MQ2 gas sensor module is highly useful for gas leakage detection at home or industry. The sensor module can detect h2, LPG, CH4, CO, Alcohol, Smoke or Propane. It is highly sensitive and very first responder. Depending on the requirements of sensitivity, the sensor can be adjusted with a Potentiometer.MQ2 is an analogue output sensor which is commonly used as combustible gas sensor in MQ sensor series. It is a Metal Oxide Semiconductor (MOS) type gas sensor . The output voltage of the gas sensor increases if the concentration of gas increases. The sensitivity of the sensor is adjustable by the Potentiometer .