How to Use MQ-4 SENSOR METHANE: Examples, Pinouts, and Specs

The MQ-4 is a popular gas sensor module used for the detection of methane (CH4) in the air. Methane is a colorless, odorless gas, which makes it difficult to detect without specialized sensors. The MQ-4 sensor is widely used in industrial and home environments to monitor gas leaks and ensure safety. Common applications include gas leak alarms, methane detection systems in mines, and environmental monitoring.

• Detection Gas: Methane, CH4
• Concentration Range: 200 to 10,000 ppm (parts per million)
• Supply Voltage: 5V DC
• Preheat Duration: 20 seconds
• High Sensitivity and Selectivity to Methane
• Analog and Digital Output
• Operating Temperature: -10 to 50°C

1. Power Connection: Connect the VCC pin to a 5V supply and the GND pin to the ground.
2. Output Reading: The analog output (AO) provides a voltage that is proportional to the methane concentration. Connect AO to an analog input on your microcontroller to read the methane levels.
3. Digital Interface: The digital output (DO) can be set to a threshold with the onboard potentiometer. When the methane level exceeds this threshold, the DO pin will output a high signal (5V).

• Calibration: The sensor requires calibration to ensure accurate readings. Expose the sensor to a known methane concentration and adjust the onboard potentiometer until the desired output is achieved.
• Warm-Up Time: Allow the sensor to preheat for at least 20 seconds to stabilize the readings.
• Ventilation: Ensure proper ventilation around the sensor to allow gas diffusion.
• Avoid Extreme Conditions: Do not expose the sensor to extreme temperatures, humidity, or corrosive gases.

// MQ-4 Methane Sensor with Arduino UNO
int analogPin = A0; // Analog input pin connected to AO
int digitalPin = 2; // Digital input pin connected to DO
int analogValue = 0; // Variable to store the analog value
int digitalValue = 0; // Variable to store the digital value

void setup() {
  Serial.begin(9600); // Initialize serial communication
  pinMode(digitalPin, INPUT); // Set the digital pin as input
}

void loop() {
  analogValue = analogRead(analogPin); // Read the analog value
  digitalValue = digitalRead(digitalPin); // Read the digital value

  // Print the results to the Serial Monitor
  Serial.print("Analog Value: ");
  Serial.print(analogValue);
  Serial.print(" | Digital Value: ");
  Serial.println(digitalValue ? "HIGH" : "LOW");

  delay(1000); // Wait for a second before the next read
}

• Inaccurate Readings: If the sensor provides inconsistent or inaccurate readings, recalibrate the sensor and ensure it has been preheated properly.
• No Response: Check the power supply and wiring connections if the sensor shows no response.

Q: How long does the MQ-4 sensor last? A: The lifespan of the MQ-4 sensor can vary based on usage, but it typically lasts for several years with proper calibration and maintenance.

Q: Can the MQ-4 sensor detect other gases? A: While the MQ-4 is designed for methane detection, it may show some sensitivity to other gases. However, it is not recommended to use it for detecting gases other than methane.

Q: Is the MQ-4 sensor suitable for outdoor use? A: The MQ-4 can be used outdoors but should be protected from water, dust, and extreme weather conditions to ensure accurate readings.

Q: How do I know if the sensor is working correctly? A: You can test the sensor by applying a known concentration of methane and checking if the readings are within the expected range. Regular calibration is also essential for maintaining accuracy.