Another good reason NOT to pull vacuum on fuels and other volitile
liquids is that if the vacuum exceeds the vapor pressure of the fluid
the liquid with boil (flash) or you will separate out the lighter
fractions (lighter weight hydrocarbons). If youve ever had a gasoline
that had 'vapor-lock' problems you'll understand this phenomenom. I
dont have by me at this time a listing of the vapor pressure range of
#2 diesel fuel but you must understand that #2 is a mix of various
fractions. From that standpoint alone and the potential of 'flashing
by vacuum application make vacuum a less conservative approach to fuel
delivery systems.