• MQ-9 Carbon Monoxide CO Methane LPG Gas Detector Module - Envistia Mall
  • MQ-9 Carbon Monoxide CO Methane LPG Gas Detector Module - Envistia Mall
  • MQ-9 Carbon Monoxide CO Methane LPG Gas Detector Module - Envistia Mall
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MQ-9 Carbon Monoxide CO Methane LPG Gas Detector Module

MQ-9 Carbon Monoxide CO Methane LPG Gas Detector Module

$3.49
$3.49
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📋 Overview

The MQ-9 gas sensor detector module is a versatile dual-purpose sensor designed to detect carbon monoxide (CO) as well as combustible gases including methane (CH₄) and LPG (Liquified Petroleum Gas). It can detect CO concentrations from 10 to 1,000 ppm and combustible gas concentrations from 100 to 10,000 ppm, making it an excellent choice for projects that need to monitor both toxic and flammable gases with a single sensor.

The module features dual signal outputs: an analog output (0V to ~5V) that increases with gas concentration, and a digital TTL output that signals when concentration exceeds an adjustable threshold. The threshold is easily set using the onboard potentiometer. With fast response and recovery characteristics, long service life, and reliable stability, the MQ-9 is suitable for both home and industrial use.

⭐ Key Features

  • Dual-Purpose Detection — Detects both carbon monoxide (CO) and combustible gases (methane, LPG) with a single sensor
  • Wide Detection Range — CO: 10–1,000 ppm; Combustible gases: 100–10,000 ppm
  • Dual Signal Output — Analog (AO) and digital TTL (DO) outputs for flexible integration
  • Adjustable Threshold — Onboard potentiometer to set the digital output trigger level
  • Indicator LEDs — Power LED and digital output (DO) status LED for visual feedback
  • Fast Response & Recovery — Quick detection and return to baseline for reliable monitoring
  • Simple 4-Pin Interface — VCC, GND, AO, DO — no library required
  • 5V Compatible — Works directly with Arduino, ESP8266, and other 5V development boards

📊 Specifications

Parameter Value
Operating Voltage 5V DC
Maximum Power Consumption 800 mW (160 mA at 5V)
Detectable Gases Carbon monoxide (CO), methane (CH₄), LPG
CO Detection Range 10–1,000 ppm
Combustible Gas Detection Range 100–10,000 ppm (CH₄, LPG)
Analog Output (AO) 0V to ~5V (proportional to gas concentration)
Digital Output (DO) TTL level — LOW normally, HIGH when gas detected
Threshold Adjustment Onboard potentiometer
Indicator LEDs Power LED, DO (Digital Output) LED
Dimensions Approx. 32 × 20 × 27 mm (1.25 x 0.8 x 1.1 inches) L × W × H
Weight ~7 grams

📦 What's in the Box

  • 1x MQ-9 Carbon Monoxide & Combustible Gas Sensor Detector Module

🔌 Compatible With

  • Arduino (Uno, Mega, Nano, Pro Mini, and compatibles)
  • ESP8266 and ESP32 development boards
  • Raspberry Pi (with ADC module for analog reading)
  • STM32, Teensy, and other 5V-compatible microcontrollers
  • Any microcontroller with analog input and 5V power supply

🚀 Getting Started

  1. Connect VCC to 5V, GND to GND, AO to an analog input pin (e.g., A0), and DO to a digital input pin (e.g., D2)
  2. Upload a basic analogRead() sketch to your Arduino — no special library is required
  3. Open the Serial Monitor at 9600 baud and allow the sensor at least 20 seconds to warm up (a few minutes is recommended for stable readings)
  4. Observe the baseline reading in clean air, then introduce a gas source (such as a butane lighter with the gas valve open but unlit) to see the value increase
  5. Adjust the onboard potentiometer to set the digital output threshold for your application

💡 Tip: See our complete User Guide linked below for detailed wiring diagrams, pinout tables, sample code, and troubleshooting tips.

📌 Pinout

Pin Function
VCC Power supply input — connect to +5V
GND Ground
DO Digital output — TTL HIGH when gas exceeds threshold
AO Analog output — voltage proportional to gas concentration (0–5V)

🎯 Typical Applications

  • Combined CO and combustible gas leak detection
  • Home gas monitoring (kitchen, furnace room, garage, water heater area)
  • Industrial gas monitoring systems
  • Arduino and microcontroller safety projects
  • Portable multi-gas sniffers and handheld detectors
  • Smart home automation — trigger ventilation fans, alarms, or shut-off valves when gas is detected
  • Air quality monitoring stations
  • Educational and STEM projects
💡 MQ-7 vs. MQ-9: Both sensors detect carbon monoxide, but the MQ-7 is a dedicated CO sensor with a heating/measurement cycle for higher accuracy, while the MQ-9 adds methane and LPG detection on a simpler constant-5V supply. Choose the MQ-7 for CO-specific monitoring, or the MQ-9 for multi-gas convenience. Use both together to differentiate between CO and combustible gases.

⚠️ Important Notes

  • The sensor element gets hot during operation — do not touch the metal mesh cylinder while powered
  • Carbon monoxide is a deadly gas — this module is for detection and indication only, not a certified safety device. Always use UL/CSA-listed CO detectors for life safety
  • Allow at least 20 seconds for warm-up; a few minutes is recommended for stable, reliable readings
  • The MQ-9 is a broad-spectrum sensor — it responds to CO, methane, and LPG simultaneously and cannot differentiate between gas types on its own
  • Raw analog readings are not direct PPM values — calibration against known concentrations is required for PPM conversion
  • The sensor draws up to 160 mA — use an external 5V supply if powering multiple sensors or experiencing unstable readings
  • Do not test the sensor by exposing it to vehicle exhaust or other combustion sources in enclosed spaces

📄 Documentation & Resources

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