Final Report Content

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INTEGRATED REFINERY FIRE AND GAS MONITORING
SYSTEM USING ZIGBEE
Submitted in partial fulfillment of the requirements for the award of
Bachelor of Engineering Degree in
Electronics and Instrumentation Engineering
By
BLESSY ANN JOSEPH (3018125)
JUL STEFFO (3018148)
DEPARTMENT OF ELECTRONICS AND INSTRUMENTATION
ENGINEERING
FACULTY OF ELECTRICAL AND ELECTRONICS
ENGINEERING
SATHYABAMA UNIVERSITY
JEPPIAAR NAGAR, RAJIV GANDHI SALAI,
CHENNAI – 600119. TAMILNADU.
MARCH 2014

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SATHYABAMA UNIVERSITY
(Established under Section 3 of UGC Act, 1956)
Jeppiaar Nagar, Rajiv Gandhi Salai, Chennai- 600 119
www.sathyabamauniversity.ac.in
DEPARTMENT OF ELECTRONICS AND INSTRUMENTATION
ENGINEERING
BONAFIDE CERTIFICATE
This is to certify that this Project Report is the bonafide work of BLESSYANN JOSEPH
(3018125) and JUL STEFFO (3018148) who carried out the project entitled
“INTEGRATED REFINERY FIRE AND GAS MONITORING SYSTEM USING
ZIGBEE” under our supervision from November 2013 to March 2014.
Internal Guide
Mr. S.AARON JAMES, M.E., M.B.A.,
Head of the Department
Mrs. SUJATHA KUMARAN M.S., (Ph.D)
Submitted for Viva voce Examination held on_____________________
Name :
Signature:
INTERNAL EXAMINER EXTERNAL EXAMINER

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DECLARATION FORMAT
We, Blessy Ann Joseph (3018125) and Jul Steffo (3018148) hereby declare that the
Project Report entitled “INTEGRATED REFINERY FIRE AND GAS MONITORING
SYSTEM USING ZIGBEE” done by us under the guidance of Mr. S.Aaron James,
M.E, M.B.A., is submitted in partial fulfillment of the requirements for the award of
Bachelor of Engineering degree in Electronics And Instrumentation.
1.
2.
DATE:
PLACE: SIGNATURE OF THE CANDIDATES

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ACKNOWLEDGEMENT
The satisfaction and elation that accompany the successful completion of any
task would be incomplete without the mention of the people who have made it a
possibility. It is our great privilege to express our gratitude and respect to all those who
have guided and inspired us during the course of the project work.
We would like to express our sincere gratitude to our honorable chancellor
Col. Dr. Jeppiar, M.A., B.L., Ph.D., for giving us a platform wherein we could perform
and give our best. We would like to thank our beloved directors
Dr. Marie Johnson, B.E., M.B.A., M.Phil., Ph.D., and
Dr. Mariazeena Johnson, B.E., M.B.A., M.Phil., Ph.D., for their support. We would
like to thank our vice chancellor Dr. B. Sheela Rani, M.S (By Research),
Ph.D., our registrar Dr.S.S.Rau Ph.D., and the Controller Of Examinations,
Dr. K. V. Narayanan Ph.D. for their timely support.
We would like to sincerely thank our Faculty Head
Dr.E.Logashanmugam,M.E., Ph.D. and our Head of the Department
Mrs. Sujatha Kumaran M.S., (Ph.D.), and Faculty Head for having been a constant
source of support and encouragement for completion of the project.
We would like to express our sincere gratitude to our guide
Mr. S.Aaron James M.E., M.B.A. for his constant guidance and supervision
throughout the course of our project work. We are grateful for his time and support till
the completion of our project.
We would also like to thank our CPCL guide Mr. A.Gowthaman M.E., M.B.A.
for his timely help and support.

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ABSTRACT
“Integrated refinery fire and gas monitoring system” is designed to monitor fire
and gas leakage and population density in the hazardous locations within the refinery.
The existing system detects any fire or any gas leakage with in geographically
distributed areas. Increase in the complexity of process industry leads to increase in
the number of instruments to detect fire and leak. This increases the number of cables
that run from industrial sensors to the control station. This also increases the size of
the duct. Troubleshooting the reduced insulation or any wire open is difficult because
it is a messy wiring and identifying the individual cable is very difficult along the duct.
This also increases the project cost in terms of cable cost. So to cope up with the
modern technology it is proposed to have a wireless communication between field
devices and the control room. With the advent of wireless technology many
parameters can be sent over a single communication medium. This reduces the messy
wiring, project cost and making trouble shoot easy. The field device can be a portable
or a fixed device which communicates the various parameters that are being
monitored, to the control room through the transmission media – ZigBee.

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CONTENTS
S.No TITLE PAGE No.
ABSTRACT i
LIST OF TABLES iv
LIST OF FIGURES v
LIST OF ABBREVIATIONS vi
1. INTRODUCTION 1
1.1. OUTLINE OF THE PROJECT 1
1.2. LITERATURE REVIEW 2
1.3. PROBLEM DEFINITION 2
1.4. OBJECTIVE 3
2. EXISTING SYSTEM 4
2.1. DEFINITION 4
2.2. FIELD VISIT 4
2.3. ICSS 5
2.4. LIMITATIONS OF THE EXISTING SYSTEM 6
2.5. FEASIBLE SOLUTIONS 6
3. PROPOSED SYSTEM 8
3.1. DESCRIPTION OF PROPOSED SYSTEM 8
3.2. BLOCK DIAGRAM 9
3.3. POWER SUPPLY 10
3.3.1. Circuit Diagram for Power Supply 10
3.3.2. Basic Functional Units 11
3.3.3. Working Principle 12
3.4. PORTABLE UNIT 12
3.4.1. Circuit Diagram for Portable Unit 14
3.5. INTRODUCTION TO SENSORS 15
3.5.1. Pressure Sensor 16
3.5.2. Temperature Sensor 16
3.5.3. Heart Beat Sensor 17
3.5.4. Gas Sensor 18
3.6. MICROCONTROLLER – PIC18F45K22 18
3.6.1. Microcontroller Features
3.6.2. Analog Features 19
3.6.3. Peripheral Features 20
3.6.4. Pin Diagram 21

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3.7. OUTPUT DEVICES 22
3.7.1. USB PC Interface 23
3.8. ZIGBEE TECHNOLOGY 25
3.8.1. Advantages of ZigBee 26
3.9. GLOBAL POSITIONING SYSTEM 27
3.9.1. Components of GPS 27
3.9.1.1. Space Segment 27
3.9.1.2. Control Segment 27
3.9.1.3. User Segment 27
3.9.2. Working of GPS 28
3.9.3. Tracking Devices 28
3.10. SOFTWARE DEVELOPMENT TOOLS 29
3.10.1. LabVIEW 29
3.10.1.1. Benefits of LabVIEW 31
3.10.1.2. Core Concepts of LabVIEW 32
3.10.1.3. Programming in LabVIEW 33
4. RESULT & DISCUSSION 34
4.1. PERFORMANCE ANALYSIS 34
4.1.1. Comparison of Communication Devices 34
4.1.2. Gas LELs and UELs 35
4.1.3. ZigBee 802.15.4 Latency Time Analysis 36
4.2. RESULT 42
4.3. ADVANTAGES OF THE DEVELOPED SYSTEM 43
5. CONCLUSION 44
5.1. SUMMARY 44
5.2. CONCLUSION 45
5.3. FUTURE SCOPE 45
REFERENCES

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LIST OF TABLES
TABLE No. TITLE PAGE No.
4.1 Analysis of various Communication
Devices 34
4.2 Analysis of various gases 35

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LIST OF FIGURES
FIGURE No. TITLE PAGE No.
3.1 Block diagram of proposed system 9
3.2 Circuit Diagram for Power Supply 10
3.3 Functional Unit of Power Supply 11
3.4 Working Principle of Power Supply 12
3.5 Block Diagram of Portable Unit 13
3.6 Circuit Diagram of Portable Unit 14
3.7 Pin Diagram of PIC18F45K22 21
3.8 Receiving Section 22
3.9 USB – PC Interface 23
3.10 Circuit for USB Interface 24
3.11 LabVIEW Front Panel 30
3.12 LabVIEW Block Diagram Panel 30
4.1 ZigBee network 36
4.2 Block Diagram of Developed System in LabVIEW 42
4.3 Front Panel of Developed System in LabVIEW 43

