Brake Horse Power

Good old Google

http://www.google.co.uk/search?q=calculating+Horse+Power&sourceid=ie7&rls=com.microsoft:en-US&ie=utf8&oe=utf8&rlz=1I7GPCK_enGB411&redir_esc=&ei=b_4VTZOjCse3hQfatpm3Dg

Happy Christmas

The "brake" bit is used to indicate the actual power drawn by the pump etc. It's based on the brake dynanometer used to measure output power of an engine etc. IMHO it doesn't really add anything to HP. At one time in Europe brake kW (bkW) was used, but I haven't seen that recently, just kW.

It's usual to add a margin to the power drawn by the pump in selecting the rated power of the motor. Also if power drawn is 10 HP at duty point it might be higher at other points on the pump curve, which the motor might need to cover.

Cheers.......Codey