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Minor Loss, Hazen-Williams, and Surface Roughness Coefficients

Tables for Pipe Fittings and Pipe Materials

Values compiled from the references listed under Discussion and References for Closed Conduit Flow


Table of Minor Loss Coefficients for Pipe Fittings used in Minor Loss Equation (K has no units)

Fitting K Fitting K
Valves:   Elbows:  
Globe, fully open 10 Regular 90°, flanged 0.3
Angle, fully open 2 Regular 90°, threaded 1.5
Gate, fully open 0.15 Long radius 90°, flanged 0.2
Gate 1/4 closed 0.26 Long radius 90°, threaded 0.7
Gate, 1/2 closed 2.1 Long radius 45°, threaded 0.2
Gate, 3/4 closed 17 Regular 45°, threaded 0.4
Swing check, forward flow 2    
Swing check, backward flow infinity Tees:  
    Line flow, flanged 0.2
180o return bends:   Line flow, threaded 0.9
Flanged 0.2 Branch flow, flanged 1.0
Threaded 1.5 Branch flow, threaded 2.0


Table of Hazen-Williams Coefficients for Hazen-Williams Equation (C has no units)

Material C Material C
Asbestos Cement 140 Copper 130-140
Brass 130-140 Galvanized iron 120
Brick sewer 100 Glass 140
  Cast-Iron:   Lead 130-140
New, unlined 130 Plastic 140-150
10 yr. old 107-113   Steel:  
20 yr. old 89-100 Coal-tar enamel lined 145-150
30 yr. old 75-90 New unlined 140-150
40 yr. old 64-83 Riveted 110
  Concrete/Concrete-lined:      
Steel forms 140 Tin 130
Wooden forms 120 Vitrified clay (good condition) 110-140
Centrifugally spun 135 Wood stave (avg. condition) 120


Table of Surface Roughnesses for Moody Friction Factor

Material Surface Roughness, e
  feet meters
PVC, plastic, glass 0.0 0.0
Commercial Steel or Wrought Iron 1.5x10-4 4.5x10-5
Galvanized Iron 5.0x10-4 1.5x10-4
Cast Iron 8.5x10-4 2.6x10-4
Asphalted Cast Iron 4.0x10-4 1.2x10-4
Riveted Steel 0.003 to 0.03 9.0x10-4 to 9.0x10-3
Drawn Tubing 5.0x10-6 1.5x10-6
Wood Stave 6.0x10-4 to 3.0x10-3 1.8x10-4 to 9.0x10-4
Concrete 0.001 to 0.01 3.0x10-4 to 3.0x10-3

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