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LIST OF ABBREVATIONS
A/D - Analog/Digital
AC - Alternating Current
ADC - Analog to Digital Converter
BOR - Brown-Out Reset
CCA - Clear Channel Assessment
CPCL - Chennai Petroleum Corporation Limited
CPU - Central Processing Unit
CSMA - Carrier Sense Multiple Access
CSMA-CA - Carrier Sense Multiple Access- Collision Avoidance
CTMU - Charge Time Measurement Unit
DC - Direct Current
EUSART - Enhanced Universal Asynchronous Receiver Transistor
F&G - Fire and Gas
Fig - Figure
GND - Ground
GOI - Government of India
GPS - Global Positioning System
HPCL - Hindustan Petroleum Corporation Limited
HRM - Heart Rate Monitor
I/P - Input
IC - Integrated Circuit
ICSP - In Circuit Serial Programmer
ICSS - Integrated Control and Safety System
IR - Infra Red
LabVIEW - Laboratory Virtual Instrument Engineering Workbench
LAN - Local Area Network
LCD - Liquid Crystal Display
LED - Light Emitting Diode

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LEL - Lower Emission Level
LNG - Liquid Nitrogen Gas
LPG - Liquid Petroleum Gas
LR-WPAN - Low Rate Wireless Personal Area Network
MAC - Medium Access Control
MATLAB - Matrix laboratory
MMT - Million metric tonnes
MMTPA - Million tonnes per annum
MRL - Madras Refinery Limited
MSSP - Master Synchronous Serial Port
NIOC - National Iranian Oil Company
PAN - Personal Area Network
PC - Personal Computer
PCS - Process control systems
PIC - Peripheral Interface Controller
POR - Power On Reset
PWRT - Power-Up Timer
RF - Radio Frequency
Rx - Receiver
SV - Space Vehicles
UART - Universal Asynchronous Receiver Transmitter
UEL - Upper Emission Level
USB - Universal Serial Bus
WDT - Watchdog Timer
WPAN - Wireless Personal Area Network
WSN - Wireless Sensor Networks

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CHAPTER 1
INTRODUCTION
1.1 OUTLINE OF THE PROJECT
“Integrated refinery fire and gas monitoring system using ZigBee” is a project
based on a wireless communication to enhance man and machine safety in a
petrochemical industry. In today’s world petrochemical industry although being the
largest process control industry it is also highly prone to major fire and gas disasters.
A petrochemical industry has excessively high amount of crude oil stored within a
confined area. Therefore presence of any external source which can cause heat or fire
would lead to a major disaster. Even the gas that are present in petroleum refineries
are hazardous.
The Bhopal gas tragedy, which claimed lives of nearly 3,787 people is one of
the major accidents due to gas leakage. And another instance, the Vishakhapatnam,
HPCL refinery tragedy claimed lives of 30 people. Though a gas and fire detection
system was present which is connected to the sensors using large number of wires
that run from the control room to various plant areas, during the fire the wire itself got
damaged, so the information did not reach the control room.
So in order to avoid any hazard due fire and gas leakage in a petrochemical
industry we have designed an integrated system which will monitor timely gas leakage
in any area around the plant using ZigBee which is a wireless communication device.
We have also proposed a new system which monitors human density within the plant
area. Therefore Integrated plant safety monitor system based on ZigBee can realize
workers attendance registration, Real-time precise positioning, Dynamic gas
concentration monitoring, Real-time data transmission & Danger alarm. This project is
focused on implementing the newly designed integrated system in CPCL, Manali,
Chennai.

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1.2 LITERATURE REVIEW:
 G.A.Arun Kumar, K.Rajasekhar, B.V.V.Satyanarayana, K.Suryanarayana
Murthy, 2012, “Implementation of Real time Detection of Gas leakage in
Industries using ARM7 &ZigBee”,September, pp 1-4.
In this Paper hardware for gas leakage detection and accurate location identification
system for the production safety in any risky Industries is proposed. The detection and
location are implemented based on Wireless Sensor Networks (WSN). However,
formerly the system was developed using Virtual Instrumentation. Based on ZIGBEE
and ARM7, the system is easy to be deployed and overcomes the shortcomings on
current systems. Using number of nodes at different places of risky areas, this system
can detect the leakage of gas and immediately sends the details of that location to the
observer. It is used to improve the rescue quality and shorten the time for rescue.
Therefore it can compensate for the weaknesses of existing systems.
 Anusha, Dr. Shaik Meeravali, 2012 “Detection Of Gas Leak And Its
Location Using Wireless Sensors”, November, pp 1-8
The aim is to develop a gas leak detection and location system for the production
safety in Petrochemical Industry. The system is based on Wireless Sensor
Networks (WSN); it can collect the data of monitoring sites wirelessly and sent to
the computer to update values in the location software. Consequently, it can give
a real-time detective of the potential risk area, collect the data of a leak accident
and locate the leakage point. However the former systems can not react in time,
even cannot obtain data from an accident and locate accurately. The paper has
three parts, first, gives the overall system design, and then provides the
approaches on both hardware and software to achieve it.
1.3 PROBLEM DEFINITION:
Increase in the complexity of process industry leads to increase in the number of
instruments to detect fire and leak. This increases the number of cables that run from
industrial sensors to the control station which leads to messy wiring. This also
increases the size of the duct. Troubleshooting the reduced insulation or any wire
open is difficult because it is a messy wiring and identifying the individual cable is

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very difficult along the duct. This also increases the project cost in terms of cable
cost.
The fire and gas system is generally required to be independent of the control system.
This is consistent with the fire and gas system normally having a higher integrity
requirement than the control system. Some fire and gas systems have been integrated
with emergency shut-down systems. This remains a contentious point.
As already mentioned, no single company can supply all the ‘best in show’
products for all the items described in this paper. There are therefore normally
interfaces between different suppliers. Minimizing interfaces, document sets and
inspections can be achieved by procuring all products from one source at the cost of
reducing choice of initiating devices and possibly increasing the initial purchase cost.
4-20mA interfaced devices are common, enabling standard or modified process
control interfaces to be used. Field interfaces for smoke detectors, heat detectors and
manual call-points are generally two wires with modifying components in the control
system or marshalling cabinets to allow a 4-20mA interface to be used. Any failure in
the loop causes the system to fail. Presently, the location of the personals working in
the site is uncertain. In case of a dangerous event, the Control station officers have to
personally check the positions of the workers in the particular sites. This calls for more
effort and time.
1.4 OBJECTIVE:
The aim of our project is to design and construct an industrial safety system for
workers working in hazardous environments, comprising of two sections.
A portable unit provided to the workers, which is capable of sensing hazardous
conditions like gases, excessive temperature and humidity etc. and a monitoring
system which interacts with the portable unit using a zigbee wireless communication
link.

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CHAPTER 2
EXISTING SYSTEM
2.1 DEFINITION
The existing system only detects the fire and gas leakage in certain important
areas only. In existing system, the fire and gas leaks are measured and the
communication is through wires to the control station. In case of faults like discontinuity
in cables, damage to cable due to environmental conditions may lead to loosing of
vital information related to plant safety.
Increase in the complexity of process industry leads to increase in the number
of instruments to detect fire and leak. This increases the number of cables that run
from industrial sensors to the control station which leads to messy wiring. This also
increases the size of the duct. Troubleshooting the reduced insulation or any wire open
is difficult because it is a messy wiring and identifying the individual cable is very
difficult along the duct. This also increases the project cost in terms of cable cost.
2.2 FIELD VISIT
An F&G safety system continuously monitors for abnormal situations such as a
fire, or combustible or toxic gas release within the plant; and provides early warning
and mitigation actions to prevent escalation of the incident and protect the process or
environment. By implementing an integrated fire and gas strategy based on the latest
automation technology, plants can meet their plant safety and critical infrastructure
protection requirements while ensuring operational and business readiness at project
start-up. Throughout the process industries, plant operators are faced with risks. For
example, a chemical facility normally has potential hazards ranging from raw material
and intermediate toxicity and reactivity, to energy release from chemical reactions,
high temperatures, high pressures, etc.
According to international standards, safety implementation is organized under a
series of protection layers, which include, at the base levels, plant design, process
control systems, work procedures, alarm systems and mechanical protection systems.
The safety shutdown system is a prevention safety layer, which takes automatic and
independent action to prevent a hazardous incident from occurring, and to protect
personnel and plant equipment against potentially serious harm.

