WIRELESS AUTO POWER TRIP DURING GAS LEAKAGE
ABSTRACT
It’s a known fact that LPG leakage during domestic usage is a disaster, especially
when we switch on any electric switch or appliances because it may produce a
spark which causes sudden loud explosion of the gas filled room. In our nation
there is an increase in such accidents and casualties related to it in the
recent times. Our main idea is to implement security system for detecting
leakage of gas in closed environment using sensors. Once the gas leakage is
detected depending on the level of gas immediately the wireless systems will
trip of the power supply so as to avoid explosion.
Keywords:
LPG leakage, Gas sensors, Wireless systems.
INTRODUCTION
LPG is indispensible part of our life as it is an important source of fuel
for cooking and also used in automobiles as an alternative to petrol and
diesel. Although it is a clean fuel it poses a threat as it is highly
combustible. As the LPG’s are available either in pressurized cylinders or as
in pipeline supply there is high chance of leakage. So if leakage occurs there
is a high chance of an explosion even when any electrical sparks occurs which
may result in causalities and loss of property.
As more and more households have started using LPG there is an increase in
the number of accidents being reported owing to gas leakage. So our work aims
at reducing accidents related to gas leakage in household as well as in
industries.
Wireless technology been adapted gives the module more
mobility and reliability.
IMPLEMENTATION
The proposed wireless gas leakage system is composed of two major modules:
the gas leakage detection and transmission module, and the receiver module. The
gas leakage detection and transmission module detects the change in
concentration of LPG and natural gas and activates an audiovisual alarm when it
exceeds a certain threshold.
Furthermore, it sends another alarm message through a radiofrequency (RF)
system to the receiver module. The receiver module is a mobile unit that could
be placed anywhere within the premises of the house so that the alarm can be
detected and heard at a distance from the place of gas leakage. A block diagram
for the proposed system is shown in Figure 1.
TRANSMITTER MODULE:
RECEIVER MODULE:
Figure 1: Block diagram for the gas leakage detection and
power trip system.
GAS LEAKAGE DETECTION- TRANSMISSION MODULE
The main functions of this module are to detect changes in gas
concentration, and transmit a signal to the receiver unit. Transmitting
Consists of a gas detection sensor, a sensing circuit, a microcontroller, and
an RF transmission system. The gas detection is done using a solid state gas
sensor that is sensitive to LPG, natural gas and other gases such as CO and H2
but not sensitive to air; therefore the reading is not affected by the presence
of air. The sensing part is made from Tin Dioxide (SnO2) layer, which is a resistive
element with a resistance (Rs) that changes with the change of
concentration of gases like LPG, CH4, CO, and alcohol. Figure 2 shows MQ-6 gas
sensor and the sensitivity characteristics. The sensor can detect small
concentrations of the above mentioned gases as small as 0.1 mg/L, which makes
it suitable for gas leak detection.
It is worth mentioning that the sensor is also sensitive to room
temperature and humidity. The driving circuit of the gas sensor, requires a DC
power supply of 5 Volts and a load resistance (RL). The sensor needs to
be heated to function properly, which is done through a heating element of a
fixed resistance (RH). This means that the sensor should be switched on
for a specific period of time before measurements are made.
The heating power supply is done through the same power supply of the
sensing circuit.
The output voltage Vo from the sensing circuit is given by:
Figure 2: MQ-6 gas
sensor and its sensitivity characteristics.
And is fed into a microcontroller where it is digitized .The
microcontroller reads the voltage from the sensor and uses it to calculate
change in concentration. Under normal conditions, the microcontroller starts
with a calibration stage where it reads the sensor voltage under normal
conditions and considers it as the zero value. The microcontroller continuously
reads the voltage from the sensor and compares the reading with the calibration
value. If the reading of the sensor voltage exceeds the predetermined threshold,
the microcontroller sends a message to the receiver module. This is done by the
microcontroller by sending out a USART encoded packet through I/O port into the
input pin of the RF transmitting module. The RF transmitting module is a low
power frequency modulation (FM) one way link that can reach a distance up to
200 m outdoor and approximately 30 m indoor.
GAS LEAKAGE DETECTION- RECEIVING MODULE
The receiver module is a mobile unit that receives state events from the
gas detection and transmitting module. It consists of an RF receiver and a
microcontroller (PIC-16F877A Or INTEL 8051). After receiving the data from the
transmitter, the RF receiver sends it to the microcontroller. The microcontroller
reads the data, decodes it, and displays it onto the output devices (LED,
buzzer, and LCD display). Apart from indication relay switch is used to trip
the power supply off which will prevent electrical sparks.
RESULTS
The wireless gas sensing and power trip system was implemented and its
working depends on the distance of receiver and the concentration of the gas
present in the air.
Furthermore the system has a calibrated threshold concentration value so
when again the concentration drops below the threshold value automatically the
power trip will be reversed and the alarm will go off.
CONCLUSION
This works represents a prototype for wireless gas leakage systems that can
be used mainly in household safety and many other applications in the industry
and environment. For example it can be used in facilities where gas cylinders
are stored. Any leakage can be recognized through the receiver module. The use
of a sensor that is sensitive to small changes of concentration provides an
excellent tool to detect a gas leak as it can detect small concentrations down
to 100 ppm. The sensitivity of the entire system can be adjusted by changing
the load resistor of the sensor which provides the flexibility to externally
calibrate. Measuring the actual concentration of a certain gas cannot be easily
done with this sensor, since it can detect many gases at the same time and has
a non-linear sensitivity curve. Further improvement can be introduced to the
system by including a temperature measurement system to be used for temperature
compensation, which can be done through the microcontroller to reduce the
number of false positives and false negatives. We can also implement silicon
control rectifier (SCR) instead of a electromagnetic relay coil for power trip which
will be more effective and further reduce sparks while tripping power.
REFERENCES
[1] Luay Fraiwan, Khaldon Lweesy, Aya Bani-Salma, Nour Mani, Jordan University
of Science & Technology.
[2] http://www.hwsensor.com.
[3] D. S. Lee, D. D. Lee, S. W. Ban, M. Lee, and Y. T. Kim, "SnO2 gas
sensing array for combustible and explosive gas leakage recognition.
[4] http://www.ni.com/wsn/
[5] indane.co.in/
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