Electronics

MQ 135 Gas Sensor Module for Benzene, Alcohol

AED 19.95

1

Description

Step into the world of MQ-135 Gas sensors, your trusty companion in monitoring and improving air quality. These sensors are specially designed to detect a wide range of gases, including NH3, NOx, alcohol, benzene, smoke, and CO2. It comes equipped with an Analog pin for the microcontroller and a Digital Pin with a pot, allowing the sensor to operate independently without the need for a microcontroller. the MQ-135 Gas sensor combines sensitivity, versatility, and ease of use, making it an ideal choice for detecting and measuring a wide range of gases in various applications.

 

Package Includes:

  • 1x MQ-135 Gas Sensors Module

 

Features:

  • Good sensitivity to combustible gases in a wide range: The sensor is highly sensitive to a variety of combustible gases, allowing for effective detection and measurement.
  • Fast response time: The MQ-135 sensor quickly responds to changes in gas concentrations, providing real-time data for prompt analysis.
  • Easy positioning with four screw holes: The sensor module is designed with four screw holes, making it convenient to position and mount in various applications.
  • Long life and low cost: The sensor offers a long lifespan, ensuring durability and reliability while maintaining an affordable price point.
  • Simple drive circuit: The sensor's drive circuit is straightforward, making it easy to connect and integrate into your projects.
  • Wide detecting scope: It can detect and measure a wide range of gases, including NH3, NOx, alcohol, benzene, smoke, CO2, and more.
  • Operating voltage: The sensor operates at +5V, ensuring compatibility with common power supplies.
  • Analog and digital outputs: The sensor provides both analog output voltage (ranging from 0V to 5V) and digital output voltage (0V or 5V, TTL Logic), offering flexibility in data acquisition.
  • Preheat duration: The sensor requires a preheat duration of 20 seconds before it stabilizes and provides accurate readings.
  • Digital or analog sensor functionality: The MQ-135 sensor can be used as either a digital or analog sensor, depending on the specific requirements of your project.
  • Adjustable sensitivity: The sensitivity of the digital pin can be easily varied using the potentiometer, allowing for customization and fine-tuning based on your specific needs.

 

Description:

The MQ-135 Gas sensor is an indispensable component in air quality control devices, specifically designed to detect and measure a range of gases including NH3, NOx, alcohol, benzene, smoke, and CO2. Whether you are concerned about indoor air quality, industrial emissions, or environmental monitoring, the MQ-135 sensor is a reliable choice. One of the notable features of the MQ-135 sensor module is its Digital Pin, which allows it to operate independently without the need for an additional microcontroller (MCU). This means you can use the sensor as a standalone device, simplifying the setup process. To monitor the concentration of gases accurately, the MQ-135 sensor employs an analog pin. This pin enables the measurement of gases in parts per million (PPM), providing precise data on air quality. The analog pin is compatible with most common MCUs as it operates on a 5V TTL logic, ensuring seamless integration with your existing systems. If you are looking for a versatile gas sensor that covers typical air quality gases like CO2, smoke, NH3, NOx, alcohol, or benzene, the MQ-135 sensor is an excellent option. Its reliable detection capabilities, coupled with easy integration and accurate measurement, make it a valuable tool for various applications, from home air quality monitoring to industrial emission control. With the MQ-135 sensor, you can take proactive steps toward ensuring a healthier and safer environment.

 

Principle of Work:

  1. Sensing Material: The core of the MQ-135 sensor is the sensing material, usually composed of tin dioxide (SnO2) or other metal oxide semiconductors. This material is highly sensitive to certain gases, such as NH3, NOx, alcohol, benzene, smoke, and CO2.
  2. Heater Element: The sensor includes a built-in heater element. When power is supplied to the sensor, the heater element warms up the sensing material to an elevated temperature. This preheating process is essential for the sensor to reach its optimal operating condition.
  3. Gas Absorption: When the sensing material is at an elevated temperature, it becomes more reactive to the gases in the air. When the target gases come into contact with the sensing material, they get adsorbed or absorbed onto the surface of the semiconductor. This process changes the electrical conductivity of the sensing material.
  4. Conductivity Changes: The adsorption of gas molecules on the surface of the semiconductor changes its electrical resistance. Different gases have varying levels of impact on the electrical conductivity of the sensing material.
  5. Output Signal: The change in electrical resistance due to the gas absorption alters the sensor's output voltage. This output voltage can be measured using either an analog or a digital pin, depending on the configuration and setup.
  6. Calibration: To ensure accurate gas detection, the sensor often requires calibration. Calibration involves exposing the sensor to known concentrations of the target gas and adjusting its sensitivity accordingly.
  7. Data Interpretation: The output voltage from the sensor can be correlated to the concentration of the target gas present in the air. By analyzing the output data, it becomes possible to determine the gas concentration within the sensor's detection range.
  8. Response Time: The response time of the sensor, i.e., how quickly it reacts to changes in gas concentrations, depends on factors such as the heating element's power, the sensitivity of the sensing material, and the surrounding environmental conditions.

