Methods for sampling, handling and measuring emissions of particulates, hydrocarbons, carbon monoxide, carbon dioxide, oxides of nitrogen and oxygenated compounds in the exhaust of aircraft turbine engines were evaluated in a cooperative experimental program conducted by industry and government at the Naval Air Propulsion Test Center in September, 1969.
Non-dispersive infrared (NDIR) instruments and a Fisher chromatographic partitioner were both well suited for measuring CO and CO2. Some additional development is needed in NDIR instruments and the phenol disulphonic acid (PDS) method for measuring NOx and in the 3-methyl-2-benzothiazolinone hydrazine hydrochloride (MBTH) method for measuring oxygenated compounds. Available flame ionization detector (FID) analyzers performed satisfactorily in measuring hydrocarbons in the range of 200-300 ppm C such as prevailed at idle rpm, but they were not reliable in measuring hydrocarbons in the range of 10 ppm or less such as prevailed at high rpm. In handling samples for hydrocarbon measurements, short, hot Teflon lines with high flow rates appear to be optimum, but with proper care, satisfactory results can be obtained with long, cold lines.
Carbonaceous particulates measured by Los Angeles County Air Pollution Control District (APCD) samplers, Leco crucibles and Scientific Advances Cascade Impactors agreed fairly well. The significance of water-soluble and solvent-soluble materials collected in the APCD samplers needs further study. Single-point sampling of the engine tail-pipe plane must be validated by a traverse before it can be taken to yield representative emissions.