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Conversely, the fire and gas system is a mitigation safety layer tasked with
taking action to reduce the consequences of a hazardous event after it has occurred.
The F&G system is used for automating emergency actions with a high-integrity safety
and control solution to mitigate further escalation. It is also important for recovering
from abnormal situations quickly to resume full production.
An industrial safety system is a countermeasure crucial in any hazardous plants
such as oil and gas plants and nuclear plants. They are used to protect human, plant,
and environment in case the process goes beyond the control margins. As the name
suggests, these systems are not intended for controlling the process itself but rather
protection. Process control is performed by means of process control systems (PCS)
and is interlocked by the safety systems so that immediate actions are taken should
the process control systems fail.
2.3 ICSS
Process control and safety systems are usually merged under one system,
called Integrated Control and Safety System (ICSS). Industrial safety systems typically
use dedicated systems that are SIL 2 certified at minimum; whereas control systems
can start with SIL 1. SIL applies to both hardware and software requirements such as
cards, processors redundancy and voting functions. Fire and gas detection systems
are designed to mitigate unexpected events. Designers need to know what is available
in order to choose the correct systems for their plants.
The main objectives of the fire and gas system are to protect personnel, environment,
and plant (including equipment and structures). The FGS shall achieve these
objectives by:
 Detecting at an early stage, the presence of flammable gas,
 Detecting at an early stage, the liquid spill (LPG and LNG),
 Detecting incipient fire and the presence of fire,
 Providing automatic and/or facilities for manual activation of the fire protection
system as required,
 Initiating environmental changes to keep liquids below their flash point.
 Initiating signals, both audible and visible as required, to warn of the detected
hazards,
 Initiating automatic shutdown of equipment and ventilation if 2 out of 2 or 2 out
of 3 detectors are triggered, and the exhausting system.

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2.4 LIMITATIONS OF EXISTING SYSTEM
The fire and gas system is generally required to be independent of the control
system. This is consistent with the fire and gas system normally having a higher
integrity requirement than the control system. Some fire and gas systems have been
integrated with emergency shut-down systems. This remains a contentious point.
As already mentioned, no single company can supply all the ‘best in show’
products for all the items described in this paper. There are therefore normally
interfaces between different suppliers. Minimizing interfaces, document sets and
inspections can be achieved by procuring all products from one source at the cost of
reducing choice of initiating devices and possibly increasing the initial purchase cost.
4-20mA interfaced devices are common, enabling standard or modified process
control interfaces to be used. Field interfaces for smoke detectors, heat detectors and
manual call-points are generally two wires with modifying components in the control
system or marshalling cabinets to allow a 4-20ma interface to be used. Any failure in
the loop causes the system to fail. Presently, the location of the personals working in
the site is uncertain. In case of a dangerous event, the Control station officers have to
personally check the positions of the workers in the particular sites. This calls for more
effort and time.
2.5 FEASIBLE SOLUTION
To overcome these difficulties we implemented a portable device. This device
can be fixed in their helmet or jacket. To measure various parameters this device
consists of sensors. They are Gas sensor, Temperature sensor, Heart beat sensor,
Pressure sensor.
These sensors in the portables device sense various parameters (gas,
temperature, pressure) continuously. And if the value exceeds the reference value,
immediately it activates the relay driver and produces an alarming sound. So it will be
useful for the person to know about hazardous situation.
Heart beat sensor, senses the workers heart beat continuously. If the person
loses his/her consciousness then this information is sensed by the sensor and it will
be passed to the control room.

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All the communications are done by wireless zigbee protocols, so that the
informations will be transmitted without any obstructions. The main advantage of
zigbee is that it is a multimode communication, so that the data’s are transmitted node
by node.
A GPS is used in our project to track the location of the person during
hazardous conditions, so that he can be rescued immediately.
Finally, all the parameters are monitored using labVIEW software. It contains
a comprehensive set of tools for acquiring, analyzing, displaying, and storing data, as
well as tools to help you troubleshoot code you write.

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CHAPTER 3
PROPOSED SYSTEM
3.1 DESCRIPTION
Our project is “Integrated Refinery Fire and Gas monitoring System using
ZigBee”. In this project, we are going to monitor and transmit the industrial parameters
such as gas leakage and fire. These parameters are monitored using gas sensor and
fire detectors. The analog outputs are converted into digital form using analog to digital
converter and then given to microcontroller. These data are sent to the control room
through a ZigBee wireless via UART also displayed in the LCD display for workers.
Corresponding to the sensor outputs the relay is activated using microcontroller to
operate the precaution devices. With this a buzzer alert is also given. In the receiver
side a PC is used to view all the parameter conditions. The relays can be activated
from the remote area too via ZigBee wireless communication.
In addition to this, this system integrates person locating with gas concentration
checking system effectively, and realizes functions of person attendance, distance
measurement positioning, gas concentration detecting and data communication. This
system is an open system, and it allows developing other applications on it. It provides
much spatial gas concentration data with the timestamp for follow-up gas prediction
research.
The field device can be a fixed device or a portable device. The portable device is
carried by the worker whenever he enters the plant area. It basically detects the gas
leakage if any, wherever the worker goes, it also sends the information about the
location of the person and the heartbeat of the person. The fixed device is fixed in the
plant area. It also detects gas leakage and transmits information to the control room.
The system will be developed in Lab view software. The hardware will be interfaced
with Lab view to collect the transmitted data and the interpretation of the received
information.
This project was accepted by CPCL and to be developed and tested in their site. We
are sure that this project will definitely help CPCL to increase its safe operation.

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3.2 BLOCK DIAGRAM
Fig 3.1: Block diagram of the proposed system
Fig 3.1 refers to the block diagram of the proposed system where the analog
parameters like the gas leakage, temperature level, pressure level & heartbeat of a
worker from the plant area is sensed by the sensors. These analog signals are sent to
the analog to digital converter and a digital signal is further sent to the PIC
microcontroller. The microcontroller is programmed in order to transmit these signals
to various output devices. The relay drive drives the relay which sets the buzzer on.
The LCD provides the direct information in case of any hazardous situation. The
portable section transmits this information through the ZigBee transmitter to the control
room where it is receiver by the ZigBee receiver and the information is displayed on
the PC.

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3.3 POWER SUPPLY
Power supply is a device that transfers electric power from a source to a load
using electronic circuits. Typical application of the power supplies is to convert utility’s
AC input power to regulated voltage required for electronic equipments.
3.3.1 Circuit for Power Supply
Fig 3.2: Circuit for power supply
The power supply circuit consists of a 12V DC adapter with a DC input, the two
IN4007 diodes is used for rectification of the signal so that no negative signal is passed
on to the further units, Vin is 12V pure DC, the capacitors, the LEDs, the LM317 and
the LM7805 as shown in Fig 3.2.
The DC I/P has two pins one is the Vout pin(pin1) and the other is the ground
pin(pin2). Diodes are used for rectification. Capacitors are incorporated for the
purpose of filtering. LEDs indicate if the power supply is ON or OFF. LM317 regulator
is used to regulate or adjust the voltage from 12V to 3.3V which is used by the
microcontroller, analog sensors and the RF section. LM7805 regulator is used to
adjust the voltage from 12V to 5V which is used by the heart beat sensor. The

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regulation of voltage is done specifically because we have used devices that are
compatible with either 5V or 3.3V. The 1k resistors are used for safety purposes.
3.3.2 Basic Functional Units
Most electronic circuits need a DC supply such as a battery to power them.
Since the mains supply is AC it has to be converted to DC to be useful in electronics.
This is what a power supply does.
Fig 3.3: Functional units of power supply
Fig 3.3 represents the functional units of power supply and is explained below.
First the AC mains supply passes through an isolating switch and safety fuse before it
enters the power supply unit. In most cases the high voltage mains supply is too high
for the electronic circuitry. It is therefore stepped down to a lower value by means of a
Transformer. The mains voltage can be stepped up where high DC voltages are
required.
From the transformer the AC voltage is fed to a rectifier circuit consisting of one
or more diodes. The rectifier converts AC voltage to DC voltage. This DC is not steady
as from a battery. It is pulsating. The pulsations are smoothed out by passing them
through a smoothing circuit called a filter. In its simplest form the filter is a capacitor
and resistor.
Any remaining small variations can, if necessary, be removed by a regulator circuit
which gives out a very steady voltage. This regulator also removes any variations in
the DC voltage output caused by the AC mains voltage changing in value.
Regulators are available in the form of Integrated Circuits with only three connections.
Each of the blocks is described in more detail below:

