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Building a Methane Gas Leak Detector
Ed

Yaremwe na

Ed

13. Nyakanga 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.

Hagati
1-2 hours

Amabwiriza

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.

Materials for this step:

Arduino Uno R3Arduino Uno R31 igice
Methane CNG Gas Sensor - MQ-4Methane CNG Gas Sensor - MQ-41 igice
Active Buzzer Module (5V, 5-Pack)Active Buzzer Module (5V, 5-Pack)1 igice
LED - Basic 5mmLED - Basic 5mm1 igice
Resistor 330 Ohm 1/6 Watt PTH - 20 packResistor 330 Ohm 1/6 Watt PTH - 20 pack1 agapaki
BreadboardBreadboard1 igice
Jumper Wires (Male-to-Male)Jumper Wires (Male-to-Male)1 agapaki
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.

Materials for this step:

USB-B CableUSB-B Cable1 igice

Tools needed:

Computer with Arduino IDEComputer with Arduino IDE
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.

Ibikoresho

8

Ibikoresho bikenewe

1
Estimated Total
$56.00

Blueprint zijyanye

Izi blueprint zisangira ubumenyi — uburyo, ibikoresho cyangwa amahame

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CC0 Umurenge rusange

Iyi blueprint yasohowe munsi ya CC0. Ushobora gukoporora, guhindura, gukwirakwiza no gukoresha nta kwemererwa.

Shyigikira Umuremyi ugura ibicuruzwa binyuze muri Blueprint ye Komisiyo y'Umuremyi byashyizweho n'Abacuruzi, cyangwa kora verisiyo nshya y'iyi Blueprint ukayinjiza nk'isano muri Blueprint yawe kugira ngo musangire inyungu.

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