2. Local expense losses

Local head losses are caused by pipe routing accidents (elbows, cones, bypasses, etc.) and by control, monitoring or regulation equipment.

Despite their importance in assessing pipe characteristics, they are difficult to quantify at the outset of the study. They therefore have to be estimated a priori to be included in the calculation, and specified when the project is finalized.

• Calculating local pressure losses

  The general expression for local head losses caused by various fittings and equipment is derived from Torricelli's law:

  $$h=\xi \times U^2\text{/}2g$$