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

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

ξ = minor loss coefficient

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 can also be expressed as head water column - mm H2O or inches H2O

Minor loss coefficients for commonly used pipe and tube system components:

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

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

= 11000 Pa

= 11 kPa