On Wyeast Lab's website, they mention that they have performed experiments on different methods of aeration. Using pure oxygen, they say that 5 gallons of wort will reach 12 ppm dissolved oxygen if you oxygenate for 60 seconds.
This information was not precise enough for me, so I used their Contact Us link to get some more information. They replied, and gave me all the details of their experiment:
To reach 12 ppm in a 5 gallon wort between 1.040 and 1.050, oxygenate for 60 seconds with a flow rate of 3.5 LPM through a 2 micron stone.