The Grove - Gas Sensor(MQ2) module is useful for gas leakage detecting(in home and industry). It can detect LPG, i-butane, methane, alcohol, Hydrogen, somke and so on.
Connect this module to the analog pin of Grove. You can gain the present voltage through the SIG pin. The higher the concentration of the gas, the bigger the output voltage of the SIG pin. Sensitivity can be regulated by rotating the potentiometer. Please note the best preheat time of the sensor is about 24 hours. For the detailed information about the MQ-2 sensor please refer to the datasheet.