Carbon monoxide gas is a very dangerous, harmful, and toxic gas for the normal environment. Since the gas has no color and is odorless, so it cannot be smelt or seen. So, if there is carbon monoxide gas in the surroundings, the person really would get no idea that they are breathing in CO until he/she feels not safe. So, it is necessary to have detected that toxic gas. Hence, there is an MQ7 gas detector sensor that can detect this harmful gas. Below is the complete description of this sensor.
An Overview about MQ7 Sensor
MQ7 sensor has an acute sensitivity to Carbon Monoxide and can detect the concentration of carbon monoxide in the surroundings. MQ7 sensor has a small heater inside with an electrochemical sensor to measure different kinds of gas combinations. Thus, it can be calibrated. We can use the gas sensor module at room temperature.
Internal structure
The MQ7 alcohol sensor comprises a tin dioxide (SnO2), a perspective layer inside aluminum oxide micro-tubes (measuring electrodes), and a heating element inside a tubular casing. There is an enclosed stainless steel net at the end face of the sensor and the backside holds the connection terminals.
Working Principle
The ability of an MQ7 Gas sensor depends on the chemiresister. The chemiresistor is Tin Dioxide (SnO2) which that has free electrons (donors). The oxygen molecules attract the free electrons present in a tin dioxide that pushes them to the surface of the tin dioxide. When there are no free electrons available output current would be zero. The oxygen molecules attract the free electrons inside the tin dioxide (SnO2) and prevent it from having free electrons to conduct current.
Features and Specifications of MQ7 Sensor
There are many prominent features and specification of MQ7 which makes it more extraordinary
Features
- The analog output voltage, the higher the concentration the higher the voltage.
- The carbon monoxide detection with better sensitivity.
- With a long service life and reliable stability.
- Rapid response and recovery characteristics
Specifications
- Temperature: 20°C ± 2°C
- Humidity: 65% ± 5% RH
- Standard Test Circuit: Vc: 5.0V ± 0.1V; Vh(high):5.0V±0.1V
- Vh(low): 1.5V±0.1V
Pinout of MQ7
| Pin Number | Pin Name | Description |
| 1 | Vcc | The [in is there to power the module, requires 5V |
| 2 | Ground | To connect the module to the system’s common ground |
| 3 | Digital Out | Digital output pin, the Threshold value can be set by using the potentiometer |
| 4 | Analog Out | Analog output pin. Analog voltage based on the concentration of the gas |
Applications of MQ7 Sensor
Industrial CO Detector
With just some easy components and some primary assembly work, one can have a basic industrial carbon monoxide detector that uses MQ7, running. You can also test it around in the neighborhood, in your street, area, or anywhere else where you would like to estimate the carbon monoxide levels.
Gas Leakage Detector
The goal of detecting a CO gas leak in industries is to prevent the worst potential causes of the gas leak, using the above type of MQ sensor. The choice of the MQ7 sensor is because of MQ4 which is suitable for detecting Carbon Monoxide gas.