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 Transformer - steps down high voltage AC mains to low voltage AC.
 Rectifier - converts AC to DC, but the DC output is varying.
 Smoothing - smoothens the DC from varying greatly to a small ripple.
 Regulator - eliminates ripple by setting DC output to a fixed voltage.
3.3.3 Working Principle
Fig 3.4: Working principle of the power supply
The first section is the transformer. The transformer steps up or steps
down the input line voltage and isolates the power supply from the power line. The
rectifier section converts the alternating current input signal to a pulsating direct
current. And the pulsating dc is not desirable. For this reason a filter section is used to
convert pulsating dc to a purer, more desirable form of dc voltage. The final section,
the regulator, does just what the name implies. It maintains the output of the power
supply at a constant level in spite of large changes in load current or input line voltages
as shown in Fig 3.4.
3.4 PORTABLE UNIT
The portable unit is the unit which the worker carries with him whenever he
enters the plant area. It can be attached to the helmet or a badge as per convenience.
The portable unit consists of the analog sensors namely the gas sensor, the
temperature sensor, the pressure sensor and the heart beat sensor whose output is
fed into the microcontroller. The microcontroller processes the information and through
the voltage conversion unit it is sent to the RF transceiver which transmits the signals
wirelessly to the receiving RF transceiver at the control room. The microcontroller can
be programmed to send out an alarm through an alarm or an LED.

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The alarm cannot be driven directly by the microcontroller and thus a relay is
used for this purpose. The microcontroller is connected to a relay drive which drives
the relay which in turn activates the alarm. The block diagram of the portable unit is
shown in fig. 3.5.
Fig 3.5: Block diagram of the portable unit

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3.4.1 Circuit diagram of the portable unit
Fig 3.6: Circuit for portable unit
The portable unit circuit consists of the four sensors namely temperature
sensor, pressure sensor, gas sensor and heart beat sensor, microcontroller
(PIC18F45K22), the RF transmitter, the In Circuit Serial Programmer (ICSP), push
button, power supply and ground as shown in Fig 3.6.
The temperature sensor, pressure sensor and the gas sensor are analog
sensors and thus are connected to the analog pins in the port A, RA0, RA1, RA2
respectively. The heart beat sensor is a digital sensor and is connected to pin RA4 of
port A which is a digital pin. Each sensor has three pins each Vcc (power dc), Vout
(analog / digital) and GND (power ground).

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The microcontroller used is PIC18F45K22, a 40pin IC which has an inbuilt ADC
in it thus the analog outputs can be directly fed into the microcontroller without getting
it through a separate ADC unit.
The RF transmitter is used for communication purpose. It uses a UART which
has two parts – a transmitting section and a receiving section. The RF in this circuit is
the transmitting section. Pin 1 of the RF is the power, pin 2 is connected to pin 30 of
the microcontroller which is the transmitting line, pin 3 is connected to pin 29 of the
microcontroller which is the receiving line and pin 4 is the ground pin.
The ICSP is used to download the program on the microcontroller chip. From
the PC, pic-it-try is used to feed the program into the ICSP and then from the ICSP the
program is downloaded to the chip. It consists of 5 pins. Pin 1 is connected to the
master clear pin of the chip, pin 2 to the programmable clock, pin 3 to the
programmable data, pin 4 is the ground pin and pin 5 is the power supply.
The push button/switch is provided to set or reset the microcontroller which is
connected to the master clear pin. The pins 11 and 32 of the microcontroller are the
power supply to the microcontroller and pins 12 and 31 are the ground pins.
3.5 INTRODUCTION TO SENSORS
A sensor is a converter that measures a physical quantity and converts it into a
signal which can be read by an observer or by an (today mostly electronic) instrument.
For example, a mercury-in-glass thermometer converts the measured temperature
into expansion and contraction of a liquid which can be read on a calibrated glass tube.
A thermocouple converts temperature to an output voltage which can be read by
a voltmeter. For accuracy, most sensors are calibrated against known standards.
Sensors used:
 Pressure sensor- MPX5050
 Temperature sensor- LM35
 Heart beat sensor- HRM 2115
 Gas sensor- MQ-5

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3.5.1 Pressure sensor:
MPX5050 is used for pressure sensing. It is a linear pressure sensor. The
MPX5050 series piezoresistive transducer is a state-of-the-art-monolithic silicon
pressure sensor designed for a wide range of applications, but particularly those
employing a microcontroller or microprocessor with A/D inputs. This patented, single
element transducer combines advanced micromachining techniques, thin-film
metallization, and bipolar processing to provide an accurate, high level analog output
signal that is proportional to the applied pressure. The output voltage is given by 0v to
5v depending upon the pressure. Can measure pressure up to 10kPa. The integrated
sensor is a simple 3pin package. It is fabricated using micro machined pies electric
technology. It is an integrated sensor and does not require any signal conditioning.
The supply voltage input is 5V dc. The analog output from the pressure sensor is
directly connected to the A/D input.
Features:
 2.5% Maximum Error over 0° to 85°C
 Ideally suited for Microprocessor or Microcontroller-Based Systems
 Temperature Compensated Over –40° to +125°C
 Patented Silicon Shear Stress Strain Gauge
 Durable Epoxy Unibody Element
 Easy-to-Use Chip Carrier Option
3.5.2 Temperature sensor:
The LM35 series are precision integrated-circuit temperature sensors, whose
output voltage is linearly proportional to the Celsius (Centigrade) temperature. The
LM35 thus has an advantage over linear temperature sensors calibrated in ° Kelvin,
as the user is not required to subtract a large constant voltage from its output to obtain
convenient Centigrade scaling. The LM35 does not require any external calibration or
trimming to provide typical accuracies of ±1⁄4°C at room temperature and ±3⁄4°C over
a full −55 to +150°C temperature range. Low cost is assured by trimming and
calibration at the wafer level. The LM35’s low output impedance, linear output, and
precise inherent calibration make interfacing to readout or control circuitry especially

28
easy. It can be used with single power supplies, or with plus and minus supplies. As it
draws only 60μA from its supply, it has very low self-heating, less than 0.1°C in still
air. The LM35 is rated to operate over a −55° to +150°C temperature range, while the
LM35C is rated for a −40° to +110°C range (−10° with improved accuracy). The LM35
series is available packaged in hermetic TO-46 transistor packages. Its accuracy is
within 0.5°C. It is an integrated sensor in a simple 3pin package. It is an integrated
sensor and does not require any signal conditioning. The supply voltage input is 5V
dc. The analog output from the temperature sensor is directly connected to the A/D
input.
Features:
 Calibrated directly in ° Celsius (Centigrade), linear + 10.0 mV/°C scale factor
 0.5°C accuracy guarantee (at +25°C)
 Rated for full −55° to +150°C range
 Suitable for remote applications
 Low cost due to wafer-level trimming
 Operates from 4 to 30 volts
 Less than 60μA current drain
 Low self-heating, 0.08°C in still air
 Nonlinearity only ±1⁄4°C typical
 Low impedance output, 0.1 W for 1 mA load
3.5.3 Heart beat sensor:
HRM 2115 is the heart beat sensor which has been used in this project.
HRM2115 is a portable heart rate monitoring module. It works on the principle of opto
interruption caused by the flow of blood. The sensor houses an IR transmitter and a
sensitive IR detector on the other side of the sensor. HRM2115 is available in two
different options for user convenience. The ‘E’ version is for using the sensor by
clipping it to the ear lobe. The ‘B’ version is for using it with the finger. Any of these
can be used depending upon user convenience and suitability. We use the ‘B’ version.
The operating input voltage is 5V. The heart beat rate sensor output is in the form of

