Selecting an industrial pump involves more than choosing a pump that can move a particular liquid. The pump also needs to deliver the required performance under the operating conditions of the system.
One of the key tools used to understand this performance is the pump curve.
For engineering and maintenance teams, understanding the basic information contained in a pump curve can help when assessing pump selection and system performance.
What Is a Pump Curve?
A pump performance curve is a graphical representation of how a pump is expected to perform under defined conditions.
For a centrifugal pump, one of the principal relationships shown is between flow and head. Rather than providing a single fixed performance figure, the curve demonstrates how the pump's performance changes across a range of operating conditions.
This information helps engineers assess whether a particular pump is suitable for the demands of an application.
Understanding Flow and Head
Flow describes the volume of liquid that needs to be moved over a given period.
Head represents the energy the pump must provide to move that liquid through the system and overcome the resistance it encounters.
These two requirements are connected. For a typical centrifugal pump operating at a fixed speed and impeller diameter, the available head changes as the flow rate changes.
This relationship is one reason why simply selecting a pump based on connection size or a single performance figure is insufficient.
The Importance of the Operating Point
A pump does not operate independently of the system around it.
The characteristics of the piping, valves, fittings and other elements within a system influence the resistance the pump must overcome. The interaction between the pump's performance characteristics and the requirements of the system determines the operating point.
Changes to the system can therefore affect where the pump operates.
For example, modifications to pipework or process requirements can mean that a pump originally selected for one set of conditions is subsequently required to operate under another.
Efficiency and Pump Selection
Pump curves may also provide information about efficiency across the operating range.
A pump should be selected with consideration for the conditions under which it will actually operate, rather than simply whether it can achieve the maximum required flow or head.
Other information supplied by a pump manufacturer may include power requirements and Net Positive Suction Head Required (NPSHr), depending on the pump and documentation provided.
All of these factors contribute to assessing whether a pump is appropriate for a particular application.
Why Pump Curves Matter During Maintenance
Pump curves are not relevant only when new equipment is being selected.
They can also provide useful context when investigating changes in pump or system performance. If process requirements have changed, understanding the intended operating characteristics of the pump can help determine whether it remains suitable for the application.
This reinforces the importance of considering the entire pumping system when troubleshooting performance problems.
Selecting Pumps for the Application
No single pump is suitable for every industrial application. Flow, head, fluid characteristics, materials, operating environment and process requirements all need to be considered.
Henry R Ayton supplies industrial pumps as part of its wider range of engineering products and services and works closely with customers to deliver solutions suited to specific requirements.
If you require assistance with pump supply or refurbishment, contact the Henry R Ayton team to discuss your application:
Cork: +353 21 4853000
Dublin: +353 1 4517922
Belfast: +44(0)28 9061 8511
Email: sales@hrayton.com
