Pipe and Tube System Components - Minor (Dynamic) Loss Coefficients

Minor loss coefficients for components used in pipe and tube systems.

Minor or dynamic pressure loss in pipe or tube system components can be expressed as

Δp_{minor_loss} = ξ ρ_f v²/ 2 (1)

where

Δp_{minor_loss} = minor pressure loss (Pa (N/m²), psf (lb/ft²))

ρ_f = 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:

Pipe and Tube System Fittings - Minor (Dynamic) Loss Coefficients
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

The minor loss a ball valve with flow velocity 2 m/s with water with density 1000 kg/m³ can be calculated as

Δp_{minor_loss} = (5.5) (1000 kg/m³) (2 m/s)²/ 2

= 11000 Pa

= 11 kPa