We used LPG(LIQUEFIED PETROLEUM
GAS) sensor that is MQ2 that is SnO2 based gas sensor for this prototype, the
circuit indicates LPG level in the pipeline.
Figure 15
The resistance of the sensor is
different depending on the type of the gas. The MQ2 sensor gas a built in
potentiometer that allows to adjust the sensor sensitivity according to how
accurate what want to detect gas.
Implementation
Sensor
Selection
When determining the distance
between two objects, there are a variety of sensors to choose from. The voltage
that the sensor outputs changes accordingly to the gas level that enter in the
pipeline. The sensor outputs a voltage that is proportional to the
concentration of gas. In other words, the relationship between voltage and gas
concentration is the greater the gas concentration, the greater the output
voltage and the lower the gas concentration, the lower the output voltage. In this case however, the gas which can be implemented by using an LPG
sensor. In this instance, the microcontroller being used is an Arduino UNO.
The output can be analog signal
(A0) that can be read with an analog input of the Arduino or a digital output
(DO) that can be read with a digital input of the Arduino Uno.
Figure 16
Technical
Specifications
this flammable gas sensor detects the concentrations of
combustible gas in the pipeline and outputs its reading as an analog voltage.
The sensor can measure concentration of flammable gas of 300 to 10,000 ppm. The
sensor can operate at level gas and consumes less than 150mA at 5V.
Figure 17
Installation
There are two different ways to connect a MQ2 LPG sensor to an
Arduino UNO microcontroller. Both will work for all applications, it is up to
the user to decide which one to use depending on how the sensors and other
devices will be used together.
Mode1
The first way is known as Mode 1, and the connection pins are
shown below in Figure , and should be connected to the Arduino Uno
microcontroller accordingly. In this mode, the trigger and echo pins are
separate, and will take up 2 I/O pins on the Arduino Uno microcontroller. This
is correct, but availability issues may arise when the sensors are used
together. In this mode, the sensors could be implemented on the Arduino Uno
micontroller. When the sensor is connected correctly, a red LED will flash to
indicate that the wire connections are correct.
Figure 18
Mode 2
Mode 2 is different from Mode 1 in that it combines the
trigger and echo pins. The LPG gas detector that turns on an LED when flammable
concentration exceed a certain level. Along with a sensitivity resistor and a 3
pin header. The carrier board pins are VCC(+5V), GND, and out, which connects
to A0 on an Arduino Uno microcontroller. Then, connect a LED to Pin 13 and Gnd as indication of LPG detected.
Figure 19
Programming
Programming the Arduino Uno
microcontroller is the most important aspect of this process. Without the
correct code, the sensors will not work. The Arduino Programming language is
based on C/C++. The first step is to download the Arduino software that will
allow for communication between the computer and microcontroller. The MQ2 LPG
sensor is considered to be a flammable sensor, and the Arduino software actually
has a demo program that can be altered to implement multiple sensors.
