Total head of liquid at any point is the total energy per unit weight of liquid and equal to the summation of pressure head, velocity head and elevation head of liquid. Thus, the total head is
Total head= Pressure head + Velocity head+ Elevation head
2.2.6 Friction head when a liquid flows from one point to another, part of the total energy is lost due to friction between the liquid and the wall and the interaction of the liquid particles. Energy lost due to friction per unit weight of liquid is called friction head or head lost due to friction Friction Head between point I and 2 is