ENGINEERING – PUMP & TURBINE CALCULATOR
Pump Specific Speed
A precise tool.
What is the Pump Specific Speed & How does it work?
Pump specific speed (Ns) is a dimensionless parameter that helps engineers compare the geometric similarity of different pumps regardless of size.
It is derived from the pump’s rotational speed, flow rate, and head, and it indicates the most suitable impeller design for a given application.
By calculating Ns, you can quickly select between radial, axial, or mixed‑flow pumps and assess performance trends across a range of operating conditions.
Ns = N\sqrt{Q} / H^{3/4}
Ns = specific speed (dimensionless)
Parameters
Result
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Frequently Asked Questions
What is pump specific speed used for?
Pump specific speed helps engineers compare different pumps, select appropriate impeller designs, and assess performance trends.
How do I calculate pump specific speed?
Use the formula Ns = N√Q / H^(3/4), where N is rotational speed, Q is flow rate, and H is head.
What does a high pump specific speed indicate?
A high pump specific speed indicates an axial or mixed-flow pump design.
Can I use this calculator for any type of pump?
Yes, it is suitable for various types of pumps, including radial, axial, and mixed-flow pumps.
What units should I use for the inputs?
Use revolutions per minute (RPM) for speed, cubic meters per second (m³/s) for flow rate, and meters (m) for head.
How does pump specific speed affect performance?
It helps in selecting the most efficient impeller design for a given application, influencing overall pump performance.
Is pump specific speed affected by fluid properties?
No, it is a dimensionless parameter and not influenced by fluid properties like density or viscosity.
Results are for informational purposes only and do not constitute professional advice.