Let's choose the calculation formula for λ 1: 10/e 1 = 10/ = 11111 . 560/e 1 = 560/ = 622222 . Since the calculated value Re 1 > 560/e 1, then the following formula should be used to find λ 1: λ 1 = ·e 1 = · = . Now it's possible to find the pressure head drop in the replaced pipe section: