Air at \(80^{\circ} \mathrm{F}\) is to flow through a 2 - \(\mathrm{ft}\) pipe at an average velocity of \(6 \mathrm{ft} / \mathrm{s}\). What size pipe should be used to move water at \(60^{\circ} \mathrm{F}\) and average velocity of \(3 \mathrm{ft} / \mathrm{s}\) if Reynolds number similarity is enforced?