A current ASTM ILS using instruments from various manufactures showed, that the measurement of a fuel containing a high Ethanol content directly followed by a QC measurement of pentane can lead to a too high reading of the QC measurement. This effect is caused by the limited solubility of Ethanol in Pentane and the formation of an azeotropic mixture of these components.
Eralytics reacted immediately and developed our so called Pure SamplingTM technology (patent pending) for the ERAVAP. With this outstanding technology the risk of cross contamination between samples was reduced to an absolute minimum. The graph below shows the worst case szenario of measuring pure Ethanol right before and after Pentane QC measurements. Even in this szenario the first measurement after changing the sample already falls within the tolerable limits of the ASTM reference values.
Further we would like to announce that recent improvements of the measurement setup also led to a superior repeatability of r ≤ 0.15 kPa and reproducibility of R ≤ 0.5 kPa for reference substances published in ASTM D5191 and D6378. Due to the limited availability of Neohexane (2,2-Dimethyl-Butane) ASTM tested cyclopentane and pentane / toluene mixtures as new reference materials for ASTM D5191. Below graph shows vapor pressure measurements (pabs) according to ASTM D6378 for Cyclopentane and Pentane at 37.8 °C (100 °F).