29
square wave in the range between 0-5V. The sensor consists of IR module coupled
with semiconductor chip.
Features:
 5V low power operation
 Output is in the form of digital pulses(square wave) corresponding to heart rate
 Consists of three pins namely Vcc(5V DC), Vout(Digital out) and GND(Power
Ground)
3.5.4 Gas sensor:
MQ-5 is used for combustible gas detection. It can detect the presence and
concentration of gases like methane, propane and butane. The sensing element used
is SnO2. Resistance of SnO2 varies in the presence of gases. It is a six pin device, with
an integrated heating coil. The sensitivity of SnO2 is greater at higher temperatures.
The supply voltage is 5V DC. The output voltage proportional to the gas concentration
is an analog voltage and is given to the A/D. They are used in gas leakage detecting
equipments in family and industry, are suitable for detecting of LPG, natural gas, town
gas, avoid the noise of alcohol and cooking fumes and cigarette smoke.
Features:
 High sensitivity to LPG, natural gas, town gas
 Small sensitivity to alcohol, smoke
 Fast response Stable and long life, Simple drive circuit
3.6 MICROCONTROLLER - PIC18F45K22
The microcontroller executes the program loaded in its Flash memory. This is
the so called executable code comprised of seemingly meaningless sequence of
zeroes and ones. It is organized in 12-, 14- or 16-bit wide words, depending on the
microcontroller’s architecture. Every word is considered by the CPU as a command
being executed during the operation of the microcontroller. For practical reasons, as it
is much easier for us to deal with hexadecimal number system, the executable code
is often represented as a sequence of hexadecimal numbers called a Hex code. It

30
used to be written by the programmer. All instructions that the microcontroller can
recognize are together called the Instruction set. As for PIC microcontrollers the
programming words of which are comprised of 14 bits, the instruction set has 35
different instructions in total.
3.6.1 Microcontroller Features:
 Full 5.5V operation (PIC18F2XK22/4XK22)
 Low voltage option available for 1.8V-3.6V operation
(PIC18LF2XK22/4XK22)
 Self-reprogrammable under software control
 Power-on Reset (POR), Power-up Timer (PWRT) and Oscillator Start-up
Timer
 Programmable Brown-out Reset (BOR)
 Extended Watchdog Timer (WDT) with on-chip oscillator and software
enable
 Programmable code protection
 In-Circuit Serial Programming (ICSP) via two pins
 In-Circuit Debug via two pins
3.6.2 Analog Features:
3.6.2.1 Analog-to-Digital Converter (ADC) module:
 10-bit resolution
 17 analog input channels (PIC18F/LF2XK22)
 Auto acquisition capability
 Conversion available during Sleep
 Programmable High/Low Voltage Detection (PLVD) module
3.6.2.2 Charge Time Measurement Unit (CTMU) for mTouch support:

31
 Up to 28 channels for button, sensor or slider input
 Analog comparator module with:
 Two rail-to-rail analog comparators
 Comparator inputs and outputs externally accessible
and configurable
3.6.2.3 Voltage reference module with:
 Programmable On-chip Voltage Reference module (% of
VDD)
 Selectable on-chip fixed voltage reference
3.6.3 Peripheral Features:
 24/35 I/O pins and 1 input-only pin
 High current sink/source 25 mA/25 mA
 Individually programmable weak pull-ups
 Individually programmable interrupt-on-pin change
 Three external interrupt pins
Up to seven Timer modules:
 Up to four 16-bit timers/counters with prescaler
 Up to three 8-bit timers/counters
 Dedicated, low-power Timer1 oscillator
 Up to two Capture/Compare/PWM (CCP) modules
Up to three Enhanced Capture/Compare/PWM (ECCP) modules with:
 One, two or four PWM outputs
 Selectable polarity
 Programmable dead time
 Auto-shutdown and Auto-restart
 PWM output steering control

32
Two Master Synchronous Serial Port (MSSP) modules with two modes of operation:
 3-wire SPI (supports all 4 SPI modes)
 I2C™ Master and Slave modes (Slave mode with address masking)
Two Enhanced Universal Synchronous Asynchronous Receiver Transmitter
modules (EUSART):
 Supports RS-232, RS-485 and LIN 2.0
3.6.4 Pin Diagram
Fig 3.7: Pin diagram of PIC18F45K22
Fig 3.7 shows the pin diagram of PIC18F45K22 microcontroller which is a 40pin
IC chip. It consists of 5 ports namely A, B, C, D and E. Ports A, B, C and D have 8pins
each and port E has 3pins. 35pins out of the 40pins of the microcontroller can be used
as input pins or output pins. Each pin has special function as well as multiple
functioning capacity. Pin 11 and pin 32 are the two supply pins. Pin 12 and 31 are the
ground pins. Pin 1 is the master clear pin which sets and resets the microcontroller.

33
3.7 OUTPUT DEVICES
An output device is any piece of computer hardware equipment used to
communicate the results of data processing carried out by an information processing
system (such as a computer) which converts the electronically generated information
into human-readable form.
They are:
 Alarm
 Liquid Crystal Display
 Compute
An alarm device or system of alarm devices gives an audible, visual or other
form of alarm signal about a problem or condition. Alarm devices are often outfitted
with a siren. A liquid-crystal display (LCD) is a flat panel display, electronic visual
display, or video display that uses the light modulating properties of liquid crystals.
Liquid crystals do not emit light directly
A computer is a general purpose device that can be programmed to carry out a
set of arithmetic or logical operations. Since a sequence of operations can be readily
changed, the computer can solve more than one kind of problem. It can be used to
monitor the whole process.
Fig. 3.8: Receiving section
The receiving end of the system, as shown in Fig 3.8 consists of a RF
transceiver, a voltage conversion unit, a USB interface and a PC. The RF transceiver
serves the purpose of receiving the signals that are transmitted by the portable or the
fixed device through the ZigBee network to the receiving end at the control room. The
voltage conversion unit is used for the conversion of the incoming signal into voltage

34
that is compatible with the PC. A USB interface is used to interface this signal into the
PC. The USB interface circuit is explained in detail in section 3.7.1.
3.7.1 USB PC Interface Circuit
Fig 3.9 shows the USB PC interface pictorially. The USB port of the computer
is used for communication with microcontroller.The microcontroller uses UART-serial
Communication. Hence, an interfacing circuit using FTDX chip is built to convert USB
signals into UART signals and vice-versa. It enables full duplex communications, while
doing the necessary voltage conversions.
The USB (Universal Serial Bus) port of a computer is a general interface to
which any external devices can be connected. The external devices can be
conventional computer input output devices like keyboard, mouse, a printer, camera
etc. Additionally other hardware like projects, embedded systems and even FPGA can
also be connected to the USB port, for communication with the various softwares on
the computer.
But most microcontrollers and other embedded hardware have a conventional
UART interface. But the USB port of a computer cannot be connected directly to the
UART interface. Additionally any hardware connected to the USB port needs device
drivers that have to be installed on the computer for the operating system to identify
the external device and communicate with it accordingly.
Hence there is a need for a device that can enable communication between the
UART interface of an embedded system or a FPGA and the USB port of a computer.
Various ICs are available that can perform this function. The FT231X is one such IC
that can perform the function of UART to USB conversion.
Fig 3.9: USB PC interface

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The FT231X is a 20 pin IC that can work either with a external 5V power supply
or it can even work with the power from the USB port of the computer. It is also capable
of communicating with external devices that have either a 5V UART interface or a 3.3V
UART interface.
The device drivers needed by the computer for communicating with the FT231X
IC are also provided by the manufacturers of the IC and hence there is no need for the
user to develop the device drivers. For all of these reasons the FT231X is a ideal IC
to use for connecting any project hardware to a PC or a laptop. The circuitary of the
USB interface unit is shown in Fig 3.10.
Fig 3.10 Circuit diagram for the USB interface

