PRESENTATION

Submitted By:-

SANCHIT BATRA

08502944

SANCHIT GARG 08502947

The ‘Combustible Gas Detector’ with the help of ‘MQ2 Gas Sensor’ is

successfully detecting the presence of Liquefied Petroleum Gas (LPG)

gas. MQ2 gas sensor was used to detect LPG at room temperature as

well as ±100 C of room temperature and the output voltage was noted.

The project, detects the gas, identifies if it is more than the required

amount or not and if it is so then it raises an alarm and a red LED

blinks.

BEFORE T2:

Choosing a suitable sensor, procurement of various measuring instruments

and then assembling the test circuit. Test is to be performed on sensor for

LPG at room conditions.

 

AFTER T2:

To make an interface with the sensor, so that the sensor could be practically

used to detect LPG.

The interface is designed in such a way that it alerts the user if the intensity

of gas increases by a certain amount.

The MQ-2 gas sensor is sensitive to LPG, alcohol, etc. The resistance of the

sensitive component changes as the concentration of the target gas changes.

Sensitive material of MQ-2 gas sensor is SnO2, which with lower

conductivity in clean air. When the target combustible gas exist, the

sensor’s conductivity is more high along with the gas concentration rising

that changes the conductivity to correspond output signal of gas

concentration. It can work from -20oC to 50oC at relative humidity of less

than 95%.

TEMPERATURE CONCENTRATION OF GAS OUTPUT VOLTAGE

34 C LOW 0.61 v

34 C HIGH 3.20 v

26 C LOW 0.70 v

26 C HIGH 3.01 v

14 C LOW 0.63 v

14 C HIGH 2.82 v

DOMESTIC GAS LEAK DETECTOR

The MQ2 gas sensor senses the gas and its output is send to the comparator

and the decision is taken. If gas is leaking then logic one is send to the

microcontroller and then red led blinks and a buzzer is sounded. If gas is

not leaking then green led glows. There is a LCD screen that displays the

condition of the room.

MICROCONTROLLER

REGULATED POWER SUPPLY LCD DISPLAY (OUTPUT)

MQ 2 GAS SENSOR (INPUT) BUZZER (OUTPUT)

COMPARATOR

The low-power Atmel 8-bit AVR RISC-based microcontroller

combines 8KB of programmable flash memory, 1KB of SRAM,

512K EEPROM, and a 6 or 8 channel 10-bit A/D converter. The

device supports throughput of 16 MIPS at 16 MHz and operates

between 2.7-5.5 volts. It has 23 programmable input-output lines.

The LM358 series consists of two independent, high

gain, internally frequency compensated operational

amplifiers which were designed specifically to operate

from a single power supply over a wide range of

voltages. Operation from split power supplies is also

possible and the low power supply current drain is

independent of the magnitude of the power supply

voltage.

We are using LM 358 as comparator to compare the sensor’s output with reference output.

 2) PORTABLE GAS DETECTOR

i) Confined Space Entry: The instrument can be used to check the

level of gas in sewers, tanks and other vessels before entering:

• Public utilities - especially water and telecoms

• Chemical and petrochemical - for entry into vessels

• Cabling contractors

• Piling contractors

• Tunneling contractors

• Civil engineers

• Landfill operators

1. The project can be combined with GSM based module to SMS the

user of a potential gas leak as well as gas leak in actual.

2. A robotic arm can also be joined to microcontroller to automatically

close the gas cylinder.

3. The project can be made for other application of gas sensor as well.

4. The sensor can be tested for smoke and can also be used as a smoke

detector and fire fighting equipment.

1. Gas sensors: principles, operation, and development by Giorgio Sberveglieri.

2. Evaluation and applications of gas sensors by Hung Viet Cao, The University

of Texas at Arlington. Electrical Engineering

3. Solid State Gas Sensing by Elisabetta Comini, Guido Faglia, Giorgio

Sberveglieri.

4.  8051 microcontrollers: an applications-based introduction by D. M. Calcutt,

Frederick J. Cowan, G. Hassan Parchizadeh.