage can cause disastrous events and need to be checked.

1.6 Major gas leak Tragedies

1. The Bhopal Gas Tragedy

The Bhopal disaster or Bhopal Gas Tragedy was an industrial catastrophe that occurred at a pesticide plant owned and operated by Union Carbide (UCIL), a wholly owned subsidiary of Dow Chemical Company in Bhopal, Madhya Pradesh, India. Around midnight on the intervening night of December 2–3, 1984, the plant released methyl isocynate (MIC) gas and other toxins, resulting in the exposure of over 500,000 people. Estimates vary on the death toll. The official immediate death toll was 2,259 and the government of Madhya Pradesh has confirmed a total of 3,787 deaths related to the gas release.

Some 25 years after the gas leak, 390 tons of toxic chemicals abandoned at the UCIL plant continue to leak and pollute the groundwater in the region and affect thousands of Bhopal residents who depend on it, though there is some dispute as to whether the chemicals still stored at the site pose any continuing health hazard.

2. Mass disasters in Greece

The accident happened at Eleusis (about 55 km southwest of Athens) in one of the largest oil refinery units in Greece, on 1 September 1992. The time of the accident was 7.15 a.m., Athens time. The cause of the accident was the leakage of flammables, mainly gases, from two different points of the pipes, in a partial distillation unit. The correct functioning of the pipes had been checked two days before the event and it was found to be sufficiently safe. This followed a six-month interruption in the operation of the unit for maintenance work. The explosions themselves originated from overheated gas in contact with air from the leakage points. The high pressure wave that was caused resulted in the shattering or collapse of every window pane in the vicinity; screaming and high flames caused the immediate automatic activation of the alarm system.

11

3. LPG Leakage at Hindustan Petroleum Corporation Limited (HPCL) at Vishakhapatnam, India

In September 1997, an LPG release occurred at the Hindustan Petroleum Corporation, Ltd. refinery in Visakhapatnam, India. The resulting explosion and fire destroyed most of the facility's administrative buildings, numerous LPG storage vessels, processing units, and an adjacent petroleum liquid storage terminal. Fifty-six people were declared dead, but the fatality number could have been as high as 3 times the official estimate. Property damage was estimated at US $15 million. It is known that a leak occurred during receipt of LPG cargo from a pressurized ship. The subsequent vapor cloud spread throughout the refinery tank farm, administrative complex, utilities area, and at least one process unit before eventually finding an ignition source. The investigation team developed numerous release theories. Vapor cloud dispersion computer modeling was used to evaluate the credibility of various release scenarios. This paper discusses the events leading up to the explosion, the damages sustained, and compares quantitative dispersion modeling results to the physical damage and witness testimony

4. Gas leak at the Mina al-Ahmadi refinery, Kuwait.

The leak occurred during an annual maintenance of the atmospheric residue desulphurization (ADR) unit at a crude distillation unit. Six workers suffered minor injuries following a gas leak on 1 July at the Mina al-Ahmadi refinery.

5. LPG Leak at CALOR Gas Limited, UK

The Gas leak occurred at the CALOR Gas Terminal in Thames Road. The 163 tons of Liquefied Petroleum Gas (LPG) leaked into the atmosphere. The leak happened while a ship was unloading gas to the site early on October 27, 2008. The gas, which is stored in a liquid form, escaped from a pipe when an over-pressure safety device operated before a vapor cloud formed. A sensor, which is designed to detect leaks of LPG, raise the alarm and shut the emergency valves, failed to operate – allowing the release to continue unchecked. Even when an employee eventually discovered the leak, no site emergency alarms were sounded.

6. Hisar Ice Factory gas leak

There was an incident of ammonia gas leakage in an Ice factory in Hisar city. Several students complained of nausea and vomiting while other felt irritation in their eyes. The affected children were rushed to the hospital and later discharged after proper treatment. The Ice factory, located in Hisar Parao Chowk area, was sealed by the local administration following the gas leak.

12

1.7 Solutions availableTill date there are many guidelines being set up by various governments across the world for setting up a gas plant. These guidelines must be kept in mind while setting up an gas plant.

