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USB powered gas leakage detector alarming system analysis

Paper Type: Free Essay Subject: Engineering
Wordcount: 4282 words Published: 1st Jan 2015

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USB powered gas leakage detector alarming system can be used in residential and commercial premises to detect the leakage of the gas and give early signs under less severe conditions and must active the alarm in case of emergency situations in order to safeguard the occupiers and users of those premises, all these can be done through by MQ5 gas sensor and pic18f1320 circuit.

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When the gas leakages from the monitoring area then MQ5 gas sensor activates and sense the gas and pass the variable voltage to pic18f1320 circuit. If the gas level normal (1.2 volt to 4 volt) then two led and a buzzer is activated in slow mode for early warning, and if the gas level goes high (volt is high from sensor more than 4 volt) then a led and 2 buzzer is activated in fast mode by the help of pic18f1320 Circuit












–   According To Specific Gravity Of Natural Gas, Its Specific Gravity Is Lighter Than The Specific Gravity Of Air, And So Natural Gas Suspends On The Ceiling. Therefore, The Alarm Should Be Installed in the Small Area Which is 0.3~1.2 Meter Less than The Ceiling and within Radii 1.5 Meter far From Gas Leakage.

Liquid petroleum Gas: It’s Specific Gravity Is Higher than Air, So It Sinks down on the Bottom. Therefore, the alarm should be installed in the area that is 0.3~ 1.2 meters far from ground and within radii 1.5 meter far from gas leakage.


The aim of the project is to save The People from Gas Leakage Accident used in places like Canteen, Houses, Hotels, & Restaurants, as well as in the various industries where Gas is very important for the people who come to Lunch & dinner as well as processes involved in the manufacturing and service industry.

According to the Gas Leakage Detector can be Save Lots of Problems. By using this system, we can also adjust the Regulation of the Gas using Mq5 and.


I used MQ5 gas sensor with the experimental kit. The sensor detect the gas and pass the variable voltage to pic18f1320 and If the gas level is normal lies between 1.2 volt to 4 volt, I activated two led’s and a buzzer in slow mode for early warning then if the gas level goes high then I activated a led and 2 buzzer in fast mode it is for high level of gas so I done it for that.

1.3- System Features:-

Gas Detectors

Type of the various gas detectors:-

Analyzers: Continuous monitoring of toxic gases at ultra low ppb levels directly integrated into life safety systems Fire & Gas: Flame, smoke & gas detectors coupled with sophisticated control solutions for offshore and industrial applications.

Fixed Controller Systems: The control systems behind integrated ‘plant-wide’ fire and gas detection.

Personal Gas Detection: Effective personal protection from gas hazards, when and where it’s needed.

Domestic Gas Detectors

We are engaged in the manufacturing of domestic gas detectors. These products are used in homes for detecting gas leaks & avoiding accidents. Easy to install, these wall-hung detectors have an audio-visual alarm that alerts the client when the gas leak concentration reaches a dangerous level. This gives adequate time to take the necessary actions towards avoiding loss of lives and property. Following are some of the salient features of these detectors


Features: Integral concussion-proof boot Continuous LCD shows real-time gas concentration with backlight in low light (auto); in alarm (auto) and on demand

Waterproof IP 66/67 rating up to 3 ft fully submerged Provides 85 dB tone and bright LED indication on alarm (typical) 3-year battery life (9,000 hours)  Available with internal vibrating alarm Equipped with plug-in, replaceable sensor Simple auto-zero and calibration procedure Peak value displayed on command (in ppm or %) TWA (time weighted average) values are recorded and displayed.

Mulit Gas Detection

We have the most advanced handheld volatile organic compound (VOC) detector on the market. Its Photo ionization Detector’s (PID) extended range of 0 to 15,000 ppm makes it an ideal instrument for applications from industrial hygiene, to leak and HazMat detection.




LPG Gas Sensor (MQ5)

It Extensively Used In Homes, Cars, Service Stations and Storage Tank. This Sensor Can Be Easily Installed Into An Alarm Unit. The Equipment Provides Visual Indication Of The Combustible Gas or LPG Concentration. It Can Be Iso-butane, Propane, LNG and Cigarette Smoke. We Hold Expertise In Offering Wireless Gas Leak Detectors For Home security systems. Given below are few highlighting features of our products-

Improvement Of Products & Its Features Is A Continuous Process.

