How to Calculate Total Head of Pump?

Short tutorial on how to calculate Total dynamic head of industrical pumps.

Total Dynamic Head of Pumps Calculation

The Pump Head (Hydraulic head or piezometric head) is a specific measurement of liquid pressure above a specific point. It is the height to which a pump can raise the water / fluid up. It is the measure of the potential of fluid at the measurement point. In this short tutorial, let us discuss on how to calculate total head of pump explained in simple step by step procedure.

Head is one of the concepts of fluid dynamics, expressed in units of height such as meters or feet, which relates the energy in an incompressible fluid to the height of an equivalent static column of that fluid. Head is independent of the type of liquid pumped as long as the viscosity is low and similar to water.

Pump head calculation uses Bernoullis Principle, which states that the total energy at a given point in a fluid depends upon the energy of movement of the fluid, plus energy from static pressure in the fluid, plus energy from the height of the fluid relative to a specific data.

Static head and friction head are the two major components to calculate the Total Dynamic Head (TDH) of Pumps When you increase the total static head the flow decreases. If you decrease the discharge static head, the flow increases.

Total Dynamic Head of Pumps Calculation:

Total Head:
The total dynamic head (TDH) in and out of a pump is calculated using the below four types of heads:
Velocity head - due to movement of fluid (kinetic energy)
Elevation head - due to the fluids weight (gravitational force)
Pressure head - due to the static pressure (static energy).
Resistance Head (Head Loss) - due to forces acting against the fluids motion by container (Friction).

Total head is obtained by subtracting the suction head from the discharge head, which is given as:

Total Head (H_^T) = H_^d - h_^s

Velocity Head:
Velocity Head represents the energy of the flowing fluid due to its bulk motion. It is expressed as a length measurement. It is given as:

h_v = v²/2g

where,
v is the velocity of fluid
g is the acceleration due to gravity

Head for incompressible fluids:
For incompressible fluids, hydraulic head is composed of pressure head and elevation head.

Total Hydraulic Head (h) = H_p + H_e

Where,
H_p is the pressure head
H_e is the elevation head

The pressure head is the gauge pressure of liquid at the base of the piezometer, and the elevation head is the relative potential energy of the fluid in terms of an elevation. The hydraulic head is also known as the Piezometric head and it is measured as length in m or ft.

Thus, the total head of pump is calculated easily.

Related Topics