Identification of forane R134a in an air-conditioned atmosphere with a TGSsensor array

For electronic nose applications based on tin oxide gas sensors, relative h umidity is a very influential parameter that may cause false gas detection. In our application, we want to distinguish a refrigerant gas (Forane R134a ) in an air-conditioned atmosphere using a TGS gas sensor array. First, thi s paper gives a brief overview for accurate test equipment for characterizi ng these types of sensors under closely controlled humidity and temperature conditions. Next, the humidity influence is experimentally shown, either f or air or for Forane R134a gas concentrations in air. Then, by using two co mplementary pattern recognition methods, principal component analysis (PCA) followed by discriminant factorial analysis (DFA), we show the ability to discriminate accurately the target gas whatever the humidity rate. We also prove that it is possible to identify unknown test cases with the resultant decisive law.