There are also various equipments available in market to detect the leakage of gas like Gas leak detection systems and alarming systems. These are the only available precautions for such events available till date.

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CHAPTER 2

SCHEME OF PROJECT

2.1Idea of Project

The Idea of the project is to design a Fully Automatic system to detect and check the LPG leakage in our Hostel Mess. Since only detection is not important, the leakage should also be checked properly so that there is least hazard of any unwanted incident to occur.

2.2 Flow Diagram

The flow diagram of LPG detector for hostel mess is shown in figure. It is shown separately for kitchen and for cylinder room. For the flow diagram we inspected and studied our hostel mess. In there, there is a cylinder room which has four cylinders and there is kitchen which has four burners. There is possibility of leakage from cylinder room as well as at each burner. So we make provision of detecting the leakage at both locations. For this we require 5 sensors one for cylinder room and other four for each burner location. Also eight relay switches are required to cut off the supply of gas when there is a leakage. The solenoid switch is clamped to the cylinder which cuts the supply off from each cylinder in cylinder room. The schematic of our hostel mess is shown in figure.

14

Main cylinder roomOutlet for burners

KITCHEN

Valve

Cylinders

Figure 1: Schematic of a hostel mess

15

SWITCH OFF ALL SOLENOID SWITCH VALVE

AT EACH CYLINDER

START

WAIT FOR 1 MIN

IF LPG LEVEL

DECREASING

IF LPG LEVEL IS BELOW

SOME CERTAIN

LEVEL

SWITCH OFF LPG SUPPLY AT S0 AND TURN ON RED BULB OUTSIDE

THE CYLINDER ROOM FOR MANUAL CHECK

Y

Y

Y

N

N

STOP

IF LPG DETECTED

IN CYLINDER

ROOM

SWITCH ON RED BULB FOR MANUAL CHECKING IN

CYLINDER ROOM FOR OTHER SOURCE

STOP

Figure 2: Flow chart for LPG detection in cylinder room of a mess

16

SWITCH OFF LPG SUPPLY AT S1 AND TURN ON RED BULB OUTSIDE

THE CYLINDER ROOM FOR MANUAL CHECK

IF LPG LEVEL IS BELOW

SOME CERTAIN

LEVEL

IF LPG LEVEL DECREASING AT

THE CORRESSPONDIN

G LOOCATION

WAIT FOR 15 SEC

IF LPG SENSED

AT SWITCH

S1

SWITCH OFF SUPPLY AT S1 AND SWITCH ON BULB

NEAR S1

START

WAIT FOR 15 SEC

IF LPG LEVEL

DECREASING AT S1

IF LPG LEVEL IS BELOW

SOME CERTAIN

LEVEL

IF LPG SENSD AT S2, S3 OR

S4

SWITCH OFF SUPPLY AT CORRESPONDING SWITCH

S2, S3 OR S4

Y

Y

Y

Y

Y

Y

N

N

NN

N

STOPFigure 3: Flow chart for LPG detection in kitchen of a mess

2.3 Working of Device

Steps taken by the device to detect the LPG leakage:

1. Suppress sensing of LPG for 15 seconds till lighter lights the gas.2. If level of LPG is above a reference value, after 15 seconds then automatically cut off gas

supply with the help of solenoid switch and switch on an indicator bulb for manual check at that point.Case1: If LPG level reduced below reference level then quickly switch off the indicator and reset the system.Case2: If anyone manually off the gas regulator then and reset the system.Case3: If still LPG or some other gas is sensed then alarm for manual check of the source.

3. After 30 sec alarm if no one comes for manual off and LPG level is below an upper limit and above lower limit, then quickly off the supply at cylinder.

4. If still sensor is sensing LPG gas from other source or detecting any other combustible gas then again alarm for manual checking of surrounding and then off the alarm.

17

CHAPTER 3

IMPLEMENTATION OF DEVICE

For implementation of LPG detector we need to interface the hardware and software. The hardware is the supply circuit, sensor, microcontroller, relays, switches and solenoid switch. The software is the program to tell the microcontroller what to do. For the implementation we need following components or parts:

1. DC regulated power supply2. LPG sensor3. Microcontroller4. Relay driving IC5. Relays6. Solenoid switch

The block diagram implementing these components is shown in figure.

