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# Centrifugal Pumps - Speed Torque Curve

## The characteristic speed torque curves for centrifugal pumps.

The speed torque curve characterize a centrifugal pump. The theoretical characteristic is a parabola starting from the origin and proportional to the square of the speed.

The torque can be expressed as

T = k n2                                   (1)

where

T = torque (Nm, lbf ft)

k = constant

n = pump speed or velocity (rpm)

With the discharge valve closed the torque amounts to 30 - 50 % of the nominal torque at full speed.

The torque at full load can be calculated as

T = 30 P / (π n)                                  (2)

where

T = torque (kN m)

P = power (kW)

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## Citation

• The Engineering ToolBox (2008). Centrifugal Pumps - Speed Torque Curve . [online] Available at: https://www.engineeringtoolbox.com/pumps-speed-torque-d_1114.html [Accessed Day Month Year].

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9.19.12