Use a sweep through purge to reduce the oxygen concentration from \(100 \%\) air ( \(21 \%\) oxygen) to \(1.25 \%\) oxygen. The vessel has a volume of 7500 gallon. Determine the \(\mathrm{ft}^{3}\) of nitrogen required if the nitrogen contains \(0.01 \%\) oxygen. Repeat this problem with nitrogen containing \(0.02 \%\) oxygen and \(0.05 \%\) oxygen. 1