MQ-5 Semiconductor Sensor for Combustible Gas

Sensitive material of MQ-5 gas sensor is SnO2, which with lower conductivity in clean air. When the

Target combustible gas exist, the sensor’s conductivity is higher along with the gas concentration rising.

MQ-5 gas sensor has high sensitivity to Methane, Propane and Butane, and could be used to detect

both Methane and Propane. The sensor could be used to detect different combustible gas especially

Methane, it is with low cost and suitable for different application.

Character Configuration

* Good sensitivity to Combustible gas in wide range

* High sensitivity to Methane, Butane and Propane

* Long life and low cost

* Simple drive circuit


* Domestic gas leakage detector

* Industrial Combustible gas detector

* Portable gas detector

Sensitivity Characteristics

Influence of Temperature/Humidity

Structure and configuration

Structure and configuration of MQ-5 gas sensor is shown as Fig. 3, sensor composed by micro AL2O3 ceramic tube, Tin Dioxide (SnO2) sensitive layer,

Measuring electrode and heater are fixed into a crust made by plastic and stainless steel net. The heater provides necessary work conditions for work of sensitive components. The enveloped MQ-4 has 6 pin, 4 of them are used to fetch signals, and other 2 are used for providing heating current.


1 Following conditions must be prohibited

1.1 Exposed to organic silicon steam

Organic silicon steam cause sensors invalid, sensors must be avoid exposing to silicon bond,

Fixtures, silicon latex, putty or plastic contain silicon environment.

1.2 High Corrosive gas

If the sensors exposed to high concentration corrosive gas (such as H2Sz, SOX¼ŒCl2¼ŒHCl etc), it will not only result in corrosion of sensors structure, also it cause sincere sensitivity attenuation.

1.3 Alkali, Alkali metals salt, halogen pollution

The sensors performance will be changed badly if sensors be sprayed polluted by alkali metals salt

especially brine, or be exposed to halogen such as fluorine.

1.4 Touch water

Sensitivity of the sensors will be reduced when spattered or dipped in water.

1.5 Freezing

Do avoid icing on sensor’ surface, otherwise sensor would lose sensitivity.

1.6 Applied voltage higher

Applied voltage on sensor should not be higher than stipulated value, otherwise it cause down-line or

heater damaged, and bring on sensors’ sensitivity characteristic changed badly.

1.7 Voltage on wrong pins

For 6 pins sensor, if apply voltage on 1/3 pins or 4/6 pins, it will make lead broken, and without signal when apply on 2/4 pins.

2 Following conditions must be avoided

2.1 Water Condensation

Indoor conditions, slight water condensation will effect sensors performance lightly. However, if water

Condensation on sensors surface and keep a certain period, sensor’ sensitivity will be decreased.

2.2 Used in high gas concentration

No matter the sensor is electrified or not, if long time placed in high gas concentration, if will affect sensors characteristic.

2.3 Long time storage

The sensors resistance produce reversible drift if it’s stored for long time without electrify, this drift is

related with storage conditions. Sensors should be stored in airproof without silicone gel bag with clean air.

For the sensors with long time storage but no electrify, they need long aging time for stability before using.

2.4 Long time exposed to adverse environment

No matter the sensors electrified or not, if exposed to adverse environment for long time, such as

high humidity, high temperature, or high pollution etc, it will affect the sensors performance badly.

2.5 Vibration

Continual vibration will result in sensors down-lead response then rapture. In transportation or assembling line, pneumatic screwdriver/ultrasonic welding machine can lead this vibration.

2.6 Concussion

If sensors meet strong concussion, it may lead its lead wire disconnected.

2.7 Usage

For sensor, handmade welding is optimal way. If use wave crest welding should meet the following conditions:

2.7.1 Soldering flux: Rosin soldering flux contains least chlorine

2.7.2 Speed: 1-2 Meter/ Minute

2.7.3 Warm-up temperature¼š100±20℃

2.7.4 Welding temperature¼š250±10℃

2.7.5 1 time pass wave crest welding machine

If disobey the above using terms, sensors sensitivity will be reduced.