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DC POWER SUPPL

YLPG

SENSOR

MICROCONTROLLER

RELAY DRIVING IC

REFERENCE VLUE

3.1 Block Diagram Description:

DC power supply provides required dc power to each component such as microcontroller, sensor, and relay driving IC and solenoid switch. The sensor senses the gas leakage and calibrates the sensing in the form of resistance change. The microcontroller has an inbuilt analog to digital converter and a comparator. It compares the output of the sensor with some reference value and converts the analog signal into digital. The reference value may be the resistance under normal condition (i.e. O2). The output of the microcontroller drives the two relay driving ICs one is for cylinder room and other for kitchen. The relay driving ICs drive the relays and whenever gas is sensed the relays cutoff the gas supply to the burner and an indicator indicates the hazard which is an LED or a siren.

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RELAYS RELAYS

TO SOLENOID SWITCH IN KITCHEN

TO SOLENOID SWITCHES IN CYLINDER ROOM

3.2 Working with program:

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START

DEFINE STACK

SET CYCLE LENGTH

SET BIT COUNTER TO HIGHEST VALUE

OUTPUT DATA DIRECTION BIT=1

OUTPUT TO CONTROL REGISTER A

TC1 CLOCK=SYSTEM CLOCK

OUTPUT TO TC1 CONTROL REGISTER B

ENABLE OVERFLOW INTERRUPT

ENABLE CPU REACTION to INTERRUPTS

GO TO SLEEP

Flow chart for main program loop

STOP

21

START

SAVE SREG FLAG REGISTER

DECREMENT CYCLE COUNTER WORD

SET CYCLE COUNTER FOR NEXT BIT

CHECK ANALOGUE COMPARATOR OUTPUT

SHIFT ACTIVE BIT ONE POSITION RIGHT

START

SET COUNTER

IF WORD<

>00

IF WORD<>

000

COPY THE RESULT & SET READY-FLAG

RESTORE SREG TO ORIGINAL CONTENT

RETURN

22

START

LOAD DUMMY INSTRUCTION BEFORE SLEEP

CHECK IF ADC IS

READY?

CLEAR READY BIT

COPY RESULT OF ADC

INVERT ALL BITS

GO TO SLEEP AGAIN

STOP

Flow chart for main loop

N

Y

INITIALIZE

23

Figure 4: C

ircuit schematic of L

PG

detection and checking in hostel mess using m

icrocontroller

3.3 Circuit Diagram

3.4 Circuit description:

The circuit consists of following main components. We will describe working of each component separately to understand the function of device.

1. DC regulated power supply(LM7805)2. LPG sensor(HS-133)3. Microcontroller(ATmega-32L)4. Relay driving IC(ULN-2003)

Regulated DC power supply:

Figure 5: Circuit diagram of power supply

The rectifier used in the power supply is centre tap rectifier which provides 12V dc and the filter used is capacitor filter. After rectification and filtering the pulsating dc is converted into regulated dc using regulator IC LM7805. The dc voltage used by the components in the circuit is 5V dc.

LPG sensor:

HS-133 LPG sensor has been used in this project. It is a highly sensitive gas sensor which can sense the LPG, methane isobutane and all combustible gases. Sensor does not trigger with noise of alcohol, cooking fumes and cigarette smoke. HS-133 has 6 pins, 4 of them are used to catch signals, and other 2 are used for providing heating current.

The operation is described below.

