Question

6A.1 Pressure drop required for a pipe with fittings. What pressure drop is needed for pumping water at 20°C through a pipe 25 cm in diameter and length 1234 m at a rate of 1.97 m/s? The pipe is at the same elevation throughout and contains four standard-radius 90° elbows and two 45 elbows. The resistance of a standard-radius 90° elbow is roughly equivalent to that offered by a pipe whose length is 32 diameters; a 45 elbow, 15 diameters. (An alternative method for calculating losses in fittings is given in 57.5.) Answer: 4.7 103psi = 33 MPa

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Answer 1

Calculate equivalent length for pipe as, Ly L+d(325n) 1234 +0.25(4 x32 +2 x15) -1273.5 m Calculate Reynolds number as, Re = 10' 1.97/(r(0.25/2)2))(0.25) 0.001 Corresponding friction factor from Moody diagram is, f 0.008 Hence, net pressure loss is, 197 (0.25/2) 1273.5 0.25 32.8 MPa