Briefly, the saturated vapor volume of an average gallon of liquid gasoline when fully evaporated is 160.4 gallons of vapor at 60° F and sea level.
Vapor volume of a liquid is the number of cubic feet of vapor resulting from the complete evaporation of the liquid. The vapor volume depends on parameters of density, temperature, pressure and molecular weight which is affected by the variety of formulas for gasoline that is comprised of a wide range of hydrocarbons.
Several approaches are available to solve this problem. One is shown below.
Using a common industrial formula:
one liquid gallon = [(8.31) x (SG) x (387 cu ft)] / (MW)
Where:
8.31 = pounds in gallon of water
SG = specific gravity of liquid being vaporized
387 = At standard conditions, one pound-molecular weight of a material will evaporate to fill 387 cubic feet of space.
MW= molecular weight of liquid being vaporized
Then using the approximate gasoline constants:
one liquid gallon of gasoline = [(8.31 pounds in a gallon of water) x (.70 approx. specific gravity of gasoline) x (387 cu ft)] / (105 molecular weight of average gasoline)
= 21.4 cubic feet of vapor volume
There is 7.481 U.S. gallons in one cubic foot.
So:
one liquid gallon of gasoline = (21.4 cubic feet) x (7.481)
= 160.4 gallons of saturated gasoline vapor
The vapor volume will vary based on the specific formulation of gasoline, pressure, and temperature.
D. Hollatz