philosofool
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- May 8, 2007
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That's exactly what the graph shows!
Since it's a log-linear graph (with the y-axis showing powers of 10), exponential decay is a straight line. Follow the yellow (15 psi) line, and after 10 cycles the remaining 02 has dropped by a factor of 1000 ~ 2^10.
Hah! Looks like I'm totally paying attention...
Anyway... for those following along at home, it is more CO2 efficient to purge more times at lower pressure. The general form of the equation is
80*(x/(x+atmos))^n * V= ppm O2
Where atmos is atmospheric pressure (11 where I live, 14 for most) and x is the regulator psi and n is number of purges. V is volume headspace in liters. This assumes a 5 gallon keg.