So, If we select the deep blue curve which is the LPG curve, the starting of the curve in X and Y coordinate is the 200 and 2. The first two data points are the starting of the LPG curve, in X and Y coordinates. The formula is to have 3 different data points. So, we need to plot this graph into our firmware similar to what we did in our Arduino Gas detector Project. Also, the resistance will change whenever the LPG gas is detected by the MQ6 sensor. Therefore, the MQ6 sensor will provide a particular resistance during the clean air condition where the LPG gas is unavailable. The MQ6 sensor is used to detect LPG gas concentration. The below logarithmic graph taken from the datasheet provides an overview of the gas concentration with the sense resistance of the MQ6 sensor. The RS is the sense resistance during the presence of a particular gas whereas the RO is the sense resistance in clean air without any particular gas.

The graph provides an overview of the gas concentration with the ratio of RS and RO. To measure the gas concentration in PPM all MQ sensors provide a logarithmic graph which is very important.

Depending on the concentration of the gas, the sensing resistance gets changed and by detecting the changing resistance, the gas concentration can be measured. The RL resistor is the right resistor of the DOUT LED.Įach MQ series sensor has a heating element and a sensing resistance. The pot is used to adjust the sensitivity.

Pin 1 is VCC, Pin 2 is the GND, Pin 3 is the Digital out (Logic low when gas is detected.) and Pin 4 is the Analog output. However, the left image is a module-based MQ6 sensor for interfacing with the microcontroller unit, the pin diagram of the module is also shown in that image. The below image shows the MQ6 sensor pin diagram. Sensorīenzene, Toluene, Alcohol, Acetone, Propane, Formaldehyde gas, Hydrogen However, by using the same hardware and firmware other MQ series sensors can also be used without major modification in the code and hardware part. For the sake of this article, we will be using the MQ6 Gas sensor with PIC that can be used to detect the LPG gas presence and concentration. In this article, we will learn how to use these gas sensors with PIC Microcontrollers, to measure the PPM value of the gas and display it on a 16x2 LCD.Īs mentioned earlier, there are different kinds of MQ series sensors available in the market and each sensor can measure different types of gases as shown in the table below. We have already used these MQ gas sensors with Arduino to measure some harmful gases like Ammonia. These sensors are widely used in all Gas related devices like from simple Smoke Detectors to Industrial Air Quality Monitors. MQ series Gas sensors are very common types of sensors used in Gas Detectors to detect or measure certain types of Gases.

How to calculate ppm from mq4