iann-urus / flag-torch

an arduino project to detect types of fires

flag-torch

an arduino project to detect types of fires

Components

Arduino Mega MQ-135 MQ-5 SHT3x RGB Led

Gases Detected

Sensor	Gases
MQ-135	Ammonia (NH3), nitrogen oxides (NOx), benzene, smoke, and CO2
MQ-5	LPG, Natural Gas, Coal Gas

Explanation

How the sensors work

Each sensor has a heated piece of tin dioxide doped with other stuff, depending on the sonsor. To detect the presence of a gas,the tin dioxide changes resistance as it reacts with the ambient gas. The heating coil is used to increase the process of the chemical reaction.

MQ-135 & MQ-5

After getting the analog reading from the ADC we need to convert the According to the datasheet each gas has a distinct power function.

Calibrating the sensors

To calibrate the sensor we need to find the ppm coefficients for each gas.

MQ-5

After plotting the points for the graph based on the datasheet , we use polynomial regression because it is a non-linear graph to estimate a line of best fit. The resulting equation we'll get we'll be in the form

y = ax + b where y = RO/RS and x = ppm

Hence RO/RS = a*ppm + b