Introduction
Composite pump curves in FluidFlow provide powerful visualization tools for understanding how multiple pumps perform together in series or parallel configurations. These curves transform complex performance data into intuitive visual representations, helping engineers predict system behavior, optimize pump combinations, and ensure systems remain efficient across varying flow demands.
Composite pump curves allow you to visualize combined pump performance, predict operation under various scenarios, and select the optimal pump arrangement for your specific application—preventing oversizing and operational inefficiencies before they occur.
Key Benefits
Visualize the combined performance of multiple pumps in one clear chart
Predict system operation under varying process demands
Select the optimal pump arrangement for specific applications
Communicate system capabilities clearly to stakeholders
Troubleshoot performance issues in existing multi-pump systems
Understanding Pump Configurations
Pumps in Parallel
Parallel pump arrangements combine multiple pumps to increase flow capacity while maintaining the same head capability:
Primary benefit: Increased flow capacity at a given head
Ideal applications: Variable flow systems, water distribution networks
Configuration notes: Typically similar pumps, though dissimilar models can be used
Required components: Non-return valves to prevent unwanted circulation
Common examples: Water distribution systems, large building services
Pumps in Series
Series pump arrangements stack multiple pumps to increase head while maintaining the same flow capacity:
Primary benefit: Increased head capability at a given flow
Ideal applications: High-head systems, long-distance transport
Configuration notes: Used when a single pump cannot achieve the required head
Required components: May need bypass lines and non-return valves
Common examples: Long-distance transport of tailings, ash, or concentrates
Creating Composite Pump Curves in FluidFlow
Build your desired pump configuration in your model
Add pumps, piping, and necessary components
Ensure all pumps have appropriate performance data
Access the composite chart tool
Go to Tools → Composite Chart
Configure the composite chart
Open the Parallel and Series Pumping tab
Select operational pumps for inclusion in the analysis
Choose either parallel or series configuration
Generate the composite chart
Click PLOT to create the visualization
Review the resulting chart showing individual and combined performance
Configure the chart to display essential information (composite and individual curves, system curve, duty point) or adjust measurement units
Analyze results
Identify the system operating point (intersection with system curve)
Compare different configurations if needed
Interpreting Composite Pump Charts
A typical FluidFlow composite pump chart displays these key elements:
Individual pump curves – Lighter dashed lines that show each pump's performance capacity
Composite curve – A solid blue line representing the combined pump performance
System curve – A thin black line that represents the overall system resistance
Duty Point – A small triangle indicating the actual operating point where the system and composite pump curves intersect
Parallel Pump Interpretation
For pumps in parallel, the composite curve demonstrates:
Increased flow capacity for a given head value
Flow values add horizontally at any given head point
Series Pump Interpretation
For pumps in series, the composite curve shows:
Increased head capability for a given flow rate
Head values add vertically at any given flow point
Illustrative Example
Parallel Pump Configuration Example
Pumps installed in parallel are typically identical pumps, but there may be applications where dissimilar pumps are used. Consider a system with four pumps in parallel, with three currently operational:
Figure 1. Dissimilar Pumps in Parallel.
Each individual pump contributes to the total flow capacity at a given head
When using dissimilar pumps (different sizes), FluidFlow can generate accurate composite curves for any combination
Figure 2 shows an example with dissimilar pumps (Pump 10 and 11) operating in parallel
Figure 2. Composite Pump Chart – Dissimilar Pumps in Parallel.
The composite curve clearly illustrates how these different-sized pumps perform together in the system
Series Pump Configuration Example
Many pumping applications require fluids to be transported over long distances and against high heads that exceed what a single pump can develop. Examples include pumping tailings, power station ash, underground fill, and concentrates.
When pumps are installed in series, the head values add vertically at any given flow rate
The composite pump chart for pumps installed in series can be plotted in FluidFlow:
Figure 3. Composite Pump Chart – Similar Pumps in Series.
Best Practices
Confirm pump status is On before generating curves
Install non-return valves in parallel setups to prevent circulation issues
Include system curves for clarity on actual operating points
Generate multiple configuration charts to identify optimal arrangements
Analyze the impact of speed changes on composite performance
Common Pitfalls to Avoid When Analyzing with Composite Charts
Ignoring pump interaction in parallel setups, which can lead to unexpected performance
Overlooking variable speed effects when analyzing system performance
Misinterpreting duty points by failing to properly consider system curve intersections
Neglecting efficiency considerations when selecting multi-pump arrangements
Skipping NPSH verification, especially in series configurations where first-stage issues can cascade throughout the system
Integrating Composite Charts into Your Workflow
FluidFlow allows you to make the most of composite pump charts:
In newer versions, composite charts automatically update when you recalculate the model
You can insert the chart directly into your flowsheet using the "Insert in Flowsheet" menu item (in FluidFlow 3.54+)
Charts can be exported for inclusion in reports and presentations
FAQs
Q: Can I mix different pump sizes or types in a composite curve analysis?
A: Yes, FluidFlow supports composite curves for dissimilar pumps in both parallel and series configurations, allowing you to model mixed pump installations accurately.
Q: How do I exclude non-operational pumps from my analysis?
A: Set non-operational pumps to Off or Closed in the Input Editor before generating the composite curve. Only pumps set to "On" and selected from the Composite Chart Setup dialog will be included in the analysis.
Q: Can I analyze variable speed effects on composite pump curves?
A: Yes, adjust pump speed settings in the pump data to see how speed changes affect the composite curve. This is valuable for VFD applications.
Q: How accurate are the curves for dissimilar pumps in parallel?
A: FluidFlow calculates these accurately using hydraulic principles, eliminating the complex manual calculations that would otherwise be required.
Q: Can I create composite curves for pumps with different fluids?
A: Pumps must be handling the same fluid for accurate composite curve generation. Different fluid properties would affect pump performance differently.
Conclusion
FluidFlow's composite pump curves offer powerful visualization tools for understanding how multiple pumps work together in your system. With this feature, engineers can select ideal pump combinations, predict system performance across varying conditions, and communicate design decisions effectively.
Mastering composite pump curves empowers engineers to design more flexible, energy-efficient pumping systems that adapt to changing flow requirements while avoiding costly oversizing or operational problems that often result from inadequate visualization of multiple pump interactions.