Use of this Pump Training website is subject to acceptance of the Disclaimer

Welcome to the start of DryMine's Free Online Pump Training. This page has basic Theory and Terminology. Start here then continue with Training, Examples, and if you want, the Quiz. DryMine also offers comprehensive Training Programs to companies for indivduals or groups.




Basic Pump Theory
Pump Terminology
Pump Enquiry Information


Reading Pump Curves
Centrifugal pump Operating Range
System Curves
Pump Parallel / Series Operation
NPSH - Nett Positive Suction Head
Affinity Laws


  1. The impeller spins & throws water out.
    Like swinging a bucket of water above your head and staying dry.

  2. Low pressure is formed in the pump inlet where the water was.
    The lower the pressure, the higher the pump can 'suck*'.

  3. Atmospheric (Air) pressure pushes more water in.
    By acting on the surface of the water supplying the pump.

This force of air pressure moving from high to low pressure explains the workings of :


Vacuum cleaners.
Car spoilers.
All types of pumps.

Drinking with a straw.
Yachts tacking - against the wind.

Experiments on the EXAMPLES page will give you some more information on how water is affected by air pressure.

*Suction is a strange term - as Pumps can't suck.

In fact, nothing 'sucks' - Many things in our world work in the same way, by creating a low pressure area and allowing higher pressure air to apply force to water, air, or an object towards the low pressure area.

See the list at left to see the power and importance of this often forgotten force.

This statement on the 'Theory' of a centrifugal pump is very, very basic, but if this operation can be understood at this level, it is then possible to grasp quite complex concepts later. 


Centrifugal pump curves show 'pressure' as head, which is the equivalent height of water with S.G. = 1 (ie: metre or feet). This makes allowance for specific gravity variations in the pressure to head conversion to cater for higher power requirements. Positive Displacement pumps use pressure (ie; psi or kPa) and then multiply power requirements by the S.G.

The vertical height difference from surface of water source to centreline of impeller is termed as static suction head or suction lift ('suction lift' can also mean total suction head).
The vertical height difference from centreline of impeller to discharge point is termed as discharge static head.
The vertical height difference from surface of water source to discharge point is termed as total static head.

Total height difference (total static head) plus friction losses & 'demand' pressure from nozzles etc. (plus other small head losses ie: velocity head) ie: Total Suction Head plus Total Discharge Head = Total Dynamic Head (TDH).

Specific gravity. weight of liquid in comparison to water at approx 20 deg C (SG = 1).


A number which is the function of pump flow, head, efficiency etc. Not used in day to day pump selection, but very useful to determine the characteristics of a pump relating to efficiency, NPSH, solids handling, if you can start against open / closed valve, etc.
See Fig.1

If the vapour pressure of a liquid is greater than the surrounding air pressure, the liquid will boil.

A measure of a liquid's resistance to flow. ie: how thick it is. The viscosity determines the type of pump used, the speed it can run at, and with gear pumps, the internal clearances required.

The amount of pressure / head required to 'force' liquid through pipe and fittings.

Nett positive suction head - related to how much suction lift a pump can achieve by creating a partial vacuum. Atmospheric pressure then pushes liquid into pump. A method of calculating if the pump will work or not.

cross section of various pumps in order of specific speed


To ensure the correct pump is selected for your application the following details are required. If you can not supply some of the information, we can assist in identifying your requirements.

These details required for all applications:
(*Additional details required if liquid is not water)
Temperature and Duty Cycle (hours operation per day, etc)
Flowrate required (per day / hour /second)
Static suction head (below or above pump)
Footvalve or any other valves in system
Suction pipe length, size & material (or inside diameter)
Static discharge head (below or above pump)
Discharge pipe length, size & material (or inside diameter)
Details of solids that will / may be pumped
Height above sea level if significant
Highest / lowest points in system
Sprinklers or other pressure requirements
Do you require a certain flow in specific areas and less in other areas?
Future expansion plans?, additional requirements, etc

Driver requirements ie:
Electric - voltage/phase/Hz
Electric - hazardous location?
Diesel - preferences
Petrol - preferences
Hydraulic - requirements and preferences

*Additional details if liquid is not water:
Full liquid description
Specific gravity
pH value
Other details or data sheet


This information is not intended as a reference source for the design of pumping or associated systems, but to promote interest and further investigation by individuals and companies into the provision of reliable pumping equipment.

Due to the complexities of pumping systems in various industries and situations, it is not possible to predict the applications encountered, and therefore not possible to apply this information to all circumstances. Much of the information shown is personal opinion and experience gained within limited industries.

DryMine Dewatering Solutions makes no representation or warranty with respect to the completeness or accuracy of the data or information contained herein, and assumes no liability for losses or damages resulting from the use or application of the data or information contained herein.


Use of this Pump Training website is subject to acceptance of the Disclaimer

|    HOME    |    COMPANY    |    PRODUCTS    |    SERVICES    |    CONTACT    |

© 2007 DryMine Dewatering Solutions.