### Head Pressure - Fluid Flow

**Fluid Flow Table of Contents**** | Hydraulic and Pneumatic Knowledge
Fluid Power Equipment**

Since the units for all the different forms of energy in
Equation 3-11 are measured in units of distance,
these terms are sometimes referred to as "heads" (pressure head,
velocity head, and elevation head). The term
*head *is used by engineers in reference to pressure. It is a reference
to the height, typically in feet, of a column of
water that a given pressure will support. Each of the
energies possessed by a fluid can be expressed in terms of head.

The elevation head represents the potential energy of a fluid due to its elevation above a reference level. The velocity head represents the kinetic energy of the fluid. It is the height in feet that a flowing fluid would rise in a column if all of its kinetic energy were converted to potential energy. The pressure head represents the flow energy of a column of fluid whose weight is equivalent to the pressure of the fluid.

The sum of the elevation head, velocity head, and pressure head of a fluid is called the totalhead. Thus, Bernoullis equation states that the total head of the fluid is constant.