The MQ-9 Gas Sensor Module is designed to detect Carbon Monoxide (CO), Methane (CH4), and LPG gases. Its sensitive material, SnO2, has low conductivity in clean air. The sensor detects CO at low temperatures (heated by 1.5V), with conductivity increasing as gas concentration rises. At higher temperatures (heated by 5V), it detects Methane, Propane, and other combustible gases, while cleaning absorbed gases at lower temperatures.

The MQ-9 is commonly used in domestic gas leak detectors, industrial gas sensors, and portable gas detectors. For more information on gas sensors, including details about different MQ sensor series, visit our blog, where we explain what a gas sensor is and how 1ppm translates.