Minor Losses

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Minor Losses

The Community Engineer
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This post was updated on .
From the Manual of British Water Engineering Practice


ENTRY LOSSES        | K=v2/2g| l/d |

Sharp-edged entrance | 0.50 | 22 |
Re-entrant entrance | 0.80 | 36 |
Slightly-rounded entrance | 0.25 | 11 |
Bellmouthed entrance | 0.05 | 2 |
Footvalve and strainer | 2.50 | 113 |
--------------------------------------------------------------------
V A L V E S | | |
Gate Valve - fully open | 0.12 | 5 |
Gate Valve - 1/4 closed (25%) | 1.00 | 45 |
Gate Valve - 1/2 closed (50%) | 6.00 | 270 |
Gate Valve - 3/4 closed (75%) | 24.00 | 1080 |
Globe Valve | 10.00 | 450 |
Right angle Valve | 5.00 | 225 |
Reflux Valve | 1.00 | 45 |
Butterfly Valve | 0.30 | 13 |
--------------------------------------------------------------------
INTERMEDIATE LOSSES | | |
E l b o w s ( R/D = « approx ) 22«ø | 0.20 | 9 |
E l b o w s ( R/D = « approx ) 45ø | 0.40 | 18 |
E l b o w s ( R/D = « approx ) 90ø | 1.00 | 45 |
Close Radius Bends ( R/D=1 approx) 22«ø | 0.15 | 7 |
Close Radius Bends ( R/D=1 approx) 45ø | 0.30 | 14 |
Close Radius Bends ( R/D=1 approx) 90ø | 0.75 | 34 |
Long Radius Bends ( R/D = 2 to 7 ) 22«ø | 0.10 | 5 |
Long Radius Bends ( R/D = 2 to 7 ) 45ø | 0.20 | 9 |
Long Radius Bends ( R/D = 2 to 7 ) 90ø | 0.40 | 18 |
S w e e p s ( R/D = 8 to 50) 22«ø | 0.05 | 2 |
S w e e p s ( R/D = 8 to 50) 45ø | 0.10 | 5 |
S w e e p s ( R/D = 8 to 50) 90ø | 0.20 | 9 |
Mitre Elbows - 2 piece 22«ø | 0.15 | 7 |
Mitre Elbows - 2 piece 30ø | 0.20 | 9 |
Mitre Elbows - 2 or 3 piece 45ø | 0.30 | 14 |
Mitre Elbows - 2 piece 60ø | 0.65 | 29 |
Mitre Elbows - 3 piece 60ø | 0.25 | 11 |
Mitre Elbows - 2 piece 90ø | 1.25 | 56 |
Mitre Elbows - 3 piece 90ø | 0.50 | 22 |
Mitre Elbows - 4 piece 90ø | 0.30 | 14 |
--------------------------------------------------------------------
T E E S | | |
Flow in line | 0.35 | 16 |
Line to branch or branch to line : sharp-edged | 1.20 | 36 |
Line to branch or branch to line : radiused | 0.80 | 36 |
Line to branch or branch to line : 30ø angle | 0.40 | 18 |
Line to branch or branch to line : 45ø angle | 0.60 | 27 |
Line to branch or branch to line : 90ø angle | 0.80 | 36 |
--------------------------------------------------------------------
SUDDEN ENLARGEMENTS ( apply to smaller diameter) | | |
Inlet diameter/Outlet diameter 4:5 | 0.15 | 7 |
Inlet diameter/Outlet diameter 3:4 | 0.20 | 9 |
Inlet diameter/Outlet diameter 2:3 | 0.35 | 16 |
Inlet diameter/Outlet diameter 1:2 | 0.60 | 27 |
Inlet diameter/Outlet diameter 1:3 | 0.80 | 36 |
Inlet diameter/Outlet diameter 1:5 and over | 1.00 | 45 |
--------------------------------------------------------------------
SUDDEN CONTRACTIONS ( apply to smaller diameter) | | |
Inlet diameter/Outlet diameter 5:4 | 0.15 | 7 |
Inlet diameter/Outlet diameter 4:3 | 0.20 | 9 |
Inlet diameter/Outlet diameter 3:2 | 0.30 | 14 |
Inlet diameter/Outlet diameter 2:1 | 0.35 | 16 |
Inlet diameter/Outlet diameter 3:1 | 0.45 | 20 |
Inlet diameter/Outlet diameter 5:1 and over | 0.50 | 22 |
--------------------------------------------------------------------
B.S TAPERS ( apply to smaller diameter) | | |
Flow to small end | negligible |
Flow to large end | | |
Inlet diameter/Outlet diameter 4:5 | 0.03 | 1.5 |
Inlet diameter/Outlet diameter 3:4 | 0.04 | 2.0 |
Inlet diameter/Outlet diameter 1:2 | 0.12 | 6.0 |
--------------------------------------------------------------------
E X I T L O S S E S | | |
Sudden Enlargement | 1.00 | 45 |
Bellmouthed Outlet | 0.20 | 9 |