With a specific electrochemical sensor Output 4-20 mA. Standard measuring ranges and substances: Ammonia (NH3): .................0-100 ppm Chlorine (Cl2): .....................0-10 ppm Carbon monoxide (CO): .............0-300 ppm Oxygen (O2): ......................0-21 (25) Vol% Nitrogen dioxide (NO2): .......0-50 ppm Nitrogen monoxide (NO): ...........0-50 ppm Hydrogen sulphide (H2S):....0-50 ppm Sulphur dioxide (SO2):...........0-100 ppm