Pipe and Tube System Components - Minor (Dynamic) Loss Coefficients
Minor or dynamic pressure loss in pipe or tube system components can be expressed as
Δ p minor_loss = ξ ρf v2/ 2 (1)
where
Δ p minor_loss = minor pressure loss (Pa (N/m2), psf (lb/ft2) )
ρf = density of fluid (kg/m3, slugs /ft3 )
v = flow velocity (m/s, ft/s)
Minor loss coefficients for commonly used pipe and tube system components:
| Type of Component or Fitting | Minor Loss Coefficient - ξ - |
|---|---|
| Tee, Flanged, Dividing Line Flow | 0.2 |
| Tee, Threaded, Dividing Line Flow | 0.9 |
| Tee, Flanged, Dividing Branched Flow | 1.0 |
| Tee, Threaded, Dividing Branch Flow | 2.0 |
| Union, Threaded | 0.08 |
| Elbow, Flanged Regular 90 o | 0.3 |
| Elbow, Threaded Regular 90 o | 1.5 |
| Elbow, Threaded Regular 45 o | 0.4 |
| Elbow, Flanged Long Radius 90 o | 0.2 |
| Elbow, Threaded Long Radius 90 o | 0.7 |
| Elbow, Flanged Long Radius 45 o | 0.2 |
| Return Bend, Flanged 180 o | 0.2 |
| Return Bend, Threaded 180 o | 1.5 |
| Globe Valve, Fully Open | 10 |
| Angle Valve, Fully Open | 2 |
| Gate Valve, Fully Open | 0.15 |
| Gate Valve, 1/4 Closed | 0.26 |
| Gate Valve, 1/2 Closed | 2.1 |
| Gate Valve, 3/4 Closed | 17 |
| Swing Check Valve, Forward Flow | 2 |
| Ball Valve, Fully Open | 0.05 |
| Ball Valve, 1/3 Closed | 5.5 |
| Ball Valve, 2/3 Closed | 200 |
| Diaphragm Valve, Open | 2.3 |
| Diaphragm Valve, Half Open | 4.3 |
| Diaphragm Valve, 1/4 Open | 21 |
| Water meter | 7 |
Example - Minor Dynamic Pressure Loss in Waterflow a Ball Valve 1/3 Closed
The minor loss a ball valve with flow velocity 2 m/s with water with density 1000 kg/m3 can be calculated as
Δ p minor_loss = (5.5) (1000 kg/m3 ) (2 m/s)2/ 2
= 11000 Pa
= 11 kPa
Related Topics
• Fluid Flow and Pressure Loss in Pipes and Tubes
Fluid flow and pressure loss in pipe lines. Water and sewer systems. Steel pipes, pvc pipes, copper tubes and more.
• Fluid Mechanics
The study of fluids - liquids and gases. Involving velocity, pressure, density and temperature as functions of space and time.
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