This what is happening internally in the sensor and as a module :

  • When you provide 5V power to the sensor module, you will notice that the power LED on the module illuminates. However, in the absence of any detected gas, the output LED will remain off, indicating that the digital output pin will be at a voltage level of 0V.
  • Before using the sensor, it is important to allow it to preheat for a certain duration. This preheating process ensures optimal performance and accuracy. Once the sensor is adequately preheated, it can effectively detect gases.
  • If, after exposing the sensor to the gas you wish to detect, the output LED does not become high, along with the digital pin, you can adjust the potentiometer. By adjusting the potentiometer, you can fine-tune the sensitivity of the sensor until the output LED responds accordingly.
  • Once properly calibrated, the digital pin will go high, reaching a voltage level of 5V when the sensor is exposed to the target gas at the specific concentration set during calibration. On the other hand, if the concentration of the gas is below the set threshold, the digital pin will remain low, at a voltage level of 0V.
  • Alternatively, the analog pin can also be used to achieve the same objective. By connecting the sensor to a microcontroller, you can read the analog values, which range from 0V to 5V. The analog value obtained is directly proportional to the amount of gas detected by the sensor.
  • By manipulating the settings and adjusting the sensitivity, you can observe and analyze how the sensor responds to various concentrations of gases. This flexibility allows you to fine-tune your program accordingly, ensuring accurate and reliable gas detection.

 

Pinout of the Sensor:

Pin No:

Pin Name:

Description:

1

Vcc

This pin powers the module, typically the operating voltage is +5V

2

Ground

Used to connect the module to system ground

3

Digital Out

You can also use this sensor to get digital output from this pin, by setting a threshold value using the potentiometer

4

Analog Out

This pin outputs 0-5V analog voltage based on the intensity of the gas 

 

Applications:

  1. Air Quality Monitoring: The MQ-135 sensor module is extensively used in air quality control devices, allowing for the detection and monitoring of gases like NH3, NOx, alcohol, benzene, smoke, and CO2. It is employed in indoor air quality monitors, outdoor pollution measurement systems, and HVAC systems to ensure healthy and safe air environments.
  2. Industrial Emission Control: Industries often use the MQ-135 sensor module to monitor and control emissions of harmful gases. It aids in maintaining compliance with environmental regulations and ensures a safer working environment for employees. The module is employed in factories, power plants, chemical plants, and refineries to detect and measure gases emitted during production processes.
  3. Safety and Fire Detection: The module is utilized in fire detection systems to sense the presence of smoke and other combustible gases, alerting occupants of potential fire hazards. It is also employed in gas leak detection systems, providing an early warning for gas leaks to prevent accidents and ensure workplace safety.
  4. Environmental Monitoring: The MQ-135 sensor module plays a vital role in environmental monitoring programs. It helps assess air pollution levels, detect the presence of harmful gases in natural ecosystems, and study the impact of human activities on the environment. Environmental agencies, research institutions, and environmentalists employ the module for such purposes.
  5. Automotive Applications: The MQ-135 sensor module is utilized in automotive applications, particularly in vehicles equipped with air quality monitoring systems. It helps monitor the cabin air quality, detect harmful gases, and activate ventilation systems to ensure a healthy and comfortable driving environment.
  6. Gas Leakage Alarms: The module is integrated into gas leakage alarm systems to detect and alert users about the presence of dangerous gases, such as LPG (liquefied petroleum gas), methane, or carbon monoxide. These systems are commonly installed in homes, hotels, and commercial buildings to enhance safety.
  7. Research and Development: Researchers and developers utilize the MQ-135 sensor module in prototyping and experimenting with gas detection and measurement projects. Its versatility and affordability make it a popular choice for academic and DIY projects exploring air quality monitoring, gas sensing technologies, and environmental research.

 

Circuit:

  • Connection with Arduino: The MQ135 sensor can be easily connected to an Arduino board for data acquisition and analysis.
  • GND Pin: The GND pin of the MQ135 sensor should be connected to the GND pin of the Arduino. This establishes a common ground reference for proper signal communication.
  • VCC Pin: The VCC pin of the MQ135 sensor needs to be connected to the +5V power source pin on the Arduino board. This provides the necessary power supply for the sensor to operate.
  • Aout Pin: The Aout pin of the MQ135 sensor should be connected to one of the analog input pins of the Arduino, such as A0. This enables the Arduino to read the analog output voltage from the sensor, which corresponds to the gas concentration being measured.

