Minor Loss Coefficients, Hazen-Williams Coefficients, and Surface Roughness

Quick links to tables on this page:
Minor Loss Coefficients   Hazen-Williams Coefficients   Surface Roughness

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

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Table of Minor Loss Coefficients (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
180° 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 (C has no units)        To top of page

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
Steel forms 140 Tin 130
Wooden forms 120 Vitrif. clay (good condition) 110-140
Centrifugally spun 135 Wood stave (avg. condition) 120


Table of Surface Roughnesses                             To top of page

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

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