Do you have access to a process simulation model like Hysys or Petro-Sim.?  I sp that would help you to do the atmospheric flashes required to answer your question.  There are a few unknowns that need to be answered:

1) What is the composition of the gasoline - gasoline composition varies widely seasonally and between regions High RVP gasoline will evaporate more quickly.

2) How quickly will the vapor diffuse away into the surrounding environment?  it will probably be much faster for the light components that evaporated first than the heavier components that will diffuse much more slowly.  You could make assumptions about max and min rates of diffusion of each component to bracket the solution.

 Setting up a series of flashes re-flashing the liquid with various assumptions about the amount of air in the mix will help you understand how the composition of the remaining gasoline will change over time and what the final composition is likely to be.  Your solution  is only about .4 inches deep.  The boundary layer  above the gasoline is probably going to be a few inches.  I would do start the flash calcs with the volume of air about 10 times the volume of liquid =  10 gallons or 1.3 SCF.

My expectation is that you will find butane  I-Pentane and N Pentane flash off relatively quickly and the heavier components will take a very long time to slowly evaporate because the heavy component have low vapor pressures and they will not diffuse away very quickly unless you put it in a laboratory hood to remove the hydrocarbons from the environment.

. 

This might help with the diffusion calcs

file:///C:/Users/Rick/Downloads/00b49529db6c70a660000000.pdf

Dan,  Sorry this is the correct link: http://www.jocet.org/papers/012-J30011.pdf

This is probably close  to what you are looking for:

http://webwormcpt.blogspot.com/2010/03/quick-estimate-evaporation-rate-from.html

Liquid in tank truck or storage tank may spill on the ground. Wind blowing, solar and ground surface heating will results evaporation of spilled liquid. The evaporation rate is one of the key information required during design phase for consequence analysis and preparation of emergency handling measures. What is the quick way to estimate evaporation rate ?

Evaporation rate from spilled liquid subjects to several factors such as :

spilled liquid volatility

spilled liquid properties

spilled liquid surface area expose to wind blowing

spilled liquid temperature

wind speed

Evaporation Rate 

Evaporation rate of spilled liquid can be estimated using following equation

E = (0.284 U0.78.MW2/3.A.VP) / (82.05 T)

where

E = Evaporation rate (lb / min) 

U = Wind speed above spilled liquid surface (m/s)

MW = Spilled liquid molecular weight

A = Spilled liquid surface area (ft2)

VP = Spilled liquid vapor pressure at liquid temperature (mmHg)

T = Spilled liquid temperature (K)

Spilled Liquid Surface Area

Spilled liquid surface area is normally fix by the containment itself. Liquid spilled from tank into diked area, the spilled liquid surface area will be the diked area itself  unless the spilled quantity is so small where it will not covers 

entire diked area. To estimate spilled liquid surface area without any containment, it is assumed that the spilled liquid will have 10mm (or 0.033 ft) thickness. Therefore,

Spilled liquid surface area (ft2)

A = V / 0.033

where

V = Spilled liquid volume (ft3)

Example

Methanol with vapor pressure (VP) of 125 mmHg and MW of 32.04 stored at 25 degC in a 25,000 US gal tank (10 ft diameter). Overfilled methanol results spillage of 1,000 US gal of methanol spread in the diked area (100ft x 40 ft) which contain 8 identical tanks. Assuming wind speed is 1.5 m/s, estimate evaporation rate.

Spilled volume,

V = 1000 US gal 

V = 1000 /  7.48051948 ft3

[1 ft3 = 7.48051948 US gallons]

Spilled area (without containment),

Awc = V / 0.033

Awc =  (1000 /  7.48051948) / 0.033

Awc = 4,050 ft2

Diked area,

Adike = Total dike area - tank area

Adike = 100x40 - 8 x (PI x 10^2)/4

Adike = 3371.7 ft2

Since Awc is larger than Adike, entire dike area will be occupied by spilled liquid.

Inputs

U =1.5 m/s

MW =32.04

A =3371.7 ft2

VP =125 mmHg

T =25 + 273.15 = 298.15 K

Evaporation rate

E = (0.284 U0.78.MW2/3.A.VP) / (82.05 T)

E = (0.284x1.50.78.(32.04)2/3.3371.7.125) / (82.05x298.15)

E =   67.7 lb / min

Above method is a quick method in determining evaporation rate.

Ref : "Risk management program guidance for offsite Consequence Analysis", US EPA, Apr 1999

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Environment related 

Labels: Environment, Greenhouse Effect

Thank you!  :-)  This is very important for comparison, but it's actually the opposite of what I'm looking for.  As originally stated; I'd like data from a controlled environment 'absent' of wind, solar, terra, humidity, and any other exterior influences.  For "baseline" data.

Extremely simplified: Pour a determined volume of gasoline (any pump grade, just pick one) in a pan with a know exposed surface area and put it in a bell jar at least 160 times that original volume of the liquid gasoline. Evacuate the bell jar to 29.9in. Hg. How long until the gasoline is evaporated?

Perform the same experiment with the bell jar evacuated to 20.6in Hg.  How long until the gasoline is evaporated?

I do not want to perform these experiments because I do not trust my own controls of the environment.  I don't have the facilities or components.  I believe my results would be significantly flawed.  I'm certain that there are already existing data somewhere in the petroleum/petrochemical worlds that already have been documented.

I do not need to know spill rate, assumed thickness. liquid properties, etc.  Just pick a pump gasoline and time the evaporation.  How much time elapses until the pan is dry?

This one is also close but not exactly what you want:

http://www.lmal.ps.pl/bufor/gasoline.pdf

This is GREAT information!!!!

@ Dan Miller use of process simulation model will simplify your problem relatively with small effort. The tools that u can try with are Hysys / Petro-Sim, SuperPro designer even Aspen?. I was trying to help  but missing your stream composition (components & % w/w) ... gasoline is just general naming.

I really appreciate all of these answers, but my question is being overly complicated.  It should be extremely simple.  I do not know how to make it more simple to ask.

Haregewoin Gebre:  I don't understand these systems.  I am not a chemist or analyst.  I'm trying to avoid the extremely long learning curve to use these programs with efficiency.  I know that there is a chemist that has already done 1000 more simulations than I can ever do.  I do not want any overly complicated answers.  I have no doubt that the information I am requesting already exists.  If someone can help me - I am just asking some one to tell me the following→ for example:

_____________________________________

////////   No wind   \\\\\\\\

////////   No solar radiation  \\\\\\\\

////////   No external catalyst  \\\\\\\\

1 ml of 91 octane gasoline @ 30°c in a container with an exposed surface area of 9cm sq and 760mmHg will completely evaporate in ?????? seconds (minutes).

Also:

1 ml of 91 octane gasoline @ 30°c in a container with an exposed surface area of 9cm sq and 520mmHg will completely evaporate in ?????? seconds (minutes).

____________________________________

It does not matter if you choose English units or metric, gallons, liters, 91 octane or 87.  I'm not concerned about all the constituents in the blend of the gasoline.  The only variable is Hg.  I am only asking for two cases.

Hg = 29.9 in. (14.7psia)  (760mm (1.03ksc))

Hg = 20.6 in. (10.1psia)  (522mm (0.71ksc))

Hello Dan. Did you find the answer to this question?