ASTM D6417 Estimation of Engine Oil Volatility by Capillary Gas Chromatography
4. Summary of Test Method
4.1 A nonpolar open tubular (capillary) gas chromatographic column is used to elute the hydrocarbon components of the sample in order of increasing boiling point.
4.2 A sample aliquot is diluted with a viscosity reducing solvent and introduced into the chromatographic system. At least one laboratory analyzed samples using neat injection without solvent dilution. The precision of the method was calculated on diluted samples. If a laboratory chooses to use neat injection, it should first confirm that it is obtaining similar results. Sample vaporization is provided by separate heating of the point of injection or in conjunction with column oven heating.
4.3 The column oven temperature is raised at a reproducible linear rate to effect separation of the hydrocarbon components in order of increasing boiling point. The elution of sample components is quantitatively determined by a flame ionization detector (FID). The detector signal integral is recorded as area slices for consecutive RT intervals during the analysis.
4.4 RTs of known hydrocarbons spanning the scope of the test method (C8-C60) are determined and correlated to their boiling point temperatures. The RT at 371°C (700°F) is calculated using linear regression, utilizing the calibration developed from the n-paraffins. The cumulative corrected area of the sample determined to the 371°C RT is used to calculate the percentage of oil volatilized at 371°C.
5. Significance and Use
5.1 The determination of engine oil volatility at 371°C(700°F) is a requirement in some lubricant specifications.
5.2 This test method is intended as an alternative to Test Methods D5800 and D5480 and the Noack method for the determination of engine oil volatility (see DIN 51.581). The data obtained from this test method are not directly equivalent to Test Method D5800. The calculated results of the oil volatility estimation by this test method can be biased by the presence of additives (polymeric materials), which may not completely elute from the gas chromatographic column, or by heavier base oils not completely eluting from the column. The results of this test method may also not correlate with other oil volatility methods for nonhydrocarbon synthetic oils.
5.3 This test method can be used on lubricant products not within the scope of other test methods using simulated distillation methodologies, such as Test Method D2887.