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3.8 ZIGBEE TECHNOLOGY
The ZigBee communication is a communication technology to connect local
wireless nodes and provides high stability and transfer rate due to data communication
with low power. In the nodes away from coordinator in one PAN, the signal strength is
weak causing the network a shortage of low performance and inefficient use of
resources due to transferring delay and increasing delay time and thus cannot conduct
seamless communication. This study suggests the grouping method, that makes it
possible to perform wide range data transferring depending on the node signal
strength in ZigBee node and analyzes the suggested algorithm through simulation.
Based on IEEE 802.15.4 Low Rate-Wireless Personal Area Network (LR-
WPAN) standard, the ZigBee standard has been proposed to interconnect simple, low
rate and battery powered wireless devices. The deployment of ZigBee networks is
expected to facilitate numerous applications such as Home-appliance net-works,
home healthcare, medical monitoring and environmental sensors. An effective routing
scheme is more important for ZigBee mesh networks. In order to achieve effective
routing in ZigBee Mesh networks, a ZigBee protocol module is realized using NS-2.
The suitable routing for different data services in the ZigBee application layer and a
best routing strategy for ZigBee mesh network is proposed. The ZigBee standard
provides network, security, and application support services operating on top of the
IEEE 802.15.4 Medium Access Control (MAC) and Physical Layer wireless standard.
It employs a group of technologies to enable scalable, self-organizing, self-healing
networks that can manage various data traffic patterns.
ZigBee is a low-cost, low-power, wireless mesh networking standard. The low
cost allows the technology to be widely deployed in wireless control and monitoring
applications, the low power-usage allows longer life with smaller batteries, and the
mesh networking which promises high reliability and larger range. ZigBee has-been
developed to meet the growing demand for capable wireless networking between
numerous low power devices. The aims of this network are to reduce the energy
consumption and latency by enhancing routing algorithm. In a traditional tree routing
when a node wants to transmit a packet to the destination, the packet has to follow
child/parent relationship and go along tree topology, even if the destination is lying at

37
nearby source. In order to solve this problem, an Enhanced Tree Routing Algorithm is
introduced using ZigBee network. This algorithm can find the shortest path by
computing the routing cost for all of router that stored in neighbor table, and transmit
the packet to the neighbor router that can reduce the hop count of transmission. The
enhanced tree routing algorithm can achieve more stable and better efficiency then
the previous traditional tree routing algorithm. Index Terms: - ZigBee, wireless
network, IEEE 802.15.4, repeater, grouping. Network Key, protocols, meshes, suite,
bandwidth.
3.8.1 Advantages of ZigBee
 Low power consumption, simply implemented.
 Users expect batteries to last many months to years! Consider that a typical
single family house has about 6 smoke/CO detectors. If the batteries for each
one only lasted six months, the home owner would be replacing batteries every
month.
 Bluetooth has many different modes and states depending upon your latency
and power requirements such as sniff, park, hold, active, etc.; ZigBee/IEEE
802.15.4 has active (transmit/receive) or sleep. Application software needs to
focus on the application, not on which power mode is optimum for each aspect
of operation.
 Even mains powered equipment needs to be conscious of energy. Consider a
future home with 100 wireless control/sensor devices, Case 1:802.11 Rx power
is 667mW (always on) @ 100 devices/home & 50,000 homes/city = 3.33
megawatts Case 2: 802.15.4 Rx power is 30mW (always on) @ 100
devices/home & 50,000 homes/city = 150 kilowatts 5)Low cost (device,
installation, maintenance): Low cost to the users means low device cost, low
installation cost and low maintenance. ZigBee devices allow batteries to last up
to years using primary cells (low cost) without any chargers (low cost and easy
installation). ZigBee’s simplicity allows for inherent configuration and
redundancy of network devices provides low maintenance.
 High density of nodes per network: ZigBee’s use of the IEEE 802.15.4 PHY and
MAC allows networks to handle any number of devices. This attribute is critical
for massive sensor arrays and control networks.

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 Simple protocol, global implementation: ZigBee’s protocol code stack is
estimated to be about 1/4th of Bluetooth’s or 802.11’s. Simplicity is essential to
cost, interoperability, and maintenance. The 2.4 GHz band is now recognized
to be a global band accepted in almost all countries.
3.9 GLOBAL POSITIONING SYSTEM
The Global Positioning System (GPS) is a space-based satellite
navigation system that provides location and time information in all weather conditions,
anywhere on or near the Earth where there is an unobstructed line of sight to four or
more GPS satellites. The system provides critical capabilities to military, civil and
commercial users around the world. It is maintained by the United States government
and is freely accessible to anyone with a GPS receiver.
3.9.1 Components of GPS
3.9.1.1 Space segment:
24 GPS space vehicles (SVs).Satellites orbit the earth in 12 hrs.6 orbital planes
inclined at 55 degrees with the equator. This constellation provides 5 to 8 SVs from
any point on the earth.
3.9.1.2 Control Segment:
The control segment comprises of 5 stations. They measure the distances of
the overhead satellites every 1.5 seconds and send the corrected data to Master
control. Here the satellite orbit, clock performance and health of the satellite are
determined and determines whether repositioning is required. This information is sent
to the three uplink stations.
3.9.1.3 User segment:
It consists of receivers that decode the signals from the satellites. The receiver
performs following tasks:
 Selecting one or more satellites
 Acquiring GPS signals
 Measuring and tracking
 Recovering navigation data

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3.9.2 Working of GPS
The actual principle of GPS is very easy to appreciate, since it is exactly the
same as traditional “triangulation”. If one imagines an orienteer needing to locate
themselves on a map, they first need to be able to find at least three points that they
recognize in the real world, which allows them to pinpoint their location on the map.
They can then measure, using a compass, the azimuth that would be needed
to take them from the point on the map to their current position. A line is then drawn
from each of the three points, and where the three lines meet is where they are on the
map.
Translating this into the GPS world, we can replace the known points with
satellites, and the azimuth with time taken for a signal to travel from each of the known
points to the GPS receiver. This enables the system to work out roughly where it is
located - it is where the circles representing the distance from the satellite, calculated
on the basis of the travel time of the signal, intersect.
Of course, this requires that the GPS locator has the same coordinated time as
the satellites, which have atomic clocks on board. To do this, it cross checks the
intersection of the three circles with a fourth circle, which it acquires from another
satellite. If the four circles no longer intersect at the same point, then the GPS system
knows that there is an error in its clock, and can adjust it by finding one common value
(one second, half a second and so on) that can be applied to the three initial signals
which would cause the circles to intersect in the same place.
Behind the scenes, there are also many complex calculations taking place
which enable the system to compensate for atmospheric distortion of the signals, and
so forth, but the principle remains the same.
3.9.3 Tracking Devices
One of the easiest applications to consider is the simple GPS tracking device;
which combines the possibility to locate itself with associated communications
technologies such as radio transmission and telephony.

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Tracking is useful because it enables a central tracking center to monitor the
position of several vehicles or people, in real time, without them needing to relay that
information explicitly. This can include children, criminals, police and emergency
vehicles, military applications, and many others.
The tracing devices themselves come in different flavors. They will always
contain a GPS receiver, and GPS software, along with some way of transmitting the
resulting coordinates. GPS watches, for example, tend to use radio waves to transmit
their location to a tracking center, while GPS phones use existing mobile phone
technology.
The tracking center can then use that information for co-ordination or alert
services. One application in the field is to allow anxious parents to locate their children
by calling the tracking station - mainly for their peace of mind.
3.10 SOFTWARE DEVELOPMENT TOOLS:
3.10.1 LabVIEW
Lab view (Laboratory Virtual Instrument Engineering Workbench) is a system-
design platform and development environment for a visual programming
language from National Instruments. It contains a comprehensive set of tools for
acquiring, analyzing, displaying, and storing data, as well as tools to help you
troubleshoot the code you write. The graphical language is named "G" (not to be
confused with G-code). Originally released for the Apple Macintosh in 1986, LabVIEW
is commonly used for data acquisition, instrument control, and industrial automation on
a variety of platforms including Microsoft Windows, various versions of UNIX, Linux,
and Mac OS X.

