FlD Analysers Gas Chromatographs FID Analysis of CH4, CO, CO2 & NMHC in PPB, PPM or % in Carbon Dioxide, Helium, Argon, Oxygen, Nitrogen, Hydrogen or Air. OrthoPure FID Analysis of CH4, CO, CO2 and NMHC in PPB and PPM. Environmental Series Air quality gas analysers. Online (continuous) Analysers THC Analyser - THC8000 Online analysers of THC in PPM level