MQ9 Carbon Monoxide Methane and LPG Gas Sensor Module

MQ9 Carbon Monoxide Methane and LPG Gas Sensor Module 

The MQ?9 Gas Sensor Module is a low?cost semiconductor gas sensor designed to detect carbon monoxide (CO), methane (CH?), and LPG (liquefied petroleum gas) in the air. It uses a sensitive tin dioxide (SnO?) sensing element whose electrical resistance changes in the presence of target gases. The module includes a heater element to bring the sensor to an optimal operating temperature and often features onboard signal conditioning circuitry, making it easy to interface with microcontrollers (e.g., Arduino, ESP32) via analog or digital outputs. The MQ?9 is widely used in safety and monitoring systems where basic detection of combustible and toxic gases is needed.

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Features

• Multi?gas detection: CO (carbon monoxide), CH? (methane), LPG (propane/butane)
• High sensitivity to target gases
• Simple analog output corresponding to gas concentration changes
• Onboard heater for stable operation
• Fast response and recovery times for real?time monitoring
• Low cost and easy to replace
• Easy to interface with microcontrollers and ADC?based systems
• Compact module suitable for prototyping and embedded systems
• Can detect other reducing gases at lower sensitivity

Applications

• Carbon monoxide safety detectors for homes, garages, and workplaces
• Methane leak detection in pipelines, mines, and industrial environments
• LPG gas leakage alarms in kitchens, gas storage areas, and vehicles
• Portable gas monitoring units and handheld safety devices
• Environmental monitoring systems for air quality
• Industrial safety systems for combustible gas detection
• Smart home automation with gas alarm integration
• Educational and hobbyist projects involving gas sensing