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Fig 3.11: LabVIEW front panel
The Front Panel as shown in Fig 3.11 is “the window through which the user
interacts with the program”. When we run a VI, we must have the front panel open so
that we can input data to the executing program. The front panel is where we see our
program’s output.
Fig 3.12: LabVIEW block diagram panel

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The block diagram window shown in Fig 3.12 holds the graphical source code
of a LabVIEW VI – it is the actual executable code. We construct the block diagram by
wiring together objects that perform specific functions. The various components of a
block diagram are terminals, nodes and wires.
3.10.1.1 Benefits of LabVIEW:
Using LabVIEW real time signals from various sensors and devices can be
seen as continuous graphs and waveforms. LabVIEW is an easy to use software.
Since it uses graphical programming, it does not require any experience in
conventional programming languages. Instruments similar to real life instruments and
even more complicated interfaces can also be implemented easily.
One benefit of LabVIEW over other development environments is the extensive
support for accessing instrumentation hardware. Drivers and abstraction layers for
many different types of instruments and buses are included or are available for
inclusion. These present themselves as graphical nodes. The abstraction layers offer
standard software interfaces to communicate with hardware devices. The provided
driver interfaces save program development time. The sales pitch of National
Instruments is, therefore, that even people with limited coding experience can write
programs and deploy test solutions in a reduced time frame when compared to more
conventional or competing systems. A new hardware driver topology (DAQmxBase),
provides platform independent hardware access to numerous data acquisition and
instrumentation devices. The DAQmxBase driver is available for LabVIEW on
Windows, Mac OS X and Linux platforms.
In terms of performance, LabVIEW includes a compiler that produces native
code for the CPU platform. The graphical code is translated into executable machine
code by interpreting the syntax and by compilation. The LabVIEW syntax is strictly
enforced during the editing process and compiled into the executable machine code
when requested to run or upon saving. In the latter case, the executable and the
source code are merged into a single file. The executable runs with the help of the
LabVIEW run-time engine, which contains some precompiled code to perform
common tasks that are defined by the G language. The run-time engine reduces
compile time and also provides a consistent interface to various operating systems,

43
graphic systems, hardware components, etc. The run-time environment makes the
code portable across platforms.
Many libraries with a large number of functions for data acquisition, signal
generation, mathematics, statistics, signal conditioning, analysis, etc., along with
numerous graphical interface elements are provided in several LabVIEW package
options. The number of advanced mathematic blocks for functions such as integration,
filters, and other specialized capabilities usually associated with data capture from
hardware sensors is immense. In addition, LabVIEW includes a text-based
programming component called MathScript with additional functionality for signal
processing, analysis and mathematics. MathScript can be integrated with graphical
programming using "script nodes" and uses .m file script syntax that is generally
compatible with MATLAB.
The fully object-oriented character of LabVIEW code allows code reuse without
modifications: as long as the data types of input and output are consistent, two sub
VIs are interchangeable.
The LabVIEW Professional Development System allows creating stand-alone
executables and the resultant executable can be distributed an unlimited number of
times. The run-time engine and its libraries can be provided freely along with the
executable.
A benefit of the LabVIEW environment is the platform independent nature of
the G code, which is (with the exception of a few platform-specific functions) portable
between the different LabVIEW systems for different operating systems (Windows,
Mac OS X and Linux). National Instruments is increasingly focusing on the capability
of deploying LabVIEW code onto an increasing number of targets including devices
like Phar Lap OS based LabVIEW real-time controllers, PocketPCs, PDAs, FieldPoint
modules and into FPGAs on special boards.
3.10.1.2 Core LabVIEW Concepts:
 LabVIEW Environment Basics – learn the most important building blocks for
any LabVIEW application, including the front panel, block diagram, palettes,
controls, and indicators

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 Graphical Programming Basics – see how to connect functions and work with
a variety of data types when constructing applications
 Common Tools – view a collection of important tools and common user
functions that all users should be familiar
 Debugging Tools – learn how to use simple tools and techniques to understand
the behavior of code and address problems or bugs
3.10.1.3 Programming in LabVIEW:
 Data Structures – arrays, clusters, and enumerated data
 Execution Structures – while loops, for loops, and case structures
 Passing Data between Loop Iterations – shift register.
 Handling Errors – error handling and error clusters

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CHAPTER 4
RESULT & DISCUSSION
4.1 PERFORMANCE ANALYSIS:
4.1.1 Comparison of communication devices
Table 4.1 Analysis of various wireless communication devices
Brand Name Wi-Fi Bluetooth ZigBee
Battery Life Several Hours Several Days Several Years
Maximum
Network
Capacity
32 Nodes 7 Nodes 64000 Nodes
Communication
Distance
100m 10m >30m
Communication
Speed
11 Mbps 1 Mbps 250 Kbps
Security
Method
SSID 64, 128 bit 32, 64, 128 bit
Application Wireless LAN Wireless speech Remote control
measurement
A comparison between the various wireless communication devices is made in
Table 4.1. The ZigBee has a long battery life, consumes less power, a higher network
capacity than the other devices. The communication distance is less, this is because
a mesh network is used in the network topology, the communication distance is
between the nodes and thus can be used in a long range. The speed is comparatively
low this drawback is bearable for the proposed system as the parameters are being
monitoring only in specified time intervals as any gas leakage reaches its UEL levels
only gradually and not in split seconds.

46
4.1.2. Gas LELs and UELs
Table 4.2: Analysis of various Gases
VARIOUS GASES LEL (%) UEL (%)
Acetone 13.5 15.5
Benzene 11 14
Butadiene 10 13
Butane 12 14.5
Carbon Disulfide 5 8
Carbon monoxide 5.5 6
Diethyl ether 10.5 13
Ethylene 10 11.5
Hydrogen 5 6
Iso Butane 12 15
Methane 12 14.5
Methyl Alcohol 10 13.5
Propane 11.5 14
Propylene 11.5 14
Hydrogen sulfide 7.5 11.5
The Lower Emission Level (LEL) and Upper Emission Level (UEL) of the
various gases are discussed in Fig4.2. The LEL is the level of gas in percentage below
which the gas is not hazardous or does not catch fire, the UEL is the upper level of
gas leakage above which it is not combustible. The LEL and UEL is measured in
percentage of the gas leaked.

47
4.1.3 ZigBee 802.15.4 latency time analysis:
Fig 4.1: ZigBee network
Digi's XBee Series 1 radio modules run 802.15.4 firmware, which allows them to
transmit data in a point-to-point, peer-to-peer or point-to-multipoint (star) network
architecture as shown in Fig 4.1. The time it takes to transmit a data packet is a sum
of the Time on Air and Time for CSMA-CA and Retries, as outlined below.
 Quick Reference:
 XBee 8021.5.4 max payload = 100 bytes
 XBee ZNET 2.5 max payload = 72 bytes
 RF baud rate (802.15.4, 2.4GHz) = 250 Kbps
 Byte time @ 250 Kbps = 32 us
 64-bit: T_air(B) = 0.8 + 0.032B ms
 16-bit: T_air(B) = 0.416 + 0.032B ms
 16-bit best case (broadcast and unicast): T_total(B) = 0.544 + 0.032B ms
 64-bit unicast best case: T_total(B) = 0.928 + 0.032B ms
 Broadcast worst case: T_total(B) = 9.376 + 0.032B ms
 16-bit unicast worst case: T_total(B) = 40.096 + 0.128B ms
 64-bit unicast worst case: left for the reader to calculate
Total transmission time = Time on air + Time delay cause by hardware

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 Time on Air
The 802.15.4 PHY layer allows a maximum 127 bytes per packet, including
payload. Due to the size of the packet header, XBee Series 1 modules can send a
maximum payload of 100 bytes. XBee Series 2 modules, which utilize more header
bytes for ZigBee mesh networking, can send a maximum payload of 72 bytes.
At 2.4 GHz the 802.15.4 PHY layer specifies an RF baud rate of 250 Kbps, which
is a 4 us bit time or 32 us byte time. This gives us enough information to compute the
"T_air(B)," the actual time on the air taken to send B payload bytes.
T_air(1) = (25 + 1) * 32 us = 0.832 ms [25-byte header + 1 payload byte) * 32 us byte
time]
T_air(100) = (25 + 100) * 32 us = 4.000 ms
T_air(B) = 0.8 + 0.032B ms
The above calculation is assuming 64-bit addressing. It is probably more
common to use only 16-bit addressing, which allows us to use a 13-byte header
instead of a 25-byte header (subtract 48 bits from 64 bits in both source and
destination addressing to reduce a total of 96 bits or 12 bytes). Using 16-bit
addressing, T_air for different payload bytes are as follows:
T_air(1) = (13 + 1) * 32 us = 0.448 ms
T_air(72) = (13 + 72) * 32 us = 2.720 ms
T_air(100) = (13 + 100) * 32 us = 3.616 ms
T_air(B) = 0.416 + 0.032B ms

49
 Time for CSMA-CA and Retries
The above calculations are the "on-air" time only. The total time it takes to
transmit an 802.15.4 packet includes the time for CSMA-CA and retries, where
applicable.
CSMA-CA stands for Carrier Sense Multiple Access - Collision Avoidance. This
basically means that before a radio actually begins transmitting on the air it senses
the carrier channel to make sure the air waves are clear (called CCA-Clear Channel
Assessment). If it senses strong enough activity on the channel, it will perform a
random delay (back off/wait time) and then try again with another CCA.
For easier reference an outline of the basic steps here:
 Perform random delay.
 Perform CCA.
 Transmit if CCA is clear. If channel is not clear, then repeat steps 1-3 up to 4
more times.
 Done if broadcast (no acknowledgment/retry).
 If unicast:
 Wait for ACK (acknowledgment of packet received) from destination
node.
 Done if ACK is received. Repeat steps 1-4 up to 3 more times.
Following are the computations for the above steps:
 Perform random delay. The random delay function is (0 : 2^BE - 1) * 0.320
ms, where BE starts at RN and increments each time (up to max value of 5)
through the loop until step 3 is cleared. (RN is default 0; it is a user-settable).
The "0:2" means it chooses a random number between 0 and 2.
 Perform CCA. This step always takes 0.128 ms.
 No computation on this step.
 Wait for ACK. This step takes up to 0.864 ms.
 No computation on this step.

