1. Rationale
The purpose of this ballot is to include piston instruments in D5188. Test method D5188 was written more than 20 years ago. At the time, only evacuated chamber (vacuum pump) technology was available for the volatility measurements. A short time later, instruments were introduced that create vacuum using a movable piston rather than a vacuum pump. Vapor pressure test method D5191 was updated to include piston instruments many years ago, but V/L test method D5188 has not been updated. Both methods require the same quality of vacuum for volatility measurements. Data from two comparative studies support the addition of piston instruments to D5188. The studies compared T V/L=20 measurements by both the piston and evacuated chamber instruments over the expected V/L range of gasoline. The combined data set was statistically evaluated according to D6708 by Alex Lau. The assessment outcome was successful, with no bias correction or sample specific bias. The D6708 assessment and sample descriptions are included in the attached research report.
Keywords
gasoline; gasoline-oxygenate blends; petroleum products; T(V/L = 20); vapor-liquid ratio; Air saturation; Evacuated chamber method; Fuel oils; Petroleum samples; Phase separation; Temperature tests--petroleum products; Vapor-liquid (V/L) ratio (V/L) ratio;
Citing ASTM Standards
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