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Chapt06

# 00 1800 1600 1400 1200 k 1000 800 600 400 200 gate

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Unformatted text preview: ere is a factor of 2 spread among the various manufacturers. Note that K in Fig. 6.19b is, as usual, based on the average pipe velocity V Q/A, not on the increased velocity of the flow as it passes through the narrow valve passage. (a) | v v Fig. 6.19 Performance of butterfly valves: (a) typical geometry (courtesy of Grinnell Corp., Cranston, R.I.); (b) loss coefficients for three different manufacturers. | e-Text Main Menu | Textbook Table of Contents | Study Guide 6.7 Minor Losses in Pipe Systems 371 1.00 0.80 0.70 Secondary flow pattern: ε = 0.01 d 0.60 0.50 0.40 0.0 02 0.30 0.0 00 0.20 d = constant K (Note: Resistance due to bend length must be added.) 01 0.0 R 5 0 0.10 0.08 1 1.5 2 Fig. 6.20 Resistance coefficients for 90° bends. 3 4 5 6 7 8 910 R d A bend or curve in a pipe, as in Fig. 6.20, always induces a loss larger than the simple Moody friction loss, due to flow separation at the walls and a swirling secondary flow arising from the centripetal acceleration. The loss coefficients K in Fig. 6.20 are for this additional bend loss. The Moody loss due to the axial length of the bend must be com...
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