The sensing material in HS-133 is metal oxide, most typically SnO2. When a metal oxide crystal such as SnO2 is heated at a certain high temperature in air, oxygen is adsorbed on the crystal

24

AC POWER SUPLLY

IN OUT

GND

1N4007

1N4007

1k0.1 uF

220 V

0.01uF470 uF

12-0-12V Center tap

surface with a negative charge. Then donor electrons in the crystal surface are transferred to the adsorbed oxygen, resulting in leaving positive charges in a space charge layer. Thus, surface potential is formed to serve as a potential barrier against electron flow (Figure 6).Inside the sensor, electric current flows through the conjunction parts (grain boundary) of SnO2 micro crystals. At grain boundaries, adsorbed oxygen forms a potential barrier which prevents carriers from moving freely. The electrical resistance of the sensor is attributed to this potential barrier. In the presence of a deoxidizing gas, the surface density of the negatively charged oxygen decreases, so the barrier height in the grain boundary is reduced (Figures 7). The reduced barrier height decreases sensor resistance.

The relationship between sensor resistance and the concentration of deoxidizing gas can be expressed by the following equation over a certain range of gas concentration:

Rs = A[C] −αWhere: Rs = electrical resistance of the sensor A = constant [C] = gas concentration

α = slope of Rs curve

25

Figure 6: Model of inter-grain potential barrier (in the absence of gases) [7]

Figure 7: Model of inter-grain potential barrier (in the presence of gases) [7]

Microcontroller ATMEGA-32:

The ATmega32 is a low-power CMOS 8-bit microcontroller based on the AVR enhanced RISC architecture. By executing powerful instructions in a single clock cycle, the ATmega32 achieves throughputs approaching 1 MIPS per MHz allowing the system designed to optimize power consumption versus processing speed.

The AVR core combines a rich instruction set with 32 general purpose working registers. All the 32 registers are directly connected to the Arithmetic Logic Unit (ALU), allowing two independent registers to be accessed in one single instruction executed in one clock cycle. The resulting architecture is more code efficient while achieving throughputs up to ten times faster than conventional CISC microcontrollers. The ATmega32 provides the following features: 32K bytes of In-System Programmable Flash Program memory with Read-While-Write capabilities, 1024 bytes EEPROM, 2K byte SRAM, 32 general purpose I/O lines, 32 general purpose working registers, a JTAG interface for Boundary-scan, On-chip Debugging support and programming, three flexible Timer/Counters with compare modes, Internal and External Interrupts, a serial programmable USART, a byte oriented Two-wire Serial Interface, an 8-channel, 10-bit ADC with optional differential input stage with programmable gain (TQFP package only), a programmable Watchdog Timer with Internal Oscillator, an SPI serial port, and six software selectable power saving modes. The Idle mode stops the CPU while allowing the USART, Two-wire interface, A/D Converter, SRAM, Timer/Counters, SPI port, and interrupt system to continue functioning. The Power-down mode saves the register contents but freezes the Oscillator, disabling all other chip functions until the next External Interrupt or Hardware Reset. In Power-save mode, the Asynchronous Timer continues to run, allowing the user to maintain a timer base while the rest of the device is sleeping. The ADC Noise Reduction mode stops the CPU and all I/O modules except Asynchronous Timer and ADC, to minimize switching noise during ADC conversions. In Standby mode, the crystal/resonator Oscillator is running while the rest of the device is sleeping. This allows very fast start-up combined with low-power consumption. In Extended Standby mode, both the main Oscillator and the Asynchronous Timer continue to run. The device is manufactured using Atmel’s high density nonvolatile memory technology. The On-chip ISP Flash allows the program memory to be reprogrammed in-system through an SPI serial interface, by a conventional nonvolatile memory programmer, or by an On-chip Boot program running on the AVR core. The boot program can use any interface to download the application program in the Application Flash memory. Software in the Boot Flash section will continue to run while the Application Flash section is updated, providing true Read-While-Write operation. By combining an 8-bit RISC CPU with In-System Self-Programmable Flash on a monolithic chip, the Atmel ATmega32 is a powerful microcontroller that provides a highly-flexible and cost-effective solution to many embedded control applications. The ATmega32 AVR is supported with a full suite of program and system development tools

26

including: C compilers, macro assemblers, program debugger/simulators, in-circuit emulators, and evaluation kits.

