GAS SENSOR

Hello geeks in this article I am going to share information about the various gas sensor and also their working principle. There are very interesting phenomena in the working of gas sensor I will share that information with some illustrations in this article.

First of all, we get a doubt about what is a gas sensor, why we need it?

What is the working principle behind it?

 What are the different gas sensor and where do we use them?

 Don’t worry, I am going to answer all these questions in this article.

 Our first question is very simple to answer a gas sensor is a device that senses the gas around it and gives us the output either in a digital signal for continuous-discrete values as an analog signal.

When when we come to the next question of why we need it then the reason is to identify the gas leakage in the home, industries, hotels and they are also used for detecting the alcoholic people. It is used to detect flammable,  toxic gases in petroleum and some other industries. They are also needed in mining areas.

External appearance

A typical gas sensor consists of a semiconductor material enclosed in a mesh-like material to prevent the contact of unwanted dust particles with the sensitive semiconductor material as shown in the below figure.

It consists of six pins they are namely two H pins in the middle and the remaining are pair of A pins on either side and likewise two B pins as shown in the below figure.

2,5 are H pins

1,3 are A pins

6,4 are B pins

Now when we come to the pins connected to the module there are four pins and namely, they are

1. Vcc

2. Digital signal pin.

3. Analog signal pin.

4. Ground pin.

Working principle :

A simple gas sensor is made up of very sensitive semiconductor material and it is SnO2. The conductivity of this material changes the concentration of the gas present around it. Higher the gas content present, the higher is the conductivity of that material. the circuit diagram is very simple to understand and it is like below

Voltage is applied to the heater that initiates the semiconductor to work when the voltage across the A and B pins vary according to the gas content due it’s conductivity and it is treated as an output signal.

For the better performance, two pairs of A and B pins are used and these pins are interchangeable as the material is simply resistor and it is a bilateral element.

Voltage fluctuations at A and B pins act as a signal data line to the microprocessor and help us to draw the outputs.

 That is the simple principle behind the working of the gas sensor.

Now I will discuss the various gas sensors. There are many gas sensors in the MQ series with names MQxx starting from 2 to 10 and each has its significant use and purpose

MQ-2 is for detecting General combustible gas

MQ-3 is for detecting the Alcohol.

MQ-4 is for detecting Natural gas, Methane

MQ-5 is for detecting LPG, Natural gas, Coal gas

MQ-6  is for detecting LPG, Propane

MQ-7 is for detecting Carbon Monoxide

MQ135 is for detecting Air Quality Control

 

Still, there are many more models present in the market. I think with this article you could understand the principle behind the working of a gas sensor and basics of it. For any queries, the comment box below is always open for you. I will be back with new interesting information once again.

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