Factory direct MQ-2 smoke gas sensor module methane liquefied flammable gas for Ardu Product DescriptionMQ-2 gas sensor using ... variety of applications.Module applications:Gas leak monitoring means, suitable for liquefied petroleum gas, butane, propane, methane, smoke, etc., ... not normal.The wiring diagram of the sensor module New Factory direct MQ-2 smoke gas sensor module methane liquefied flammable ...