Pump Characteristic Curve

ENGINEERING – PUMP & TURBINE CALCULATOR Pump Characteristic Curve A precise tool.
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What is the Pump Characteristic Curve & How does it work?
A pump’s characteristic curve describes how the generated head (H) varies with the volumetric flow rate (Q) at a given speed and impeller size. The curve is typically approximated by a quadratic relation because hydraulic losses increase with the square of the flow velocity. For many centrifugal pumps the simplified form
H = H\_{0} – b,Q^{2}
H = head (m) , H\_{0} = shut‑off head (m) , b = curve coefficient (mΒ·hΒ²Β·m⁻⁢) , Q = flow rate (mΒ³/h)
provides a good fit. The coefficient b captures the combined effects of hydraulic losses and system resistance. Once the head at a desired operating flow is known, the required shaft power can be estimated from the energy balance:
P = frac{rho,g,Q,H}{eta,3600}
P = power (kW) , rho = fluid density (kg/mΒ³) , g = 9.81β€―m/sΒ² , eta = pump efficiency (decimal)
. This allows engineers to size motors and evaluate performance under different operating points.
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Parameters
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Frequently Asked Questions
What is a pump characteristic curve?
A pump's characteristic curve shows how the generated head varies with flow rate at a given speed and impeller size.
How is the quadratic relation for pump head calculated?
The formula H = H0 - bQ^2, where H is head (m), H0 is shut-off head (m), b is curve coefficient (m·h²·m⁻⁢), and Q is flow rate (m³/h).
What does the coefficient 'b' represent in the pump characteristic curve?
The coefficient 'b' captures hydraulic losses, which increase with the square of the flow velocity.
Why is a quadratic relation used for pump head calculations?
A quadratic relation is used because hydraulic losses increase with the square of the flow velocity in many centrifugal pumps.
How do changes in flow rate affect the pump head according to this formula?
Changes in flow rate (Q) quadratically affect the pump head (H), as indicated by the term -bQ^2 in the formula.

Results are for informational purposes only and do not constitute professional advice.