This Gas Sensor Module features an MQ-2 sensor which can detect alcohol, carbon monoxide, smoke and other harmful gases.
The MQ-2 sensor is a versatile gas sensor capable of detecting a wide range of gases including: alcohol, carbon monoxide, hydrogen, isobutene, liquefied petroleum gas, methane, propane and smoke. This module has both a 3 pin male header interface and a "grove" style connector.
Attach the (V) Voltage and (G) Ground pins to a 5V power supply and then and analog (S) Signal output pins to an analog input on your microcontroller. The voltage read for the (S) Signal will correspond to the amount of gas present.