Lpg Sensor

Lpg level Sensor With Mechanical Reading By Means Of A Gauge Fitted On The Multivalve, Tank Level Indication From Empty To Full Is Shown. The Sensor Transforms The Position Of the Float Into An Electric Signal If Combined With A Switch Unit Pre-arranged For the purpose.

Cng Sensor With Pressure Gauge

Cng Pressure Sensor With Mechanical Reading By Means Of A Gauge Indicates From Empty To Full Be Shown In Clockwise Direction. It Transforms Tank Pressure In To An Electrical Signal Indicates From 0 to 400 Bars. 


Continuous monitoring of toxic gases at ultra low ppb levels directly integrated into life safety systems Fire & Gas: Flame, smoke & gas detectors coupled with sophisticated control solutions for offshore and industrial applications.

Fixed Controller Systems:

The control system behind integrated ‘plant-wide’ fire and gas detection.

Personal Gas Detection:

Effective personal protection from gas hazards, when and where it’s needed.


This is for high level gas red led is on in fast mode and two buzzers are on in fast mode (delay 50ms)

This is for low level of gas led’s green and yellow are on in slow mode (delay 100ms) and a buzzer is on in slow mode (100ms delay)

Circuit Design

Microchip icd2 in circuit debugger this is the device used to feed the programme into the pic18f1320 please explain a about this also please give some sentence about MPLAB IDE.




What is a PIC Microcontroller?

A PIC Microcontroller Is a Single Integrated Circuit Small Enough To Fit in the Palm Of A Hand. ‘Traditional’ Microprocessor Circuits Contain Four or Five Separate Integrated Circuits – The Microprocessor (CPU) Itself, an EPROM Program Memory Chip, Some

RAM Memory and an Input/output Interface. With PIC Microcontrollers All These Functions Are Included Within One Single Package, Making Them Cost Effective And Easy To Use.

PIC Microcontrollers Can Be Used As The ‘Brain’ To Control A Large Variety Of Products. In Order To Control Devices, It Is Necessary To Interface Them To The PIC Microcontroller. This Section will help to enable those with limited Electronics Experience to successfully complete these interfacing tasks. Interfacing to the PIC Microcontroller this section explains how to interface many different inputs and output devices to the PIC microcontroller. BASIC code examples are provided for users of the Basic Stamp or PICAXE systems. Explanations of BASIC commands are provided in the Commands section (available separately). The interfacing circuits can also be used with any PIC microcontrollers such as the PIC16F84, although these microcontrollers may require programming in assembler code.

This section is split into four subsections:

• Introduction to ‘standard’ interfacing circuits

• Output Device Interfacing

• Input Device Interfacing

• Advanced Component Interfacing

Standard Interfacing Circuits

1. The Standard Transistor Interfacing Circuit

2. Using a Darlington Driver IC

3. The Standard Relay Interfacing Circuit

4. The Standard FET Interfacing Circuit

Output Device Interfacing

1. LED

2. Signal Lamp

3. Buzzer

4. Piezo Sounder & Speakers

5. Solar & DC (“toy”) Motors

6. Unipolar Stepper Motor

7. Bipolar Stepper Motor

8. Radio-Control Servo

9. Counter Module

10. Seven Segment Display

11. Solenoid & Isonic Solenoid Valve

12. Smart Wire / springs

Input Device Interfacing

1. Switches

2. Potentiometers

3. Light Dependant Resistor (LDR)

4. Thermistor

Advanced Component Interfacing

1. Liquid Crystal Display (LCD)

2. Serial Communication with a Computer

The Printed Circuit Board (PCB) Layout

The connections on the PCB should be identical to the circuit diagram, but while the circuit diagram is arranged to be readable, the PCB layout is arranged to be functional, so there is rarely any visible correlation between the circuit diagram and the layout.

