Pump Head
Follow us on Twitter 
Question, remark ? Contact us at contact@myengineeringtools.com
| Section summary |
|---|
| 1. Definition |
| 2. Calculation |
| 3. Use |
1. Definition
What is the pump head ?
The pump head is the actual pressure developped by a pump. It is expressed in vertical m of liquid (water for pump characteristics graphs).
The pump head takes into consideration the difference of pressure in between suction and discharge but also the speed difference, all converted to m of liquid.
2. Calculation
How to calculate the pump head ?
Equation 1 : Pump Head
\[ H = \frac{p_d - p_s}{spgr_{4t}} \times 10.2 + \frac{u_d^2 - u_s^2}{2 \times 9.81} \]
With
ps : pressure at suction (bar)
pd : pressure at discharge (bar)
spgr4t : specific gravity of the liquid processed
us : velocity at suction (m/s)
ud : velocity at discharge (m/s)
- The factor 10.2 converts a pressure in bar into metres of water column (1 bar ≈ 10.2 m H₂O at 4 °C).
- For liquids other than water, divide the pressure term by the specific gravity spgr4t relative to water at 4 °C.
- The velocity term is usually small (a few tenths of a metre) and can often be neglected for a first estimate when suction and discharge line sizes are identical.
- Pump head is independent of the liquid density — the same characteristic curve applies to any fluid, only the absorbed power changes.
- Typical centrifugal pump heads: 10–30 m per stage for process pumps; multistage pumps can reach several hundred metres.
- Always check the calculated head against the pump characteristic curve at the required flow rate, and verify NPSH available > NPSH required with margin.
Interactive Pump Head Calculator
3. Use of pump head
Pump head is a key piece of information found on pump characteristic.
Figure 1 : Pump characteristic curve