Note:

  • Normal air returns approximately 100-150
  • Alcohol returns approximately 700
  • Lighter gas returns approximately 750

 

Library:

This Module doesn't need any Library to function.

 

Code:

#define MQ135pin 0
float sensorValue; //variable to store sensor value
void setup() {
 pinMode(13,1);
 Serial.begin(9600); // sets the serial port to 9600
 Serial.println(" MQ135 warming up!");
 delay(20000); // allow the MQ135 to warm up
}
void loop() {
 sensorValue = analogRead( MQ135pin); // read analog input pin 0
 Serial.print("Sensor Value: ");
 Serial.println(sensorValue);
 if(sensorValue > 700){
 digitalWrite(13,1);
 }else{
 digitalWrite(13,0);
 }
 delay(2000); // wait 2s for next reading
}

 

  • The #define MQ135pin 0 line defines a constant MQ135pin with the value 0, representing the analog input pin connected to the MQ135 sensor.
  • The float sensorValue variable is declared to store the sensor reading.
  • In the setup() function:
    • pinMode(13, OUTPUT) sets pin 13 as an output, which can be used to control an LED.
    • Serial.begin(9600) initializes the serial communication at a baud rate of 9600.
    • Serial.println("MQ135 warming up!") displays a message on the serial monitor.
    • delay(20000) waits for 20 seconds to allow the MQ135 sensor to warm up.
  • In the loop() function:
    • sensorValue = analogRead(MQ135pin) reads the analog input pin 0 and stores the value in the sensorValue variable.
    • Serial.print() and Serial.println() are used to display the sensor value on the serial monitor for monitoring purposes.
    • The if statement checks if the sensorValue is greater than 700. If true, it turns on the LED connected to pin 13 using digitalWrite(13, HIGH). Otherwise, it turns off the LED using digitalWrite(13, LOW).
    • delay(2000) adds a 2-second delay before the next reading to allow for proper sensor stabilization.

 

Technical Details:

  • Input Voltage: 5V
  • Resolution: 10 ~ 1000ppm
  • Sensitive resistance: 2kΩ to 20kΩ in 100ppm CO
  • Accuracy: ≥ 3%
  • Reaction time: ≤ 1s
  • AN response time after switching on: ≤ the 30s
  • Heating current: ≤ 180mA
  • Heating voltage: 5.0V ± 0.2V / 1.5 ± 0.1V
  • Sensitive to CO2, Smoke, NH3, NOx, Alcohol, and Benzene.
  • Analog Output: 0 ~ 5V
  • Detectable Concentration: 10ppm ~ 1,000ppm
  • Operating Temperature: -10°C to 50°C
  • Dimensions of the module: 40mm x 21mm

 

Resources:

Datasheet of the MQ135

 

Comparisons:

Both the MQ135 and MQ3 modules are gas sensors used for air quality monitoring, they have different target gases and specific applications. The MQ135 is suitable for detecting multiple gases, including NH3, NOx, alcohol, benzene, smoke, and CO2, while the MQ3 is specialized for alcohol vapor detection. Consider the specific requirements of your project or application to choose the appropriate sensor module:

  1. Target Gases:

    • MQ135: The MQ135 module is designed to detect gases such as NH3, NOx, alcohol, benzene, smoke, and CO2.
    • MQ3: The MQ3 module is specifically designed for detecting alcohol vapor in the air.
  2. Sensitivity:

    • MQ135: The MQ135 module has good sensitivity to a wide range of combustible gases.
    • MQ3: The MQ3 module has high sensitivity specifically to alcohol vapors.
  3. Operating Voltage:

    • MQ135: The MQ135 module operates at a voltage of +5V.
    • MQ3: The MQ3 module also operates at a voltage of +5V.
  4. Analog Output:

    • MQ135: The MQ135 module provides an analog output voltage (0V to 5V) that can be used to measure the gas concentration.
    • MQ3: The MQ3 module also provides an analog output voltage (0V to 5V) proportional to the alcohol concentration.
  5. Digital Output:

    • MQ135: The MQ135 module does not have a built-in digital output pin. It requires external circuitry or an MCU to convert the analog output to a digital signal.
    • MQ3: The MQ3 module does not have a built-in digital output pin either. It requires external circuitry or an MCU for digital signal conversion.
  6. Applications:

    • MQ135: The MQ135 module is widely used in air quality control devices, industrial emission control systems, safety and fire detection systems, environmental monitoring, automotive applications, and research projects.
    • MQ3: The MQ3 module is primarily used in breathalyzer devices, alcohol detection systems, and research projects focused on alcohol vapor detection.