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Building a Methane Gas Leak Detector
Ed

Creado por

Ed

13. julio 2026FI
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Building a Methane Gas Leak Detector

Build a circuit that sniffs out methane — the main component of natural gas — and alarms when it rises. An MQ-4 sensor's reading climbs when combustible gas is present; the Arduino compares it to clean air and triggers a buzzer and red LED. A great combustible-gas sensing project — with two honest notes: methane is flammable, and this is a demonstration, NOT a certified gas-leak detector.

Intermedio
1-2 hours

Instrucciones

1

Wire the sensor, buzzer and LED

On the breadboard: MQ-4 VCC to Arduino 5V, GND to GND, and its analog output (AOUT) to A0. Active buzzer + to pin 8, - to GND. Red LED anode to pin 7 through a 330 Ω resistor, cathode to GND.

Materiales para este paso:

Arduino Uno R3Arduino Uno R31 pieza
Methane CNG Gas Sensor - MQ-4Methane CNG Gas Sensor - MQ-41 pieza
Módulo de zumbador activoMódulo de zumbador activo1 pieza
LED de 5 mmLED de 5 mm1 pieza
Resistencia de 330 ohmiosResistencia de 330 ohmios1 paquete
Placa de pruebasPlaca de pruebas1 pieza
Cables de puenteCables de puente1 paquete
2

Connect and open the IDE

Plug the Arduino into your computer with the USB cable, open the Arduino IDE, and select Arduino Uno and its serial port.

Herramientas necesarias:

Ordenador con el IDE de ArduinoOrdenador con el IDE de Arduino
Cable USB-BCable USB-B
3

Upload the detector sketch

Paste this sketch and upload. It warms the sensor, records a clean-air baseline, then sounds the buzzer and lights the LED whenever the reading rises above that baseline.

methane_detector.inoarduino
// Methane / natural-gas leak INDICATOR using an MQ-4 sensor.
// NOT a certified gas-leak detector - see the safety note. Methane is flammable.
// MQ-4 analog output on A0; buzzer on pin 8; red warning LED on pin 7.

const int MQ4_PIN = A0;
const int BUZZER_PIN = 8;
const int LED_PIN = 7;

int cleanAirValue = 0;          // baseline, measured at startup
const int ALARM_MARGIN = 150;   // how far above baseline triggers the alarm

void setup() {
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(LED_PIN, OUTPUT);
  Serial.begin(9600);

  Serial.println("Warming up the MQ-4 (2 min) in clean air...");
  delay(120000);
  cleanAirValue = analogRead(MQ4_PIN);
  Serial.print("Clean-air baseline: ");
  Serial.println(cleanAirValue);
}

void loop() {
  int reading = analogRead(MQ4_PIN);
  Serial.println(reading);

  if (reading > cleanAirValue + ALARM_MARGIN) {
    digitalWrite(LED_PIN, HIGH);      // combustible gas above baseline -> alarm
    digitalWrite(BUZZER_PIN, HIGH);
  } else {
    digitalWrite(LED_PIN, LOW);
    digitalWrite(BUZZER_PIN, LOW);
  }
  delay(500);
}
4

Warm up, baseline and test SAFELY

Power it in fresh air and let the 2-minute warm-up set the baseline (a new MQ-4 also needs a 24–48 h burn-in). Test with only a TINY controlled source in a well-ventilated room — a brief puff of gas from an UNLIT lighter held near the sensor. NEVER test with a real gas leak, a large amount of gas, or anywhere near a flame or spark. Adjust ALARM_MARGIN for sensitivity.

5

Safety limits

Methane is highly flammable and, in enough concentration, explosive. This circuit is a LEARNING project and at best a supplementary indicator — it is NOT a certified gas-leak detector: the hobby MQ-4 gives a relative reading, not calibrated ppm, drifts, and needs re-baselining. For real protection use a certified natural-gas detector, and if you ever smell gas, do not switch anything on or off — leave and call your gas utility.

Materiales

7

Herramientas requeridas

3
Total estimado
Lo que compró quien lo hizo. Los materiales sin precio se consiguen donde tú los compres.
€4.51

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