EXPLANATION
The tendency of a fuel to vaporize in common automobile fuel systems is indicated by the vapor-liquid ratio of that fuel at conditions approximating those in critical parts of the fuel systems. Dry glycerol can be used as the containing liquid for nonoxygenated fuels. Mercury can be used as the containing liquid with both oxygenated and nonoxygenated fuels.
TEST SUMMARY
A measured volume of liquid fuel at 32 to 40° F is introduced through a rubber septum into a glycerol or mercury filled buret. The charged buret is placed in a temperature controlled water bath. The volume of vapor in equilibrium with liquid fuel is measured at the desired temperature or temperatures and the specified pressure, usually 760 mm Hg. The vapor-liquid ratio is then calculated.
TEST PRECISION
There is no bias between this test method and Test Method D5188.