Measured [[Minor Losses]] are usually given as a ratio of head loss to velocity head $K= \frac{\Delta p}{\frac{1}{2}\rho v^2}$ It is dimensionless. $v$ is the average upstream velocity Some typical contraction and expansion loss coefficients | Transition | Contraction | Expansion | | ---------- | ----------- | --------- | | Gradual | 0.1 | 0.3 | | Abrupt | 0.6 | 0.8 | Loss coefficient for : - [[Sudden Expansion or Contraction]] - [[Gradual Expansion or Contractions]]