Relay driving IC:

The ULN2001A, ULN2002A, ULN2003 and ULN2004A are high voltage, high current darlington arrays each containing seven open collector darlington pairs with common emitters. Each channel rated at 500mA and can withstand peak currents of 600mA. Suppression diodes are included for inductive load driving and the inputs are pinned opposite the outputs to simplify board layout. These versatile devices are useful for driving a wide range of loads including solenoids, relays DC motors; LED displays filament lamps, thermal printheads and high power buffers. The ULN2001A/2002A/2003A and 2004A are supplied in 16 pin plastic DIP packages with a copper lead frame to reduce thermal resistance.

27

CHAPTER 4

RESULT AND CONCLUSION

The idea for LPG detection and checking is materialized with the help of a working prototype of the same

which can be implemented at large scale for various industries. This system can be installed at kitchen, at

hostel mess, and any other areas. Thus can be helpful in reducing accidents caused due to LPG leakage in

household as well as in any similar commercial set up.

The microcontroller has the calculation function and the memory like the CPU and is controlled by the

software. It provides us with the facility for automatic control and check of the whole system. The system

is flexible as more number of sensors and relays can be added to it according to the whole LPG supply set

up in that premises.

There are several factors which affect the proper working of project like ventilation in the room, presence

of other gas and sensitivity of sensor which might vary with different sensors available in the market.

This system can effectively ensure its proper functioning and provide effective security measures against

LPG leakage.

28

REFERENCES:

[1]. ATmega 32 datasheet and specifications “www.atmel.com”.

[2]. www.cpu.com.tw/kh/sensor/gas/ hs133 .pdf

LPG Sensor Specifications and Datasheet

[3]. www. datasheet catalog.com/ datasheets .../ ULN2003 .shtml

Relay driving IC ULN2003 specifications.

[4].http://www.rochford-today.co.uk/tn/News.cfm?id=17990&headline=Calor%20Gas%20fined%20for%20causing%20major%20leak retrieved on 10 June 2010

COLAR Gas Leak event

[5].http://timesofindia.indiatimes.com/city/hyderabad/On-the-brink-of-disaster-/articleshow/4109545.cms HPCL Gas Leak

[6]. www.iitk.ac.in/che/jpg/papersb/full%20papers/S%20-%20108.doc

Sanjeev Saraf “Literary and Economic Impact of the Bhopal Gas Tragedy” pp 2-3.

[7]. The Dangerous Substances and Explosive Atmospheres Regulations” http://www.desktoplawyer.co.uk/dt/browse/law/index.cfm?fs=lga&sid=75858&aid=35391 retrieved on 10 June 2010.

[8]. Qi, D; Bian, Y; Ma, Z; Zhang, C; Liu, S (2007). "Combustion and exhaust emission characteristics of a compression ignition engine using liquefied petroleum gas–fuel-oil blended fuel". Energy Conversion and Management 48: 500.

29

APPENDIX A

LIST OF COMPONENTS

Components QuantityICsMicrocontroller ATmega32LM7805

0102

Capacitors470 µF0.1 µF/16V electrolytic0.01 µF

010102

Resistors1kΩ10kΩ

1206

LEDsRedGreen

120309

SensorHS-133 05Diode1N4007 02Relay 08Relay driving ICUln 2003 02Solenoid switch 12V 01

30

APPENDIX B

1. Specifications Of HS133 :

Table 1. Specifications[2]

Symbol Parameter name Technical condition Remarks

VC Circuit voltage 5V±0.1 AC OR DC

VL Heating voltage 5V±0.1 ACOR DC

PL Load resistance 20KΩ

RH Heater resistance 33Ω±5% Room Temperature

PH Heating consumption less than 800mw

Tao Using Temp -20-50Tas Storage Temp -20-70RH Relative humidity less than 95%Rh

O2 Oxygen concentration 21%(standard condition)Oxygenconcentration can affect sensitivity

minimum value isover 2%

31

APPENDIX C

1. Pin Configurations

The figure below shows the PDIP configuration of ATmega32.

Figure 8: Pin outs of ATmega32 (PDIP) [1]

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APPENDIX D

ULN-2003

Table 2. Absolute maximum rating [3]

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Figure 9: pin configuration of ULN2003 [3]

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