MQ-5 LPG & Coal Gas Sensor Module - Liquefied Petroleum Gas Detector

Specifications

• Target Gases: LPG (Liquefied Petroleum Gas), Natural Gas, Coal Gas.

• Interference Rejection: Low sensitivity to Alcohol and Smoke (reduces false alarms).

• Operating Voltage: 5V DC ±0.1

• Heater Consumption: ~150mA

• Detection Range: 200ppm – 10,000ppm (LPG/Propane)

• Output Format:

  • Analogue (A0): Voltage increases linearly with gas concentration.

  • Digital (D0): Logic High/Low trigger based on potentiometer setting.

• Response Time: < 10s

• Dimensions: 32mm x 20mm x 22mm

Compatibility & Platform Support

• Arduino (Uno/Nano/Mega): Directly Compatible. The 5V logic matches perfectly.

• ESP32 / ESP8266: ⚠️ Caution Required. The Analog output typically ranges 0-4V. You MUST use a voltage divider (e.g., 10kΩ & 20kΩ resistors) to drop the signal below 3.3V to avoid damaging the ESP32 ADC.

• Raspberry Pi: ⚠️ Requires ADC. The Pi cannot read analog voltages. Use an external ADC chip (MCP3008) or a digital-only trigger via the D0 pin.

Key Applications & Projects

• Smart Kitchen Safety Monitor: Detect LPG cylinder leaks and automatically trigger a solenoid valve to shut off the supply.

• Camper/RV Gas Alarm: Monitor propane levels in recreational vehicles.

• Industrial Gas Sniffer: Portable device for checking pipeline integrity.

• Coal Mine Safety: Detect coal gas accumulation in underground models.

Project Evolution

• Prerequisites: Basic understanding of digital inputs (digitalRead) and triggering buzzers.

• The Upgrade: Combining this with a Relay Module unlocks "Active Safety"—not just sensing the leak, but physically cutting off the power or gas flow.

• Effort Level: Beginner to Intermediate. The D0 trigger is easy to set up; A0 calibration requires more coding logic.

Virtual Technician: Wiring & Safety ⚠️

• VCC: Connect to 5V (Stable supply required).

• GND: Connect to Ground.

• D0 (Digital Out): Connect to Digital Pin (for simple High/Low alarm).

• A0 (Analog Out): Connect to Analog Pin (for PPM measurement).

• Heater Warning: The sensor will get warm (~40°C) during operation. This is normal and necessary for the chemistry to work.

Accessories

• Included in the Package: 1 x MQ-5 LPG & Coal Gas Sensor Module

• Required Accessories (Not Included):

  • Controller: Arduino Uno or compatible board.

  • Wiring: Female-to-Male Jumper Wires.

  • Power: 5V 1A Adapter (USB power may sag if multiple sensors are used).

  • Alert: 5V Active Buzzer.

Frequently Asked Questions (FAQ)

• Why choose MQ-5 over MQ-2? MQ-5 is much better at ignoring cooking smoke and alcohol fumes, reducing false alarms in kitchens. MQ-2 is a general-purpose "smoke & gas" sensor.
• Can it detect piped Natural Gas? Yes, it is sensitive to Natural Gas (Methane) as well.
• Does it detect Carbon Monoxide (CO)? No. For CO detection, you must use the MQ-7 sensor.
• How long does it take to "warm up"? For a quick test, 1-2 minutes. For stable calibration, run it for 24 hours.
• Is it safe to use in a real home? This is a prototyping module. While accurate, it is not a certified safety device (UL/ISI) and should not be the only safety measure in a home.
• Can I power it with a 9V battery? No! 9V will burn out the heater coil instantly. Use a 5V regulator (7805) or buck converter.
• Why is the LED always ON? Adjust the blue potentiometer on the back. Turn it counter-clockwise until the LED just turns off to set the sensitivity threshold.
• What is the output voltage range? Typically 0.1V in clean air to ~4.0V in high gas concentrations. 9. Is it waterproof? No. Water will damage the chemical coating.
• Can I use it outdoors? Wind can affect the sensor reading by cooling the heater. Use a shield if using outdoors.
• How do I calibrate the PPM? You need to measure the sensor resistance in clean air (Ro) and compare it to the resistance in gas (Rs) using the log-log chart in the datasheet.
• Does it detect city gas? Yes, "City Gas" is usually coal gas or methane, both of which MQ-5 detects.
• Can I use this with NodeMCU? Yes, but NodeMCU has only one Analog pin (A0) which takes max 3.3V (or 1V on some boards). Check your board's specs and use a voltage divider!
• What is the lifespan? Usually 4-5 years if kept clean and dry.
• Does it detect Petrol/Gasoline vapors? It has some sensitivity to petrol vapors, but MQ-3 or MQ-138 are better suited for that.
• Why does the reading drift? Temperature and humidity changes affect the reading. Software calibration is needed for precision.
• Can I use multiple sensors on one Arduino? Yes, but ensure your power supply can handle the current (150mA per sensor). The Arduino 5V pin might struggle with more than 2 sensors.
• What happens if I touch the mesh? Oils from your fingers can coat the sensor and reduce sensitivity. Handle by the PCB edges.
• Is the sensitivity adjustable? Digital threshold: Yes (via Potentiometer). Analog gain: No (Fixed).
• Does it work in a vacuum? No, it requires oxygen to function.