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The Flame Ionization Detection (FID) is the most sensitive and widely used technology for the measurement of total hydrocarbons (THC). In the automotive emission testing of hydrocarbons, the fuel used for the flame in the FID analyzer is a mixture of hydrogen and helium in the ratio of 40:60. The Environmental Protection Agency (EPA) revised 40CFR part 1065 in April 2014 to include nitrogen as a balance gas alternative to helium for FID fuel mixtures used in the automotive industry. In addition to the balance gas alternative, the FID fuel blend tolerance was decreased from 40±2% to 40±1% (0.39 to 0.41mol/mol) hydrogen to minimize the impact on analyzer response. The feasibility of nitrogen as a FID fuel balance gas was studied and compared with a helium balance gas to understand the relative impact on emission testing. The study evaluated multiple hydrogen concentrations ranging from 38-42% in both balance gases.

Infrared spectroscopic methods are the most common methods in the automotive industry for measuring carbon monoxide (CO) and carbon dioxide (CO2) gases. Concentrations of both gases, which are emitted from the combustion of fuels, are required to be determined accurately in order to follow strict environmental regulations. Appropriate analytical techniques and accurate calibration gas mixtures are therefore critical for successful measurements. Regulatory documents such as the EPA’s Code of Federal Regulations 40 (CFR 40) part 1065.250, UN ECE-R83, and (EU) 2017/1151 recommend a nondispersive infrared (NDIR) analyzer to measure CO and CO2 concentrations in raw or diluted exhaust gas samples. Over the last decade, Fourier Transform Infrared (FTIR) spectrometry has been validated and recommended in engine exhaust certification testing as well as in engine and vehicle development activities.