01-03-2011, 04:39 PM
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1.1 INTRODUCTION
This project is microcontroller based project. A Gas sensor is used to Detect dangerous gas leaks in the kitchen or near the gas heater. This unit detects 300 to 5000ppm of Natural Gas. Ideal to detect dangerous gas leaks in the kitchen. Sensor can be easily configured as an alarm unit. The sensor can also sense LPG and Coal Gas. Ideal sensor for use to detect the presence of a dangerous LPG leak in your car or in a service station, storage tank environment. This unit can be easily incorporated into an alarm unit, to sound an alarm or give a visual indication of the LPG concentration. The sensor has excellent sensitivity combined with a quick response time. detected is messaged to the authorized person using cellular network called GSM.
In this project there are mainly two units, GSM modem and microcontroller unit.GSM modem can be configured by standard GSM AT command set for sending and receiving SMS and getting modem status. Depending upon the Gas sensor output microcontroller can send message to the authorized person and also depending upon the message received the microcontroller unit will control the devices and acknowledges the device status to the user as SMS.
1.2. SOFTWARE & HARDWARE REQUIREMENTS
a) SOFTWARE REQUIREMENTS
Keil software programming using assembly language
Flash magic
b) HARDWARE REQUIREMENTS
Gas sensor
Microcontroller
LCD display
GSM
MAX 232
GAS SENSOR
2.1. GAS SENSOR:
A NATURAL GAS SENSOR is an electronic device which Detect dangerous gas leaks in the kitchen or near the gas heater. This unit detects 300 to 5000ppm of Natural Gas. Ideal to detect dangerous gas leaks in the kitchen. Sensor can be easily configured as an alarm unit. The sensor can also sense LPG and Coal Gas.
A LPG SENSOR Ideal sensor for use to detect the presence of a dangerous LPG leak in your car or in a service station, storage tank environment. This unit can be easily incorporated into an alarm unit, to sound an alarm or give a visual indication of the LPG concentration. The sensor has excellent sensitivity combined with a quick response time. The sensor can also sense iso-butane, propane, LNG and cigarette smoke.
FEATURES:
• High sensitivity to LPG, iso-butane, propane
• Small sensitivity to alcohol, smoke.
• Fast response .
. Stable and long life
• Simple drive circuit
2.2 NATURAL/LPG GAS SENSOR:
STRUCTURE AND CONFIGURATION:
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-5 have 6 pin ,4 of them are used to fetch signals, and other 2 are used for providing heating current.
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. The gas sensor gives 12v to 16 v output when triggered and this output voltage is given to the microcontroller using NPN transistor BC547.The gas sensor output is taken across he HS1527 OTP Encoder, HS1527 It can reduce any code collision and unauthorized code scanning possibilities.
Natural gas is an energy source that is commonly used in homes for cooking, heating, and Water heating. It is primarily composed of methane. (Methane is a highly flammable chemical compound consisting of one carbon atom surrounded by four hydrogen atoms.) Although it only happens rarely, a natural gas leak can sometimes occur inside the home. A natural gas leak can be dangerous because it increases the risk of fire or explosion. Your local gas company works hard to provide adequate warning in the event of a gas leak. Because methane—and therefore, natural gas—does not have any odor, the gas company adds a warni“rottenegg” smell (mercaptan or a similar sulfur-based compound) that can be easily detected by most people. However, people who have a diminished sense of smell may not be able to rely upon this safety mechanism. If you have a concern about your ability to smell the additive that signals a gas leak, you need to see a physician and use a different safety signal. A gas detector can be an important tool to help protect you and your family.
PRECAUTIONS TO BE TAKEN WHEN GAS LEAKAGE
DETECTED:
What to do if your gas detector alerts you to a natural gas leak
1. Leave the house immediately.
2. DO NOT make calls from your home. Phones are capable of producing a spark, which could start a fire or explosion. Contact your local gas utility company or call 911 from a phone outside and away from your home.
3. DO NOT light a match or other combustible material. Likewise, DO NOT turn any light switches on or off, and DO NOT plug or unplug electrical appliances such as a television or vacuum cleaner. These activities also can produce a spark that could start a fire or explosion.
4. Do not re-enter the house until the gas company finds the source of the leak and corrects it.
2.3 SOURCES OF NATURAL GAS SENSORS:
1. Leaks from gas appliances, heating systems, and water heaters
2. Leaks from interior natural gas piping systems
3. Migration of natural gas indoors from leaks in outdoor piping systems