50
 Total Transmit Time
Let's do some examples to compute "T_total(B)," the total time taken to send B
payload bytes.
 Best case:
Broadcast 1 byte, RN = 0
Random Delay = (0 : 2^0 - 1) * 0.320 = 0 ms
CCA = 0.128 ms
T_air(1) = 0.448 ms
T_total(1) = 0 + 0.128 + 0.448 = 0.576 ms
To generalize this "best case" timing calculation (works for both broadcast and
unicast since "best case" assumes no time spent waiting on the ACK in step 4.a):
16-bit: T_total(B) = 0.544 + 0.032B ms
Similarly, we can compute the "best case" timing for a 64-bit addressed unicast
packet, assuming ~0 time spent waiting on the ACK:
64-bit: T_total(B) = 0.928 + 0.032B ms
 Worst case:
Example: Broadcast 1 byte, RN = 0
Random Delay = 0 ms
CCA = 0.128 ms [Assume CC did not clear. Go back to step 1.]
Random Delay = (0 : 1) * 0.320 = 0.320 ms
CCA = 0.128 ms

51
Random Delay = (0 : 3) * 0.320 = 0.960 ms [Assuming (0 : 3) yielded 3.]
CCA = 0.128 ms
CCA = 0.128 ms
CCA = 0.128 ms
Subtotal for this CSMA-CA section: 8.96 ms
T_air(1) = 0.448 ms
T_total(1) = 8.96 + 0.448 = 9.408 ms
To generalize this "worst case" timing calculation for a broadcast message:
T_total(B) = 9.376 + 0.032B ms
4.2 RESULT
Thus, an industrial safety system is designed and constructed for workers
working in hazardous environments, comprising of two sections.
A portable unit is provided to the workers, which is capable of sensing
hazardous conditions like gases, excessive temperature, heart beat and humidity etc.
and a monitoring system at the receiving end (control room) which interacts with the
portable unit using a ZigBee wireless communication link is developed.

52
Fig 4.2 Block Diagram of Developed System in LabVIEW
Fig. 4.3: Front Panel of the Developed System in LabVIEW
Fig 4.2 shows the block diagram developed in labview for the system. Fig 4.3
illustrates the front panel of the developed system in LabVIEW. The digital indicators
indicates the output from various sensors implemented in the system. If the outputs of
the sensors exceed the set point, the LED flashes. The plot depicts the variation of
output with respect to time.

53
4.3 ADVANTAGES OF THE DEVELOPED SYSTEM
 Communication channel availability is maximized
 Workers distribution at any given time for any area is known.
 Open system, allows developing other applications
 Long time archiving helps analysis
 Safety system integrity is improved

54
CHAPTER 5
CONCLUSION
5.1 SUMMARY
“Integrated refinery fire and gas monitoring system using ZigBee” is a project based
on a wireless communication to enhance man and machine safety in a petrochemical
industry. As petroleum industries are the largest process control industry it is also
highly prone to major fire and gas disasters. A petrochemical industry has excessively
high amount of crude oil stored within a confined area. Therefore presence of any
external source which can cause heat or fire would lead to a major disaster. Even the
gas that are present in petroleum refineries are hazardous. And another instance, the
Vishakhapatnam, HPCL refinery tragedy claimed lives of 30 people. Though a gas
and fire detection system was present which is connected to the sensors using large
number of wires that run from the control room to various plant areas. But during the
fire the wire itself got damaged, so the information did not reach the control room.
Therefore our system is developed with the aim of overcoming the restrictions and
disadvantages of the existing system. The system we have designed is an integrated
system which will monitor timely gas leakage in any area around the plant using
ZigBee which is a wireless communication device. We have also proposed a new
system which monitors human density within the plant area. Therefore Integrated plant
safety monitor system based on ZigBee can realize workers attendance registration,
Real-time precise positioning, Dynamic gas concentration monitoring, Real-time data
transmission & Danger alarm. This project is focused on implementing the newly
designed integrated system in CPCL, Manali.

55
5.2 CONCLUSION
“Integrated refinery fire and gas monitoring system using ZigBee” is developed to
enhance man and machine safety in a petroleum refinery. The main objective of the
project was early detection of gas leakage around the plant area. With the detection
of a gas leak the sensor present in the plant area as well as with the plant area workers
alerts the control room personnel. Therefore with this system even the human density
in the plant area was determined. We have also analyzed various wireless
technologies and various hardware and software approaches that can be
implemented. After implementing this system in CPCL, Manali it was found out to be
more efficient than the previously existing system. And with the introduction of ZigBee
the whole project cost was also reduced and human safety level was also increased.
5.3 FUTURE SCOPE
In addition to the developed system, the system can be enhanced by adding a
control element which controls the gas leakage if it exceeds the specified upper
explosive level for the various gases in the plant area. This can be achieved by any
gas leakage indication in any part of the plant alerts the control room and then the
control valve is shut off. Therefore preventing any hazard arising due to gas leakage.

56
REFERENCES
[1] Chih-Ning Huang, Chia-Tai Chan, “ZigBee-based indoor location system by k-
nearest neighbor algorithm with weighted RSSI”, Procedia Computer Science,
Volume 5, 2011, pp. 58-65.
[2] Ebrahim A. Soujeri,Harikrishnan A. I, Rahim Rajan,Sumi M, “Design of a
zigbee-based RFID network for industry applications”, proceedings of the 2nd
international conference on Security of information and networks, 2009, pp.
111-116.
[3] Fabio Graziosi, Fortunato Santucci,Marco Di Renzo, Stefano Tennina,
“Locating zigbee nodes using the tis cc2431 location engine: a testbed latform
and new solutions for positioning estimation of wsns in dynamic indoor
environments”
[4] Fire and Gas System Engineering –Performance Based Methods for Process
Facilities , ISA manual, 2011
[5] G. A. Arun Kumar, K.Rajasekhar, B.V.V.Satyanarayana, K.Suryanarayana
Murthy, “Implementation of Real time Detection of Gas leakage in Industries
usingARM7 &ZigBee” International Journal of Engineering Research &
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[6] IEEE Reference: Restful Web Service Mashup Based Coal Mine Safety
Monitoring and Control Automation with Wireless Sensor Network
[7] Instrument Hand Book Of CPCL By Gowthaman 2012 May edition
[8] Integrity Level Selection: Systematic Methods Including Layer of
[9] Jeffrey Wong,Haruo Noma,Kiyoshi Kogure, Masakazu Miyamae,Satoshi
Takahashi,Shojiro Nishio, Tomoji Toriyama, Tsutomu Terada, “A ZigBee-
based sensor node for tracking people's locations”, proceedings of the 2nd
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[10] Jin Hyung Park, Joon Goo Park, Sharly Joana Halder, Sin Woo Park, Sung Hun
Kang, Tae Young Choi, “Enhanced ranging using adaptive filter of ZIGBEE

57
RSSI and LQI measurement”, Proceedings of the 10th International Conference
on Information Integration and Web-based Applications & Services, 2008, pp.
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[11] MSA Gas detection hand book, 2008
[12] Protection Analysis Eric William Scharpf, The Instrumentation, Systems, and
Automation Society (May 1, 2002)Year of Publication: 2012

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