The pressure in one point of the network is the sum of energies of dynamic and static pressures. These transformations of energy are reversible or irreversible

the pressure loss is irreversible loss of pressure because the head loss is converted into heat or noise that we do not know re-transformed into pressure.

The pressure generated by changing altitude or height of load (hydrostatic pressure) is reversible: If the duct up of 1 meter, and down of 1 meter, the balance is zero:l:

the pressure generated by the change in velocity (dynamic pressure) is reversible:If for a given flow a converging cone accelerates the fluid the pressure decreases (see Bernoulli), but if another diverging cone, positioned downstream, slows down the fluid to its original speed, the balance of dynamic pressure is zero:

Hydrostatic load pressure and meter fluid column

The height of a column of fluid generates a pressure at its base.

Fluid height (in meters) x density of the fluid (kg/m3) x gravity (9.81) = hydrostatic pressure (in Pascals)

1 meter of water density 1000Kg/m3 =9810 pascals (Newtons/m²)

This pressure is called hydrostatic pressure when to pump and raise the water column.

For sucking a liquid in a duct is created a depression, If the pressure drop of the liquid falls below its saturation vapor pressure,the liquid begins to boil. (Steam production) This phenomenon is called cavitation.This vacuum vaporizing water is achieved when a column of water is sucked, around 10 meters in height, Water vaporizes and releases steam which fills the depression, it is thus impossible to pump more than 8-10 meters deep, by aspirating. It is therefore necessary to pump the fluid outlet and place the pump in the bottom of the well ... see cavitation

Pressure losses (head loss) are often expressed in meters column of fluid:

hydrostatic head interface mecaflux