MQ5 liquefied gas and Methane Gas Sensor Module

Key Features

• High sensitivity to methane and LPG.
• Detects other flammable gases like hydrogen and alcohol.
• Analog and digital outputs for flexible interfacing.
• Adjustable sensitivity via a built-in potentiometer.
• Low cost and easy to use.

Specifications

• Operating Voltage: 3.3V–5V DC
• Operating Current: ~150 mA
• Detectable Gases: Methane (CH₄), LPG, hydrogen, and alcohol vapors.
• Output Types:
  • Analog Output (AO): Proportional to gas concentration.
  • Digital Output (DO): HIGH/LOW signal based on the threshold set by the potentiometer.
• Sensitivity Range: Detects concentrations from 200 ppm to 10,000 ppm.
• Preheat Time: ~20 seconds for stable operation.
• Operating Temperature: -10°C to 50°C.

Pinout

1. VCC: Power supply (3.3V or 5V)
2. GND: Ground
3. DO: Digital output
4. AO: Analog output

Working Principle

The MQ5 sensor uses a SnO₂ (tin dioxide) sensing layer, which has low conductivity in clean air. When exposed to methane, LPG, or other flammable gases, the conductivity increases. This change in resistance is measured to determine the gas concentration.

Interfacing with Arduino

Hardware Setup

1. Connect VCC to the Arduino’s 5V pin.
2. Connect GND to the Arduino’s GND pin.
3. Connect AO (Analog Output) to an analog input pin (e.g., A0).
4. (Optional) Connect DO (Digital Output) to a digital input pin for threshold-based detection.

Sample Code

const int analogPin = A0; // Analog output pin
const int digitalPin = 2; // Digital output pin
int analogValue = 0;

void setup() {
  Serial.begin(9600);
  pinMode(digitalPin, INPUT);
}

void loop() {
  // Read analog value
  analogValue = analogRead(analogPin);
  
  // Print analog value (gas concentration)
  Serial.print("Analog Value: ");
  Serial.println(analogValue);

  // Check digital output
  if (digitalRead(digitalPin) == HIGH) {
    Serial.println("Gas concentration exceeded threshold!");
  }
  
  delay(1000);
}

Calibrating the Sensor

1. Preheating: Allow the sensor to preheat for at least 24 hours before precise calibration.
2. Sensitivity Adjustment: Use the potentiometer to adjust the digital threshold for gas detection.
3. Calibration Curve: Expose the sensor to known gas concentrations, record the analog values, and create a calibration curve for accurate measurements.

Applications

• LPG and natural gas leak detection.
• Industrial safety systems.
• Smart home gas detection systems.
• Combustible gas monitoring.
• IoT-based gas detection and alert systems.