Sensitive material of MQ-2 gas sensor is SnO2, which with lower conductivity in clean air. When thetarget combustible gas exist, The sensor’s conductivity is more higher along with the gas concentrationrising. Please use simple electrocircuit, Convert change of conductivity to correspond output signal ofgas concentration.MQ-2 gas sensor has high sensitity to LPG, Propane and Hydrogen, also could be used to Methaneand other combustible steam, it is with low cost and suitable for different application.