MQ6 liquefied Propane Butane LPG Sensor

The MQ6 Gas Sensor is specifically designed for detecting liquefied petroleum gas (LPG), but it can also detect propane and other combustible gases. It is commonly used in gas leak detection systems, industrial safety devices, and home automation projects.

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Key Features

• High sensitivity to LPG and propane.
• Detects other flammable gases to a lesser extent.
• Provides both analog and digital outputs.
• Adjustable sensitivity via a built-in potentiometer.
• Compact and easy to use with microcontrollers like Arduino.

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Specifications

• Operating Voltage: 3.3V–5V DC
• Operating Current: ~150 mA
• Detectable Gases: LPG, propane, and other flammable gases.
• 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.

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Pinout

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

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Working Principle

The MQ6 sensor uses a SnO₂ (tin dioxide) sensing layer, which has low conductivity in clean air. When exposed to LPG or other combustible gases, the conductivity increases. This change in resistance is used to measure the concentration of gases in the surrounding environment.

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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.

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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);
}

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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 set the desired digital detection threshold.
3. Calibration Curve: Expose the sensor to known gas concentrations, record the analog output, and map it to actual gas concentrations for precise readings.

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Applications

• LPG leak detection in homes and industries.
• Gas monitoring in automotive systems.
• Industrial safety systems.
• Combustible gas detectors.
• IoT-based environmental monitoring systems.