PCB layout can be performed manually (using CAD) or in combination with an Auto router. The best results are usually still achieved using at least some manual routing – simply because the design engineer has a far better judgments of how to arrange circuitry. Surprisingly, many auto routed boards are often completely illogical in their track routing – the program has optimized the connections, and sacrificed any small amount of order that may have been put in place by manual routing. Generally auto routed boards are somewhat harder for a technician to repair or debug, for this reason. Historically, PCBs used to be laid out by drawing or using stick on paper shapes on Mylar film, – that really WAS manual routing!

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The CAD PCB layout consists of several layers, for illustration often the layers will be colored and compressed into the one overlay image. When we layout boards, we usually try to use actual size check plots at some stage during the design process. Most overlays need to be printed out enlarged to show the detail, but an actual size print, with mounting holes and possibly cutouts, is a great check tool. The print itself can be placed inside the actual enclosure; we can see how it will be positioned in relation to other parts. We can also place components up against the pad markings as a quick idiot-check of dimensions.

We put a bit of effort into the PCB design – it is somewhere where quality of design can make a difference. The width of the tracks is a trade-off based on current flow, space available, size of parts, and electromagnetic interference. The track layout is a similar trade-off that also picks when to dodge from one side of the board to the other avoid an obstacle, but overall normally aims to find the shortest regular path between the connected points.

A rotten layout

Our replacement

Most Of the circuit boards are automatically assembled and tested – but people still install and repair them. Having a quality design can make all the difference between a product that is pleasant to work on and one that they will hate. Machine test points, for ATE (Automated Test Equipment) bed of nails testing, only need to be plain pads or lands. Some test points, however, are really intended to be for engineering test or modification – for these we put in labeled, circled pads.

To make a better product we put a complete silkscreen identification overlay on most of our boards. The silkscreen contains important information that assists people to service and install the product. Aside from the PCB functionality the overlay is the chief distinguishing feature between a purpose-built products, such as we deliver, and a general-purpose controller or ready made PLC. We would label terminals as: “+12v red” “-pwr black” “solenoid+” “solenoid-” whereas competitors may often just give you: “A1 A2 A3 A4”. They don’t have much of a choice – they have no idea what you will attach to the terminals.

For dense surface mount boards, we often need to leave off component values, and sometimes need to omit the component designators. The truth is, we first try to drop the size of the lettering – small text being better than no text. The silkscreen is the primary method for labeling connectors, replaceable parts, orientation, and even installation notes (for instance “Remove J2 while replacing battery – observe battery polarity”). It can also used as a backup for manufacturing notes (for example “Mount R2 approx 5mm off circuit board due to high temperature”) although now we normally put these notes in the BOM.

The PCB layout also needs to take account of emi and esd compliance and we have a separate page on some techniques that we use to get our PCBs to comply. 

Etched PCB laminates are:

Double sided Laminate

It has two layers of copper tracks, one each side of the board

In progressively smaller Quantities

4 Layers, 6 Layers, 8 Layer

Plated Through Hole

PTH – each hole is copper plated and providing a circuit between the two sides of the PCB. We also Tent the vies – cover them with solder mask.

Component legend

Identifying lettering, component outlines and values in white ink.

Different methods of PCB construction:


A rigid PCB having thickness of 1.6mm with wire-leaded components mounted on only one side of the PCB, with all the leads through holes, soldered and clipped. Conventional circuitry is generally easier to debug and repair than Surface mount.

Surface Mount Technology (SMT) or devices (SMD)

A PCB with tag-leaded components soldered flush to PCB pads. Holes are still needed on the PCB, but not where the component leads are attached. Surface mount circuitry is generally smaller than conventional. Surface mount is generally more suited to automated assembly than conventional.

Surface mount & conventional mix

Generally the most of the boards are a mix of surface mount and conventional components. And we know that the two technologies require different methods of insertion and soldering, this can have its disadvantages.

Double sided Laminate

A bare PCB laminate having tracks on both sides, normally with PTH holes connecting circuitry on the two sides together.

Double sided Component Assembly

Mounting components on both sides of the PCB. Normally only surface mount circuitry would be mounted on both sides of a PCB, but some conventional components (such as LEDs) may be mounted on the reverse of a PCB to suit the enclosure design.

