Smoke Sensor MQ-2
Smoke Sensor MQ-2 – Smoke and gas sensor module that detects LPG, Propane, and Hydrogen
Actual product LINK

TSB Smoke Sensor MQ-2 is based on MQ-2 smoke/gas sensor. It can detect LPG, i-butane, propane, methane ,alcohol, Hydrogen, smoke. This sensors can be used in gas leakage detecting equipments in family and industry. These sensor gives analog voltage value in the signal pin which is proportional to the presence and density of gas. So, if we read the analog value wih an arduino, we can detect gas easily. With the variable pot, we can adjust the sensitivity of the sensor.