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Brake Horsepower

The power required to drive a centrifugal pump is usually known as the brake horsepower. It can be expressed in terms of the water horsepower divided by efficiency.

brake horsepower

In the metric system, kilowatts (kW) are used. Due to hydraulic, mechanical, and volumetric losses in a pump, the actual or water horsepower available for work on the fluid is less than the total horsepower supplied.

Pump Efficiency

Pump efficiency is the ratio of the water horsepower delivered by the pump and the brake horsepower delivered to the pump shaft. When selecting a pump, a key concern is optimizing pumping efficiency. The energy usage in a pumping installation is determined by the flow required, the height lifted, and the length and friction characteristics of the pipeline. The power required to drive a pump is defined simply using SI units by:

pump efficiency


  • P is the input power required (W)
  • BHP is the brake horsepower
  • ρ is the fluid density (kg/m3 )
  • g is the standard acceleration of gravity (9.81 m/s2 )
  • H is the net pump head added to the flow (m)
  • Q is the flow rate (m3 /s)
  • η is the efficiency of the pump

performace curve - brake horsepower

Reactor Physics and Thermal Hydraulics:
  1. J. R. Lamarsh, Introduction to Nuclear Reactor Theory, 2nd ed., Addison-Wesley, Reading, MA (1983).
  2. J. R. Lamarsh, A. J. Baratta, Introduction to Nuclear Engineering, 3d ed., Prentice-Hall, 2001, ISBN: 0-201-82498-1.
  3. W. M. Stacey, Nuclear Reactor Physics, John Wiley & Sons, 2001, ISBN: 0- 471-39127-1.
  4. Glasstone, Sesonske. Nuclear Reactor Engineering: Reactor Systems Engineering, Springer; 4th edition, 1994, ISBN: 978-0412985317
  5. Todreas Neil E., Kazimi Mujid S. Nuclear Systems Volume I: Thermal Hydraulic Fundamentals, Second Edition. CRC Press; 2 edition, 2012, ISBN: 978-0415802871
  6. Zohuri B., McDaniel P. Thermodynamics in Nuclear Power Plant Systems. Springer; 2015, ISBN: 978-3-319-13419-2
  7. Moran Michal J., Shapiro Howard N. Fundamentals of Engineering Thermodynamics, Fifth Edition, John Wiley & Sons, 2006, ISBN: 978-0-470-03037-0
  8. Kleinstreuer C. Modern Fluid Dynamics. Springer, 2010, ISBN 978-1-4020-8670-0.
  9. U.S. Department of Energy, THERMODYNAMICS, HEAT TRANSFER, AND FLUID FLOW. DOE Fundamentals Handbook, Volume 1, 2, and 3. June 1992.
  10. White Frank M., Fluid Mechanics, McGraw-Hill Education, 7th edition, February, 2010, ISBN: 978-0077422417

See above:

Centrifugal Pumps