Multi-layer A PCB Laminate may be manufactured with more than two layers of copper tracks by using a sandwich construction. The cost of the laminate reflects the number of layers. The extra layers may be used to route more complicated circuitry, and/or distribute the power supply more effectively.

Gold plated

To the use in contact pads or as a ROHS-compliant board finish, the certain areas on the PCB is gold plated. Normally only thin gold plating is required, and this can be achieved with electro less gold. If thicker gold plating is required an electrolytic process is needed. Normally this is limited to pads on the edge of a PCB, as an electrolytic plating bar must be attached to the pads, and then removed part way through the PCB manufacturing process. Gold plating normally needs a nickel under plate or the Gold quickly disappears through migration effects into the underlying copper.

Immersion Silver plating

A ROHS-compliant board finish that is a cost effective alternative to Gold.

Chip On Board (COB)

Where the IC die is attached direct to a PCB, and bond out wires from the IC connect directly to PCB lands. The chip is then covered with a black blob of epoxy. A technique used mostly with very high volume, cost sensitive applications, e.g. musical greeting cards.

Phenolic PCB

As distinct from Fiberglass, Phenolic is a cheaper PCB laminate material.


A circuit board which can be connected to the another circuit.

 IC pin numbers

IC pins are numbered anti-clockwise around the IC starting near the notch or dot. The diagram shows the numbering for 8-pin and 14-pin ICs, but the principle is the same for all sizes.

Components without suitable leads-

Some components such as switches and variable resistors do not have suitable leads of their own so you must solder some on yourself. Use single-core plastic-coated wire of 0.6mm diameter (the standard size). Stranded wire is not suitable because it will crumple when pushed into a hole and it may damage the board if strands break off.

Building the example circuit:

Begin by carefully insert the 555 IC in the centre of the breadboard with its notch or dot to the left.

Then deal with each pin of the 555:

Monostable Circuit on Breadboard

1. Connect a wire (black) to 0V.

2. Connect the 10k resistor to +9V. 

Connect a push switch to 0V (you will need to solder leads onto the switch.

Connect the 470 resistor to a used block of 5 holes, then… Connect an LED (any color) from that block to 0V (short lead to 0V).

Connect a wire (red) to +9V.

Connect the 0.01µF capacitor to 0V. 

You will probably find that its leads are too short to connect directly, so put in a wire link to an unused block of holes and connect to that.

Connect the 100µF capacitor to 0V (+ lead to pin 6). Connect a wire (blue) to pin 7.

Connect 47k resistor to +9V. 

Check: there should be a wire already connected to pin 6.

Connect a wire (red) to +9V.


Check all the connections carefully.

Check that parts are the correct way round (LED and 100µF capacitor).

Check that no leads are touching unless they connect to the same block.

Connect the breadboard to a 9V supply and press the push switch to test the circuit.

If your circuit does not work disconnect (or switch off) the power supply and very carefully re-check every connection against the circuit diagram.




Simple BASIC code examples are provided within each subsection. The samples are not ‘complete’ programs but sections of code that can be included within a main program when using that particular component. When using these code samples it must be remembered that:

1. Each pin should be set up as an input or output before using the code (stamp users only).

2. If the hardware pins are changed from those given in the circuit diagrams it will be necessary to modify the pin numbers in the code.

3. Any let dirs = or let pins = commands will adjust all 8 pins, in the port.

4. Try to keep variables independent of each other. If a sub-procedure uses a variable, do not use the same variable anywhere else in the code. If the same variable must be used again, make sure there is no way it can clash with any other part of the code. This is the most common way of adding ‘hard-to-find’ bugs into software code.



Gas leakage detective system is a very important system for the safety point of view and it has a popular responsibility to care from any disaster caused by the gas leakage. It can be used anywhere in a process industries with little modifications in software coding according to the requirements. This concept not only ensures that our work will be usable in the future but also provides the flexibility to adapt and extend, as needs change.

In this project work we have studied and implemented a complete working model using a PIC microcontroller, MQ5 sensor. The programming and interfering of PIC microcontroller has been mastered during the implementation. This work includes the study of gas leakage detector system in many applications.


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