RAPID SPECTROSCOPIC DETERMINATION OF PER CENT AROMATICS, PER CENT SATURATES AND FREEZING-POINT OF JP-4 AVIATION FUEL

Near-infrared (n.i.r.) spectroscopy in both the short wavelength region (700-1100 nm) and the long wavelength region (1100-1500 nm) is evaluated as a rapid method for the simultaneous estimation of the freezing point and volume percentages of aromatics and saturates of aviation fuels. Thirty-three JP-4 samples were independently analysed by six industrial and government laboratories for freezing point and for volume per cent aromatics and volume per cent saturates by fluorescent indicator adsorption. These results were then used to calibrate the sample's n.i.r. spectra. Both multiple linear regression and partial least squares calibration methods were evaluated and gave comparable performance. The n.i.r. spectral analysis predictions for these properties were within the standard deviations of the round-robin values. Specifically, the per cent aromatics and per cent saturates were within 1% and the freezing point within 2.5-degrees-C of the laboratory-determined values. N.i.r. spectroscopy appears to have considerable promise as a rapid non-destructive method for jet fuel analysis.