CO + flammable gases MQ-9

MQ-9 CO & Combustible Gas Sensor
The MQ-9 uses a Tin Dioxide (SnO_2) sensing layer that reacts differently depending on the temperature of its internal heater. By cycling the voltage, the sensor "tunes" itself to different molecules at different times, effectively acting as two sensors in one.

 
Why the MQ-9 is a "Universal" Safety Choice:
• Hybrid Detection: Most homes face two distinct gas threats: poisoning from CO (from faulty heaters) and explosions from LPG/Methane (from stove leaks). The MQ-9 covers both bases, reducing the need for multiple sensor modules.
• Smart Temperature Cycling: * Low Temperature (1.5V): The sensor becomes highly sensitive to Carbon Monoxide.
* High Temperature (5.0V): The sensor pivots to detect Methane, LPG, and Propane.
• Wide Detection Range: It can detect CO from 10 to 1000 ppm and combustible gases from 100 to 10,000 ppm.
• Dual Output Utility:
* Analog (A0): Provides a continuous 0V–5V signal, allowing you to track rising gas levels before they become critical.
* Digital (D0): Provides an immediate TTL logic signal. You can adjust the "danger threshold" using the onboard potentiometer to trigger an external alarm or shut-off valve.

 
Technical Capabilities:
• Operating Voltage: 5V (Standard for the module).
• Current Draw: ~150mA (Powering the internal heater).
• High Sensitivity: Capable of detecting gas leaks long before they reach dangerous concentrations or the Lower Explosive Limit (LEL).

 
Best For:
The MQ-9 is the primary component for domestic hybrid gas alarms, industrial plant safety monitoring, caravan/RV multi-gas detectors, and smart city air quality nodes.